BlueSci Issue 51 - Easter 2021

Easter 2021 Issue 51 www.bluesci.co.uk

Cambridge University science magazine

FOCUS

Rivers: Arteries of the Earth

Visualising Science . Whale Telemetry Animal Magnetism . Earthquakes

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Cambridge University science magazine

Contents Regulars

Features 6

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On The Cover News Reviews

Animal Magnetism

Susanne Mesoy investigates the mechanisms of magnetoreception

FOCUS

Remote Sensing: the Key to Reducing Seismic Hazard?

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Natalie Forrest discusses how satelite data can shed light on seismic processes

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Collapsing Ecosystems and Melting Permafrost in a Warming World

Mahlaqua Noor examines the effects of climate change on permafrost ecosystems

Synchrotron Science

Fran Seymour investigates the creation of synchrotron light in accelerators

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ARTERIES OF THE EARTH: WHY RIVERS RUN EVERYTHING Will Knapp and Seán Thor Herron

Whale Tracking Technology

Hazel Walker takes a deep dive into the world of cetacean tracking

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Pavilion: Seeing the Supernatural?

Grace Exley explores how photography helped to expose a war-time witch

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To See in a New Light

Xavior Wang discusses optical technologies of the past, present, and future 26

Geology Rocks!

Juliane Borchert explores the history of the Sedgwick Museum

BlueSci was established in 2004 to provide a student forum for science communication. As the longest running science magazine in Cambridge, BlueSci publishes the best science writing from across the University each term. We combine high quality writing with stunning images to provide fascinating yet accessible science to everyone.

But BlueSci does not stop there. At www.bluesci.co.uk, we have extra articles, regular news stories, podcasts and science films to inform and entertain between print issues. Produced entirely by members of the University, the diversity of expertise and talent combine to produce a unique science experience

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Visualising Science

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The Ties that Bind the Mind

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Weird and Wonderful

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Bethan Clark tackles the problems and pitfalls of data visualisation

Tom Wilkins discusses cultural limitations of thought

Is Seeing Truly Believing?

Being Baby-Faced How to Avoid Being Seen

President: Leia Judge ...................................................................................... president@bluesci.co.uk Managing Editor: Sarah Lindsay..................................................

Lindsay........................................................managing-editor@bluesci.co.uk ......managing-editor@bluesci.co.uk Secretary: Tanvi Acharya.................................................................................

Acharya.................................................................................enquiries@bluesci.co.uk enquiries@bluesci.co.uk Finance Officers: Juliana Cudini & Kate O’Flaherty.....................................finance@bluesci.co.uk Film Editors: Tanjakin Fu, Roxy Francombe ........................................................ film@bluesci.co.uk Podcast Editors: Ruby Coates & Simone Eizagirre.....................................podcast@bluesci.co.uk News Editors: Zak Lakota-Baldwin & Adiyant Lamba .................................... ....................................news@bluesci.co.uk news@bluesci.co.uk Webmaster: Clifford Sia.............................................................................webmaster@bluesci.co.uk Communications Officer: Emma Soh........................

Soh........................... ....................communications@bluesci.co.uk .................communications@bluesci.co.uk Art Editor: Pauline Kerekes.........................................................................art-editor@bluesci.co.uk

Contents

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Issue 51: Easter 2021 Issue Editor: Lizzie Knight Managing Editor: Sarah Lindsay First Editors: Ruby Coates, Jessica Corry, William Guo Shi Yu, Lucy Hart, Kate Howlett, Ernestine Hui, Swastika Issar, Liam Ives, Miriam Lisci, Andrew Smith, Anna Townley, Adriana Wolf Perez, Amber Wright, Charlotte Zemmel Second editors: Gesa Dünnweber,William Guo Shi Yu, Ernestine Hui, Swastika Issar, Daniel Lim, Miriam Lisci, Susanne Mesoy, Fran Seymour, Julie Tang,Yimian Tang, Rebecca Wang, Georgina Withers, Alea Yang Art Editor: Pauline Kerekes News Team: Zak Lakota-Baldwin, Adiyant Lamba, James Lee, Lauren Lee Reviews: William Guo Shi Yu, Sarah Lindsay, Ellie Wilding Feature Writers: Juliane Borchert, Bethan Clark, Natalie Forrest, Susanne Mesoy, Mahlaqua Noor, Fran Seymour, Hazel Walker, Xavior Wang,Tom Wilkens Focus Team: Seán Thor Herron & Will Knapp Pavilion: Grace Exley Weird and Wonderful: Mirlinda Ademi, Hannah Lin, Sona Popat Production Team: Leia Judge, Lizzie Knight, Sarah Lindsay Caption Writer: Leia Judge, Lizzie Knight, Sarah Lindsay Copy Editors: Leia Judge, Lizzie Knight, Sarah Lindsay, Hazel Walker Illustrators: Bethan Clark, Debbie Ho, Mary Holmes, Mariadaria Ianni-Ravn, Josh Langfield, Rianna Man, Clara Munger, Eva Pillai, Rosanna Rann, Pedro Riera Cover Image: Biliana Tchavdarova Todorova

Observing the Earth AFTER A YEAR of working from home, many of us have found that our world has shrunk. Confined to our houses, tracing the same streets on our daily walks, COVID-19 has made it easy to lose perspective. In the 51st issue of BlueSci, we invite readers to leave their bubble and join us as we explore the ways in which scientists, citizens, animals, and even microorganisms 'observe the Earth'. Dive into the ocean to learn how soundwaves are used to track whales, lose yourself in the magical world of magnetoreception, and meander through Earth’s history as we discover how rivers have evolved through time and continue to shape human civilization.

In the first half of the magazine, we begin by observing the Earth on both micro and macro scales. Natalie Forrest introduces us to the remote sensing technologies which allow scientists to study earthquakes on the other side of the world, whilst also discussing the limits of earthquake forecasting. Susanne Mesoy explores the mechanisms of magnetoreception, investigating how organisms can detect the Earth’s invisible magnetic field.

We zoom into the atomic realm as Francesca Seymour explains how synchrotron light is created and its uses in probing nano-scale structures. We then travel to colder climes as Mahlaqua Noor examines the links between climate change, permafrost, and ecosystem collapse. The section finishes with Hazel Walker taking a deep dive into the whale tracking technologies which aid conservation efforts within the Earth’s increasingly busy oceans.

In this issue’s FOCUS piece, Seán Thor Herron and Will Knapp take us on a journey — through deep time to the present — to explore how rivers have shaped both our planet and our communities. They investigate how scientists study ancient and modern rivers, and discuss the interplay between the mighty Mekong River, industry, and communities in southeast Asia. BlueSci then turns its attention to the supernatural domain in the Pavilion piece, as Grace Exley explains how photography helped to reveal the true nature of Scottish psychic medium, Helen Duncan.

Our ability to observe the Earth would be greatly hindered if not for the development of optical instruments like the microscope and the telescope. Xavior Wang begins the second half of the magazine with a brief history of these technologies and also discusses how the recent discovery of gravitational waves might herald a new era of 'gravitational optics'. Although most museums sadly remain closed to the public, Juliane Borchert takes us on a trip through the Sedgwick Museum’s collection and discusses its links to the ever-changing field of geology. The COVID-19 pandemic has shown us that data presentation is a critical resource when it comes to communicating with the public, but is not without its flaws, and so Bethan Clark explores how different methods of data visualisation can influence our interpretation of scientific results. The section finishes with a philosophical piece from Tom Wilkins, who discusses how our personal observations of nature can be limited by cultural and societal frameworks.

Now more than ever, it’s important that we take a step back and consider the bigger picture.

I hope that this issue can offer some fresh perspective on the ways we observe and interact with the world around us, and perhaps inspire us to open our eyes and broaden our horizons once again Lizzie Knight Issue Editor #51

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License (unless marked by a ©, in which case the copyright remains with the original rights holder). To view a copy of this license, visit http://creativecommons.org/licenses/ by-nc-nd/3.0/ or send a letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA.

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Editorial

Easter 2021

On the Cover I strove to incorporate many of the natural themes featured in the issue in this landscape, complete with diligent little scientists and their tools of observation; in this way, we can all ‘observe the Earth’ when we peruse the cover. On the lower right is a nod to our FOCUS article on rivers as the arteries of the Earth — I hoped to create a branching similar to that of blood vessels, with stripes of burgundy and blue somewhat reminiscent of the red-and-blue lines of arteries and veins in anatomical diagrams. Other nods include the falling rocks, triggered by the earthquakes you can read about in this issue. Luckily, none of the little scientists are in danger of being crushed — or, indeed, infected by pathogens from the melting glaciers. I hope they provide a sobering sense of scale in this oddly proportioned landscape. Finally, we also see a whale come to say hello and thanks for reading the issue!

Biliana Tchavdarova Todorova Cover Artist

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On the Cover

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News

Check out www.bluesci.co.uk, our Facebook page, or @BlueSci on Twitter for regular science news and updates

A Giant Vortex of Liquid Light

How Much Sugar is in That Drink?

FROM GIGANTIC whirlpools to milk in coffee, the idea of a liquid vortex is familiar to many. Less known is the fact that these structures of circulating fluid can also be seen in ‘quantum fluids’, which are fluids that exhibit quantum mechanical properties (e.g. wave-particle duality or the quantization of energy). However, the task of forming large and stable quantum fluid vortices has previously been met with great difficulty. Now, a study from Samuel Alperin and Professor Natalia Berloff at the University of Cambridge has shown theoretically that such giant structures can stabilise in quantum fluids. The results are useful in understanding quantum dynamics but can also be extrapolated to understanding the nature of black holes, which behave similarly to quantum vortices.

For making the ‘quantum fluid’, the researchers used a quantum hybrid of light and matter, called a polariton.

Polariton fluids are constantly expelling light and need fresh light stimulation to survive, making them dynamic and unable to settle. This dynamic property of the quantum fluid was exploited by researchers in their theoretical model for the vortex: by having the light stimulation as a ring around the liquid (rather than directly on the particles), the inward ‘drain’ of light into the system causes the vortex to form.

However, the researchers highlight that this work represents just the beginning for understanding giant quantum vortices, as the properties of such structures need to be further investigated. AL

OBESITY IS a national problem in the United Kingdom, which has some of the worst rates in Europe. In 2019-20 a record 21% of Year 6 children were classed as obese, while in the year previous the rate in adults was 28%, more than 1 in 4.

To help combat this problem, a tax on sugar in soft drinks was introduced, set at 24 or 18 pence per litre, depending on sugar content. While the volume of soft drinks purchased did not change between 2018 and 2019, the year following the introduction on the levy, a recent study found that the amount of sugar in those drinks was 30 g lower per household per week. This represents at 10% reduction in the amount of sugar purchased by households through soft drinks.

The research was led by a team from Cambridge’s Centre for Diet and Activity Research (CEDAR). Dr David Pell, the study’s first author, said, ‘A 10% drop in the amount of sugar purchased from soft drinks might sound modest, but… cutting out even a relatively small amount of sugar should have important impacts on the number of people with obesity and diabetes’.

This result represents a win for not only public health but also the beverage industry itself, since volume of soft drinks sold did not change — a key consideration when looking for business support for new health policy. While obesity rates are still high, this research represents a step towards addressing major health issues, including the growing spectre of childhood obesity. JL

Tracing the Evolution of Antibiotic Resistance THE COMMENSAL gut bacterium Enterococcus faecalis is commonly found in hospitals and can cause life-threatening infections in immunocompromised patients. Antibiotic resistance is common in this species, with over 18% of isolates studied harbouring antibiotic resistance genes.

In a recent study published in Nature Communications, scientists from Wellcome Sanger Institute, University of Oslo, and University of Cambridge collaborated to elucidate the evolution of E. faecalis. To understand how human behaviours, agriculture, and medicines have influenced the development of different strains of the bacterium, the researchers sequenced the genomes of 2027 bacterial isolates from clinical and non-clinical sources ranging from the pre-antibiotic era in 1936 to 2018.

Sequencing the bacterial genomes revealed broad genetic similarities between isolates collected from humans, wild birds, farm animals, and the environment. The genetic similarity between isolates from different environments indicates that these bacteria are ecological generalists with relatively little adaptation to different host species.

The researchers found that 18% of the isolates possessed antibiotic resistance genes, with 54% collected from hospital patients.

Sequencing of isolates collected between 1940–1985 revealed acquired antibiotic resistance genes as early as 1960. Antibiotic resistance was also common in isolates collected from wild birds, likely reflecting the spread of antibiotic resistant strains across host species. These data highlight the urgent need for better screening programmes to prevent further spread of untreatable bacterial strains. LL Artwork by Josh Langfield

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News

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Reviews Kiss the Ground A STAR-STUDDED documentary narrated by Woody Harrelson, ‘Kiss the Ground’ optimistically explores the potential climate crisis solution beneath our feet: soil. Viewers are taken on a journey from the dawn of common (and polluting) agricultural practices to how future farming can address the climate crisis. This documentary’s basis is illustrated by a poignant projection of the atmospheric carbon heat map overlaid onto the Earth’s surface.

Using occasionally scaremongering imagery, Harrelson described the erosion and desertification that are decimating our food supplies, before directing the viewers to the proposed solution: regenerative agriculture. Interviewees, from scientists to celebrities, call for focus to be brought to soil health and restoration. Aside from the slightly nebulous ‘healing the Earth’ language, the evidence was clearly communicated.

Despite being recently produced, this film fundamentally lacked diversity in all forms. It focused intensely on the US agricultural system and on US farmers pushing for regenerative agriculture. This included American farmers showing small rural communities in other countries how to do agriculture ‘better’. I felt that there was far more to learn from traditional practices than this documentary cared to explore. However, on the whole, it was a rare and freshly optimistic film about the climate crisis, which provided some real hope for the future. EW

Southern Reach Trilogy IN JEFF VanderMeer’s Southern Reach Trilogy, ‘alien’ is not so much extra-terrestrial as it is the staunch refusal to abide by human logic. The series (on which the 2018 film Annihilation is based) takes place in Area X, a vast landscape in the southern United States that has been transformed by an inexplicable environmental change. In this pristine rampant wilderness, nature is too alive. For the protagonists, aptly named ‘the biologist’ and ‘Control’, danger comes not as predictable blood-thirsty monsters, but as disconcerting phenomena of nature. These range from waves full of eyes to word-forming bioluminescent fungi and they haunt the protagonists throughout their separate approaches to explain Area X’s existence.

On a deeper level, VanderMeer describes a fundamental clash between two forces: the all too human desire to comprehend the world from a human perspective and an alien entity that simply refuses to abide by mankind’s rules.

Using dialogue that obfuscates and denying readers even the simple comforts of familiar character names, VanderMeer asks the question: Are we ‘the biologist’, willing to accept the frustrating reality of a world beyond our comprehension; or are we ‘Control’, clinging on to our fragile sense of humanity until the end? WG

Nature Live Online, Natural History Museum NATURE LIVE Online — bringing science to your home.

Every Tuesday, the Natural History Museum hosts a live interactive chat with different scientists who work through collections in the museum. Voyage to volcanic sites, become immersed in the world of insects, or travel back in time to visit the dinosaurs. There is certainly something for everyone.

Being structured as a Q&A as opposed to a lecture, the topics are accessible to adults and curious children alike. The audience is encouraged to ask questions, with the host facilitating discussion with follow-up questions. The live elements provide an engaging discussion whilst involving the technical difficulties we have all grown to love — or tolerate — over the past year of video calls. However, this is not a show and tell talk and the relevant images are few and far between.

It would be better if images or videos from the collections are used liberally so as to both communicate the science more effectively and to allow the audience to experience the museum from their homes.

Hopefully, these talks will continue in person in the not-too-distant future, but for now, travelling to London is not essential to enjoy the science behind the fascinating collections at the Natural History Museum. SL

Artwork by Biliana Tchavdarova Todorova Easter 2021

Reviews

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Animal Magnetism Susanne Mesoy investigates the mechanisms of magnetoreception AS SPRING takes hold, I enjoy the warmth of sunlight on my skin, the sound of birdsong, and the fresh scent of grass outside. But I am entirely insensible to an enormous grid of energy that runs right through me on its path between the poles: the Earth’s magnetic field. Many mammals, birds, fishes, insects, plants, and even some bacteria can detect the Earth’s magnetic field. It is clear how this sense serves migratory species like birds and fish, though the advantage for plants is less obvious. Exactly how it works though, is widely debated. Determining the mechanisms of natural magnetoreception would not only increase our understanding of animal physiology and behaviour, but also pave the way for technological advances from the laboratory to the clinic: possible applications include biological manufacture of extremely precise magnets, and the development of noninvasive tools to monitor and control cells in the human body.

Challenges of Magnetoreception | The Earth’s magnetic field strength is about 20-60 microtesla (less than 100 times the strength of a fridge magnet). The energy of a molecule interacting with this field is less than a millionth of its thermal energy at body temperature, and therefore far too small to affect normal chemical reactions. Even if the Earth’s field were stronger, most biological tissue is unaffected by magnetic fields, and so cannot detect them at all. This makes potential magnetosensory organs almost impossible to find, as they could be distributed throughout an animal’s body, rather than being restricted to the surface. To detect the tiny signal of the Earth’s magnetic field, an organism must either have hypersensitive detectors, be able to amplify the signal, or somehow circumvent the noise of thermal energy in the body.

Three main mechanisms have been proposed for biological magnetoreception, each answering to one of these conditions.

The first one has been observed in some marine animals, the second in bacteria, and the third has never been proven, but is theoretically appealing, and the hunt is on as we speak.

Delicate Detectors | As some of us may remember from high school physics, a conductive wire moving through a magnetic field induces a current in that wire. Sharks and rays (together termed ‘elasmobranchs’), among others, exploit this principle to build exquisitely sensitive organs capable of picking up the tiny signal of the Earth’s magnetic field. These organs consist of hundreds of long tubes running from tiny skin pores into their body, filled with a conductive jelly. These act as wires, and at the end of each are the ‘ampullae of Lorenzini’ — collections of cells sensitive to voltage changes. These tubes are sufficiently sensitive to detect the voltage generated by a shark swimming through the Earth’s magnetic field, but that 6

Animal Magnetism

alone is insufficient for functional magnetoreception. One complication is that swimming forward would generate a DC current (electrons flowing one way) in these jelly tubes, but elasmobranch electroreceptors can only detect AC currents (where electrons flow back and forth). They might solve this by swaying their heads back and forth as they swim, thereby reversing the electron flow at every head turn, to generate AC currents. This might also filter out noise from ocean currents (which are also fundamentally conductive ‘wires’ moving through a magnetic field). To test these theories, scientists stuck small magnets (and nonmagnetic brass as a control) up the noses of captive rays, which gave some indications to the nature of their magnetoreception but was not definitively conclusive; as one review (Johnsen and Lohmann, 2008) sardonically noted, ‘sharks and rays are not ideal experimental animals’. Regardless, this mechanism is unworkable for most magnetoreceptive insects and animals, as it would require internal organs filled with conductive liquid that have not yet been observed outside marine animals.

Strengthened Signals | Phytoplankton and bacteria have gone another way, building signal amplifiers that augment the Earth’s field strength. These amplifiers consist of chains of magnetic material (magnetite or greigite) that amplify the Earth’s magnetic field until it’s large enough to rotate the entire organism. The individual ‘magnets’ must be about 0.1–1 µm in diameter to fulfil their purpose, but one magnet that size cannot amplify the Earth’s field sufficiently: hence daisychains of exquisitely-sized magnetic particles. There are also reports of microbes acquiring magnetoreception by consuming magnetoreceptive bacteria, and of sustainable symbioses between magnetoreceptive bacteria and unicellular flagellates.

Could this mechanism be used by insects and larger animals?

While magnetite has been detected in many magnetoreceptive species, including honeybees, salmon, sea turtles, and some birds, specific magnetoreceptors have so far only been conclusively found in microorganisms. The discovery of these ‘mini-magnets’ in animals would be extremely technically challenging, if they do exist: they are too small to be seen with light microscopy, are dissolved by many common tissue preservatives, and their constituent iron is commonly found outdoors, in labs, and in organs.

Creative Chemistry | The final option for sensing the Earth’s magnetic field is so far only theoretical, but the circumstantial evidence is undeniably attractive. The theory is this: when two transient radicals (atoms or molecules with an unpaired outer electron) are created at the same time, the spins of the two electrons are correlated. The chemical properties of these kinds Easter 2021

of radicals are strongly affected by magnetic fields, and largely insensitive to ambient temperature. This is an exceptional workaround to the problem of detecting a weak magnetic signal amidst the energetic noise of the body. Now this kind of a reaction would only detect the axis of a magnetic field, not its polarity.

Intriguingly, most magnetosensory animals tested seem to be insensitive to field polarity, often simply defining ‘polewards’ as the direction which gives the smallest angle between the field and Earth’s surface.

The exceptions shown to detect field polarity include lobsters, salamanders, and mole rats.

Now the hunt is on for radical pair formation in animals with magnetoreception senses.

Cryptochromes, proteins involved in timing and biological rhythms in plants and animals, were the first vertebrate pigments shown to generate radical pairs, though only when exposed to blue light. Surprisingly, some of the best evidence for cryptochrome function in magnetoreception comes from plants. Plants grown in 500 microtesla magnetic fields grow much more slowly than plants grown in

50 microtesla magnetic fields – but only under blue light. When grown in the dark or under red light, these plants all grow at the same speed. In addition, when the gene for this cryptochrome was removed, the effect of the magnetic field vanished, proving that cryptochromes are required for plants to react to magnetic fields.

In birds and mammals, however, the search for magnetoreceptors has been more inconclusive – including an interlude where it was suggested that birds’ magnetic compasses were located only in the right eye, and not the left (it has now been proven to exist in both). Determining the mechanisms of animal magnetoreception remains a key goal not only for understanding the natural world around us, but also as potential blueprints to new inventions.

Already scientists are working to apply the lessons learned from magnetotactic bacteria to building tools to monitor and control cell fate with microscopic magnets. How much more might not be learned from finally determining the basis for exquisitely sensitive animal magnetoreception?

“Determining the mechanisms of animal magnetoreception remains a key goal not only for understanding the natural world around us, but also as potential blueprints to new inventions”

Susanne is a fourth year PhD student at Girton College studying Biochemistry. Artwork by Debbie Ho.

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Animal Magnetism

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Remote Sensing: the Key to Reducing Seismic Hazard?

Natalie Forrest discusses how satellite data can shed light on seismic processes IT IS A common misconception that seismologists can predict earthquakes. In the Italian town of L'Aquila in 2009, following a magnitude 4 earthquake, a group of government-appointed scientists claimed that there was a low probability of a larger earthquake occurring.

Miscommunication with local politicians led to newspaper headlines stating that there was ‘no danger’.

Only a week later, a magnitude 6 earthquake occurred in the middle of the night, killing 29 people. Public outcry led to seven of the scientists being convicted of manslaughter in 2012. The justification: that they communicated the earthquake hazard ineffectively and didn’t tell residents to leave their houses. An appeal was successful in 2014 after scientists across the world highlighted the limits of science's ability to predict earthquakes. This case study demonstrates the importance of clear scientific communication, which ensures that citizens are well-informed of any potential seismic hazard, but are also aware of the uncertainties.

Due to our limited knowledge of previous events and plate motions, the exact time and place of earthquakes cannot be predicted. Scientists can only make educated guesses as to where the next big one will be. This is because it is not possible to directly look into the Earth to measure forces building up, nor measure frictional properties of the fault planes where earthquakes are hosted. During my MSci research in the Cambridge Department of Earth Sciences, I have explored how remote sensing techniques can elucidate the nature of earthquakes.

How Does Remote Sensing Improve Seismic Hazard? | In general, the largest and most common earthquakes occur where two major plates grind past each other. In 2011, the magnitude 9 Tohoku-Oki earthquake in Japan, wellknown for the resulting tsunami and Fukushima nuclear disaster, occurred as the Pacific Plate subducts under Japan. Whereas, intraplate earthquakes occur on weak fault planes within the large plates, away from major boundaries. Stresses slowly build-up on these fault planes over time, due to immense forces at plate boundaries.

These are then released in smaller magnitude earthquakes, when a critical breaking stress is reached.

Technological advances mean that orbiting satellites can now measure deformations of the surface of the Earth with unprecedented detail. Synthetic Aperture Radar

8 Remote Sensing: the Key to Reducing Seismic Hazard?

Interferometry (InSAR) can show how a fault plane ruptured at the surface with millimetre-scale accuracy, as well as estimate how the fault moved at depth. In addition, the Global Positioning System (GPS) shows how a large region is deforming in response to tectonic forces, including estimating the strain accumulating on individual faults. High resolution Digital Elevation Models (DEMs) and satellite images allow large faults to be remotely located in the landscape. These data can be interpreted to create better forecasts of where the deadliest earthquakes are likely to occur in tectonic settings around the world. With this information, scientists can create more accurate seismic hazard maps, inform policymakers on where the strictest building regulations should be, and how the public should take precautions for a large earthquake.

Investigating the Mochiyama Fault From the Other Side of the World | On a smaller scale, my research investigates fault behaviour. I focus on the intraplate Mochiyama Fault in Japan, which intriguingly ruptured twice in an extremely short period of time: firstly a magnitude 6 earthquake in March 2011, and then another magnitude 6 event in December 2016. I estimated the maximum stress that may have built up on the Mochiyama Fault from 2011 to 2016 using InSAR, GPS and microseismicity data, and modelling simple fault plane processes. I found that the stress built up over this time was less than half the magnitude of that which caused the initial earthquake. This makes it unlikely that the fault reached the same critical breaking stress as before, suggesting that the fault somehow became weaker over time.

‘I think the most important outcome from your work is that the yield strength of the Mochiyama fault may have decreased between the two earthquakes. This would be one of the first inferences that a fault has changed strength over the time-scale of a few years,’ Dr Sam Wimpenny, my MSci project supervisor, writes to me. Many seismic hazard models assume that strain accumulates slowly on faults, and that the repeat time between them is on the order of hundreds of years. My unique case study suggests an alternative; that faults can rupture again only a few years after a previous major event. My research demonstrates how increased accuracy of remote sensing techniques increases our understanding of fundamental processes occurring on fault planes.

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Limits of Remote Sensing in Reducing Seismic Risk | Space-based monitoring is biased towards seismic activity which occurs on land. This is primarily due to the difficulties of installing permanent seismic and GPS stations on the seafloor, and transmitting signals through the dense medium of water. This issue is starting to be resolved with new technologies, such as underwater GPS. A group of scientists in New Zealand have been using modern equipment to characterise how the large offshore faults move in earthquakes, which is key to understanding how tsunamis form. This is particularly important following the 2011 Tohoku earthquake, because the tsunami defences along the coast of Japan were insufficient, as demonstrated by the Fukushima nuclear disaster. With better characterisation of how these faults move, the immense potential for loss and damage in future massive tsunamis across the world can be greatly reduced through preparation strategies.

The fastest deforming regions, where surface deformation is easiest to measure with satellites, are usually the areas which experience large earthquakes anyway. This leads to a well-prepared population, such as in Japan or California. In contrast, the Alpine-Himalayan mountain range is a widelydeforming region, and can host large earthquakes across a broad area. These earthquakes occur much less often, meaning the population is often less prepared. An example of this is the devastating magnitude 6.5 earthquake in 2003, in the historic city of Bam, Iran. Historic mud-brick buildings

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collapsed, causing over 25,000 deaths as the city slept. The earthquake occurred on an unknown fault with no obvious expression in the landscape.

This is because the repeat time of earthquakes on this fault is likely to be much longer than erosional processes occurring in the region. In addition, the GPS strain measured in this area would likely be very small, in comparison to Japan, and therefore it would be difficult to suggest whether enough stress has accumulated on a fault plane in order for it to rupture.

What Can We Do to Reduce Seismic Risk? | A great deal of work is put into finding which faults have the greatest probability of breaking in devastating earthquakes. That research is often well-communicated through seismic hazard maps.

Armed with this knowledge, local governments and residents should take necessary precautions to protect themselves and prevent widespread damage.

Investment should be made to ensure all buildings are prepared for substantial shaking. My research into the short recurrence time between the two earthquakes in Japan has demonstrated the unpredictability of large earthquakes. There is only so much that earthquake science, through both remote sensing and field-based techniques, can tell us about how to reduce seismic risk. The impact of earthquakes is well-known, and focus should always be on preparation rather than short-term prediction Natalie Forrest is a fourth year undergraduate student at Corpus Christi College studying Earth Sciences. Artwork by Rianna Man.

Remote Sensing: the Key to Reducing Seismic Hazard? 9

Collapsing Ecosystems and Melting Permafrost in a Warming World: Is This the Future We Choose?

Mahlaqua Noor discusses the effect of climate change on permafrost ecosystems ONE OF MY fondest childhood memories is my annual trips to my ancestral village in Pakistan. The lush wheat farms that seem to span across eternity drew me in. I would accompany my uncle on his tractor rides as he drove around his farm boasting about his ripe harvest. As I grew older, I noticed his gregarious nature was often marred by a pitiful harvest. A few times locusts attacked his crops, other times extreme droughts or flash floods gripped our village. He was constantly worried about feeding his family and paying his workers. He was the first victim of climate change I encountered in my life. Unfortunately, he won’t be the last.

We are finding evidence of climate change all around us. Unfortunately, each year the climate predictions are getting more ominous, the environmental transformations are getting more dramatic, and the social, health and economic impacts of climate change are getting more disastrous.

The Troubling Thaw | One of the ecosystems vulnerable to climate change is the permafrost. It is the permanently frozen layer below the Earth's surface covering 15 million km2 of the land surface.

That’s almost double the size of Australia! The organic-rich permafrost is an extensive storage unit for carbon. Containing almost 1,700 billion tonnes, the frozen soil harbours almost twice the amount of carbon as the atmosphere. However, rising global temperatures are accelerating the permafrost's transformation from a carbon sink to a carbon source.

In fact, scientists have warned that up to 15% of the carbon stored in the permafrost is vulnerable to release in the form of greenhouse gases by the end of the century.

Carbon Time Bomb | As the temperature of the ground above rises, microbes trapped in the permafrost start to decompose organic matter into potent greenhouse gases including carbon dioxide, methane, and nitrous oxide. Permafrost thawing perturbs the methane hydrates — these are slushlike deposits formed when underground methane is trapped in high pressure and low temperature conditions — opening a gateway for methane to

vent into the environment. Methane is 80 times more powerful than carbon dioxide in warming the Earth over a 20-year period. Greenhouse gases absorb infrared radiation (IR) — heat energy from the sun — and re-emit it back to the surface warming the Earth. The rapid release of greenhouse gases is accelerating global warming. The rising planetary temperatures create a vicious positive feedback, further melting slabs of permafrost. Scientists have predicted that a 2°C increase in global average temperatures will result in a loss of about 40% of the world's permafrost by the end of this century.

These worrying statistics propelled the world leaders of 195 countries to sign the historic Paris Agreement in 2015. Each nation committed to taking measures to limit global warming well below 2°C, preferably to 1.5°C. But even a 1.5°C rise in temperature will manifest in unprecedented transformation across the Earth’s frozen landscape resulting in a 4.8 million km2 loss of permafrost. We are headed towards losing ice mass that is bigger than the combined area of the European Union.

Colossal Craters | Permafrost is not just a rich carbon reservoir. It also acts as the glue that binds the peat, gravel, soil, vegetation, and ice together. As the permafrost disintegrates abruptly, destabilisation episodes inflict the landscape giving rise to massive craters called thermokarst. These disfigured fissures get inundated with melting ice water forming new lakes and wetlands. In fact, if you dare to venture into the taiga forests of eastern Siberia, you will encounter the treacherous Batagaika megaslump, known to locals as the ‘gateway to the underworld’. Measuring up at over 3000 feet long and 280 feet deep, it is the largest thaw slump on the planet, and it continues to grow at a disturbing speed.

Permafrost Pandemic | The Batagaika crater has exposed remnants of ancient creatures that walked on earth eons ago including a woolly mammoth, a musk ox, and a perfectly preserved 40,000-year-old foal. Microbes that seek refuge in the carcasses of these ancient animals are a threat to communities and cattle. In 2016, the Siberian tundra experienced a wildly warm summer. Soon, dozens of people fell

10 Collapsing Ecosystems and Melting Permafrost in a Warming World: Is This the Future We Choose?

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ill to a mysterious sickness that ended up killing 200,000 reindeer herds. The culprit? A reindeer carcass that died in an anthrax outbreak some 75 years ago. As the infected reindeer corpse decomposed in the heat, the dormant anthrax-causing bacteria sprung to life. As the permafrost melts across the Arctic and Antarctic, the chances of us catching a disease from a Neanderthal's remains is very much a possibility. Are modern humans and health systems ready to fight a never-before-seen biological foe? If climate change continues to dissolve the permafrost, our survival on this planet in the coming centuries is in grave jeopardy.

Crumbling Cities and Mass Migration | Collapsing permafrost ecosystems are also a threat to ground stability. Diminishing periglacial ground steadiness will affect at least a third of the infrastructure in the Arctic’s permafrost zone and upend the lives of nearly four million people by 2050. Vanishing permafrost, receding glaciers, rising sea-levels, and climbing global temperatures are paving way for climate catastrophes such as floods, droughts, and water shortages. According to a World Bank report, more than 143 million people from Latin America, sub-Saharan Africa, and Southeast Asia will be forced to become 'environmental migrants' as they flee their homes due to climate disruption. Mass internal displacement and international migration of communities from these low-income regions will create an unprecedented human rights crisis. Millions will be forced into abject poverty, further widening the wealth gap and creating social disparities that are bound to reverberate across generations.

Past Perils and Terrifying Tomorrows | Climate change drives irregular weather patterns. Heavy pre-monsoon rainfall caused by usually warm ocean waters provides a fertile breeding ground for swarms of locusts. The 2019-2021 locust infestation across the Horn of Africa and parts of India and Pakistan was the worst locust attack in decades, eviscerating crops in their wake. Low crop yields pushes up the prices of staple foods such as wheat and rice,

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eventually creating inflation and food shortages.

Hunger is deadly. It paves way for civil unrest and political instability in regions that are already bearing the brunt of climate change. This is just the tip of the iceberg, in this case, a fast-melting iceberg. While natural disasters have always rocked our planet, they are now occurring with an unprecedented severity and frequency. In 2020 alone, our world was ravaged

by Australian bushfires; Siberian heat waves; record fires in Pantanal-world's largest tropical wetlands; devastating floods in Kenya and Uganda; supercyclone Ampham in India; and typhoon Goni in the Philippines. All of these unwelcome weather records are directly or indirectly driven by human fingerprints on the climate. And from what the climate experts predict, this is just the beginning.

Attention, Activism, and Action | Millennials and Gen-Z are guaranteed to witness the imploding impact of climate change in their lifetimes, and these demographic cohorts are the most concerned about the climate emergency.

We organise ‘Fridays For Future’ and ‘Zero Hour’ movements to push our leaders to take concrete action to rein in on carbon emissions.

We ardently support green deals, favour eco-friendly products, and challenge climate change deniers. We are climate pessimists, yet we remain hopeful. We hope that collective activism will potentially mitigate the irreversible climate damages that have been inflicted. We owe our planet at least that.

After encountering failed crops year after year, my uncle ended up selling his farm to a sugarcane factory.

My annual visits to my village no longer consists of bumpy tractor rides across the lush farms. Instead, I inhale toxic factory fumes and walk on the tar-laced cobbled streets paved on the land that once belonged to my forefathers Mahlaqua Noor is a first year Immunology PhD student at Hughes Hall College. Artwork by Eva Pillai.

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Synchrotron Science: A Deep Dive into the Atomic World Fran Seymour explores the creation of synchrotron light in accelerators and its many usages CERN, THE European Organization for Nuclear Research, boasts the world’s largest particle physics laboratory and is located in Geneva, Switzerland. It houses the Large Hadron Collider (LHC), a huge machine that creates high-energy particles and smashes them together at high velocities. With a whopping circumference of 27 kilometres, the LHC is the world’s biggest and most powerful particle accelerator.

The LHC is a synchrotron; a type of cyclic particle accelerator. Subatomic particles such as protons and electrons are accelerated to very high speeds and focused into beams.

Many experiments conducted in the LHC involve creating and observing high-energy proton beam collisions. Colliders like the LHC have been responsible for some of the most important breakthroughs in particle physics, including the discovery of the Higgs boson. The Higgs boson has long been predicted by the standard model — a single theory which describes all known forces apart from gravity — but was not observed until 2012.

Still, there is a lesser-known area of synchrotron science which has become a crucial research tool: synchrotron radiation.

Also known as synchrotron light, this radiation is emitted when charged particles are accelerated. Once an unwanted by-product of particle accelerators, synchrotron light is now used to facilitate highly specialised experiments, which have important applications in many areas of science. Synchrotron light sources — facilities producing this radiation — are capable of generating light 100 billion times brighter than the Sun. This radiation enables scientists to study samples on sub-nanometre scales.

Synchrotron Light | Whilst colliders like the LHC use proton beams in their experiments, synchrotron light sources make use of electrons instead. Since electrons are lighter than protons, it takes less energy to accelerate them. In synchrotron light sources, electrons are generated by an electron gun, accelerated to near-light speeds, and then focused into a high-energy beam. The final stage of acceleration involves circulating the electron beam around a ring of superconducting electromagnets. The powerful magnetic fields generated by these electromagnets pull the particles into a circular path. When electrons that are travelling at very high speeds are accelerated in this manner, they emit synchrotron radiation.

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This radiation is then projected out of the ring and captured by beamlines. Beamlines consist of an optics cabin, an experimental cabin, and a control cabin. In the optics cabin, the light is fine-tuned before entering the experimental cabin. Here, synchrotron light facilitates experiments using microscopes and other high-tech gadgets, allowing a glimpse into the atomic world. Finally, at the control cabin, scientists begin to conduct their work.

Synchrotron light is a powerful research tool as it is very bright and highly tunable. These sources generate radiation across the electromagnetic spectrum, ranging in frequency from microwaves up to x-rays. This versatility is handy, as each beamline is optimised for every experiment. Accompanied by sophisticated analytical techniques, synchrotron light is our key to unlocking the complex structure of matter, uncovering otherwise inaccessible information.

A Brief History of Particle Accelerators | The first particle accelerator was built by physicists Cockroft and Walton in 1930, at the Cavendish Laboratory in Cambridge. One year later, the American nuclear physicist Lawrence designed a more compact machine: the cyclotron, the first circular particle accelerator. Lawrence was awarded the 1939 Nobel Prize in Physics for his invention.

The cyclotron was the most powerful particle accelerator until the 1940s, when it was surpassed by the much larger synchrotron. Soviet experimental physicist Veksler, and American physicist McMillan, are both credited for devising the synchrotron. Initially a waste product, some time passed before scientists realised the potential of synchrotron light. Almost 30 years after the invention of the synchrotron, the first light source was constructed at the Synchrotron Radiation Centre in Wisconsin, US. Diamond Light Source | Colliders like the LHC have made important contributions to particle physics, furthering our understanding of galaxies, black holes, and dark matter.

In other research areas, the use of synchrotron light extends further, facilitating advancements in medicine, paleontology, engineering, and more.

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There are now over 50 synchrotron light sources worldwide, with more under construction. The UK’s own synchrotron centre, Diamond Light Source, is located at the Harwell Science and Innovation Campus in Oxfordshire. This glamorous-sounding facility has been in operation since 2007.

The 3 GeV synchrotron is encased in a silver ring-like building, covering an area of over 43,000 square meters. This futuristic toroidal structure wouldn’t look out of place in a Star Wars film.

Diamond is in its third developmental phase, due to be complete in a few years. The centre will accommodate a grand total of 33 beamlines. As it stands, the facility hosts a third generation synchrotron; compared to earlier models, these machines are capable of producing more intense and malleable light. This is because third generation machines make use of special arrays of magnets called undulators. These magnets are periodically placed along the ring, guiding electrons through a wiggling path, to produce even more synchrotron light.

There are plans for a Diamond-II upgrade, which will involve the replacement and improvement of instruments and computer technology, greatly increasing the performance quality. These renovations herald a bright future for synchrotron science, paving the way for more pioneering research

Artificial Heart Valves | Researchers at the University of Cambridge studied the properties of polymers to determine their suitability for artificial heart valves.

Polymers are compounds consisting of very large molecules, and can be naturally occurring or man-made. In recent years, polymers have become increasingly popular in biomedical applications, as they are inert, non-toxic and have good elasticity properties.

Artificial heart valves have been used since the 1960’s to replace defective natural valves. The function of these is to allow blood to flow through the heart in only one direction. The valves open and close to enable blood flow, and are thus able to withstand repeated loading and unloading of pressure.

At Diamond, researchers investigated the properties of special copolymers for use in prosthetic heart valves. One of the beamlines was used to study real-time microstructural changes within samples being subject to repeated pressure cycles. These experiments yielded exciting results and inspired novel designs for artificial heart valves.

Debris Particles from Fukushima | In 2011, northeastern Japan was hit by a magnitude 9.0 earthquake, followed by a powerful 33 feet high tsunami wave. The natural disaster was one of the most destructive and deadly in Japanese history. The tsunami resulted in extensive flooding and power cuts throughout the northeast. Fukushima’s nuclear plant was left without power, causing the cooling mechanism to fail. Disastrously, the fuel rods partially melted, releasing radioactive debris into the surrounding area.

Working alongside the Japan Atomic Energy Agency, researchers from the University of Bristol collected and examined samples from the restricted zone. The team used a unique combination of beamlines at Diamond to investigate the long-term physical and chemical properties of the radioactive debris.

The specialist techniques offered at Diamond enabled the research group to learn more about radioactive debris and the processes that caused the accident. In future incidents, similar methodology can be used to assess the dangers associated with restricted radioactive zones.

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Fran Seymour is an undergraduate student in Physical Natural Sciences at Gonvillle and Caius College. Artwork by Mary Holmes.

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Whale Tracking Technology Hopes for a Sea Change in Conservation Hazel Walker takes a deep dive into the world of cetacean tracking

WITH A tongue that can weigh as much as an elephant and songs louder than a jet engine, the blue whale has long captured people’s hearts the world over. It is tempting to think the accolade of largest creature on our planet might have kept these giants safe from commercial whaling, but while some saw their remarkable size as something to be marvelled at, others saw it as a possibility for profit. In the first half of the 20th century, more than 340,000 blue whales were killed for their meat and blubber, pushing them to the brink of extinction.

This sad story was repeated across many of the 89 species of whales, dolphins, and porpoises, collectively known as cetaceans. The true death toll of commercial whaling remains unknown, but recent estimates indicate close to 3 million cetaceans were killed between 1900 and 1999. This may be the largest animal cull in our history in terms of total biomass.

The cessation of commercial whaling by most countries, following a global moratorium in 1986, allowed some 14

Whale Tracking Technology Hopes for a Sea Change in Conservation

populations to begin to recover. However, the slow reproduction rate of many whale species left them vulnerable to extinction. The threat of whaling has been replaced by numerous other human hazards. The sheer number of vessels on our seas and oceans dramatically increases the likelihood of fatal ship strikes. Smaller cetaceans risk becoming bycatch in fishing nets, while larger whales face entanglement in fishing ropes and equipment, which can lead to death through drowning, infection, or starvation.

An ever-increasing threat to cetaceans is man-made noise pollution. Sources are varied, and their impacts on cetaceans can be acute — such as seismic exploration for oil and gas — or cumulative — including constant noise from ships.

Cetaceans are known for their songs, calls, and clicks, and use hearing as their dominant sense. Baleen whales, such as blue whales and humpbacks, tend to use low frequency sounds for long distance communication. Toothed whales, including sperm whales and beaked whales, use higher frequency echolocation to navigate, essentially allowing them to ‘see’.

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Interruptions to these vital communication and navigation mechanisms are likely to have huge negative impacts on how cetaceans search for food and mates, as well as how they identify and avoid obstacles in the water. Mid-range sonar frequencies used in military operations have even been implicated in fatal stranding events of beaked whales.

In order to safeguard cetaceans and encourage recovery of their populations, human impact in cetacean habitats must be lessened. Given the number of different species, each with a unique set of characteristics, such as diet, migration behaviour, and range, a greater understanding of each species is required in order to identify their distribution and inform beneficial policies which facilitate population recovery.

Sadly though, the elusive nature of whales can make them particularly difficult to study. Only a small proportion of their lives is spent at the surface of the water where they can be seen, so marine scientists are increasingly turning to innovative technology to gain an insight into the world of cetaceans.

A study published in Nature Scientific Reports used satellite tracking to investigate the distribution of a population of blue whales off Chilean Patagonia, confirming this area as an important feeding ground. By combining satellite tracking data of an individual blue whale with daily vessel trafficking information, researchers produced a striking animation that illustrated the struggle of one blue whale to avoid the many ships crossing the area in a week, which amounted to almost 1,000 vessels. ‘What the blue whale graphic illustrated so well was ... the constant physical obstruction. The cumulative impact is worrying at both an acoustic and a physical level,’ says Emma Clarke, a marine biologist who studied at Dalhousie University in Halifax, Canada.

Satellite tracking provides a snapshot of the movements of individual whales, as opposed to methods such as passive acoustic recordings, which allow for constant monitoring of an area. Acoustic recording can also circumvent the difficulty of finding and tagging smaller, more elusive whales.

Clarke, whose research with Fisheries and Oceans Canada involved monitoring beaked whales using acoustic recordings, explains, ‘There are more and more hydrophones recording in the ocean, so if you can draw on that data and start to identify ... where species are being heard at what times, you can start to get spatial and temporal resolution of their distribution.’ For toothed whales, which rely on echolocation, ‘acoustic recording can come in really handy and allow you to identify particular species, because those clicks have species-specific characteristics’.

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A huge benefit of passive recording is that it can pick up changes in species distribution over years, but analysing this data manually is no mean feat. As Clarke describes, ‘To find clicks, you are searching at the scale of milliseconds and then you have to look at that for a minute and then for a day and these underwater recorders are often out there for a year, so it is a huge amount of data to process’. The development of machine learning tools that can identify cetacean vocalisations has vastly increased the amount of data which can be processed, in some cases allowing for near real-time detection.

The wealth of knowledge provided by these kinds of data can be used to identify areas in which enforced regulations could lessen our impact on endangered cetaceans. These areas can be designated as ‘Marine Protected Areas’ (MPAs) and range from marine national parks to special areas of conservation. There are currently 600 MPAs for the protection of cetacean habitats, each with a different set of rules depending on the location and the reason for the MPA. However, only a small proportion have tight restrictions such as total bans on commercial fishing.

“...more than 340,000 blue whales were killed for their meat and blubber, pushing them to the brink of extinction”

As well as MPAs, it is still possible to reduce the impact of human activity by rerouting busy shipping lanes, banning seismic exploration in cetacean habitats, establishing temporary fishery closures, and enforcing vessel speed limits. For example, mandatory season-long speed limits of 10 knots along the U.S. eastern seaboard led to an 86% reduction in lethal ship collision risks for North Atlantic Right whales.

Yet, with fewer than 100 breeding females of this species left, many conservationists are calling for tougher restrictions. A report by Fisheries and Oceans Canada showed that vessels often speed up before reaching a speed restricted area in anticipation of the reduced speed, raising the risk of fatality from a collision to 100% just outside the zone. This example alone illustrates the complexity of safeguarding cetaceans while still accommodating a level of human activity, which is unlikely to be drastically reduced in the near future.

As our understanding of cetacean habitats evolves, it is essential that governments, industry, commerce, and the military work with marine scientists to put in place and adhere to regulations that are flexible, under constant review, and based on area-specific cetacean presence and behaviours. As Clarke puts it, ‘To lose them before we even get to know them feels [like] a huge tragedy, especially knowing that we caused this in the first place and there are very tangible actions that we can take to help lessen our impacts’

“To lose them before we even get to know them feels [like] a huge tragedy, especially knowing that we caused this in the first place”

Hazel Walker is a fourth year PhD in Immunology at Fitzwilliam College. Artwork by Eva Pillai.

Whale Tracking Technology Hopes for a Sea Change in Conservation

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Arteries of the Earth: Why Rivers Run Everything Will Knapp and Séan Thor Herron investigate how scientists study the importance of river systems throughout Earth's history

L ESS THAN one percent of rivers in England and Wales are free of man-made barriers. Such is the extent to which our nation is built around running courses of fresh water.

The story around the planet is no different — Europeans have removed 90 percent of their original wetlands and floodplains, which are crucial parts of river ecosystems. A study published in the journal Nature as far back as 2010 estimated that human impacts threaten the quality of rivers that serve 80 percent of the world’s population.

Not only do rivers play a vital role in our economies and everyday lives today — fertilising floodplains and providing clean hydro-electric power (HEP) to cities and rural communities — they also represent a fundamental control on the global carbon cycle, regulating climate feedbacks on 100,000-year timescales. The role of rivers has developed and changed through the evolution of our planet, but rivers have always played a critical role in shaping Earth’s surface and the life that takes place there. Rivers truly are the arteries of the Earth.

In this issue’s FOCUS piece, BlueSci takes a look at different ways in which scientists — within Cambridge and outside — study rivers to tell us about the world we live in and underscore their importance to our civilisation. First, we explore the co-evolution of rivers with our planet across billions of years, looking at how they shaped the different ecosystems for life across its entire evolutionary history. In section two, we discuss rivers’ vital role in the cycling of Earth’s crust, which has kept Earth’s climate habitable for hundreds of millions of years, and how we can use modern rivers to understand this. Finally, we look at the importance of rivers to the human communities who rely on them — taking a focussed look at sand mining and damming in south east Asia. These are just some of the ways scientists observe rivers, giving us fascinating insight into the power of studying just one small facet of our incredibly complex planet Earth.

Rivers in Deep Time | Here’s an interesting question: what is the oldest (extant) river on Earth? The answer is, as it turns out, contentious. The geological methods for determining the age of rivers can be tricky, and there is also debate about how far a river can be considered the

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same river over time if, for example, it veers too far off course. The Mississippi is thought to have existed in one form or another, draining the North American continent for 300 million years. But the prize may go to Australia’s River Finke, whose course cuts right through mountains known to be over 350 million years old. This puts its age as Devonian — the name geologists give to the period between 419 and 359 million years ago.

Imagine the history this river has seen; the Devonian hosted the first serious radiations of both plant and animal life onto dry land, leaving the water for the first time. It has seen Pangaea rise and fall. The world in which that river was born is one fundamentally different to our own.

Indeed, how rivers themselves have changed over time is an area of active research in the Earth Sciences. The Devonian period was actually a critical interval for rivers on Earth. Before the Devonian, most rivers on Earth were sheet-like and braided. Picture wide, unconstrained streams flowing over sandy plains stretching hundreds of kilometres across. Today, some of the closest analogues to pre-Devonian rivers are found not on Earth but in the three-billion year old dried-up stream beds etched into the surface of Mars. In the Devonian, the evolution and spread of deeply rooting, vascular land plants saw river banks stabilised, becoming resistant to the erosive forces that had caused their previous unconstrained style. Plant growth on river banks also baffled flooding fluids, trapping mud and building up established floodplains and levees. This was the beginning of the dominance of meandering rivers. Today, almost all rivers on Earth are meandering for a major part of their course, and so it has been since the Devonian.

What effects could such a drastic change in the flow of freshwater on a global scale oversee? For one thing, changing fossils found in preserved river systems reveals the development and expansion of vibrant new ecosystems.

Trees develop in the late Devonian, and their subsequent evolution lead to logs falling into and being transported by streams — causing the Earth’s first log jams — and piling up in anoxic swamps, eventually giving rise to the world’s first ‘coal age’. Coal seams from this era form most anthracite and bituminous coals mined today.

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Perhaps most important though is that trapped mud mentioned earlier — the mud trapped in river systems after the evolution of their meandering, floodplainbearing character, and also the mud created by the chemical action of the land plants colonising the river banks. These muds are made up mainly of a group of minerals called silicates. When silicates are transported to the ocean, they play a key part in reactions that can draw down atmospheric carbon dioxide (CO2). That means the advent of land plants and their impact on rivers — in this sense, silicate-routing systems — could have a fundamental control on atmospheric CO2 levels. This issue is at the cutting edge of geological research today.

How Rivers Shape the Planet We See Today | At a global scale, rivers act as nutrient highways — providing the oceans with manna that sustains life in the deep blue. The collision of tectonic plates, over millions of years, heaves rocky material to the surface forming mountain belts, which are subsequently pummelled by monsoon rainfall over similar timescales; a process that removes CO2 from the atmosphere. Eventually, the rocky titans are diminished to no more than rolling hills. The products of these weathering reactions are transported by rivers to the oceans, where plankton and other organisms such as oysters, mussels and corals, utilise the nutrients to construct their shells. Without mountains and structured,

An interview with Dr William McMahon

Post-doctoral research associate in the Depar tment of Ear th Sciences at Cambridge, who studies environments and ecosystems on the early ear th STH: What to you is the importance of studying ancient rivers?

WJM: I think what people don’t appreciate so much is the significance vegetation makes up today as a percentage of global biomass. There was a study published in PNAS in 2018 that estimated that if you added all the biomass of all the different forms of life on Earth, 87% of it is plant biomass. Plants are in effect earth's most powerful ecosystem engineer, they really dictate all sedimentary processes on earth — be it in the river systems which they directly affect, or downstream into the marine realm where there are no plants but the effects of plants upstream have been so profoundly felt that they have a serious knock-on effect. Everything we know about how river systems behave at the present day is fundamentally tied to how we know plants influence river systems. You can't study rivers at the modern day and not consider vegetation effects. But what geologists need to appreciate, is that for 90% of Earth history, that was not true. Plants are a relatively recent intervention. They caused a profound biological change, possibly the most profound biological change Earth ever underwent, and it happened in just a 100-million-year interval [amidst 4,500 million years of Earth history].

We then see a couple of key transitions, relating to mud production and mud retention on floodplains.

STH: And this is important for the global carbon cycle.

WJM: Yes — plants decrease the rate at which mud is moved from the land to the oceans, by trapping it on river floodplains, and might even increase the amount of mud produced, by chemical weathering. The global carbon cycle depends on the functioning of the entire ‘Earth circuit’, from eroding mountains all the way through rivers into oceans, then subduction [rocks being forced back inside the earth and melted down at

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boundaries between tectonic plates]. If you tamper with any part of that system, it's going to have a knock-on effect on the cycle. It will have a lag effect on the next bit and then the next bit the next bit. Adding plants to the equation can even have a knock-on effect on igneous geology [new rocks that come from volcanoes].

There is a study published recently that showed that the composition of some magmas over time has changed a little bit. And the reason it's changed a little bit is because the composition of the crust that is subducted has changed over time. One of the factors they cite in the study is this muddying of the continents by land plants.

STH: What's next for those studying the impact of land plants on the world?

WJM: I think that's a really cool question. I’ll keep my answer topical. NASA have just managed to successfully land their Perseverance rover on Mars. The reason we're going there is because we want to find mudstone.

Mudstone is a highly sought out astrobiological target because it has this capacity to preserve organic matter.

The rover will sample the mudstone, and bring it back in 2031 — and some of it might be coming to Cambridge. They will look at the clay minerals inside these muds. Some of these minerals are produced biotically and some of them are produced abiotically.

Now what we started to do in our line of work is look at Precambrian muds — pre-vegetation muds — and actually look at the minerals that make it up. They are all this type that form abiotically. So they've got a different petrological signature to the biological equivalent. All you have to do is find one type of clay mineral on Mars that you know from an Earth analogue can only form biotically. Then you can do backflips! Then you have found your evidence for life. Convincing the general public, that'll be another thing!

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efficient, meandering rivers, shelled seafood would be very scarce; something to ponder over during your next moules marinière. The huge numbers of plankton that have benefitted from the nutrients supplied by weathering will eventually die; their shells will sink and some will find their way to elevated portions of the seabed and form limestone and chalk beds, such as those in Dover, England. Those unlucky plankton that do not come to rest on an oceanic ridge will be dissolved in the caustic bottom waters of the ocean, the dissolved products will one day, after a few thousand years, reach the ocean surface via upwelling and release a tiny amount of CO2 into the atmosphere. Through ocean ridge spreading and tectonic collision, the lucky plankton may be uplifted or subducted. If uplifted, mountains are formed and the process begins again; if subducted, the plankton will be melted and outgassed as CO2 into the atmosphere through volcanoes. To observe the part of this cycle that regulates global climate — known as weathering — scientists use rivers as their periscope.

The system is therefore always in excess of weatherable material, this makes the Himalayas a great place to study climate regulation via the mechanisms discussed previously. Dr Tipper goes on to talk about the specifics of his Himalayan fieldwork; ‘The goal of the work is to understand the weathering processes and quantify weathering fluxes (using rivers). It’s an interesting idea as the transport time of river particles is longer than the residence time of the water (residence time refers to the amount of time water spends within the river system), so there is an opportunity to determine time-integrated weathering rates. Another major goal of our Himalayan work is to consider the role of tectonics in mediating the supply of matter to Himalayan rivers. This work began after the 2015 Gorka earthquake and aftershock’.

Through studying the chemistry and sediment characteristics of rivers in Himalayan rivers, Dr Tipper et al. are able to understand how weathering, hence climate regulation, varies with both time and material supply (from tectonic interventions like earthquakes).

By studying the chemistry of some of the world’s largest rivers, scientists are edging closer to understanding the large role weathering plays in regulating atmospheric CO2 concentrations. Canonically, climate is regulated on long time scales in two ways; the weathering of silicate rocks (like granite) with slightly acidic rain (this dissolves atmospheric CO2), and the exportation of organic carbon from the continents to anoxic (oxygen absent) portions of the oceans. These two processes sequester carbon in the deep ocean for millions of years; it is thought that silicate weathering and organic carbon export have regulated temperature and kept Earth habitable for ca. 3.5 billion years. Understanding the chemistry and particle physics of rivers gives scientists a chance of quantifying the climate regulation ‘work’ that rivers do in the modern day. To understand this further we interviewed Dr Ed Tipper of the University of Cambridge. Dr Tipper is a geochemist studying ‘flowing carbon’ in Himalayan megarivers such as the Irrawaddy, Salween, and Mekong to name a few. Dr Tipper and his research group undertake yearly field campaigns to try and understand how these chemical reactions are regulating climate on million-year timescales.

Dr Tipper’s most recent research utilises a global river dataset to show that silicate weathering probably plays a lesser role in climate regulation than first thought. This means some other mechanism, such as organic carbon transport, is doing far more climate regulation work than canonically understood. Dr Tipper explains: ‘Large rivers transport water and sediment to the floodplains and oceans, supplying the nutrients that sustain life. They also transport carbon, removed from the atmosphere during mineral dissolution reactions, which are thought to provide a key negative climate feedback on long time-scales. We demonstrate that the (million year) carbon flux associated with mineral dissolution has been over-estimated by up to 28% because of a reactive pool of elements transported with river-borne suspended sediment. This is most acute in regions of high erosion, where silicate weathering is thought to be most intense’.

The piece was published in PNAS January, 2021.

So why the Himalayas? ‘The Himalayas are one of the most rapidly eroding areas on the planet, they are so-called “weathering limited” because the supply of material to the weathering reactor is very high, as a result, weathering fluxes are amongst the highest in the world’. By weathering reactor here, Dr Tipper is referring to the thin veneer of sediment (up to a metre below the surface) that is actively being chemically weathered. The term weathering limited refers to the fact that the supply of material is greater than removal during monsoons!

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On a global scale, the role of the river is obvious. As arteries deliver nutrients to organs, rivers deliver nutrients to oceans and in doing so sequester carbon from the atmosphere, storing it on the seabed for millions of years.

Observations of river chemistry and physics have put our current anthropogenic climate change in the context of natural slow processes that have regulated climate for billions of years. Current CO2 emissions outpace any natural CO2 removal mechanism and geo-engineering strategies must be implemented to achieve any reduction in warming during the next century. By understanding and observing the processes that regulate Earth’s climate in rivers, scientists can develop new modelling approaches to predict how our anthropogenic perturbation may impact global element cycling in rivers for years to come.

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Modern Mega-Rivers in Rural Communities | Intricately coupled to rivers and anthropogenic climate change are the people and communities who make a living out of rivers. The Mekong Delta, referred to as the ‘Rice Bowl’, is the most prominent irrigated rice system in Vietnam, producing on average 20 million tonnes of rice per year. Without the constant supply of nutrients and sediment from the Mekong river this invaluable resource would diminish to nothing. In order to feed the world without costing the Earth it is critical to protect places like the Mekong Delta, especially as 50% of the world’s population rely on rice as a staple food. However, the humble rice grain is not the sole interest of those concerned with the Mekong, where separate industries include sand mining and damming for hydro-electric power (HEP).

Vital for construction, sand is the main constituent in mortar, concrete and some varieties of bricks. The inconspicuous sand grain is the second most extracted resource on Earth, behind water. Strolling through the streets of Cambridge you may be unknowingly treading on sand dredged from the Mekong, which once was probably part of the Himalayas, one way to feel on top of the world. In a recent Nature Sustainability paper, a set of novel acoustic experiments are used to determine the sediment flux entering the Mekong delta. Alarmingly, the study concludes that only 6.18 ± 2.01 Mt/yr (1 Mt = 106 tonnes) of sediment enters the Mekong Delta, whilst current sand extraction rates are 50 Mt/yr. This mismatch in supply and demand has detrimental impacts for the Mekong, and potentially other large rivers subject to sand mining. A separate issue with similar consequences is damming. The rush to industrialise in a carbon conscious world has resulted in the construction of eleven major dams on the Mekong, with more planned for the future. The dams provide much of South-East Asia with electricity, but in some areas have reduced the once bloated silt rich river to a shadow of its former self. A paper published in Science of The Total Environment uses a sediment model coupled to future climate projections to predict the impacts of damming on sediment fluxes in the Mekong. In the next two decades, the model predicts the suspended sediment flux in the lower Mekong will decrease by 50% compared to current levels; that is despite an increase in monsoonal intensity as a consequence of climate change.

Dr Chris Hackney, a geomorphologist and lecturer at the University of Newcastle, was one of the scientists involved in producing the research previously mentioned.

Along with colleagues from the Universities of Southampton, Hull, Oxford, Exeter, Illinois, Montpellier, and New York, this research group have been studying the dynamics of sediment transport in the Mekong river and delta for close to a decade. We interviewed Dr

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Hackney to gain a deeper insight into the multifaceted implications of sand mining and damming on the Mekong and its delta.

What are the main physical impacts of sand mining and damming on the Mekong? ‘Sand mining and damming remove sediment from the river basin. The Mekong delta has lost ~70% of its sediment load in the last few decades as it’s being trapped behind hydropower dams upstream — what sediment reaches the delta is removed for construction by mining’. Dr Hackney goes on to explain the implications of this sand removal on the Mekong.

‘Sand removal has resulted in the gradual lowering of the river bed throughout the delta and upstream in Cambodia, this means saline seawater is propagating upstream into the delta, affecting rice crops and agriculture. Work I led, published in Nature Sustainability last year, has shown that a three metre drop in river bed level is enough to shift river banks to an unstable condition — current rates of bed lowering are 10-20 cm a year. It’s conceivable that in a decade river banks may begin to fail at an increasing rate’.

The impacts of sand removal are detrimental to the physical processes that make the Mekong what it is, but what about the people who live there? Do the benefits of HEP and sand mining outweigh the negatives? ‘It’s important to remember that HEP and sand mining have positive and negative aspects. As the Mekong countries develop and their economies grow, the need for energy and material for construction does too. Both HEP and sand mining act as income for the residents in the Mekong basin — improving livelihoods for millions of people. However, as mentioned before, the environmental impacts being felt will ultimately impact livelihoods in a negative way. Negative impacts include the loss of land and infrastructure due to coastal/bank erosion, changes in salinity reducing agricultural yields — meaning people may be unable to provide for their families, and finally HEP and sand mining have a major impact on fisheries, which millions of people rely on for food’.

What’s the solution — are policy interventions in the process of being made? Is there a ‘one-size-fitsall’ solution? ‘This is a really important question, at the moment I don’t think there is an answer. Society needs sand to function — a demand that will not go away overnight. Alternative building and construction materials may be found in the long run, but right now ensuring the sustainability of the sediment supply through the Mekong is vital to maintain ecosystems and biodiversity of the region. This may involve limiting mining to areas where there are large sand deposits, or limiting mining to periods of the year when sand supply is high. What is clear, however, is that greater regulation and environmental impact assessment is needed across

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the Mekong, and other river systems to ensure we do not adversely impact on the natural environment’.

As a point of interest — how do you actually measure a sediment flux in such a large, deep, fast flowing river? ‘In my research, I use high-resolution acoustic techniques.

Acoustic Doppler current profilers work by sending out pulses of sound through the water column. These sound waves reflect off particles in suspension and back to the sensor on the boat — telling us how fast these particles (and the water) are moving. The strength of the signal also tells us something about the amount of sediment at a particular depth. Similarly we use acoustic techniques to map the river’s bedload (larger particles transported along the river bed) at centimetre resolution, using a multi-beam echo sounder. This is effectively sonar — by repeating surveys of the same parts of a river over hours or days, we can track bedforms (such as dunes) moving along the river bed’.

By observing the Mekong we see how intricately linked society is to modern day mega rivers. By utilising acoustic

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techniques we are capable of monitoring the health of these rivers, and observe the huge impacts humans can have on our vast life-lines that endeavour to keep the planet in good health.

Rivers provide the observer with a spyglass into the inner workings of Earth’s climate system. Since inception over 400-million years ago rivers have carried mountains and carbon to the oceans, and in doing so regulated Earth’s climate and sustained ocean life. Observing river morphology and chemistry not only provides scientists with information about how we may engineer climate sustainably, but also imparts real-time information concerning the health of our Earth’s arteries. Depended on by millions of people, current unsustainable practices, such as sand mining, require immediate policy interventions to facilitate food security and livelihoods in both the developing and developed world Will and Séan are both second year PhD students at Magdalene College studying Earth Science. Artwork by Mariadaria Ianni-Ravn.

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Pavilion: Seeing the Supernatural?

Grace Exley explores how photography helped to expose a war-time witch

Picture a witch. Broomstick, pointed hat, a cat… perhaps even green skin? Whatever you pictured, forget it.

I have a real witch for you.

Ectoplasm: a viscous fluid produced by mediums during séances. In physical mediumship, it assumes the shape of hands, faces, bodies of materialising spirits.

THIS IS HELEN Duncan, otherwise known as ‘Hellish Nell’.

Nell was a witch in criminal conviction only; there are no broomsticks in this story. What I can offer you is ectoplasm, psychical research, and an odd image from the archives of Cambridge University Library. This is the story of how Helen Duncan, a medium hailing from Callander, ended up in a photograph belonging to a Cambridge scientific society — the Society for Psychical Research. It also happens to be the story of how a medium became a witch.

But before that, we have several questions to answer.

Ghosts and ghouls are not part of the science we know today, so how do we go from science to spirits? The answer is psychical research. Psychical research was, and remains, the study of ‘debateable phenomena designated by such terms as mesmeric, psychical, and Spiritualistic’.

In the Victorian period, entertainment had a supernatural flavour; from mesmerising party guests to attending the Victorian séance, the inexplicable was high fashion. Invariably, the inexplicable attracts people who want to explain it. In 1883, the Society for Psychical 22 Pavilion: Seeing the Supernatural?

Research (SPR) was founded, with philosopher Henry Sidgwick as its first president and, amongst others, the physicist Lord Rayleigh in its membership. Assemble a group of academic paranormal enthusiasts and the result is a systematic effort to apply scientific methods to the supernatural: the scientific study of everything from UFOs to mediums.

Studying the paranormal is hard. We’re not talking in physical quantities we can measure, nor about compliant cultures we can grow in controlled conditions. How do you scientifically investigate mediumship? Can you analyse ectoplasm? Psychical researchers certainly tried.

Their techniques ranged from weighing mediums before and after séances to testing their blood and taking their photographs. When cameras were invented, they were considered ideal objective observers — and what better to see the supernatural than this picture-perfect device?

Ectoplasm Exposed | Almost four decades after the founding of the SPR, a host of other psychical research societies had sprung up. One of the earliest was the Easter 2021

London Spiritualist Alliance (LSA), which moved into its headquarters at 16 Queensberry Place, South Kensington in 1925 — and if you happened to be there in October 1930, you might have encountered Helen Duncan. The LSA brought Helen to London from Scotland because they wanted her to sit for them, offering research séances alongside public sittings. A physical medium, Duncan’s séances were more than speaking with those beyond the veil: she made things materialise. By candlelight, ectoplasm flowed and spirit guides moved. This was the inexplicable the LSA wanted to capture. To do this, they photographed her séances, producing seventeen images in total. Attendees could hold the hand of Duncan’s spirit guide, Albert, whilst psychical researchers would watch everything unfold through the camera lens.

That was, at least, the idea.

Yet capturing Duncan’s séances in photographs bred doubt in the LSA. As investigators gathered more and more evidence, they had more and more questions: did that photograph show a doll or a spirit guide? Why did enlarged images of Helen’s ectoplasm seem to show the warp and weft of cheesecloth? And why did her maid report suspicious pre-séance disappearances? Despite these niggling suspicions, the fact was that Helen was immensely profitable for the LSA. Her success had brought her to their attention in the first place, and her fame lent her credibility. What the LSA didn’t know was that Helen’s data had been leaked to the National Laboratory of Psychical Research (NLPR).

Leaking information to the NLPR was not difficult.

From 1926, Harry Price — ghost hunter and NLPR founder — leased the top floor of 16 Queensberry Place. Within the LSA headquarters, Price systematically investigated mediums and spiritualists, and it was there that he encountered Helen. The first time they met, as Helen watched Price ascend to his laboratory, she felt uneasy. There was something about Price she did not trust. Despite her misgivings, and because of growing LSA scepticism, Helen consented to NLPR investigation.

But Helen was not the only one with doubts. The leaked evidence meant Price had analysed her ectoplasm sample; he was suspicious of her photographs, and that was why he wanted to investigate.

And now we find ourselves in the NLPR séance room on May 4th, 1931: Helen’s first sitting for Price.

This sitting was the beginning of the end for psychical research into Duncan. Unnerved by observers from the SPR, Helen began her sitting. Again, the séance was photographed, this time by Price himself, and the results were… unfavourable. Unlike the magic lantern slide we first saw, Helen’s ectoplasm didn’t look like billowing, ethereal clouds. It looked like knotted cloth. Worse still, the photographs seemed to show a clip holding Duncan’s Easter 2021

ectoplasm in place. Following this first séance, Duncan’s run of misfortune continued. Her fourth sitting for Price was her last — and it marked a dramatic end.

This time, Price’s penchant for picturing mediums went a step further: he brought in x-ray equipment to see inside Helen. If, as he suspected, Helen was a fraud, x-ray photography would expose her by showing that she had swallowed cheesecloth to regurgitate as ‘ectoplasm.’

If not, she was in the clear. Mid-séance, however, Duncan stopped proceedings. Agitated, she ran screaming to the bathroom, resisting efforts to calm her. With the attendees in hot pursuit, she rushed outside, where she eventually calmed down — but not before surreptitiously passing something to her husband, Henry. Back inside, she submitted to the x-ray, which, perhaps unsurprisingly, revealed nothing. Helen was finished with Harry, but his efforts to expose her were not over. He went on to publish his photographs in a defamatory book – for Price, photography exposed the medium.

Winding Up a Witch | Having cost the London psychical societies around £500 (approximately £34,200 today) in investigations, the Duncans headed for home.

Being an expensive medium doesn’t make you a witch, though, so let’s now come full circle, from medium to witch. Despite the scepticism of London’s psychical researchers, Helen continued working as a medium.

Whether or not she was a fraud, there was some truth in Helen’s séances — fatal truth during a 1941 séance in Portsmouth. Duncan revealed the sinking of the HMS Barham, but only the families of those lost had been informed, which made it something of a national secret.

Arrested mid-séance, Helen was initially (and bizarrely) charged under the Vagrancy Act, but her crime was perceived as more serious than that. What if she revealed more? Duncan posed a threat, a threat dealt with using the 1735 Witchcraft Act for the last time. The Act outlawed fraudulent spiritualism, and with this she was charged. Imprisoned under witchcraft law, Helen Duncan became known as Scotland’s last witch — a witch by criminal conviction. But how can authorities become so convinced of a woman’s deception as to invoke obscure witchcraft law? The photographs and conclusions contained in Harry Price’s book — Regurgitation and the Duncan Mediumship — certainly helped Grace Exley is a Part III History and Philosophy of Science student at Murray Edwards College.

Image: Ectoplasm, Cambridge Digital Library: MS SPR Mediums/ Duncan/Ectoplasm. Licensed under CC BY-NC. Background image from pixabay.com.

Pavilion: Seeing the Supernatural? 23

To See in a New Light:There is More than Meets the Eye Xavior Wang explores scientific advancements in optical technology that transformed our perception of reality

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SAY YOU were robbed of all but one of your senses, which would you rather not lose? Unsurprisingly, an overwhelming majority would choose their sense of sight. In fact, we estimate that about two-thirds of our brain is involved in processing visual information. We, as a species, interact with the world primarily through our vision. However, the human eye, as complex an organ it may be, is still rather limited. The smallest objects that the naked eye can resolve are about 0.1 mm, and the furthest objects we can see are the indistinguishable twinkles of starlight. It is no wonder that throughout history, people have devised various apparatuses to supplement our rudimentary vision, inasmuch as to augment it with the very forces of nature.

heavens for the first time and observed the hitherto unseen moons of Jupiter, pioneering the field of observational astronomy. Interestingly, in the same year, Galileo made a few tweaks to his telescope, flipped it around, and invented the first compound microscope.

First Light | From the ancient Egyptian’s depiction of glass meniscal lenses in 2000 BC, the Mesopotamian’s use of the Nimrud lenses in 700 BC, and 1st century AD Roman philosopher Seneca's application of refractive crystals in perusing fineprints and spectating distant gladiatorial showdowns, optical technologies have come a long way in their intricacy, clarity, and capability. Most notably, in 1609, Galileo Galilei pointed an array of calibrated lenses to the

The Electromagnetic Paradigm | Nonetheless, even with the mind-boggling sophistication that enabled these powerful devices, the fundamental principle is consistent — they are all manifestations of electromagnetism. Optical microscopes reflect and refract light into useful geometries, the Hubble Space Telescope detects signals from the infrared to ultraviolet spectrum, and even the electron or atomic force-mediated apparatuses exploit the electrostatic

To See in a New Light

Since then, optical technology has become an indispensable and ubiquitous visual aid. Today, we can zoom in to the scale of individual atoms with transmission electron microscopes and atomic force microscopes. At the other extreme, the Hubble Space Telescope sheds light on Icarus, a star halfway across the universe nine billion lightyears away, the farthest observed yet.

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interactions between particles. In fact, you can even say that almost all human inventions, interactions, and experiences predicate on this medium.

the strong nuclear force, 1,036 times weaker than the electromagnetic force, and 1,029 times weaker than even the weak nuclear force.

You take a spoonful of hot chicken soup. It stays in the spoon and doesn’t fall through because of the electromagnetic repulsion from the metal atoms. You get distracted by Netflix and spill the soup on your thigh, your pain receptors mobilise waves of potassium and sodium ions that bind to ion channels down a chain of neurons to tell your brain: ‘ouch’. You call mum with your phone, made with semiconductors, transistors, and other electronics, and you ask her how to soothe a bad scald, your voice carried by radiowaves across the globe to your worried mother. Yes, it always has been electromagnetism.

A Resounding Success | We seem to have steered quite far from the theme of optical technology.

However, where we are heading now is in fact the way forward. Recent discoveries have highlighted that despite all the razzle-dazzle we can do with light, we are still mostly in the dark. Indeed, there is truly more than meets the eyes. And now, it is time to break a few paradigms from time immemorial.

Forces of Nature | However, electromagnetism is not the only force of nature. At the frontier of particle physics, scientists have established the Standard Model, describing a collection of elementary particles of matter and energy, smaller than even protons and neutrons, as the all-encompassing constituents of the universe.

In theory, if we can understand precisely the properties and interactions of each particle, we will have a complete description of nature and the laws governing it. With this knowledge, every chemical reaction, biological process, and cosmological phenomenon can be impeccably modelled. That is, if we understand the Standard Model to infinite precision and have infinite computing power.

The point of introducing this exotic theory is not to comment on the plausibility of a ‘theory of everything’, but to bring to light the fact that the model describes not one, but three fundamental forces.

The omnipresent electromagnetic force is mediated by particles of energy termed photons. The strong nuclear force and weak nuclear force governing the subatomic realm are carried by particles named gluons, W bosons, and Z bosons. Unlike electromagnetism, which permeates the whole universe, and whose reach extends ad infinitum, the nuclear forces are, as the name suggests, confined within dimensions smaller than an atomic nucleus. With its counterparts barely manifesting on the scale of our human experience, it is no surprise that we regard electromagnetism as the singular conduit of nature.

So far, we have been avoiding the elephant in the room. There is a fourth fundamental force much like electromagnetism, which facilitates the interaction between all things, whose range knows no bound. This entity, excluded from the Standard Model due to our lack of understanding, is all-pervasive but remains the most mysterious. We are of course talking about gravity. We know so little of gravity because it is weak.

So weak that its magnitude is 1,038 times weaker than Easter 2021

Far out in the unremarkable corners of the desolated lands of the North American continent lie two oddly shaped facilities with long, orthogonal arms. On 14th September 2015, a few beams of laser bounced about in these arms to create strange patterns and everyone cheered. The first direct detection of gravitational waves had been made at the Laser Interferometer Gravitational-Wave Observatory (LIGO). Gravitational waves are a type of periodic oscillation. Specifically, like how sound waves are the compression and expansion of air molecules, gravitational waves are the cycles of stretching and squeezing of space itself. The particular gravitational waves detected at LIGO originated from two black holes 1.4 billion lightyears away. Their perpetual inward spiral ended in a cataclysmic merger, and the sheer impact of this marriage resonated through the universe like a cosmic church bell.

“With its counterparts barely manifesting on the scale of our human experience, it is no surprise that we regard electromagnetism as the singular conduit of nature”

This discovery was so exciting for three reasons.

Firstly, we had proven Einstein right, yet again.

The next cause for celebration was the incredible engineering feat involved in the detection. As mentioned, gravitational effects are extremely weak, and even the collision of two cosmic monstrosities could only produce a stretch in spacetime a thousandth of the width of a proton. Yet, this minute signal was detected and isolated from chaotic background noises. Finally, and most crucially, the discovery opened the door to a whole new way of observing the universe. Thus far, we have been blind to half of the happenings in the cosmos. But now, we have set the precedent for seeing the world in a completely new way.

A Bright Future | The potential of ‘gravitational optics’ is limitless. Recall how much progress we have made as a technological civilisation since we learned to wield light to our advantage. If we were to be able to harness gravity and bend it to our will as we do with light, then near-light speed spacecraft, artificial gravity, and even micro black holes would just be a few technical problems away. The world truly changes when you change your perspective and see it in a new light Xavior Wang is a first year NatSci at St. Edmunds College.

Artwork by Pedro Riera.

To See in a New Light

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Geology Rocks! — How Rock Collections Shaped the Understanding of the Earth Juliane Borchert explores the history of the Sedgwick Museum FOR CENTURIES, observing the Earth has meant collecting earth. Minerals, rocks, and ores were collected from around the world and gathered into vast collections. One such collection with hundreds of thousands of specimens is housed at Cambridge University’s Sedgwick Museum of Earth Sciences. Rock collections played a crucial role in the foundation of modern geology as a scientific discipline and have been important for its development ever since.

In the past, rock collections were crucial to be able to compare rocks from many different locations. This helped researchers work out the different periods of the geological timescale and what the Earth looked like billions of years ago. Careful comparison of rocks from different continents provided important evidence to build the scientific theory of plate tectonics. More recently, researchers have revisited the collection equipped with new measurement techniques. A team led by Professor John Maclennan re-examined rocks that were collected from volcanic islands in the 1800s. Using electron beams to study the rocks’ composition enabled them to understand the conditions and processes in the Earth’s mantle.

Having rocks from so many volcanic islands already neatly arranged in museum drawers made their study much easier — they didn’t have to travel to remote locations around the world to retrieve their own specimens. In this way, the rock collections that shaped the beginnings of modern geology continue to enable scientific advances today.

The Dirty Past of Geology | Collecting and analysing rocks has always been closely tied to economic interests. Knowledge of the layers of rocks in a particular region helps assess the potential for exploitation of resources like coal, oil, and valuable minerals. This is a major driver behind funding for geological surveys and expeditions in the 19th century and to this day. Geologists are frequently employed by mining, oil, and gas companies to gauge prospects for resources.

In the 1800s, Britain and other Colonial powers commissioned geological surveys around the world.

They brought back rocks which helped grow collections around the country. The knowledge they gained enabled the British Empire and individual 26

imperialists to target specific regions to bring under colonial control and exploit the local resources.

Typically, this went along with the exploitation of the indigenous population who were made to do the labour to extract the resources from the ground. The geologists conducting these surveys also gathered information about the local people and their politics, making it easier to force them under imperial control.

Many of the rocks in today’s collections were brought back from such colonial expeditions. The collectors didn’t pay any attention to who might own the specimens they were shipping back to museums in the UK and elsewhere in Europe. There are now several cases in which formerly colonised countries have issued repatriation requests for fossils that were taken during colonial times. An important discussion about how to proceed with specimens that were taken without consent is ongoing.

In the 20th and 21st century, geology played an important role in locating and exploiting fossil fuels around the world. This has led to close ties between oil companies and museums. For example, until 2017 the Natural History Museum in London did consultancy work for oil companies to help them locate underground oil and gas reserves.

The History of The Sedgwick Museum | The Sedgwick Museum of Earth Sciences is the oldest of the University of Cambridge museums, but its rock collections are actually older than the museum itself - private collectors bequeathed parts of their rock collections to the University as early as 1728.

In the 19th century, Adam Sedgwick began to more systematically expand the collection and used it for scientific studies. He was particularly interested in how different types of rock layer on top of each other and used these layers to propose several new periods of the geological timescale, including the Cambrian and Devonian periods. His systematic collecting and studying of rocks and minerals made him one of the founders of modern geology and also the founder of what grew into the Sedgwick Museum. He was also a teacher of the young Charles Darwin, but later vehemently disagreed with Darwin’s theory of evolution. Nevertheless, rocks collected

by Darwin during his Beagle voyage are now part of the Sedgwick Museum’s collection. In Sedgwick’s time, the fields of geology and paleontology were

Geology Rocks! — How Rock Collections Shaped the Understanding of the Earth

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closely linked and rock collectors were often also fossil collectors. Sedgwick bought rocks and fossils frequently, including from Mary Anning, the prolific fossil collector who was famous for collecting and describing fossils from the cliffs along the English Channel.

The new field of geology attracted many keen students, and soon debates arose about who was allowed to study and work in this new field. Adam Sedgwick strongly disagreed with the efforts of women to obtain full student status at Cambridge, calling these women ‘nasty forward minxes’. His successor, Thomas McKenny Hughes, was more open towards the academic pursuits of women and from the 1870s frequently took women on his geology research field trips. This was enabled by his wife Mary Hughes, a geologist in her own right, who acted as their chaperone. She participated in those field trips for the benefit of her own research, which she published independently as well as with her husband.

Several of the women whom she and her husband taught on these field trips went on to become the first female fellows to be admitted to the Geological Society of London.

Today, the rock collections are housed in the Sedgwick Museum, which like all Cambridge Museums, is currently closed due to the COVID-19 pandemic. But if you could visit it, in the Mineral Gallery you would find display case after display case filled with stones. Some are shiny and colourful eye-catchers; others are dull and in muted colours. The Mineral Gallery houses only a small fraction of the vast collection of rocks that the museum owns. In addition to the mineral collection, the museum is also in charge of a petrology collection and a separate collection of building stones. The rocks are used to study how the Earth’s crust has formed and changed over billions of years, as they reveal information about the history of the earth and its current condition. Pick up the right set of rocks, and you might just be able to work out where ancient oceans used to be, when a volcano erupted, or where to dig for gold!

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Launching Geology’s Future | Today, we are able to collect rocks from locations that Sedgwick could have only dreamed of. Diving robots can retrieve rocks from the bottom of the ocean and space missions are bringing rocks from the moon (and soon Mars) back to Earth — some of which have made their way into the Sedgwick Museum’s collection. In 1969, rocks collected during the Apollo 11 mission were analyzed in Cambridge and continue to be used for research into the geology of the moon.

The bigger shift for the field of geology is likely to come from the need for an energy transition away from fossil fuels.With the push towards more sustainable energy sources, the role of geological knowledge is shifting. Now, rocks are analyzed to determine where the geological layers below our feet are suitable for the construction of geothermal power plants, where to store carbon after capturing it from the atmosphere, and where to find the right materials to build the wind turbines, solar panels, and batteries needed for a sustainable future. Geology remains critical to understanding our relationship with the world around us, and as the subject evolves then so will the Sedgwick Museum — perhaps one day we will see special exhibits on the geology of renewable energy sources and Martian rocks settled amongst Sedgwick's initial collection Juliane Borchert is a postdoctoral researcher in optoelectronics.

Artwork by Josh Langfield.

Geology Rocks! — How Rock Collections Shaped the Understanding of the Earth 27

Visualising Science Bethan Clark tackles the problems and pitfalls of data visualisation

IT IS rare to find a scientific paper without figures. In many ways they are the most important art of a paper, providing the evidence for claims in research papers and rendering concepts easily understood in reviews. But their importance is not confined to papers. Be it science textbooks, infographics, news articles, patient information materials or even adverts, visualising science is key to communicating scientific ideas. As visual creatures, humans tend to find information in graphic form easier to comprehend. Yet visualising science is not straightforward — so it is often badly done.

Firstly, there’s chart choice. In different types of graphs, different visual elements are used to compare data: position in box plots, length in bar charts, angle in pie charts, area in bubble plots, shading or colour saturation in heat maps, just to name a few.

But not all visual elements are made equal to the human eye: studies of crowd-sourced assessments have shown that position and length are the most effective way to convey differences between data groups, as in bar charts. Differences are hardest to spot in heat maps, pie charts, and bubble plots.

Large differences between groups are usually noticeable regardless, but subtle disparities may be missed — or hidden — if a less effective element is used.

That doesn’t mean, however, that bar charts are always the solution. Chart choice should depend on data type and the pattern to be demonstrated, such as distribution, correlation, ranking, or change over time.

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Visualising Science

Although continuous data are usually best represented by scatterplots and histograms, many published papers fall at this first hurdle. A 2015 survey

by Tracey Weissburger at the Mayo Clinic in Minnesota found bar graphs representing continuous data in 85% of papers in top physiology journals. For continuous data, bar graphs hide sample sizes and data distributions — but they aren’t alone in this limitation. Summary graphs including box plots have the same drawbacks. The solution that’s increasingly advocated for is to show as much of the raw data as possible alongside the summary plot, which can be achieved with scatter or violin plots.

Colour is another problematic aspect of data visualisation. Even though colour coding is eye-catching and can provide another data dimension, human colour perception isn’t as straightforward as we tend to assume. Take, for example, the commonly used rainbow scale. This scale isn’t perceived evenly: some colour transitions appear gradual and others abrupt, stretching differences in the data out of proportion in the viewer’s mind. Plus, the middle of the rainbow is brightest instead of the end, so mid-points are mistakenly interpreted as the highest values. Compounding these issues, a rainbow scale loses meaning for people with colour-blindness (approximately 1 in 12 men and 1 in 200 women globally), as does the all-too-common redgreen colour coding.

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There are alternatives that display data more accurately and accessibly. Information about simple colour combinations that work for colour-blind vision, like magenta and cyan, can be easily found online such as in the American Society of Cell Biology colour accessibility guide. In the statistical software R, the ‘colorbrewer’ package has colour blind friendly palettes. As for scales, perceptually uniform gradients have been developed such as ‘viridis’ and ‘cividis’; these have been added to plotting software libraries in MATLAB and Python.

The need for better science visualisation goes beyond communicating findings to other scientists. Similar visualisation principles apply to creating graphics to engage broader audiences in science.

Despite an increasing amount of practical knowledge about what does and doesn’t work for data visualisation, change is slow.

Often, many scientists are used to using a conventional set of data visualisation methods and simply aren’t aware of the problems with them. For example, Weissberg notes in Knowable Magazine that bar graphs are generally accepted for showing continuous data in biomedical sciences. Even when scientists are aware of the issues with their figures, there is little incentive to spend precious time identifying the better alternatives.

It isn’t fair or realistic to expect individual researchers to be solely responsible for improving data visualisation.

Dr Sean O'Donoghue, at the Garvan Institute of Medical Research, suggests that software tools and journal standards could be more effective for driving change.

O’Donoghue chairs VIZBI, an annual international conference dedicated to visualising biological data. He points out that incorporating better tools as the default in plotting software naturally leads to their higher uptake; this has been done with some colour schemes. Similarly, journal submission guidelines can have widespread impact.

There is some progress in this area too. Nature Methods adapted a column on figures advice into submission guidelines including avoidance of red/green colour combinations. Other journals including PLoS Biology and eLife have added policies about using bar graphs.

An important area where little has changed is education.

Most scientists receive little-to-no training in data visualisation, with their only exposure often being through statistics courses. Of course, postgraduate students may receive advice from peers and mentors on figure design, but this learning route is susceptible to perpetuating bad practice rather than applying best principles. To remedy this, institutions could make scientific visualisation classes a core component of science students’ education.

The need for better education on science visualisation goes beyond effectively communicating research findings.

In the 2018 Annual Review of Biomedical Data Science, O’Donoghue argued that data visualisation also plays a key role in analysis and discovery. Visualisation is a crucial method for finding patterns in complex, high-dimensional data-sets. Therefore, bad data visualisation can mean missing out on new findings.

More insidiously, bad data visualisation allows the researcher’s bias to creep into data analysis. As we have seen, it is easy to mis-represent patterns in data simply through the choice of charts and visual elements, affecting both analysis and communication. It needn’t be overtly intentional — if you see what you expect with your default plot, you might not think to check another. Or vice-versa, if a chart brings out an inconvenient pattern that you believe is irrelevant, you might then investigate alternatives. This susceptibility to bias makes the need for an educational grounding in effective, responsible, and ethical data visualisation all the more pressing.

Scientists depend on data visualisation at all stages of the research process, but currently it falls short of its full potential. Better science visualisation is possible: innovative tools exist and new approaches are constantly being developed. It’s time to step up the standards and empower all researchers to revolutionise their data visualisation Bethan Clark is a first year PhD student at King’s College studying evolution and development at the Department of Zoology. Artwork by Bethan Clark.

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Visualising Science

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The Ties that Bind the Mind: Exploring the Limitations of Thought Tom Wilkins discusses seeing the forest for the trees FOR MANY, humans are defined by our intelligence and capacity for abstract thought. Aristotle explained humans as similar to animals in that we have life and perception, but distinct in that we also have reason. Linnaeus boasted of our wisdom as a species when he named us Homo sapiens.

However, as this article explores, we are not as wise as we would like to think.

Software Limitations | At the most basic level, human observations are limited by the shortcomings of our minds, known as cognitive biases. Consider this story: a man new to poker has great confidence in his own abilities. His friend, a veteran player, is less confident. After winning several hands, the first man fancies his chances, betting more and winning big. He then uses his winnings to buy himself a new car, only to notice that this model is everywhere. In order, this exhibits: the Dunning-Kruger effect (an overconfidence in ability demonstrated by the unqualified and underestimate of abilities by those more qualified), the hot-hand fallacy (previous successes making subsequent success seem more likely) and the Baader-Meinhof phenomenon (noticing something once makes you more likely to notice it again).

This story illustrates just a few ways in which our observations misalign in basic ways with reality. This is especially true in our modern, information-saturated age. Take, for example, confirmation bias, the tendency to pick out and retain information that conforms to existing beliefs; not a very useful trait when it comes to changing one’s mind. Or, similarly, our inability to comprehend probability; a 1996 study by Robert Hamm at the University of Oklahoma found doctors susceptible to base rate neglect, whereby the disregard of background information in favour of individuating information leads to overdiagnosis of rare diseases.

Conceptual Frameworks, or, the Cognitive Constraints of Cultural Context | The philosopher Alfred North Whitehead coined the phrase ‘the fallacy of misplaced concreteness’ to refer to how we can sometimes mistake our interpretations of the world for reality itself. The separation of the various sciences represents an artificial vivisection of the natural; admittedly, this compartmentalisation is useful in breaking down the infinitely complex natural world into manageable, researchable chunks.

However, such subdivisions can prove problematic. As naturalist John Muir once said, ‘When we try to pick out anything by itself, we find it hitched to everything else in the Universe’.

The intellectual root of this idea can be traced back to the revolutionary 19th century scientist Alexander von Humboldt.

Humboldt is most famous for his Naturgemälde, a diagram 30

The Ties that Bind the Mind

indicating how temperature, humidity, atmospheric pressure, flora and fauna varied with altitude in the Andes. He was the first to define global climate and vegetation zones, and to describe and identify the cause of anthropogenic climate change. While in the 21st century these observations are discussed by separate communities at separate conferences, Humboldt’s success as a scientist was partly due to his ability to see nature as one great tapestry. This gives one pause to wonder: what interactions and connections are we missing in a world where children are being taught to separate the natural world into the physical, chemical and biological, with no attempt to stitch the tapestry back together?

The fallacy of misplaced concreteness is rooted in culture.

Western culture has, for the past two centuries, been heavily influenced by capitalistic ideals such as competition and individualism.

In his book Entangled Lives, mycologist Merlin Sheldrake uses lichen to demonstrate how the lens of competition can inhibit our understanding of the natural world. Lichen are now understood to comprise multiple symbiotic partners, but, as Sheldrake notes, when botanist Simon Schwedener first proposed in 1867 that lichen Easter 2021

comprised fungi and either algae or cyanobacteria he was ‘laughed out of the house’. However, even the iconoclastic Schwedener was subject to cultural influence; his Dual Hypothesis described a ‘master’ and a ‘slave’ species operating together. Mutual beneficence was clearly not an option in 19th century biology.

Sheldrake then demonstrates the limitations of conceptualising nature in strictly individualistic terms with the example of fungi. Fungi cannot move to seek nutrition. Rather, they grow through their environment in order to reach food sources which they can then digest.

They do this by extending their mycelium, a network of fibres, the growing ends of which are known as hyphal tips. This prompts the question: at what level do we apply the idea of the individual — to the mycelium, or to the hyphal tips?

The mycelium as a whole seems like the obvious candidate, but there is a flaw in this thinking.

When a hyphal tip reaches a source of nutrition, the rest of the network recedes, and the fungus’s energies are focused on exploiting this food source.

The issue is that, in Sheldrake’s words, fungi have ‘no operational centres... no seats of government’; coordination happens ‘everywhere at once and nowhere in particular’.

ing in on a single ism, and how it misses The other magnifying collectivism like China Rosanna Rann Easter 2021

Viewing nature through our cultural lens.

An illustration of a UK shaped magnifying glass zoomtree from a forest to represent individualthings that don't fit in that frame of view. glass, one from a nation that favours seeing a lot of the trees but less detail.

Our notions of individuality suggest a central locus of control, yet this is not always the case. Since there is a whole kingdom of life subverting the idea of the individual it is worth wondering where else we could gain greater understanding of nature by disabusing ourselves of our preconceptions.

Even understanding our own biology is limited by the lens of the individual. Recent research suggests that human microbiomes aid digestion, influence the fine-tuning of our immune systems and impact our cognitive function and behaviour. At what point do we draw the line between us and our microbiomes? Do our gut bacteria affect our cognition, or are they simply part of our cognition, and thus extensions of ourselves? And what does this imply for the bacteria themselves? Perhaps these questions would be illuminated by a Humboldtian view of nature — that is, one that recognises the individual as ‘more of an assumption than a fact’, as Sheldrake puts it.

Other Perspectives | Europeans, and the Western cultures that succeeded them as a result of colonialism, have a long history of seeing the natural world as something to dominate.

In this world view, humans are alienated from nature, rather than just one (albeit powerful) piece in a huge and complex puzzle. The natural world is a commodity — it is there to be exploited and used as humans see fit. Conservation of endangered species is often framed in terms of the species’ use to humanity, rather than having inherent value of their own. This mindset can also lead to feelings of disconnection, and an urge to return to nature. Yet this is not the default human view; rather, this is just a view. In an interview with Dissent magazine, Nick Estes, academic, activist, and member of the Lower Brule Sioux Tribe of South Dakota, describes his culture’s relationship with the natural world through the example of buffalo; while acknowledging that the relationship was ‘very material’, he also argues that it ‘wasn’t just oneway’, and how ‘reverence’ for the buffalo as part of cultural traditions ensured over-exploitation and loss of balance in that relationship was avoided. In another example, anthropologist Juan Barletti’s 2013 TedTalk explains how the Ashaninka tribe of the Peruvian Amazon see Earth ‘not as a commodity’ but as a ‘social agent’, to be interacted with in a way that our Western worldview does not allow space for.

Final Thoughts | In his speech This Is Water, David Foster Wallace warns against adopting the ‘default setting’ — a worldview shaped by biological and cultural hard-wiring. This default setting operates at many levels; this article has explored just a few of the cultural and cognitive defaults which affect our understanding. It is the duty of scientists, as those who seek to expand human knowledge, to know our minds and most importantly to appreciate their limitations, so that we may inch closer to the Truth Tom Wilkins is a fourth year medical student at Christ’s College. Artwork by Rosanna Rann.

The Ties that Bind the Mind 31

Weird and Wonderful Is Seeing Truly Believing?

Being Baby-Faced

ATTEMPTS TO explain how visual illusions work date back to the Ancient Greeks. Aristotle, for instance, was the first to describe the waterfall illusion: focusing on moving water causes stationary objects, like rocks, to appear to be moving in the opposite direction. Illusions may seem like a glitch in our brain, but they actually help us draw useful conclusions on how perception works.

While there is no universal explanation for why optical illusions happen, studies suggest that our frontal lobe, where higher-level thinking and decision-making happens, may be involved in misapplying existing knowledge. Why does our brain make unconscious inferences then? Our bodies are incapable of processing all the information we are bombarded with daily. In addition, our vision lags: When light reaches the retina milliseconds pass before the information is translated into a visual perception. Prediction mechanisms have evolved to compensate for neural delays and help us to perform timecritical motor actions, such as catching a ball.

A philosophical and more thought-provoking question: could realizing that even physiological processes are heavily influenced by the environment help us become more empathetic towards those we disagree with? As we have seen with our vision, we like to predict reality based on prior experiences, but perhaps with more complicated processes, like political views or stances regarding climate change, too. MA

OUR FACES are vital for distinguishing between individuals and social communication — studying their evolution can therefore tell us a lot about human development.

In 1926, German anthropologist Adolf Naef commented on the remarkable similarity between the human face and that of a baby chimpanzee’s, saying ‘[It] is the most human-like picture of an animal, of any that is known to me’. Although adult chimpanzees can be distinguished by a small cranium and protruded jaw, the structure of a baby chimpanzee’s face demonstrates their close evolutionary relationship with humans.

This observation in humans is an example of neoteny — where traits seem to develop in the same way as chimpanzees, but stop earlier. It causes adult features, such as the flat, hairless face, to appear more juvenile, resembling infants in other primate species.

Many evolutionary biologists consider neoteny a key feature in human evolution, given how it varies across primate and early human species, and its link to a longer developmental duration before adulthood. Potential factors that have contributed towards this protracted development period include diet, speech, non-verbal communication, and even climate. Understanding the history of the human face not only provides clues about how humans evolved as a species, it may even hint at how our faces could change in the future. HL

How to Avoid Being Seen

Artwork by Clara Munger 32

Weird and Wonderful

WANTING TO undetectably conceal objects or just excited by the idea of an invisibility cloak, scientists have been investigating camouflage and cloaking technology for years. Recent research has been inspired by the octopuses’ ability to change colour and shape to mimic the texture of their surroundings, allowing them to hide from both predators and prey.

Octopus skin contains chromatophores, pigment-containing bundles that appear to change colour due to the contraction of surrounding muscles regulating their visibility. Meanwhile, another three types of muscles coordinate the shape of skin protrusions (known as papillae), allowing them to form complex shapes such as ridges and bumps.

This is mediated by the nervous system, allowing rapid detection and response to the environment.

Inspired by octopus evolution, scientists at Rutgers University have developed a 3D-printed hydrogel containing light-sensing nanoparticles that detect the light conditions and can similarly respond by contracting to change shape and reveal different colours; this ‘artificial muscle’ could one day be used for camouflage, robotics, or flexible displays. But first, the scientists hope to improve the response time and durability of the hydrogels. Who knows? In the future, we could be in a pretty good position to win a game of hide-and-seek with an octopus! SP Easter 2021

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