Health & Science

How a volcano gave us life’s gift of oxygen

OXYGEN arrived in large quantities and for good on Earth about 2.4 billion years ago in what is called the Great Oxidation Event. According to a www.bigthink.com report, it is believed that this was the result of an explosion in living organisms capable of photosynthesizing carbon dioxide and water into sugar, with oxygen released as a side product.

However, in 2007, researchers discovered evidence of a brief earlier period of oxygen, in shale from Mount McRae in Western Australia. is pu occurred 50 to 100 million years before oxygen’s permanent arrival on Earth.

It has been theorised that these whi s were the result of a temporary reduction in physical and chemical processes. But Roger Buick, co-author of a new study, says this is wrong:

“Our study suggests that for these transient whi s of oxygen, the immediate trigger was an increase in oxygen production, rather than a decrease in oxygen consumption by rocks or other non-living processes. It’s important because the presence of oxygen in the atmosphere is fundamental — it’s the biggest driver for the evolution of large, complex life.”

So what produced the oxygen? e researchers say it was life itself, in the form of microbes feasting on phosphorus draining into waterways from volcanic ash and lava elds.

“ ere are other nutrients that modulate biological activity on short timescales, but phosphorus is the one that is most important on long timescales,” says study lead author Jana Meixnerová. ere is lots of phosphorus now — indeed, it is found in fertiliser — but in the Precambrian era, its only source would have been volcanic. According to the authors, therefore, when the period’s volcanoes erupted, they provided early life the phosphorus kick that it needed. It is a dramatic case of the geological directly in uencing the biological. e authors of the study returned to the Mount McRae shale in search of mercury isotopes. When volcanoes erupt, they spew mercury high into the atmosphere, after which it eventually settles to the ground over the course of a year or two. “Sure enough,” says Buick, “in the rock below the transient spike in oxygen we found evi-

Stop that now! Why you shouldn’t pick your nose

FOR some people, children in particular, picking your nose is a perfectly normal, natural thing to do — but there are limits to just how far you should be getting up in there.

In a new YouTube video, Justin Cottle, Lab Director at the Institute of Human Anatomy, o ers a primer on the nasal cavity, and explains exactly why we get nosebleeds.

“ e nose is soft and imsy, but still rm and rigid. at’s because it’s made of cartilage—specifcally, hyaline cartilage,” says Cottle. e main reason for the nose being made of cartilage and not bone is that this enables it to deform under pressure, reducing the risk of injury given how much it protrudes from the face.

He also explains that hyaline cartilage can be found all over the body, as it is good for reducing friction between joints.

In the case of our noses, that friction reduction is useful considering the amount of air fIow.

Cottle goes on to detail what is happening inside our nose when we get a nosebleed — also known as an epistaxis — and explains that there are two types: anterior, where the bleeding is occurring in the front portion of the nose (these account for around 90% of nosebleeds), and posterior, which is happening behind the nose, and which can lead to the swallowing of blood. And one easy way to get an anterior epistaxis? Picking your nose.

“It actually makes sense to pick your nose,” he says, “to pick out those dried pieces of mucus containing dirt and all kinds of other stu ... But you want to be careful, because if you pick too aggressively, if you scratch too much, you can rupture those blood vessels, and then it starts to bleed.”

90% of nosebleeds), and posterior, which is happening behind the nose, and which can lead to the swallowing of blood. And one easy way to get an anterior epistaxis? Picking your nose.

“It actually makes sense to pick your nose,” he says, “to pick out those dried pieces of mucus containing dirt and all kinds of other stu ... But you want to be careful, because if you pick too aggressively, if you scratch too much, you can rupture those blood vessels, and then it starts to bleed.”

dence of mercury, both in its abundance and isotopes, that would most reasonably be explained by volcanic eruptions into the atmosphere.”

“During weathering under the Archaean [the early-tomiddle period of the Precambrian era] atmosphere, the fresh basaltic rock would have slowly dissolved, releasing the essential macronutrient phosphorus into the rivers.

“ at would have fed microbes that were living in the shallow coastal zones and triggered increased biological productivity that would have created, as a byproduct, an oxygen spike,” he says, e researchers have no way to know exactly where the implicated volcanoes erupted, but they note that there are ancient large lava elds of the appropriate geological age in India, Canada, and elsewhere.

“What has started to become obvious in the past few decades is there actually are quite a number of connections between the solid, non-living Earth and the evolution of life,” says Meixnerová.

“But what are the speci c connections that facilitated the evolution of life on Earth as we know it?”

Concussion needs an extra 14 days

THE largest study of concussion ever conducted rede nes the timeline for recovery from the suggested normal recovery time of up to 14 days to up to 28 days.

“Normal return-to-play time was previously set at 14 days–meaning 50% of people recovered in that time.

“Our paper suggests that 28 days more fully encapsulates the recovery process. At that point, 85% of people have returned to play,” says Steve Broglio, director of the University of Michigan Concussion Centre. e study, which appears in the journal Sports Medicine, shows that though median recovery times were consistent with the previously suggested 14 days, it was not until one month post-injury that most athletes were cleared for unrestricted sport participation.

Reframing the normal recovery time to 28 days helps eliminate unintentional social pressure from teammates, managers, or parents who hope to see their player back on the eld.

If a concussed athlete takes longer than 14 days or up to a month, that’s completely normal, he says.

Concussion management recommendations are outlined every four years by the Concussion In Sport Group (CISG), an international body that reviews the medical literature and develops guidelines on clinical care.