More on the origins of species

past is more complicated than our species evolving in just a single location or in isolation,” lead author Aaron Ragsdale, a population geneticist at the University of Wisconsin–Madison, told Reuters.

For the new study, the researchers looked at genomic data from living humans, which included people from produce electricity from air humidity,” Yao said.

“But that time, we considered the e ect exclusive to this speci c material (although we had some initial intuition/ indication that the e ect may expand to other materials as well),” he continued. “ e current work is based on our initial intuition, which then leads to the discovery of this ‘generic’ Air-gen e ect working with literally all kinds of materials. So it turns an initially narrow window to a wide-open door for broad potential/impact.”

Indeed, the results revealed that practically any material could become an Air-gen device provided it was perforated with tiny holes measuring 100 nanometers or fewer. At this scale, the holes are big enough to allow water to pass through an upper chamber into a lower chamber, but are small enough that the droplets make contact with the material as they move down through the holes. e microscale device was able to produce continuous energy equivalent to several hundred millivolts for a test period of a week, which is much longer than other air generator concepts that had a one-time power output that lasted no more than 48 hours. Its material versatility opens up the possibility of scaling the idea up to meet commercial or industrial energy demands.

As a consequence, a charge imbalance is created in the device because the water droplets increase the charge of the upper layer by soaking it as they move into the lower chamber.

“A general understanding is that the energy density is low (which can be intuitively understood that the air is very thin), so a single-layer of Airgen has no way to compete with other power sources (eg, solar, wind) for matched power volume,” Yao explained.

“However, the beauty is that air is di usive and lled in the entire vertical space, which means that we can stack many layers of air-gen devices in the vertical space to improve power (without taking up additional space footprint).”

“So in principle, Air-gen can be more space e cient” than other power sources, he continued. “Moreover, they can be engineered into varied form factors and neatly blend into the environment (even without one’s notice)” versus the example of “a solar panel that exclusively takes up space.” computer model that the stem population wasn’t quite as solid, but that parts of it would occasionally branch o and then later merge back together, we get a much better match with the genetic variation found in human populations today,” Ragsdale tells National Geographic. e di erences between these separate but intermingling groups would have been “almost as low as seen between contemporary human populations,” says Simon Gravel, a co-author of the study and human geneticist at McGill University in Canada. various groups: the Mende in Sierra Leone, the Nama in South Africa and the Amhara, Oromo and Gumuz groups in Ethiopia, according to Reuters. ey also examined DNA from living Europeans and from the remains of a Neanderthal.

It’s wild to imagine a future where homes, factories, and perhaps whole cities might be powered by the electricity that is concealed in the air. For now, the Air-gen concept remains in a developmental phase, though Yao and his colleagues are already working to scale up the concept and optimise the structure of their materials to boost energy efciency.

“Importantly, since air humidity is ubiquitous and continuous 24/7, Air-gen can be deployed almost anywhere for continuous energy harvesting, transcending the inherent intermittence of existing harvesters restricted to time or location,” the researchers said in the study.

“ e sustainable Air-gen technology holds promising prospects” that make it “a possible ‘greener’ energy technology for the future,” they concluded.

Jessica ompson, a paleoanthropologist at Yale University who did not con- tribute to the research, tells National Geographic that it might have been useful for the researchers to also include ancient DNA from Africa in the study.

“People alive today may be quite di erent from those who lived in the same place in the past,” she tells the publication.

Using the modern DNA, the researchers modelled di er- ent explanations for today’s human diversity—including the single origin theory and the idea that Homo sapiens mixed with other early human species. But they found the scenario that best t the DNA data was one in which humans had multiple points of origin.

“When we assume in our e oldest fossils from early humans come from Africa, and the rst modern humans likely came about around 315,000 years ago. Between 300,000 and 100,000 years ago, evidence of modern humans was spread throughout the continent—more support for the multiple origins theory, Scerri tells Nature News. Had humans originated in one spot, the oldest artifacts would be found there, with increasingly more recent remains found at sites emanating from the origin, but that is not the case.

Before setting o to Florence in Italy , there are a few things you need to keep in mind. Florence is a treasure trove of discovery. e city boasts an impressive amount of world-renowned artwork, incredible ancient architecture, and delectable local cuisine. In addition, Florence has an undeniable charm that has delighted visitors for ages.

Florence is compact, making it easy to navigate on foot, and there is something incredible to see (and eat) around every corner.

But before setting o to this wonderful city, there are a few things you need to keep in mind.

Accommodation

Accommodation in Florence uctuates quite a bit with the seasons, so if you can’t a ord these peak summer rates, consider traveling during the o -season.

Average hotel price: One night at a 3-star hotel typically costs around €310, or €430 for a 4-star hotel.

Luxury 5-star hotels: Florence has some great 5-star hotels which can cost about €800 a night. If you really want to indulge, ultra-luxury hotels like the gorgeous St Regis Florence where Premium rooms start at €2,300 a night!

If you’re on a budget: Florence’s hostels range from €35-60 for a bed in a dorm during peak travel times, or around €90 – €175 a night for a private room.

Food

A three-course meal at a midrange restaurant for two costs around €70. For a cheap meal at an inexpensive restaurant, expect to pay less than €20.

A beer costs about €5.50, while a cappuccino is a steal at €1.75.

Transportation e most convenient and a ordable way to navigate Florence is on foot. e city is compact enough that the top sites are easily reachable by walking.

Public transportation in Florence consists of a reliable bus network called the Autolinee Toscane. 90-minute tickets are available for about €1.60.

Florence is at enough that cycling is a good option.

Traditional bikes can be rented for around €15 a day or you can rent an e-bike for around €40 aday.

If you need to take a taxi while in Florence, expect to pay about €4 plus an additional €2.20 a mile.

Car rentals are available for about €75 – €125 a day during peak season if you plan on exploring the surrounding region by car.

Culture And Etiquette

Check this list before your trip! Here are some of the major Dos and Don’ts in Florence. DO book in advance: To avoid disappointment (and to avoid long hot lines), book tickets for the attractions you want to see well in advance.

DON’T expect to eat early: