Humans

Claire Plumridge
PICTURE the scene: you are making a cup of tea for a friend who is on their way and won’t be arriving for a little while. But – disaster – you have already poured hot water onto a teabag! The question is, if you don’t want their tea to be too cold when they come to drink it, do you add the cold milk straight away or wait until your friend arrives?
Luckily, maths has the answer. When a hot object like a cup of tea is exposed to cooler air, it will cool down by losing heat. This is the … More

A pierced deer tooth discovered in Denisova cave in SiberiaMax Planck Institute for Evolutionary Anthropology
DNA that seeped into an elk tooth pendant about 25,000 years ago has yielded clues about the ancient woman who wore it.
The tooth, worn as a necklace bead, probably absorbed DNA from the person’s sweat as it lay against her chest and neck. Marie Soressi at Leiden University in the Netherlands and her colleagues were able to extract that DNA without damaging the tooth through a new process that took eight years to develop. The technique might reveal unprecedented details about the social customs and gender roles of ancient populations, says Soressi.
“For the first time, we can link an object to individuals,” she says. “So, for example, were bone needles made and used by only women, or also men? Were those bone-tipped spears made and used only by men, or also by women? With this new technique, we can finally start talking about that and investigating the roles of individuals according to their biological sex or their genetic identity and family relationships.”Advertisement
Scientists have often suspected that ancient tools, weapons, ornamental beads and other crafted artefacts contain DNA from the people who touched them. But getting DNA out of these objects typically means removing sections for analysis – causing permanent damage. “We absolutely didn’t want to do that,” says Soressi.
To see if DNA could be coaxed out of ancient artefacts without destroying them, Soressi and her colleagues tested numerous combinations of chemicals and heating regimes on 10 previously excavated artefacts from Palaeolithic caves in France. They found that placing them in a sodium phosphate solution and raising the temperature incrementally from 21°C to 90°C (70°F to 194°F) led to the release of relatively large amounts of human DNA with no damage to the specimens.
The team then tested the procedure on another 15 excavated bone specimens from one of the caves. Genetic sequencing revealed DNA from many different humans – probably the scientists and technicians who had worked with the artefacts across the years, says Soressi.
To avoid such modern DNA contamination, the researchers then tried their technique on four tooth pendants excavated by colleagues in Russia and Bulgaria who wore sterile gloves and face masks. Their analysis revealed mostly animal DNA that matched the species used to make the pendants.
One tooth pendant from Denisova cave in Russia, however, also contained human DNA fragments, primarily from a single individual. There was enough genetic material for the researchers to positively identify a female Homo sapiens, in addition to the elk (Cervus canadensis) that provided the tooth.
While the human might have rubbed her DNA into the pendant if she had crafted it, the large quantity of DNA recovered suggests she was the individual who wore it, says Soressi. “As a porous material, that tooth was likely soaking in sweat,” she says. “It worked like a sponge, pulling in that human DNA and trapping it there for 25,000 years.”
The DNA showed that the woman was closely related to an ancient tribe that, thus far, had only been found more than 1500 kilometres to the east.

Daniella Bar-Yosef Mayer at Tel-Aviv University, Israel, finds the paper “very exciting”, in part because it could help explain the purpose of ancient jewellery. For example, it might signal something about the identity of the wearer or their group, or their marital status, she says. “If we find them in different contexts on men, on women or children of this species or another species, or different age groups, that would give us some better clues about what they’re meant for.”
The technique might also help resolve long-running scientific debates about whether certain artefacts were made and worn by Homo sapiens or Neanderthals, she adds.
The study could open the door to DNA analyses of museum artefacts across the globe, says David Frayer at the University of Kansas. “Curators are often hesitant to allow their specimens to be damaged for DNA analysis, however small the extraction,” he says. “The absolute strength of this paper is that [their] procedure gets around that. If it can be extended to specimens cleaned long ago, this would represent a great leap forward for ancient DNA work.”

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Around 1 in 10 people are left-handedEva-Katalin/Getty Images
Fewer than 3 per cent of people in China report being left-handed, despite the global average being closer to 10 per cent. Researchers think the difference is probably due to a continuing cultural stigma against left-handedness, which is less of an issue elsewhere, rather than genetics.
Hugo Spiers at University College London and his colleagues are overseeing a long-running study that assesses people’s ability to navigate using the mobile phone game Sea Hero Quest.
As part of this research, more than 400,000 … More

Nataliia Suietska/shutterstock
I LIVED happily without a microwave for 10 years, but, since acquiring one when I moved house last year, I have come to appreciate what a useful gadget it is. I have also realised that much of what I thought I knew about microwaves wasn’t quite right.
Microwave ovens work using electromagnetic waves, also called microwaves, with wavelengths of 12 centimetres or so – much longer than visible light, but shorter than most radio waves. Microwaves create an oscillating magnetic field that puts certain molecules in a spin: namely, molecules like water, which have positively and negatively charged portions. Anything … More

This piece of bone from 39,600 years ago has multiple puncture marks on it that seem to have been made by puncturing leatherF. d'Errico and L. Doyon
An analysis of a 39,600-year-old bone containing strange indentations claims it was used as a punch board for making holes in leather, revealing how Homo sapiens in Europe made clothes to help them survive cold climates at that time.
“We do not have much information about clothes because they’re perishable,” says Luc Doyon at the University of Bordeaux, France, who led the study. “They are an early technology we’re in the dark about.”
The bone, from the hip of a large mammal such as a horse or bison, was discovered at a site called Terrasses de la Riera dels Canyars near Barcelona, Spain. It has 28 puncture marks on its flat surface, including a linear sequence of 10 holes about 5 millimetres apart from each other, as well as other holes in more random positions.Advertisement

This pattern was “highly intriguing”, says Doyon, because it didn’t appear to be a decoration or to represent a counting tally – the usual explanations for deliberate patterns of lines or dots on prehistoric objects. Microscopic analysis revealed that the line of 10 indents was made by one tool and the other dots were made at different times by five different tools. “Why do we have different types of arrangements on the same bone?” says Doyon.
The researchers used an approach called experimental archaeology, in which you try out different ancient tools to see how marks were made. “We’re attempting to replicate the gestures that were used by prehistoric people to produce a specific modification on the bone,” says Doyon.
They found that the only way to recreate the type of indents on the Canyars bone was to knock a chisel-like stone tool called a burin through a thick hide, a technique called indirect percussion. The same method is still used by modern-day cobblers and in traditional societies to pierce leather.
The most likely explanation for the indents is that they were made during the manufacture or repair of leather items, say the researchers. After punching a hole in the animal hide, a thread could be pushed through the material with a pointed tool to make a tight seam, says Doyon.
“It’s a very significant discovery,” says Ian Gilligan at the University of Sydney, Australia. “We have no direct evidence for clothes in the Pleistocene, so finding any indirect evidence is valuable. The oldest surviving fragments of cloth in the world date from around 10,000 years ago.”
This discovery helps solve a mystery about the emergence of fitted clothing. Homo sapiens reached Europe around 42,000 years ago, yet eyed needles haven’t been found in this region from earlier than around 26,000 years ago and these aren’t strong enough to repeatedly puncture thick leather – raising the question of how these ancient people managed to make garments to fit them.

“The knowledge about making fitting clothing without bone needles is something we didn’t have access to before,” says Doyon.
“The location and date are interesting: southern Europe nearly 40,000 years ago,” says Gilligan. “That’s quite soon after the arrival of Homo sapiens, during some rapid cold swings in the climate. It’s when and where we’d expect our ancestors to need good clothes for protection.”
Doyon and his colleagues argue that this punch board marks a crucial cultural adaptation to climate change that helped modern humans expand to new regions.
The punch board was one of six artefacts found at the Canyars site, they say, and could have been part of a repair kit.

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A detail of the Benin Bronzes displayed at the British Museum Shutterstock / Mltz
The world-famous Benin Bronze artworks created by African metalsmiths between the 16th and 19th centuries were made of brass rings produced in Germany’s Rhineland region. These rings were used as currency in the transatlantic slave trade.
The Edo people in what is now modern-day Nigeria created the Benin Bronzes in the shape of heads, plaques, figurines and other objects by combining metal components with carved ivory or wood. Researchers had previously suspected that Edo metalsmiths used metals from manillas – horseshoe-shaped brass rings produced by Europeans specifically for trade in Africa – but had no definitive proof until now.
Tobias Skowronek at the Georg Agricola University of Applied Sciences in Germany and his colleagues performed a chemical analysis of 67 manillas discovered in five Atlantic shipwreck sites – including those off Cape Cod near Massachusetts and the English Channel – along with several land-based archaeological sources in Sweden, Ghana and Sierra Leona.Advertisement
The researchers measured the amount of trace elements and the ratio of lead isotopes in the manillas and compared them with those of the Benin Bronzes and the ores used by the German Rhineland’s brass industry. They found a strong similarity between all the metals, indicating that African metalsmiths probably used manillas obtained from European traders as a key source of material for the Benin Bronzes.

The findings align with historical sources, such as a 1548 contract between a German merchant family and the Portuguese king relating to the production of manillas for trade in West Africa. Other written sources have documented contracts between slave-trading countries of the time, including Portugal and the Netherlands, and the German brass industry located between the cities of Cologne and Aachen.
This new evidence could reshape the story of Germany’s involvement with the Benin Bronzes, says Cresa Pugh at The New School in New York. Much of the focus has typically been on the later colonial period and the Berlin Conference in 1884-1885, when European powers convened to divide up Africa into so-called spheres of influence for colonisation and exploitation.
Thousands of Benin Bronzes were looted by a British military expedition in 1897 and distributed or sold to various European museums, with many ending up in German museums.
“We understand Germany’s role during the colonial period as these artifacts were being looted and circulated following the Berlin Conference, but we really didn’t have a sense of what was happening before the colonial period during the period of slavery,” says Pugh. “And so I think this really does provide a kind of missing link between those periods.”
Starting in 2022, Germany began returning some of the Benin Bronzes to Nigeria as part of a broader international discussion about cultural restitution and decolonisation.

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Analytics is widely used in basketball to inform team tacticsG Fiume/Getty Images
An artificial intelligence can quickly assess basketball game data and extract information about the habits, strengths and weaknesses of players, which could prove valuable for coaches, particularly from smaller teams.
Alejandro Rodríguez Pascual at the University of Massachusetts, Amherst, and his colleagues have used data compiled and publicly released by US company Second Spectrum to train an AI model. The data included the 3D location of players and the ball throughout games in the 2015/16 National Basketball Association (NBA) … More

“We learn that to be good people and to be good citizens, we need to constantly be working on ourselves.”Getty Images
From at-home stool tests to foot baths claiming to draw impurities from the body, the wellness industry is big business, worth $1.5 trillion and counting. As it has grown, so too have concerns that people are taking unproven therapies to treat serious medical conditions. Just this month, the US Food and Drug Administration recalled Natural Solutions Foundation’s “Nano Silver 10ppm dietary supplement” over its label’s “unsubstantiated health claims to prevent, treat, or cure COVID-19”.
Colleen Derkatch, whose research at Toronto Metropolitan University in Canada focuses on the rhetoric of science, medicine and health, has noticed a rise in unsubstantiated claims and celebrity hype in the unregulated wellness industry, whose products promise to increase energy, reduce stress, slow the ageing process and more. Rather than expose the claims, however, she wanted to find out why people are drawn to wellness therapies in the first place.
In her latest book, Why Wellness Sells, Derkatch held in-depth interviews with 40 people who use supplements and other wellness therapies in their day-to-day lives. She also analysed the arguments and language used by members of online communities centred around “natural” healing. She found that the allure of the wellness industry has far less to do with individual gullibility and far more to do with societal failings.

Wendy Glauser: Let’s start with the biggest question of the book – why … More