Philippa Kaur

By Michael Marshall
The skull of the Australopithecus fossil known as “Little Foot” is preserved well enough to maintain evidence of blood vessels
Themba Hadebe/AP/Shutterstock
A famous member of an extinct human group went through hard times early in her life. The fossil, known as Little Foot, has telltale signs in her teeth that suggest she was either deprived of food or seriously ill during her childhood. Analysis of the fossil also revealed blood vessels in the skull, which could help us better understand the evolution of human brains.
Little Foot lived about 3.67 million years ago in what is now South Africa. She was an ape-like hominin with a much smaller brain than modern humans. She belonged to the genus Australopithecus, but there is disagreement about her exact species. Little Foot was old when she died, and her remains were found with those of a baboon, suggesting she died in a fight.

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To find out more details of Little Foot’s biology, Amélie Beaudet at the University of Cambridge and her colleagues scanned the fossil’s skull using the X-ray synchrotron at the Diamond Light Source in the UK. This allowed them to see details as small as 3 micrometres, compared with 100 micrometres in a CT scanner.
“In the teeth, we can see some defects, like lines or grooves,” says Beaudet. “It means at some point the enamel could not form properly.” This must have happened during childhood when Little Foot’s body was still developing.

There are several possible explanations, says Beaudet. One is that Little Foot’s environment changed, perhaps because the climate shifted, and, as a result, she found herself short of food. “We know that the environment was not always stable,” says Beaudet.
But it is also possible that Little Foot was ill, perhaps due to an infection. “We cannot say it was because of a food shortage, or because she was sick, or something else,” says Beaudet.
The team was also able to see tiny blood vessels in the bones of the skull and lower jaw. Beaudet says it was a “big surprise” that the fossil was preserved well enough to see such details.
Understanding Little Foot’s blood supply may ultimately shed light on the evolution of our unusually large brains. The brain needs to receive a lot of nutrients and it generates heat that must be carried away. Blood does both, so as our ancestors’ brains evolved to be larger, the blood vessels must have also evolved. “What part of the system had to evolve first for the rest to happen?” asks Beaudet.

Journal reference: eLife, DOI: 10.7554/eLife.64804
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By Christa Lesté-Lasserre
People mask how they feel about an ongoing conversation and leave others unsure of whether to stop talking, suggests a study in the US
KT images/Getty Images
Conversations often end later than people would like – and sometimes too early – because people mask how they really feel about the ongoing dialogue, according to a study in the US. This leaves all partners in a conversation unsure of whether to stop talking.
“People feel like it’s a social rupture to say: ‘I’m ready to go’, or to say: ‘I want to keep going although I feel like you don’t want to keep going’,” says Adam M. Mastroianni at Harvard University. “Because of that, we’re pretty skilled at not broadcasting that information.”

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Mastroianni remembers attending a black-tie event and wondering how many people at the party were engaged in conversations that they really wanted to end. So, he and his colleagues later surveyed more than 800 people – 367 women and 439 men, three-quarters of whom were white – randomly recruited from a crowdsourcing marketplace website. Participants responded to questions about recent conversations they had had with a friend or family member, including how they felt about the conversation’s length and how it ended.
The researchers also recruited more than 250 students and non-students pooled from volunteers available for studies in the Harvard University psychology department. The group, slightly under half of whom were white, included 157 women, 92 men, and three people of unspecified gender. These people participated in one-on-one conversations with another participant, who they didn’t already know, in the laboratory.

Mastroianni’s team recorded each conversation and asked the two participants to talk about anything they liked for at least a minute. When the conversation had ended, both study participants could leave the room, where they were each – separately – quizzed about the conversation. If the conversation lasted 45 minutes, someone stepped into the room to end it.
The conversations rarely ended when people wanted them to – whether it was one participant or both participants who wanted to stop, says Mastroianni. In fact, on average, the length of the conversations were off by about 50 per cent compared with how long people would have liked them to last.
Mastroianni also found that that some people – 10 per cent of the participants – were actually ending the conversations even though both people wanted to continue.
“They could have kept going; they had time left,” Mastroianni says. “But for some reason they stopped, maybe thinking they were doing a nice thing by letting the other person go.”

Essentially, people in conversations not only want different endpoints, but they also know “precious little” about what their conversational partners really want, he says.
That doesn’t mean the people don’t enjoy their conversations. On the contrary: when asked, his study participants said they found the conversation more entertaining than they expected it to be.
“But what we didn’t realise as scientists – and what they didn’t realise as people – was that beneath that good time that people generally have is this whole coordination failure,” says Mastroianni.
The study only covered people from the US and conversations might play out differently in other languages and cultures.
Journal reference: PNAS, DOI: 10.1073/pnas.2011809118
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By Krista Charles
A reconstruction of a Neanderthal man and woman
S. ENTRESSANGLE/E. DAYNES/SCIENCE PHOTO LIBRARY
Virtual reconstructions of Neanderthal ears show that our extinct cousins had the same physical capacity for hearing as modern humans, and by inference could also make the same sounds we can – although whether they actually spoke a language is still unknown.
“We don’t know if they had a language, but at least they had all the anatomical parts needed to have the kind of speech that we have,” says Mercedes Conde-Valverde at the University of Alcalá in Spain. “It’s not that they had the same language, not English, not Spanish, nothing like this. But if we could hear them, we would recognise that they were humans.”

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Conde-Valverde and her colleagues used medical imaging software to create virtual reconstructions of Neanderthal external and middle ear cavities, based on CT scans of their skulls. With these models, they could determine the range of sounds that Neanderthals could hear, and thus probably produce as speech. This technique has previously been used to study speech and hearing in other ancient humans and chimps.

The team also did the same for a group of fossils known as the Sima de los Huesos hominins that are thought to be the immediate ancestors of Neanderthals. The results showed that, unlike these ancestors, Neanderthals had the same capacity for hearing as modern humans.
Neanderthal hearing was optimised towards production of consonants that often appear in modern human languages, such as “s”, “k”, “t” and “th”, in the same way our hearing is, says Conde-Valverde.
While we don’t know if this means they had the mental capacity for language development, Conde-Valverde says that recent archaeological evidence, including stone tool use, jewellery making and art hint towards complex behaviour in Neanderthals that could indicate language ability.

“It becomes more and more hard to dismiss the fact that probably they had some sort of speech,” says Dan Dediu at Lumière University Lyon 2 in France. It was likely very similar to ours, but not identical, he says.
Journal reference: Nature Ecology and Evolution, DOI: 10.1038/s41559-021-01391-6
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By Karina Shah
The skull of Ardipithecus ramidus – a hominin that swung from branches?
PvE/Alamy
Our distant ancestors may have swung from branches and knuckle-walked like a chimpanzee – challenging recent thinking that the earliest hominins did neither. That is the conclusion of an analysis of 4.4-million-year-old Ardipithecus ramidus, thought to be one of the earliest known hominins.
In popular thinking, humans are often imagined to have evolved from a chimpanzee-like ape, but many researchers now challenge this idea – particularly in light of fossil evidence from A. ramidus that was published in 2009. One well-preserved individual – nicknamed Ardi – had bones that suggested it typically walked along branches like a monkey rather than swinging below them like a chimp. This hinted that our last common ancestor with chimps also walked along branches, and that chimps evolved to swing and knuckle-walk after they branched off from hominins.

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Thomas C. Prang at Texas A&M University and his colleagues disagree with this conclusion. They have taken the measurements of Ardi’s hands reported in 2009 and compared them with 416 measurements from hands across 53 species of living primates, including chimpanzees, bonobos and humans.
“The analysis of this hand, one of the earliest hands in the human fossil record, suggests that it is chimpanzee-like, implying that both humans and chimps evolved from an ancestor that was chimp-like,” says Prang.

They found that Ardi’s metacarpals and phalanges – the bones of the fingers and palms – were similar in size to those of living apes, with relatively large joint and knuckle dimensions. These adaptations are present in existing primates that move around forests by swinging below branches and may have helped the hominin to grasp onto branches, and even knuckle-walk.
“Ardi also has elongated, more curved finger bones, and we see this increased elongation and curvature in animals that habitually hang from branches,” says Prang.
Larger-bodied primates tend to hang from branches and climb trees, while smaller-bodied animals, like monkeys, are able to walk along the branches.
“[The study] quite convincingly demonstrates that the Ardipithecus hand has some suspensory adaptations, which I think makes more sense given the body size,” says Tracy Kivell at the University of Kent, UK.

The researchers also confirmed this using evolutionary modelling. This involved comparing traits of different primates, both living and extinct, to understand the evolutionary relationship between physical features and movement. “In short, this approach models the evolution of traits across a tree of life, which in this case includes all the species in our analysis,” says Prang.

Understanding hand morphology of our earliest human relative brings us one step closer to explaining why humans are so different from our close relatives. This may suggest that the last common ancestor of chimpanzees and humans was relatively chimpanzee-like, before the major evolutionary shift towards bipedalism and hand dexterity.
Tim White at the University of California, Berkeley, who discovered the A. ramidus fossil and helped describe it in 2009, remains unconvinced. “This is another failed resurrection of the antiquated notion that living chimpanzees are good models for our ancestors,” says White. He says that the Ardipithecus hand, aside from having five fingers and the ability to grasp, wasn’t specifically chimpanzee-like, as he and his colleagues originally reported in 2009.
Sergio Almécija at the American Museum of Natural History in New York is also largely unconvinced. “We need more Miocene [epoch] ape fossils pre-dating the human-chimp split to test fundamental aspects of our last ancestor with apes,” he says.
Journal reference: Science Advances, DOI: 10.1126/sciadv.abf2474
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We too often turn to insulting people’s brain power – and that closes off our ability to understand others, argues Melanie Challenger

Humans | Comment 24 February 2021Michelle D’urbano
BELITTLING the minds of others is commonplace. Stupid! Brainless! Imbecile! Dozy! Just scroll through the comments on pretty much any contentious article and you will find criticism by mental slander. Social media is littered with words like “unthinking” and “idiot”, especially when people are confronted with views with which they disagree.
Indeed, Twitter is a lightning rod of prejudices about minds. Former US president Donald Trump was perhaps the kingpin here, before Twitter banned him. Not only did he routinely boast of his own mental prowess – “sorry losers and haters, but my I.Q. is one of the highest” – but he persistently used mental slurs to silence critics: “dummy!”.
Yet we can all be guilty of mental slander. Right-wing supporters frequently call those on the left “libtards”. Meanwhile, according to the Oxford English Dictionary’s New Monitor Corpus, conservative voters in the US are often derided as “nutjobs”. Mental slurs are a fast and simple trick to silence an unwanted voice and to lower trust in evidence we resist. A growing body of research is allowing us to understand where this prejudice comes from.

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Humans are group-living animals. Probing and judging other minds is a part of how we coordinate with each other, cooperate and make and break alliances. By the age of 5, children make assumptions about people’s mental states, such as understanding that someone can be mistaken in their beliefs. Particular parts of the brain are implicated: the medial prefrontal cortex, the temporal poles and the posterior superior temporal sulcus. These work in concert to enable us to detect and make judgements about minds – both our own and those of others.
All this doesn’t stop at the neck. When we bond in a group – whether that is with kin or co-workers, friends or football fans – our bodies produce hormones like oxytocin that play a role in bringing us together. But, as psychologist Carsten De Dreu points out, these hormones don’t just unite us; they encourage exclusivity. This – directly or indirectly – can alter our views on other minds. In effect, we believe those in our group more readily, often exaggerating the mental abilities of those with whom we feel allegiance.
What follows from this is that we can undervalue the intelligence of those whose views differ from our own. Even more troubling, we can find ourselves responding more slowly to signals of emotion or experience from outsiders. Social psychologists Susan Fiske and Lasana Harris have used neurological imaging and behaviour studies to show that we shut down the medial prefrontal cortex, which is involved in social cognition, when confronted with minds we wish to ignore. When we suspend parts of our brain key to recognising another’s mental and emotional states, we not only close our minds to one another, we cease to care.
All this has real-world consequences for whom we listen to and whose voices we trust. In an age of political polarisation and misinformation, the echo chambers created by social media do more than just seal us off from diverse possibilities and points of view; they muffle our ability to care about those whose views we might not like.

What can we do about it? First, we need to recognise the biases that prevent us from keeping one another in mind. We must make it less socially acceptable to use mental slander in the service of an argument. Beyond this, we would benefit from greater opportunities to hear one another out.
This pandemic is a reminder that we have very few mechanisms for listening and deliberating together. That needs to change. But a more radical option lies in a much larger paradigm shift. Is it time for our species to stop using the idea of own superior cognition as validation?
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Burn promises to change the way we think about food, exercise and life, as evolutionary biologist Herman Pontzer brings his 20 years of research experience to bear on the mysteries of human metabolism. (Buy from Amazon)

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The Big Freeze, the Scott Polar Research Institute’s arts festival, launches online on 4 March with the European premiere of Polar Self Portraits 2, a creative project connecting artists and their work from six continents.

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Klara and the Sun is Kazuo Ishiguro’s first novel since he was awarded the Nobel prize for literature in 2017. It tells the story of an artificial friend who is learning not to invest too much in the promises of humans. (Buy from Amazon)
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Let’s imagine you have inherited a fortune and want to solve the world’s most pressing problems. Here’s the best way to spend your money to make a difference to climate change, disease and poverty

Life 24 February 2021
By Rowan Hooper
Andrea Ucini
MOST of us have had that conversation: what would you do if you won the lottery? Pay off the mortgage, quit your job, maybe start a small business doing something you have always dreamed of. But what if you acquired a truly vast fortune – not just a few million but a trillion dollars? And what if you had to spend it on making the world a better place?
I know, a trillion dollars – a thousand billion dollars – sounds like a vast amount of money, especially during the twin crises of recession and pandemic. But in the grand scheme of things, it isn’t. A trillion dollars is about 1 per cent of world GDP. It is what Jeff Bezos, the founder of Amazon, is on course to be worth by 2026. The world’s richest 1 per cent together own $162 trillion in assets. And it’s just one-twelfth of what governments around the world found in 2020 alone for economic stimulus packages in response to the new coronavirus.
What could you do with such a relatively modest sum, if charged to spend it on the world’s biggest challenges? This is the central question of my book, How to Spend a Trillion Dollars, in which I choose 10 megaprojects (all things scientists are working on now) and explore what could be achieved if we showered them with money. Here we examine three of the most urgent of those challenges: solving world poverty, halting runaway climate change and curing all disease.

Eradicate world poverty

Perhaps the most important thing we could do for human welfare would be to alleviate poverty. According … More