Humans

By Ibrahim Sawal
The bacteria that causes tuberculosis
Phanie/Alamy
Ancient DNA reveals that people of European ancestry have lost a gene linked to tuberculosis (TB) susceptibility over centuries.
TB is one of the world’s deadliest diseases and is caused by Mycobacterium tuberculosis bacteria. People with two copies of a genetic variant called P1104A are more likely to develop symptoms of TB after being infected with the bacteria.

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To trace the frequency of P1104A over time, Gaspard Kerner at the Pasteur Institute in France and his team analysed modern human DNA from around the world and compared it to more than 1000 samples of ancient DNA from Europeans from the past 10,000 years.
They found that the variant first appeared in ancient DNA in low numbers around 8500 years ago in Western Eurasia. Using simulations and demographic models to date the origins and movements of this variant, the team predicted it may have originated in the same region around 30,000 years ago, long before the existence of TB in Europe. “It may have appeared randomly, like when animals have mutations in their genome,” says Kerner.
It then spread across central Europe 5000 years ago, and reached its highest frequency 3000 years ago, with around 10 per cent of the population carrying P1104A.
Kerner says it was able to spread without affecting an individual’s susceptibility to TB during that time as many people would only have one copy of the variant.

The frequency of the variant drastically decreased 2000 years ago, around the time modern TB bacteria became common. This may be because it was under strong negative selection from TB, Kerner says, as increasing migration made people more likely to inherit two copies of the variant and therefore become more susceptible to TB.
“Individuals carrying this mutation may have died faster than other individuals,” he says. The spread of TB during this time may have been aided by human migrations increasing populations and bringing new bacteria and diseases to Europe.

In modern Europeans and Americans, the variant appears in low frequencies, but it is absent in African and Eastern Asians populations. Kerner says this is consistent with the findings P1104A emerged in Eurasia, and that other genes may be behind the prevalence of TB in Africa and Asia today.
“People still get sick from TB, both in Europe and elsewhere,” says Vegard Eldholm at the Norwegian Institute of Public Health. Around 10 per cent of those infected with the bacteria develop TB. “This might reflect a long history of co-evolution, and humans having adapted to contain the infection. But it takes time for evolution to purge the gene,” Eldholm says.
Journal reference: The American Journal of Human Genetics, 10.1016/j.ajhg.2021.02.009., DOI: 10.1016/j.ajhg.2021.02.009.
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By Simon Ings
The symbol of the QAnon far-right conspiracy theory
Pacific Press/Lightrocket via Getty Images
You Are Here
Whitney Phillips and Ryan M. Milner

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MIT Press
THIS is a book about pollution, not of the physical environment, but of our civic discourse. It concerns disinformation (false, misleading information deliberately spread), misinformation (false, misleading information inadvertently spread) and malinformation (information with a basis in reality spread specifically to cause harm).
Communications experts Whitney Phillips and Ryan Milner finished their book just before the election that replaced Donald Trump with Joe Biden. That election and the seditious activities that prompted Trump’s second impeachment have clarified many of the issues the authors were at pains to explore. You Are Here: A field guide for navigating polarized speech, conspiracy theories, and our polluted media landscape is an invaluable guide to our problems around news, truth and fact.
The authors’ US-centric – but globally applicable – account of “fake news” begins with the rise of the Ku Klux Klan. Its deliberately silly name, cartoonish robes and the routines that accompanied all its activities, from rallies to lynchings, prefigured the “only joking” subcultures of Pepe the Frog and the like that dominate social media.
Next, their examination of the 1980s Satanic panics reveals much about conspiracy theories. They also unpick QAnon, a far-right conspiracy theory alleging that a secret cabal of cannibalistic, Satan-worshipping paedophiles plotted against Trump. This pulls together their points in a way that is more troubling for being so closely argued.
Polluted information is, they say, a public health emergency. By treating the information sphere as a threatened ecology, the authors push past factionalism to reveal how, when we use media, “the everyday actions of everyone else feed into and are reinforced by the worst actions of the worst actors”.

This is their most striking takeaway: the media landscape that enabled QAnon isn’t a machine out of alignment, or out of control, or somehow infected, but “a system that damages so much because it works so well”.
It is founded on principles that seem only laudable. Top of the list is the idea that to counter harms, we must call attention to them: “in other words, that light disinfects”. This is fine as long as light is hard to generate. But what happens when that light – the confluence of competing information sets, depicting competing realities – becomes blinding?
Take Google. The authors characterise it as an advertising platform that makes more money the more people use it. The deeper down the rabbit holes our searches go, the more Google and others earn, incentivising promulgators of conspiracy theories to produce content, creating “alternative media echo-systems”. When facts run out, create more. Media algorithms don’t care: they are designed to serve up as much as possible of what Phillips and Milner call pollution.
The authors bemoan the way memes, rumours and conspiracy theories have swallowed political discourse. They teeter on the edge of a more important truth: that our moral discourse has been swallowed too. You Are Here comes dangerously close to saying that social media has made whining cowards of us all. So what is to be done? The authors’ call for “foundational, systematic, top-to-bottom change” is mere floundering. It has taken the environmental movement decades to work out mechanisms to address the climate emergency. Nothing in You Are Here suggests the media emergency will be less intractable.

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Read
The Spike is computational neuroscientist Mark Humphries’s vivid tale of the epic 2.1-second journey taken by a single electrical impulse as it propagates through the billions of neurons of a human brain.
Hulu
Watch
Boss Level, a new film streaming on Hulu from 5 March, stars Frank Grillo, Naomi Watts and Mel Gibson in a not entirely serious sci-fi shoot-em-up involving a dastardly government project, time loops and a race to save tomorrow.

Read
Under the Blue, by debut novelist Oana Aristide, sees speculation about artificial intelligence collide with the story of an artist fleeing a global plague: a startling, intellectual, post-covid adventure.
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For All Mankind, the alternative space race story from Apple TV+, returns with US-Soviet relations at a new low and NASA under pressure to militarise the moon

Humans 3 March 2021
By Bethan Ackerley
Molly Cobb (played by Sonya Walger) faces some tough choices
Apple TV
For All Mankind
Created by Ronald D. Moore, Matt Wolpert and Ben Nedivi

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Apple TV+
EARLY in the second season of For All Mankind, Ronald D. Moore’s counterfactual take on the space race, astronaut Molly Cobb is faced with an impossible decision: let a friend die on the lunar surface as a massive solar storm hits, or rescue him and risk getting a fatal dose of radiation. Viewers know Cobb has beaten tougher odds before, but as she is forced to choose, you fear that she is living in a world that no longer rewards heroics.
The show’s alternative history began with one key change: in this universe, the US was beaten to the moon by the Soviet Union in 1969. The rivalry between the nations grew and accelerated progress in space, with NASA sending women to the moon in the early 1970s and establishing a base, Jamestown, there in 1973.
After a slow start, the first season did a terrific job of conveying the importance of space travel, while killing off astronauts left and right to show what a grim endeavour it can be. All the same, despite the thrills, it felt a little soulless at times.
When the second series begins, after a jump to 1983, life on Earth doesn’t look too rosy. In its version of world events, Ronald Reagan became president earlier than he really did and superpower relations curdled, prompting yet more resources to be poured into space exploration. History fans should comb through the opening montage to catch all the ways this drama diverges from the real timeline: the Camp David Accords that brought peace between Israel and Egypt, the Three Mile Island nuclear accident and the Iran hostage crisis among them.
“Politicking threatens to scupper plans for an astronaut and a cosmonaut to shake hands while in orbit”

In this version of the 1980s, the moon is just another front of the cold war. Up to 30 astronauts at a time now live at Jamestown while looking for lithium at Shackleton crater, but the Russians edge ever closer to US mining operations. On Earth, the Johnson Space Center’s director Margo Madison and other NASA officials are under pressure to militarise the moon. Politicking even threatens to scupper plans for an astronaut and a cosmonaut to shake hands while in orbit, the lone gesture of peace in a world on the brink of annihilation.
For All Mankind is hardly the most nuanced take on the US-Soviet relationship – aside from a few scenes between Madison, astronaut Danielle Poole and their Russian counterparts, almost no common ground is acknowledged between the nations. Yet the cold war setting has made the show a leaner, darker beast.
Underdeveloped characters like Ed Baldwin, the sour-faced, square-jawed lead, have fewer but better things to do this time around. Ed, for instance, is now unhappily settled in his role as head of the astronaut office, sartorially muzzled by milquetoast sweaters and clearly longing for adventure.
And despite the streamlining, key plot threads from last season aren’t left dangling. Take Poole’s decision to break her own arm to hide a fellow astronaut’s declining mental health. Though she was the first African-American person in space, Poole’s “accident” gave NASA an excuse to sideline her – like the few other black astronauts.
As the season progresses, it is clear the astronauts and the NASA team are at the mercy of natural and geopolitical forces almost entirely outside their control – almost. It is in the small moments of defiance and sacrifice, whether that is staring down a solar storm or shaking an enemy’s hand, that For All Mankind proves it has figured out what kind of show it wants to be.

Bethan also recommends…
TV
Battlestar Galactica (2004-9)
Ronald D. Moore
When human civilisation is decimated, survivors must travel the galaxy in search of a home. Moore’s thoughtful series doesn’t shy away from the grim practicalities of space exploration.
Film
The Martian Ridley Scott
Stranded on Mars, astronaut Mark Watney goes to ingenious lengths to survive. A rare space blockbuster in terms of its homage to realism – or something close.

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Evolutionary psychologist Robin Dunbar has found that our friendships are governed by secret rules, based on everything from your sex to your sleep schedule. Our unique social fingerprints help determine who we are drawn to, which friendships last and why some friends are ultimately replaceable

Humans 3 March 2021
By Robin Dunbar
Anđela Janković
FACEBOOK users used to have a lot more friends. The social networking site pursues a commercial strategy of trying to persuade people to “friend” as many others as possible. However, sometime around 2007, users began to question who all these people they had befriended were. Then, someone pointed out that we can only manage around 150 relationships at any time. A flurry of “friend” culling followed and, since then, the number 150 has been known as “Dunbar’s number”. Thank you Facebook!
Modern technology may have brought me notoriety, but Dunbar’s number is rooted in evolutionary biology. Although humans are a highly social species, juggling relationships isn’t easy and, like other primates, the size of our social network is constrained by brain size. Two decades ago, my research revealed that this means we cannot meaningfully engage with more than about 150 others. No matter how gregarious you are, that is your limit. In this, we are all alike. However, more recent research on friendship has uncovered some fascinating individual differences.
My colleagues and I have made eye-opening discoveries about how much time people spend cultivating various members of their social networks, how friendships form and dissolve and what we are looking for in our friends. What has really surprised us is that each person has a unique “social fingerprint” – an idiosyncratic way in which they allocate their social effort. This pattern is quite impervious to who is in your friendship circle at any given time. It does, however, reveal quite a lot about your own identity – and could even be influencing how well you are coping with … More

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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