Humans

By Michael Marshall

Childbirth may have been difficult for ancient hominins CHRISTIAN JEGOU PUBLIPHOTO DIFFUSION/SCIENCE PHOTO LIBRARY
It isn’t just modern humans that have found giving birth painful and dangerous. Growing evidence suggests birth was difficult for our hominin relatives millions of years ago. As a result, earlier hominins like Australopithecus may have needed help to deliver their babies.
Birth is strikingly dangerous for modern humans compared with other primates. Globally, for every 100,000 births in 2017, 211 mothers died. In the worst-affected countries, such as South Sudan, the maternal mortality rate is more than five times that. Many nations have … More

By Michael Marshall

The cerebellum may have had a larger role in human evolution than once thoughtKATERYNA KON/SCIENCE PHOTO LIBRARY
The key to human evolution may have been at the back of our minds all along – literally. Some of the biggest biochemical differences between human brains and those of other primates are found in the cerebellum, a region at the rear of the brain that has often been overlooked in evolutionary studies.
The finding adds to growing evidence that changes to the cerebellum have been crucial for the origin of the human mind.

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All backboned animals have a cerebellum, which is involved in controlling movement.
“It’s not really associated with much that’s uniquely human,” says Elaine Guevara at Duke University in North Carolina. Instead, neuroscientists seeking to explain the evolution of our brains have tended to focus on the cortex, the thick outer layer of the forebrain – especially the prefrontal cortex, which underpins our ability to consciously decide what to do.
In recent years, some neuroscientists have argued that the cerebellum has changed more than thought during human evolution, and that these changes may have been crucial.

Guevara and her colleagues studied the cerebellum and prefrontal cortex at the molecular level. They took brain samples from humans, chimpanzees and monkeys called rhesus macaques, and extracted DNA from both brain regions.
The team looked to see which parts of the DNA had small molecules called methyl groups attached. Methylation is an example of a so-called epigenetic influence on our genes. Patterns of methylation reflect which genes have been active and inactive during an animal’s life, and they vary between body parts and between species.
Guevara’s team found that the pattern of methylation in human DNA was different to that in chimps and macaques. Crucially, the difference between species was greater in the cerebellum than in the prefrontal cortex, suggesting there had been more changes there during our evolution.
It isn’t clear what the methylation changes did, says Guevara. But there are intriguing clues. Some of the genes where the cerebellar methylation patterns were different are known to be involved in changing the strengths of the connections between neurons, a process thought to be important for learning.
Some of these are also associated with neurodevelopmental differences such as autism and neuropsychiatric conditions such as schizophrenia, both of which may be unique to humans or at least more common in humans, says Guevara.
Journal reference: PLoS Genetics, DOI: 10.1371/journal.pgen.1009506
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Remains of a 3-year-old child discovered in a cave in Kenya called Panga ya Saidi are the oldest known burial in Africa. Researchers named the child Mtoto, which means “child” in Swahili, and estimate that they lived around 78,300 years ago, making this the oldest deliberate burial found in Africa. “It was a child and someone gave it a farewell,” says Martinón-Torres.

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By Karina Shah

Older teenagers in a year group tend to be more popularStockbroker/MBI/Alamy
Older teenagers tend, on average, to be more popular than their younger peers in the same class.
Danelien van Aalst at the University of Groningen in the Netherlands and her colleagues have investigated how relative age affects popularity among 14 to 15-year-olds in the Netherlands, Sweden and England. They collected survey data from 13,251 students from the three countries, who were quizzed between October 2010 and April 2011.

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Each teenager was asked to identify five of the most popular students in their class. The researchers then compared the popularity of each child to their age relative to that of their peers. They discovered a correlation: the older the student was, the more likely they were to be considered popular.
“A child enters school before or after a certain cut-off date and that determines how old or young you are relative to your year group,” says van Aalst. “We found that if you’re born right after the cut-off date [making you one of the oldest members of your class], you’re going to be popular.”

They found that the same effect also applied at the year-group level. Here, it was the children who were oldest relative to all of their peers in the year group – rather than just those in their particular class – that were the most popular.
All three countries showed roughly the same pattern. However, at the year-group scale, it was most pronounced in England.
At the classroom level, it was in the Netherlands that the pattern was strongest. This is partly because the country has a system of grade retention – when students don’t meet their academic requirements, their teachers will hold them back a year, which means they then become the oldest in their class and often the most popular.
This relative age effect has been shown in other areas. “Relative age has earlier been demonstrated to affect school performance – relatively older children do better in school,” says Herman van de Werfhorst at the University of Amsterdam, who wasn’t involved in the study.
Similarly, previous research has shown that older children tend to be better at sports than younger students in the same year group.
Journal reference: PLoS One, DOI: 10.1371/journal.pone.0249336

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By Sam Wong

OksanaKiian/Getty ImagesFOR many of us, food has been one of the most dependable pleasures in a year when so many normal activities have been put on hold. It seems particularly cruel that a common, lingering symptom of covid-19 is an altered sense of taste and smell, with studies finding that between 40 and 85 per cent of people with the illness experience some loss of these senses.
The virus that causes covid-19 attaches to ACE2 proteins in the olfactory epithelium, the tissue inside the nose where our smell receptors are located. Once the virus enters these cells, … More

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Oxygen, Alexandre Aja’s sci-fi thriller, is the story of a woman with amnesia (Mélanie Laurent) who is trapped in a cryogenic chamber. Her oxygen is running out and she will survive only if she remembers who she is. On Netflix from 12 May.

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Crooked Cats tell their own bloody tales in anthropologist Nayanika Mathur’s study of how big cats – tigers, leopards and lions – come to prey on humans. Ecological collapse is an important reason why such attacks occur, but is it the whole story?
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Cosmos: Reverse perspective looks at Earth from space through collages and graphics, capturing the changes we have lived through since Yuri Gagarin’s first orbit. Online from Pushkin House until 18 May. More

By Jacob Aron

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Disco Elysium
ZA/UM
PC, PlayStation 4 and 5, Xbox One, Series X and S

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YOU wake up, unable to remember anything about your life or how you got here. This is the opening of so many video games that an amnesiac protagonist has become something of a cliché.
But Robert Kurvitz, lead writer and designer of Disco Elysium prefers to see it as an essential part of video game storytelling. “There’s a promise of newness and being someone else, and for that the player needs to forget who they were,” he told me when we spoke after the game’s recent console release.
To be fair, Disco Elysium doesn’t quite start with waking up. The game’s first words are uttered by your ancient reptilian brain, which you engage in a conversation about whether to become conscious. Soon, your limbic system joins the exchange as you become increasingly aware of your surroundings, before waking up half-naked and hung-over. It is a unique and arresting beginning.
Stumbling out of your hotel room and speaking to the people you meet, it becomes apparent that you are a police detective trying to solve a murder, and you have been on a three-day bender, leading to complete memory loss.
Like many role-playing games, your character has a number of skills that determine your ability to perform tasks or unlock dialogue options. But while a traditional fantasy RPG might rate you for strength or magic, Disco Elysium‘s skills are more unusual – what’s more, they talk.
Your Encyclopaedia skill, for example, might feed you bits of information about the vaguely Eastern European setting of the game, while Composure helps you read other people’s body language and Electrochemistry pushes you towards indulging in alcohol and other addictive substances.
Kurvitz says the team wanted to avoid presenting the skill characters as the kind of intrusive voices that might be experienced by someone with, say, dissociative identity disorder. The skills are clearly facets of one personality rather than a mental cacophony. The team wanted to simulate the way the mind works through internal monologue, says Kurvitz.
This means that while the basic plot is about solving a murder, the game’s real concern is the construction of identity. When playing, you gain points you can invest in skills, boosting the chances of success when you use them and further moulding your personality. Increase your Drama skill and you will find it easier to be inventive and spot when people are lying; boost it too high and you could become overly dramatic.
In addition to the skills, certain characters or experiences you come across in the game can trigger thoughts that you can choose to engage with and internalise. I found myself going for dialogue options dealing with art or creativity, which resulted in my Conceptualisation skill offering me the chance to be an “art cop”.
The result is you can make some really strange choices about how your detective behaves, sending you deeper into Disco Elysium‘s weird world. I have been taking full advantage, but Kurvitz says it has proved surprisingly difficult to get players to embrace these options.
To nudge people towards more interesting role playing, a message on the loading screen reassures you that making odd choices won’t mean you fail in the game.
Perhaps the lesson is that when we are invited to reinvent ourselves, we tend to stick to the familiar.
Jacob also recommends…
Planescape: Torment
Black Isle Studios
PC, PlayStation 4, Xbox One, Nintendo Switch, Android, iOS
This cult classic role-playing game, also starring an amnesiac protagonist, is set across a strange fantasy multiverse and was a big inspiration for Disco Elysium.

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By Alison George

This partial skeleton (left) and skull were discovered in a cave in KenyaMartinón-Torres, et al., 2021
The oldest known burial in Africa is of a 3-year-old child who died around 78,000 years ago. The discovery sheds light on how people in the region cared for their dead at that time.
In 2017, archaeologists uncovered the top of a bundle of bones in a cave in Kenya called Panga ya Saidi. The remains were so fragile that a block of sediment around the bones was extracted intact and sent to the National Research Centre on Human Evolution (CENIEH) in Spain, where a painstaking forensic investigation took place.

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“We didn’t know until a year later what was really going on in there,” says María Martinón-Torres at CENIEH. “Unexpectedly, that sediment block was holding the body of a child.”
The researchers named the child Mtoto, which means “child” in Swahili, and estimate that they lived around 78,300 years ago, making this the oldest deliberate burial found in Africa. “It was a child and someone gave it a farewell,” says Martinón-Torres.

Analysis of the sediment surrounding the remains revealed that the child had been placed in a deliberately excavated pit and covered with sediment from the cave floor. They had been placed on their side with their legs drawn up to their chest. As the body decayed, most of Mtoto’s bones stayed in position with the exception of a few key ones.
The collarbone and top two ribs were displaced in a way typical of a body tightly bound in a shroud. And Mtoto’s head had the characteristic tilt of a corpse whose head was placed on a cushion. This points to a deliberate burial, something that is often difficult to prove from archaeological remains.
“From these little pieces of bone that were preserved, the work that we have done has allowed us to reconstruct the human behaviour surrounding the moment the body was put in the pit,” says Francesco d’Errico at the University of Bordeaux, France.

“The authors did a fantastic job in making the case that this is a deliberate burial. They have raised the bar and, in my opinion, actually set the standard on what should be done, scientifically, to demonstrate deliberate burial,” says Eleanor Scerri at the Max Planck Institute for the Science of Human History in Germany, who wasn’t involved with the research.
The discovery of any ancient human remains in Africa is big news in itself. “Human fossils are rare everywhere in Africa. We have huge temporal and spatial gaps, so this discovery is extremely important,” says Scerri..
Mtoto’s burial took place in the Middle Stone Age, which spans from roughly 300,000 to 30,000 years ago, when a suite of modern human innovations developed in Africa. Early evidence of burials in Africa is rare. No buried adults have been found from this period, although the burial of an infant in Border cave in South Africa dates to around 74,000 years ago, and the burial of a child who was about 9 years old in Taramsa Hill, Egypt, dates to around 69,000 years ago.
“I find it very interesting that we have interments of two or three children in Africa dating to around the same period,” says Paul Pettitt of the University of Durham, UK. “Mtoto’s burial is an exceptionally early example of a very rare treatment of the dead which might be commonplace in the modern world, but during the early prehistory of our species was rare, exceptional and probably marked odd deaths.”
This lack of burials shows the mortuary practices of modern humans in Africa differed from those of Neanderthals and modern humans in Eurasia, who, from about 120,000 years ago, commonly buried their dead. “That is a quite a paradox,” says d’Errico. “In Africa, where we have the origin of symbolic behaviour in the form of beads and abstract engravings, these modern humans wait quite long to make primary burials.”
Journal reference: Nature, DOI: 10.1038/s41586-021-03457-8
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