Humans

Fossils of Homo nalediRobert Clark, National Geographic
A species of ancient human with a brain the size of a chimpanzee’s may have engraved symbols on cave walls and deliberately buried its dead. These new discoveries about Homo naledi, a supposedly primitive hominin, could potentially prompt a rethink of the origins of complex behaviours once thought to be only the domain of large-brained humans like us.
“It’s a remarkable thing. My mind is blown,” says Lee Berger at the National Geographic Society in Washington DC, who led the research. “Much of what we thought about the origin of intelligence and the cognitive powers of having a big brain clearly just died,” he says, though other researchers who spoke to New Scientist question this view. 

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H. naledi was discovered in 2013 in the Rising Star cave system in South Africa when two cavers squeezed through an incredibly tight passage into a hitherto-unexplored chamber littered with fossil bones. In 2015, it was declared that these belonged to a new species. We now know that this hominin was around 144 centimetres tall and had a mix of primitive and modern features, with a brain a third of the size of ours.
It isn’t yet known how H. naledi fits in the hominin family tree, but its morphology suggests that its common ancestor with Neanderthals and modern humans dates back a million years or more. Dating of its fossil remains in 2017 showed that it lived relatively … recently, from 335,000 to at least 241,000 years ago, so might have met Homo sapiens, which evolved in Africa around 300,000 years ago.
In 2021, the discovery of an infant skull in a narrow fissure that is almost impossible to access indicated that this hominin deliberately interred its dead. The finding also implied that H. naledi must have been able to control fire in order to navigate through the labyrinth of dark passages and, in December last year, Berger announced evidence of extensive use of fire in the Rising Star cave system, such as soot, hearths and burnt bones.
Now, Berger and his colleagues have published more remarkable findings from the Rising Star caves.
Crosshatch engravings thought to have been made by Homo nalediBerger et al., 2023.
The team only discovered engravings in the caves in July last year, when Berger entered them for the first time. He had to lose 25 kilograms of weight in order to squeeze through passages in the rock as narrow as 17.5 centimetres wide.  “It was incredibly hard to get in, and I wasn’t sure I could get back out,” he says.
To his amazement, Berger spotted some engravings on a natural pillar that forms the entrance to a passage connecting the Dinaledi chamber – where H. naledi fossils were first discovered – and the Hill antechamber, where other remains had been found.
In three different areas of the walls, he saw geometric shapes, mainly composed of lines 5 to 15 centimetres long, deeply engraved into the dolomite stone. This is an incredibly hard rock, so the engravings would have taken considerable effort to make. Many of these lines intersect to form geometric patterns, such as squares, triangles, crosses and ladder shapes.
“There was this moment of awe and surprise in seeing these highly recognisable symbols carved into the wall,” says Berger. “Seeing these symbols was entirely unexpected.”
Aside from the 47 people who had recently accessed the caves, there is no evidence that anyone else except H. naledi had ever been inside, so the researchers argue that these extinct hominins must have carved the marks. However, this is only a preliminary report of the findings and the team hasn’t dated them yet.

We know that Neanderthals created similar symbols more than 64,000 years ago, as did modern humans in southern Africa from around 80,000 years ago. If the symbols in the Rising Star caves were indeed made by H. naledi, they could be far older.
Berger argues that to go to the effort of engraving this incredibly hard rock “in what appear to be important positions within these extraordinarily remote places, the interpretation is that they must have some meaning”.

Others are more cautious. “It is premature to conclude that symbolic markings were made by small-brained hominins, specifically H. naledi,” says Emma Pomeroy at the University of Cambridge. “While intriguing, exciting and suggestive, these findings require more evidence and analysis to support the substantial claims being made about them.”
Berger’s team has also detailed new evidence of what could be deliberate burials in the ground – a different mortuary practice to the internment of corpses in niches, such as the infant skull discovered in 2021. At one place in the Dinaledi chamber, the researchers found 83 bone fragments and teeth, seemingly from a single body, in an oval-shaped area of disturbed soil.
Artist’s reconstruction of the burial of an adult Homo naledi found in the Dinaledi ChamberBerger et al., 2023
They also found another possible burial site in the Hill antechamber. In this instance, they encased an area of debris with a high concentration of bone fragments in plaster, allowing them to remove it from the cave system intact and use a CT scanner to reveal its contents.
This showed many bone and teeth fragments, mainly from one juvenile that seemed to have been in a fetal position, an arrangement also found in prehistoric H. sapiens burials, along with some fragmented remains of three other juveniles. Intriguingly, a single stone artefact – a distinctive crescent-shaped stone, 14 cm long, with striations on its surface – was found close to the hand of one of the bodies.
Although these analyses are only preliminary, the researchers argue that the orientation of the bones and patterns of soil disturbance indicate that bodies were interred in pits that had been deliberately dug out, then covered in sediment. If confirmed, these burials would predate the earliest known human burial in Africa by at least 160,000 years.
Other experts aren’t yet convinced. “This is an admirable attempt to demonstrate that the corpses of at least two individuals were deliberately buried in shallow pits, and one can certainly not rule this out,” says Paul Pettitt at the University of Durham, UK. “I’m not convinced that the team have demonstrated that this was a deliberate burial. Let’s walk before we can run.”
Silvia Bello at the Natural History Museum in London points out that the bones are fragmented, while skeletons that are deliberately buried usually show better preservation.

Remarkable behaviour
Further analysis, such as a more detailed scan of the Hill feature, should help clear up this issue. Nevertheless, the new studies are already building an ever-richer picture of H. naledi and its behaviour. “The evidence is impressive,” says Chris Stringer, also at the Natural History Museum.
“These humans were taking carcasses, bodies of fellow naledis, down deep into the cave, and they must have had artificial lighting,” he says. “This is remarkable behaviour for a creature that’s got an ape-sized brain. It suggests organisation, because this is not something a single individual would have done, it must have been a group activity. And it’s obviously happened multiple times. That implies the existence of what we might call a culture – a different species, not closely related to us.”
“There’s a lot of very intentional behaviour in that cave complex,” says Genevieve von Petzinger at the Polytechnic Institute of Tomar, Portugal. “It’s not like a bunch of people fell in a hole and scraped some marks.”
These kinds of sophisticated behaviours were only thought to be possible in hominins with large brains, such as Homo sapiens and Neanderthals. “These are challenging finds, and they certainly make us think about what it is to be human,” says Stringer, raising questions about why we developed such large brains.
In the meantime, further research at the Rising Star cave system will be limited while the researchers work out how best to investigate this site without destroying it.
“Homo naledi altered almost every single space. That has caused me to become incredibly cautious about allowing people into that space until we decide exactly how we’re going to approach it,” says Berger, who wants to engage the world’s scientific community in addressing this question. “We, as humans, have to decide how we’re going to approach the space of another species that they clearly saw as critically important to them.”
Reference: bioRxiv, DOI: 10.1101/2023.06.01.543133 and 10.1101/2023.06.01.543127

Topics:Homo naledi More

Magnetic resonance imaging scans showing healthy human brainsSIMON FRASER/SCIENCE PHOTO LIBRARY
The human brain has greater energy demands than that of any other animal, especially in certain important regions, which may have been key to the evolution of our complex cognition. Knowing how energy use differs across the brain could also help us better understand and treat certain conditions, such as Alzheimer’s disease and depression.
Some mammals have bigger brains and more nerve cells, or neurons, than humans, making it unclear how we evolved a uniquely advanced ability to think critically … More

A carving at Luxor Temple in Egypt depicting Pharaoh Ramses and Queen Nefertiti embracingAgung Parameswara/Getty Images
Sexual kissing was practised in ancient Mesopotamia and Egypt at least 4500 years ago, according to a review of ancient texts.
There is considerable debate about when humans began kissing in a romantic way. Many sources say the earliest evidence of sexual kissing is in Sanskrit texts written in what is now India around 3500 years ago. Some researchers have suggested that sexual kissing spread from there around the world, and the conquests of Alexander the Great are often said to have played a part in this spread.
The idea that sexual kissing spread around the world from one place has, in turn, been linked to changes in the spread of diseases that can be transmitted orally. For instance, a paper published last year suggested that the herpes simplex virus 1, which causes cold sores, became more much common because of “the advent of sexual-romantic kissing”.Advertisement
But evidence from Mesopotamia and Egypt suggests sexual kissing arose independently in many places and didn’t suddenly spread around the world, says Troels Pank Arbøll at the University of Copenhagen in Denmark. “It shows it was known in a much wider area in the ancient world than the people formulating these theories have considered,” he says.
This has been known for decades by the few experts who can read the cuneiform writing system used by several ancient civilisations, but not more widely, says Arbøll. “In the general scientific community, people were not aware of this evidence because it’s not cited anywhere.”
So, Arbøll and his wife, biologist Sophie Lund Rasmussen at the University of Oxford, decided to write a paper describing the overlooked evidence.
While kissing is rarely referred to in Mesopotamian texts, those mentions show it was considered an ordinary part of romantic intimacy in ancient times, says Arbøll. For instance, one text from around 3800 years ago describes how a married woman came close to being unfaithful after a kiss. Another text from the same time describes an unmarried woman vowing to avoid kissing and having sex with a man.
“Considering the geographical distribution, I think [sexual kissing] must have had multiple origins,” says Arbøll. “It’s not something that originated in a single place.”
He and Rasmussen also point out that there is tentative evidence that modern humans and Neanderthals kissed, or at least exchanged saliva in some way. What is more, bonobos also engage in mouth-to-mouth sexual kissing. So it is possible that people have been kissing sexually for much longer than written history suggests. “I think it’s very likely that it goes far back,” says Arbøll.

However, a 2015 study by William Jankowiak at the University of Nevada, Las Vegas, and his colleagues found no evidence of sexual kissing in hunter-gatherer societies.
“My hunch is that kissing arose or was discovered amongst the elite in complex societies,” says Jankowiak. The elite were able to pursue pleasure and turn sex into an erotic encounter, he says.
Jankowiak did find that sexual kissing is more common in cold climes. This may be because in places where people’s bodies are covered in clothes, the face is the sole zone available to touch, he says.

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Aerial view of a desert kite from Jebel az-Zilliyat, Saudi ArabiaO. Barge, CNRS
Architects drew up highly precise plans of vast stone-walled hunting traps 9000 years ago, representing the oldest known architectural plans to scale in human history.
The plans were etched into massive stone tablets that have been recently discovered close to the elaborate traps, known as desert kites, which span such wide distances that their shapes are only recognisable from the sky. The findings confirm that Neolithic humans had an “underestimated mental mastery” of landscapes and space, well before they became literate, says Rémy Crassard at the French National Centre for Scientific Research (CNRS).
“There’s no doubt that these Homo sapiens had the same degree of intelligence that we do, but this is the first time we actually have concrete proof of their spatial perception – in both these gigantic kites and now also in their very precise corresponding plans,” he says. “It shows to what extent this way of thinking was anchored into their culture.”Advertisement
Kites in Saudi Arabia and Jordan feature funnelling lines up to 5 kilometres long and up to 10 pointed branches leading to pits as much as 4 metres deep. Named by aeroplane pilots who first discovered them from the air in the 1920s and thought they looked like toy kites, the structures probably lured gazelles or other wild prey into narrower parts of the structure where they would get cornered or fall, says Wael Abu-Azizeh at the French Institute for the Near East.
A stone at Jibal al-Khashabiyeh, Jordan, engraved with a plan of a desert kiteSEBAP & Crassard et al. 2023 PLOS ONE
But despite the complexity of these Stone Age structures, the rare artistic representations of them found so far have been nothing more than rough abstract sketches. Scientists believed that the oldest true architectural plans that were at least intended to be to scale dated to Mesopotamian civilisations 2300 years ago.
In March 2015, Crassard and his colleagues accidentally came across an 80-centimetre-tall, 92-kilogram limestone tablet in an excavated campsite near a 9000-year-old kite in Jordan, with detailed architectural plans etched into it. They could hardly believe it, but, even more surprisingly, they stumbled across a second kite plan only three months later, this time etched into a 3.8-metre-tall sandstone boulder that had fallen from a cliff near a pair of 7500-year-old kites in Saudi Arabia.
“These were really emotional moments for us in our scientific careers,” says Crassard. “Finding one was already exceptional, but finding two was even more exceptional. We were yelling and dancing around!”
Recognising similarities with the kites nearby, the researchers used computer modelling to mathematically compare the engraved images with satellite images of 69 kites. They found that the plans etched into stone were “surprisingly realistic and accurate” depictions of actual kites within a distance of 1 to 2 kilometres, says Crassard. The two plans had been created at scales of 1:175 and 1:425 and even included three-dimensional pitting to represent the kites’ pit traps.
The plans might have helped build the huge, complex structures, but they might also have guided hunters to understand how best to use them, says Abu-Azizeh.

That seems like the most plausible explanation, says Sam Smith at Oxford Brookes University, UK, who wasn’t involved in the study. Like football coaches drawing their tactics on a white board, members of the Neolithic community may have used the scale images to communicate with each other about group hunting strategies. “I can easily imagine that these engravings would have formed a vital element of planning,” he says.
The fact that they were engraved in “such a durable medium” suggests they may have been intended to last for future generations, he adds. “New members of the community, or hunting party, would not have any real way to comprehend the kites without depictions such as these,” says Smith.
How these ancient engineers attained such geometric accuracy without modern tools like GPS or a tacheometer is perplexing, says Olivier Barge, also at the CNRS. “We don’t know how they did it.”

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Mosquitoes may pick up on the fragrances in body washesbrizmaker/iStockphoto/Getty Images
The body wash you use in the shower may react with your natural odour to make you more attractive to mosquitoes.
Mosquitoes use various methods to find a target for their next blood meal, such as detecting an animal’s body heat, odour and the carbon dioxide they emit.
To learn if the body wash we use may have an effect, Clément Vinauger at Virginia Polytechnic Institute and State University and his colleagues selected varieties from the brands Dial, Dove, Native and Simple Truth.Advertisement
First, they placed two strips of nylon on one of the forearms of four volunteers and wrapped that area in foil, to collect the participants’ natural odour.
Next, the researchers washed part of each participants’ other forearm with about 1 gram of one of the body washes for 10 seconds, before rinsing it with water for a further 10 seconds. They then similarly applied two strips of nylon and foil to these forearms, to collect the wash’s scent. The researchers repeated this with the three other body washes.
One hour after each sample was taken, they took two strips – one from each of the body wash-exposed areas and one from the body wash-free areas – for chemical analysis while the other body wash-free and body wash-exposed strips were put in separate cups.
The researchers placed these inside cages with 16 to 25 female Aedes aegypti mosquitoes, which can transmit yellow fever, that were free to visit either cup.
The Simple Truth body wash appeared to increase the attractiveness of all of the participants, measured by the number of times the mosquitoes landed on their body wash-exposed strips compared with their body wash-free strips. The Dove wash had a similar effect, but the increase in attractiveness was only pronounced for three of the participants.
Dial’s body wash similarly made the participants more attractive to mosquitoes, but to a lesser extent than Simple Truth’s or Dove’s.
In contrast, the mosquitoes tended to avoid the strips washed in the Native body wash, but displayed a particularly strong aversion towards one participant’s Native-washed strip.
This suggests the body washes’ fragrances and the participants’ individual odours combined to create a scent that was detectable to the mosquitoes.
“Our study highlights the importance of the interaction between the specific soap chemicals and the body odour of each person in determining whether a person would become more or less attractive to mosquitoes after applying soap to their skin,” says Vinauger.
The experiment’s chemical analysis suggests that the compounds benzaldehyde, benzyl benzoate and γ-nonalactone may repel mosquitoes.

The researchers are planning to repeat their study with a larger group of participants and more body washes, and will investigate how long a wash’s potential mosquito-attracting or mosquito-repelling effects last after it is washed off the skin.
“The discovery that personal care products may cause mosquitoes to be attracted or repelled by the user opens the door for developing user-friendly mosquito repellents,” says Walter Leal of the University of California, Davis.
“The chemicals in such products may not directly affect mosquito behaviour, but they may disrupt the specific ratio of human emissions that attract mosquitoes,” he says. “Regardless of the mechanism, reducing human-mosquito interactions mitigates the transmission of vector-borne diseases.”
New Scientist contacted the four body washes’ manufacturers for comment but received no reply prior to publication.

Topics:Mosquitoes/Hygiene More

SolStock/Getty Images
MORE than 2300 years ago, Aristotle argued that happiness was the highest good. Later, the US founding fathers considered its pursuit to be an unalienable human right. These days, you will find countless books promising to reveal the secrets of a happy life. But have millennia of philosophical and scientific enquiry taught us anything about how to achieve that?
First, let’s look at how people who study happiness measure it. One of the most common strategies is to ask people to rate statements such as “In most ways, my life is close to my ideal” and “If I could live my life over, I would change almost nothing”. These aim to capture someone’s overall satisfaction with life, rather than their mood on a specific day.
That makes sense, says Richard Layard, co-director of the Community Wellbeing Programme at the London School of Economics, because asking people to sum up their general contentment is often more practical than measuring their emotional state over an extended period. The other thing, says Layard, is that general contentment fits better with philosophical definitions of happiness as an overarching quality, as opposed to transient pleasures.
Using this kind of scale, psychologists have attempted to identify the specific ingredients that contribute to happiness. Contrary to the idea that “money can’t buy happiness”, income does play a role: it is easier to feel pleased with your lot when you don’t have to worry about bills and can treat yourself to luxuries.
We are also influenced by the riches of others – we are less happy if we know our neighbour is earning more than us. … More

Shutterstock/sumikophoto
IMAGINE a child, running barefoot through a forest, and a broken glass bottle buried just beneath the soil. What’s worse: that a present-day child steps on the shards, or that a child in 100 years from now does?
This question, posed by philosopher Derek Parfit in the 1980s, was intended to clarify our moral obligations towards unborn generations. Knowingly risking harm to a future person, he argued, is just as bad whether it is today or in a century.
Parfit’s ideas inspired a branch of moral philosophy called longtermism. It rests on three premises: future people matter, there could be a lot of them and we have the power to make their lives better or worse. Ensuring the future goes well should therefore be a key moral priority of our time.
All of which seems reasonable, at first glance: it apparently promotes the universal values of stewardship, the duty to posterity and being a “good ancestor”. But longtermism has proven controversial, with some critics arguing that it is a “dangerous ideology” that permits or even encourages the suffering of people alive today.
Is that fair? To make up your own mind, the first thing you need to know is that longtermism comes in different flavours. Many of the most strident criticisms focus on the implications of “strong longtermism”, a variant introduced in a 2021 paper by the University of Oxford’s Hilary Greaves and William MacAskill, which says that it should be the top moral priority of our time.
This would have striking consequences for how money is spent in the real world. Indeed, it is already having an influence. … More

Wine drinkers have a lot of options when choosing their preferred varietyKlaus Vedfelt/Getty Images
Variations in our salivary proteins may explain why different people can like different wines. Researchers have linked the concentrations of two types of proteins to how intense wine drinkers find a wine’s notes, such as fruity or floral, and their preferences for the alcoholic drink.
A person’s wine preferences may at least partially come down to their cultural background, knowledge of the drink and individual taste. But Kate Howell at the University of Melbourne, Australia, and her colleagues … More