Some chimpanzees seem to use sexual behaviour like genital rubbing to manage stressful situations, which shows they aren’t as different from hypersexual bonobos – our other closest living ape relatives – or, indeed, people as we thought.

at Durham University, UK, and his colleagues have investigated the sexual behaviour of non-human primates at the in the Democratic Republic of the Congo and the in Zambia. Both sanctuaries include a mix of wild and captive-born apes that can roam and forage freely within them.

The researchers observed 53 bonobos (Pan paniscus) across three groups at Lola ya Bonobo and 75 chimpanzees (Pan troglodytes) across two groups at Chimfunshi in the course of feeding events that involved a swing distributing a limited supply of peanuts over a particular area.

“Bonobos and chimpanzees both live in very complex social structures with very rich social interactions that they have to navigate on a daily basis,” says team member , also at Durham University. Anticipating such feeding events can be stressful because of competition over who gets to the food first.

The researchers observed 107 instances of genital contact in the bonobos and 201 in the chimpanzees in the 5 minutes before 45 feeding events across the five groups.

“This is either putting a hand or foot onto another primate’s anogenital region and it also might involve the genitals touching each other, like the genital rubbing behaviour that bonobos are very famous for,” says Brooker.

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The study also revealed differences between the species: “We found the frequency of sex in these situations was more common in female bonobos with other females, whereas it was more common among males in chimps,” says Clay. That may be linked to the fact that bonobos live in matriarchal groups, while chimpanzees live in patriarchal ones, she says.

“Using sex as a social tool to navigate all sorts of social problems has given bonobos a bit of a reputation as a sort of sexy, hippie ape,” says Clay. “This work shows us that the differences between the two species are maybe not as big as was previously assumed. Chimpanzees, although they’re known to be aggressive and violent, actually have a really rich repertoire of behaviours that they use to manage their social lives.”

“Chimps have definitely drawn the PR short straw by comparison to bonobos,” says at the University of Oxford.

The chimps use sex in a way that goes beyond reproduction and although it is different from sexuality in humans, we also don’t just have sex for reproduction, says Clay. For instance, has been given as a reason people have sex.

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at the University of Bristol, UK, wonders whether the same level of behaviour would be seen in wild settings rather than sanctuaries.

The work may also shed light on our last common ancestor, which lived some 5 million to 7 million years ago, before humans diverged from chimps and bonobos, he says.

“Given that all three species use sexual behaviours to navigate social relationships, the common ancestor we share likely did too,” says Brindle.

Wild chimpanzees appear to learn skills from each other and then – much as humans do – improve on those techniques from one generation to the next.

In particular, young females that migrate between groups bring their cultural knowledge with them, and groups can combine new techniques with existing ones to get better at foraging for food. Such “cumulative culture” means some chimpanzee communities are becoming more technologically advanced over time – albeit very slowly, says at the University of St Andrews, UK.

“If chimpanzees have some cultural knowledge that the community they’re moving into doesn’t have, they may pass it on – just in the same way they’re passing the genes on,” he says. “And then that culture builds up from there.”

Scientists already knew that chimpanzees were capable of using tools in sophisticated ways and passing on that knowledge to their offspring. But in comparison with the rapid technological development of humans, it seemed that chimpanzees weren’t improving on previous innovations, says Whiten. The fact that chimpanzee tools are often made from biodegrading plants makes it difficult for scientists to track their cultural evolution.

at the University of Zurich in Switzerland suspected she might be able to apply genetic analysis to the puzzle. While male chimpanzees stay in their home area, young females leave their native communities to find mates elsewhere. She wondered if those females have brought their skill sets with them into their new groups.

To find out, she and her colleagues acquired data on 240 chimpanzees representing all four subspecies, which were at 35 study sites in Africa. The data included precise information about what tools, if any, each of the animals used, and their genetic connections over the past 15,000 years. “The genetics give us a kind of time machine into the way culture has been transmitted across chimpanzees in the past,” says Whiten. “It’s quite a revelation that we can have these new insights.”

Some chimpanzees used complex combinations of tools, for example a drilling stick and a fishing brush fashioned by pulling a plant stem between their teeth, for hunting termites. The researchers found that the chimpanzees with the most advanced tool sets were three to five times more likely to share the same DNA than those that used simple tools or no tools at all, even though they might live thousands of kilometres away. And advanced tool use was also more strongly associated with female migration compared with simple or no tool use.

“Our interpretation is that these complex tool sets are really invented by perhaps building on a simpler form from before, and therefore they have to depend on transmission by females from the communities that invented them initially to all the other communities along the way,” says Whiten.

“It shows that complex tools would rely on social exchanges across groups – which is very surprising and exciting,” says Gunasekaram.

at the University of Geneva isn’t surprised by the results, but says the definition of complex behaviour is debatable. ��“After working with chimps for 20 years, I would argue that stick use itself is complex,” he says.

His own team, for example, found what they called cumulative culture in chimpanzees that make sponges out of moss instead of leaves – which is no more complex, but . “It’s not a question of being more complex, but of just having a technique that builds on a previously established one,” he says.

Cumulative culture is still markedly slower in chimpanzees compared with humans, probably due to their different cognitive abilities and lack of speech, says Gunasekaram. Also, chimpanzees interact far less with others outside their communities compared with humans, giving them fewer opportunities to share culture.

A tiny, vegetarian great ape may have lived in western Europe 11.6 million years ago. Smaller and lighter than any other known great ape, the newly discovered 10-kilogram primate was a skilled climber that probably ate leaves, says at the University of Tübingen in Germany.

“It’s quite a small primate,” she says. “But it differs from all known fossils and, of course, all living great apes we know so far.”

About 15 million years ago, in the middle of the Miocene Epoch, hominoids – the great apes – became rarer in Africa and more abundant in Europe. While they sometimes shared habitats with other primates such as pliopithecoids – extinct cousins of apes and Old World monkeys – hominoid species didn’t appear to coexist with each other in Europe.

In 2019, Böhme and her colleagues reported the discovery of 37 bones at Bavaria’s Hammerschmiede archaeological site that appeared to come from an early bipedal ape from 11.6 million years ago, which they named Danuvius guggenmosi.

During the excavations, Böhme was surprised when she found two tiny, ape-like teeth and a kneecap in the same layer of sediment as the Danuvius fossils.

“We kept saying: ‘What is this?’” she says of these smaller fossils. “And then we decided, OK, it’s clear: this is something new.”

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The fossils are too old for DNA analysis, says Böhme. So the researchers took detailed measurements of the 7-millimetre-long molar and the 16-millimetre-wide kneecap, both from a juvenile, as well as a smaller premolar fragment, which they say came from a young adult. They also calculated the thickness of the enamel and ran microscopic CT scanning of the teeth.

The thin enamel, like that of gorillas, suggests a soft diet probably composed of leaves, says Böhme. The shape, thickness and ligament attachment sites of the kneecap resemble those of tree-living primates, hinting that the ape was a proficient climber.

The researchers named the new ape Buronius manfredschmidi, after the medieval name of a city near the Hammerschmiede site, and a dentist named Manfred Schmid who has been collecting fossils from the site since the 1970s.

Lack of competition for resources might explain why the Buronius and Danuvius apes could live together, says Böhme – Danuvius is thought to have eaten hard foods like nuts and possibly meat. The team cannot rule out the possibility that the larger ape, which might have been up to three times heavier, may have sometimes fed on the smaller species, she adds.

However, the three fossils might not be sufficient to make such “grandiloquent” conclusions, says at the American Museum of Natural History in New York City. “Could the smaller fossil elements belong to an infantile Danuvius individual?” he asks. “The teeth certainly look like they could be deciduous [baby teeth].”

He also wonders whether the kneecap represents the same species as the teeth. “Even though it is suggested that it belongs to a juvenile individual, its size overlaps with the lower range of adult orangutans [which are much larger apes],” says Almécija.

at the University of Bordeaux, in France, also has doubts. “It is not very clear to me if the teeth – and in particular the molar – belong to the hominoids or to another primate superfamily, the pliopithecoids.”

Böhme and her colleagues say their comparisons ruled out the possibility that the teeth are baby teeth or pliopithecoid teeth.

In any case, the possibility that two primate species shared the same habitat and perhaps even interacted with each other is a “fantastic discovery”, says Zanolli. “This shows once again that, at that time, Europe was a luxurious and hospitable place for primates to evolve.”

Have we misjudged our two closest relatives? Chimpanzees are known for lethal violence while bonobos are widely seen as paragons of peaceful coexistence, free love and female empowerment – but a new study suggests that the reality is more complicated.

at Boston University in Massachusetts says she has always thought bonobos’ peaceful reputation was “very reductionist”.

To compare the differences in aggression between bonobo and chimpanzee males, she and her colleagues followed 12 males from three bonobo communities at the Kokolopori Bonobo Reserve in the Democratic Republic of the Congo and 14 males from two chimpanzee communities at Gombe National Park in Tanzania.

The researchers tracked each of the primates from when they woke up each morning to when they returned to their nests to sleep at night, recording details of every aggressive incident. Altogether, they logged over 2000 hours following the bonobo males and over 7300 hours tracking chimpanzees.

Aggressive behaviours included contact aggression – such as hitting, pulling, biting or kicking – and non-contact aggression, such as charging and chasing.

The team found that bonobo males had 2.8 times as many aggressive interactions as chimp males in total, and three times as many incidents of contact aggression.

However, chimp aggression was more likely to involve coalitions of males and to be directed towards females, whereas male bonobo aggression towards females was extremely rare.

“I was not expecting to find such rates of aggression among [bonobo] males,” says Mouginot.

Bonobo males that acted more aggressively towards other males were more likely to mate with females while they were fertile.

According to Mouginot, one explanation for why bonobos act more aggressively could be the differences in bonobo and chimpanzee coalitions, which change the costs and benefits of aggression.

“In bonobos, females form coalitions but rarely males,” she says. “In chimpanzees, males form coalitions against within-group males or to defend a territory. Therefore, if one [chimpanzee] male acts aggressively against another one, he might face a coalitionary retaliation.”

But for male bonobos, the risk of provoking a group response is lower, so the consequences of aggression are more predictable and less dangerous, she says.

The study also found that male-female interactions are very different between the two species. In bonobos, males avoid acting aggressively towards females and they form close associations with them.

Mouginot says she doesn’t think that conclusions can be drawn from this about any traits that humans might share with chimpanzees, bonobos or a common ancestor.

“Researchers often refer to chimpanzees, or sometimes bonobos, as the ‘best model’ for our last common ancestor,” she says. “I think none of those species are a good model – they all went through their own evolutionary path. What is interesting is to look at how some strategies evolve in some species and not others.”

at Arizona State University says this data suggests that bonobo males are at least as aggressive as chimpanzee males, which isn’t what we would expect of “peaceful” apes. It will be important to look at other groups of bonobos and chimpanzees to see if the results are replicated, she adds.

However, at the University of New England in Armidale, Australia, says she found the paper extremely frustrating and that the word “aggression” is being misused.

Chimpanzee groups are ruled by one dominant male, whereas bonobos are ruled by females. Competitions for dominance and mating rights in bonobos shouldn’t be confused with aggression, says Kaplan. “There’s more pointless violence in chimpanzees and humans than in other species like bonobos,” she says.