Humans

Noelia de Alda
Is it in the way we live, laugh and love? Or maybe it is our dislike of cheesy clichés? Deep within each of us, there must be something that makes us distinctly human. The trouble is, after centuries of searching, we still haven’t found it. Perhaps that’s because we have been looking in the wrong place.
Ever since researchers began unearthing ancient hominin bones and stone artefacts, their work has held the tantalising promise of identifying the moment long ago when our ancestors made the transition to become human. Two of the most important fossil discoveries in this quest celebrate significant milestones this year. It is 100 years since the very first “almost human” Australopithecus fossil came to light in South Africa, overturning established thinking about our place of origin. And it is 50 years since the most famous Australopithecus of them all – Lucy, also known as “the grandmother of humanity” – emerged from a dusty hillside in Ethiopia. Both fossils led researchers to believe we really could identify humanity’s big bang: the time when a dramatic pulse of evolution saw the emergence of our human genus, Homo.

But today, the story of humanity’s birth has become far more complicated. A string of discoveries over the past two decades suggests the dawn of our genus is harder to pin down than we had thought. So why did it once seem like Lucy and her ilk allowed us to define humanity and pinpoint its emergence? Why do we now find ourselves as far as ever from establishing what, exactly, a human is?… More

Noelia de Alda
Is it in the way we live, laugh and love? Or maybe it is our dislike of cheesy clichés? Deep within each of us, there must be something that makes us distinctly human. The trouble is, after centuries of searching, we still haven’t found it. Perhaps that’s because we have been looking in the wrong place.
Ever since researchers began unearthing ancient hominin bones and stone artefacts, their work has held the tantalising promise of identifying the moment long ago when our ancestors made the transition to become human. Two of the most important fossil discoveries in this quest celebrate significant milestones this year. It is 100 years since the very first “almost human” Australopithecus fossil came to light in South Africa, overturning established thinking about our place of origin. And it is 50 years since the most famous Australopithecus of them all – Lucy, also known as “the grandmother of humanity” – emerged from a dusty hillside in Ethiopia. Both fossils led researchers to believe we really could identify humanity’s big bang: the time when a dramatic pulse of evolution saw the emergence of our human genus, Homo.

But today, the story of humanity’s birth has become far more complicated. A string of discoveries over the past two decades suggests the dawn of our genus is harder to pin down than we had thought. So why did it once seem like Lucy and her ilk allowed us to define humanity and pinpoint its emergence? Why do we now find ourselves as far as ever from establishing what, exactly, a human is?… More

A hoard of Bronze Age metal fragments from Weißig, GermanyJ. Lipták/Landesamt für Archäologie Sachsen
Bronze Age Europeans earned and spent money in much the same way as we do today, indicating that the origins of the “market economy” are far more ancient than expected.
That is the controversial conclusion of new research that challenges the view that elites were the dominant force in Bronze Age economies, and proposes that human economic behaviour may not have changed much over the past 3500 years – and perhaps even longer.
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“We often tend to romanticise European prehistory, but the Bronze Age was not a fantasy realm where townsfolk and peasants were merely the background for some great lord providing for their needs,” says Nicola Ialongo at Aarhus University in Denmark. “It was a very familiar world where people had families, friends, a social network, marketplaces and a job, and ultimately had to figure out how to make ends meet.”
Europeans of the Bronze Age, a period that spans 3300 to 800 BC, were not meticulous bookkeepers like people of some other ancient societies, such as Mesopotamia. But Ialongo and Giancarlo Lago at the University of Bologna, Italy, suggest that important revelations about their daily lives, and the roots of our own modern economic behaviour, can be found in the troves of metal fragments, known as hoards, that they left behind.
Lago and Ialongo analysed more than 20,000 metal objects from hoards buried in Italy, Switzerland, Austria, Slovenia and Germany during the Bronze Age. The pieces appear in many forms, but around 1500 BC, they start to become standardised by weight, a shift that many experts believe distinguishes them as a form of pre-coinage money.
“The discovery of a widespread measurement and weight system makes it possible to model things that have been known about for centuries in a way that they have never been modelled before,” says Ialongo. “This opens up new results to old questions, but also new questions that no one was asking before.”
To that end, the team found that the weight values of the huge sample follow the same statistical distribution as the daily expenses of a modern Western household: small everyday expenses, represented by lighter fragments, made up the vast majority of consumption patterns, while larger expenses, represented by heavier fragments, were comparatively rare. This pattern is analogous to what you might find in an average modern wallet, with lots of smaller banknotes and very few high-value ones.
Lago and Ialongo interpret the findings as evidence that Bronze Age economic systems were regulated by supply and demand market forces, in which everyone participates proportionally to how much they earn. This hypothesis stands in contrast to an influential view put forth in the 1940s by the anthropologist Karl Polanyi, who cast modern economies based on monetary profit as a new and distinct phenomenon from ancient economies centred around barter, gift exchange and social standing.
Richard Blanton at Purdue University in Indiana finds the study to be credible. “The argument, I think, will prompt discussion among archaeologists and economic anthropologists, who have been labouring under false assumptions about the antiquity of market economies for decades,” he says.
“I think this paper will beneficially add fuel to that kind of critique,” says Blanton. “For me, the paper throws a whole new light on the function of the bronze hoards and their potential for the use of bronze pieces as units of exchange.”

However, Erica Schoenberger at Johns Hopkins University in Maryland is sceptical of the team’s conclusions. “It’s risky to assume that ordinary people in pre-modern times used money in ordinary economic ways,” says Schoenberger. “Medieval English peasants, for example, only began selling their produce for money when their lords began demanding money in place of in-kind rents and taxes. The peasants handed most – if not all – of that money directly to the lord. They sold in order to get money, but they did not use it to buy things they needed. We’re still a long way from modern economic behaviour [in the Middle Ages].”
Lago and Ialongo hope their research will inspire specialists in other fields to develop similar work on artefacts from different regions and cultures. They suggest that market economies naturally arose across time and cultures, and that such systems are not new or special inventions of Western societies that emerged over the past few centuries.
“Technically, we do not prove that the Bronze Age economy was a market economy,” says Ialongo. “We simply find no evidence that it wasn’t. And we simply point out the paradox: why is everyone convinced that the market economy did not exist, if everything we see can be explained by a market economy model? In other words, why should we imagine a more complex explanation, if the simplest one works just fine?”

Topics:archaeology/economics More

Did the Step Pyramid of Djoser include a hydraulic lift?Peter Brown / Alamy
The construction of ancient Egypt’s oldest known pyramid may have benefited from a water elevator capable of lifting 50 to 100 tonnes of stones at a time.
The suggestion draws upon the fact that the Step Pyramid of Djoser – built 4500 years ago as the burial place for an Egyptian pharaoh as part of the Saqqara necropolis site – is near two dry channels, probably once active waterways. These could have supplied rainfall runoff and Nile river water to the pyramid construction site, where… More

A researcher plucks a bird as part of an experiment into Neanderthals’ cooking skillsMariana Nabais
Archaeologists have cooked and prepared five wild birds using only fire, their hands and stone tools to learn more about the culinary abilities of Neanderthals. The experiment shows it took considerable manual skill for our ancient relatives to butcher animals using flint blades without injuring themselves.
Neanderthals inhabited Europe and Asia until around 40,000 years ago. Hearths have been found at many Neanderthal sites, and we also have evidence they hunted large animals like elephants and cave lions.
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Mariana Nabais at the Catalan Institute of Human Paleoecology and Social Evolution in Tarragona, Spain, says by replicating ancient activities such as cooking and butchering with the tools available at the time, scientists can gain insight into how prehistoric humans lived.
She and her colleagues wanted to better understand archaeological bird remains associated with Neanderthals that were recovered from deposits in Portugal, which date to approximately 90,000 years ago.
The team selected five birds that had died in a Portuguese wildlife rehabilitation centre and were of a similar size and species to those found in the archaeological deposits: two carrion crows (Corvus corone), a common wood pigeon (Columba palumbus) and two Eurasian collared doves (Streptopelia decaocto). The tools used in the experiment were flint flakes prepared by lithic technology students.
All five birds were plucked by hand. A crow and a dove were butchered uncooked and the remaining three birds were baked on a bed of coals. The cooked birds could be easily pulled apart without stone tools, but the raw birds required considerable effort using the flint blades.
“Palaeolithic knives were indeed very sharp, requiring careful handling,” says Nabais. “The precision and effort needed to use these tools without causing self-injury emphasised the practical challenges Neanderthals might have faced in their daily food-processing activities.”
Once the butchering was complete, the researchers prepared the bones and then analysed them for distinctive signs caused by the stone tools and the fire. They also identified wear marks on the flint tools.
The burn marks and tool scars were then compared with Neanderthal food remains from the Figuiera Brava and Oliveira archaeological sites, both in Portugal. Bird bones with burning stains and cut marks found at the sites align with those seen in the team’s replications, says Nabais.
“Our experimental study demonstrated that raw birds processed with flakes show distinctive cut marks, especially around tendons and joints, while roasted birds show burn marks and increased fragility, leading to bone breakage,” she says. “These finds help distinguish human-induced modifications from those caused by natural processes or other animals, such as trampling or the activity of rodents, raptors and carnivores.”
Neanderthals were skilled enough to catch and cook small, quick animals like birds, says Nabais. “This study highlights the cognitive abilities of Neanderthals, demonstrating their capacity to catch and process small, fast-moving prey like birds, thus challenging the traditional notion that Neanderthals were not capable of such complex tasks.”

Sam Lin at the University of Wollongong, Australia, says experimental archaeology is like reverse engineering where you compare what happens to a modern sample with archaeological material to try to interpret what may have happened in the past.
In this case, one of the main findings was that cooked birds don’t need tools to be prepared for eating, which could mean some bones won’t necessarily have tool scars. “They learned you can just rip a cooked wild bird apart the same way we eat a barbecue chicken,” says Lin.

Topics:Neanderthals/cooking More

Those living in Papua New Guinea’s highlands may benefit from having Denisovan DNAMichael Runkel/Danita Delimont/Getty Images/Gallo Images ROOTS
People living in the highlands and lowlands of Papua New Guinea have different frequencies of several Denisovan genetic variants, which may help them adapt to their local environmental conditions.
The Denisovans were hominins that lived across eastern Eurasia for hundreds of thousands of years, giving them plenty of time to adapt to a variety of environments.

After leaving Africa, Homo sapiens interbred with other human species, including Denisovans,… More

The culture that built Stonehenge suffered a mysterious population declineWirestock, Inc./Alamy
The Neolithic culture in Europe that produced megastructures such as Stonehenge went into a major decline around 5400 years ago. Now we have the best evidence yet that this was due to plague.
Sequencing of ancient DNA from 108 individuals who lived in northern Europe at this time has revealed that the plague bacterium Yersinia pestis was present in 18 of them when they died.
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“We think that the plague did kill them,” says Frederik Seersholm at the University of Copenhagen in Denmark.
Around 5400 years ago, the population of Europe fell sharply, particularly in northern regions. Why this happened has long been a mystery.
Over the past decade, studies of ancient human DNA have revealed that local populations didn’t fully recover from the Neolithic decline. Instead, they were largely replaced by other people moving in from the Eurasian steppes. In Britain, by around 4000 years ago, for instance, less than 10 per cent of the population was derived from the people who built Stonehenge.
These studies of ancient humans also revealed several cases where the plague bacterium was present. This suggested a potential explanation – the plague might have wiped out Europe’s population, allowing the steppes people to move in with little opposition.
But not everyone agreed. Occasional sporadic plague cases are to be expected and aren’t evidence of a major pandemic, argued Ben Krause-Kyora at Kiel University in Germany in 2021. These early forms of Y. pestis were unlikely to cause a pandemic because their DNA shows they couldn’t survive in fleas, he and his colleagues wrote. Bites from infected fleas are the main way people contract bubonic plague, the form of the illness that killed people during the medieval Black Death.
So Seersholm and his colleagues set out to find more evidence of a plague pandemic. The 108 individuals whose DNA his team managed to sequence were buried in nine tombs in Sweden and Denmark. Most died between 5200 and 4900 years ago, and they represent several generations of four families.
There seem to have been three separate outbreaks of the plague over these generations. The last outbreak was caused by a strain with reshuffled genes that might have been much more dangerous.
“It’s present in a lot of individuals,” says Seersholm. “And it’s all the same version, which is exactly what you would expect if something spreads very quickly.”
The plague DNA was found mainly in teeth, which shows that the bacterium entered the blood and caused serious illness, and was probably the cause of death, he says. In some cases, closely related individuals were infected, implying person-to-person spread.
The team suggests this could be a result of Y. pestis infecting the lungs and spreading via droplets – a form of the illness known as pneumonic plague. Recent studies also indicate that human lice can cause bubonic plague, not just fleas, so it is possible that plague bacteria spread by this route.
“Of course, it’s worth noting that all of these individuals were buried properly,” says Seersholm, so society hadn’t broken down at this time. “If there was in fact an epidemic, we only see the very beginning of it.”

After about 4900 years ago, the megalithic tombs seem to have been abandoned for centuries. But 10 of the sequenced individuals were buried in them much later, most between 4100 and 3000 years ago. These individuals were of steppes origin, unrelated to those who built the tombs.
“It is 100 per cent complete replacement,” says Seersholm. “Five thousand years ago, these Neolithic people disappear. And now we show that plague was widespread and abundant at exactly the same time.”
The researchers aren’t claiming their findings are definitive, but they do bolster the case that plague caused the Neolithic decline, says Seersholm.
“I would say that we’ve definitely shown that it had the potential to spread within humans, and that it had the potential to kill an entire family, for example.”
Krause-Kyora accepts that the findings show the plague was highly prevalent in this particular place and time. “Our previous explanation needs to be revised somewhat, and we can’t just talk about isolated cases,” he says.
But there is no evidence of high prevalence in other regions, he says. And he thinks the normal burials show there was no deadly epidemic. “The results could even suggest that the Yersinia infection was more of a chronic disease over a long period of time.”
Seersholm and his team will now look for more evidence elsewhere in Europe. But the only way to know for sure how deadly the reshuffled strain was would be to bring it back to life, he says, and that is far too risky to attempt.
“I think that this paper will convince many colleagues who were skeptical about our previous work,” says Nicolás Rascovan at the Pasteur Institute in Paris, whose team proposed in 2018 that the plague was responsible for the Neolithic decline after finding it in two individuals from the period.

Topics:archaeology/infectious diseases More

Cast of the Sahelanthropus tchadensis skullDidier Descouens CC BY-SA 4.0
This is an extract from Our Human Story, our newsletter about the revolution in archaeology. Sign up to receive it in your inbox for free every month.
The period between 7 million and 4 million years ago is a bit of a nebulous phase in the story of human evolution. There are basically four data points: Sahelanthropus tchadensis from 7 million years ago, Orrorin tugenensis from 6 million years ago and the two species of Ardipithecus from 5.6 million and 4.4 million years ago. Each is known from a handful of incomplete fossils. For a period of 3 million years, that’s not much. For comparison, there are dozens of Neanderthal sites from the past 500,000 years.
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This means that the few fossils we have from the nebulous phase of hominin evolution have taken on an outsized importance. Every detail of their interpretation is scrutinised and discussed endlessly.
Despite being the oldest known hominin, Sahelanthropus is a relatively recent discovery, first described in 2002 by a group of researchers largely based at the University of Poitiers in France. The remains were found in the deserts of Chad, which is in north-central Africa, a long way from eastern countries of the continent like Ethiopia and Tanzania that had yielded many famous fossils.
The main find was a skull, which was named Toumaï. In New Scientist’s report at the time, writer Jeff Hecht said it didn’t resemble any modern great ape: “Although its body and brain were the size of a modern chimp’s, its face was quite different, with large brow ridges and much smaller canine teeth.” The researchers also found some teeth and bits of jawbone.
What they didn’t find were leg bones. This was unfortunate, because leg bones ought to tell us about how Sahelanthropus walked: did it walk on two legs like us and many later hominins, did it knuckle-walk like a chimpanzee or did it do something else entirely?
The French researchers who described Sahelanthropus argued it was bipedal. This was based mainly on the base of the skull and how it apparently fitted onto the spine: it looked like the skull sat directly atop the spinal column, as opposed to being at an angle like in an ape skeleton. It was an intriguing argument – but far from conclusive.
For the better part of two decades, this was largely how things rested. Which was weird, because, in fact, limb bones had been found: the original team had found a femur (thigh bone) and two ulnas (forearm bones). A student at the University of Poitiers, Aude Bergeret-Medina, identified the femur as belonging to Sahelanthropus in 2004. Her tutor, Roberto Macchiarelli, supported her. However, they were denied further access to the bone.
In 2018, the pair tried to present their own analyses of the femur at a conference at the University of Poitiers, but they were blocked by the organisers. Other palaeoanthropologists criticised this decision. John Hawks at the University of Wisconsin-Madison wrote a blog post that, while couched in polite academic language, was basically furious. “All of the critics could be silenced within hours by data and evidence,” Hawks wrote. “Instead, silence about these key fossils has reigned for fifteen years.”
3D models of the femur (left) and ulnae (centre and right) of Sahelanthropus tchadensisFranck Guy/PALEVOPRIM/CNRS – University of Poitiers
The following year, Macchiarelli and Bergeret-Medina submitted a paper about the femur to the Journal of Human Evolution, which was finally published in November 2020. The key point was that the Sahelanthropus femur was curved. This is typical of a great ape like a chimpanzee, and not what you’d expect of an upright-walking hominin. Our leg bones are straight because they need to act like pillars supporting the entire weight of our bodies. I consulted two independent palaeoanthropologists, including the discoverer of Orrorin, and they both agreed: Sahelanthropus didn’t look like a biped.
However, the original Poitiers research team, after years of silence, decided to start talking. In September 2020, two months before the publication of Macchiarelli and Bergeret-Medina’s new paper, researchers led by Franck Guy (a co-author of the original Sahelanthropus paper from 2002) and Guillaume Daver at the University of Poitiers released a preprint, which was eventually published in Nature in 2022.
Guy and his colleagues highlighted a number of features of the femur that they say indicate bipedality. For instance, thicker regions along the shaft of the bone correspond to those seen in modern humans and are different from those in great apes. There was also “a rough surface at the top of the femur where the buttock muscles attach”.
So, case closed? Not quite.
No to bipedalism
In June, a team that included Macchiarelli and Bergeret-Medina published a response in the Journal of Human Evolution. The paper is a point-by-point rebuttal of Guy and Daver’s paper.
“Most of the analysis they published in this paper [does] not show any signal of bipedalism, in our opinion,” says Clément Zanolli at the University of Bordeaux in France, one of the authors of the new study. Features that Daver and Guy claimed were solely found in later bipedal hominins can actually be found in some older ape species, which weren’t bipedal.
For example, the top end of a femur has a ball-shaped bit sticking out, which fits into the pelvis. This ball is missing from the Sahelanthropus femur, but we do have the section immediately below. This includes a thickened section called the calcar femorale, which helps support the weight of the body.
“It was supposed to be a hallmark of bipedalism,” says Zanolli. Daver and Guy interpreted the presence and shape of the calcar femorale as evidence that Sahelanthropus habitually walked on two legs. However, “this feature is actually found also in African apes and in many primates,” says Zanolli. So, he argues, it isn’t useful for deciding whether a species was bipedal.
Zanolli’s team also reanalysed the two arm bones, in order to estimate the relative lengths of Sahelanthropus’s arms and legs. Bipedal hominins have proportionally longer legs and shorter arms than knuckle-walking apes, so this is another clue to how Sahelanthropus got around. On this measure, the team found that Sahelanthropus was most similar to modern gorillas and orangutans, and nowhere near bipedal hominins like Australopithecus or Homo.

The paper has other analyses, but you have probably got the gist at this point. The overall message is that the few pieces we have of Sahelanthropus’s limbs don’t show strong evidence of habitual bipedal walking. “It’s generally indistinguishable from the African apes,” says Zanolli.
At this point, you will be wondering what the authors of the 2022 paper have to say about all this. I’m afraid you will have to keep wondering, because Guy declined to comment. He told me that he and his colleagues are writing a reply, which will be published in the same journal, and which they expect to have finished “before August”. He didn’t want to discuss the results until that was done.
Meanwhile, some of Zanolli’s colleagues are pressing ahead with analyses of computer tomography (CT) scans of the bones. Not all of them, though, because some members, including Zanolli, were denied access by the government of Chad. Zanolli says this is highly unusual: “In most countries I’ve been, it’s quite easy, or at least it’s possible, to access fossil material.” He says this is the only time he has been denied access.
Other parts of the skeleton could also shed more light. “I think the teeth should be investigated further,” says Zanolli. “There is not really a paper published on the teeth.”
The future of the past
Finally, let’s step back from the details of the Sahelanthropus fossils and put them into their full context.
As a first step, suppose Zanolli and his colleagues are right. That means Sahelanthropus isn’t bipedal and possibly isn’t even a hominin. That doesn’t mean it’s suddenly a boring fossil. If anything, it becomes even more important.
That’s because Sahelanthropus would become a key fossil for the evolution of African great apes. That’s something we know almost nothing about. “If it’s an ancestor of gorillas, for example, it would be also fantastic, because we have not a single fossil for the ancestors of gorillas,” says Zanolli.
More broadly, it would help to find more hominin and ape fossils from that nebulous time between 7 million and 4 million years ago. Zanolli says part of the problem is that much of central Africa was tropical forest at the time, and some of it still is: fossils tend not to be preserved in such places. Still, there are places like Chad that are promising but under-investigated.
At the moment, this gap in the fossil record is a target for fascinating but unproven speculations. When and where did bipedality evolve? Did it evolve only once in one lineage of apes, or multiple times independently? What evolutionary pressures led to the emergence of bipedal hominins?
For now, we can’t even be sure that bipedality evolved in Africa. It’s tempting to think so, because the oldest bipedal hominins we know of are African, even if you discount Sahelanthropus. A study published in May combined the locations of known hominin and ape fossils and their suspected relationships, and concluded that the group that includes both chimpanzees and hominins probably originated in north-central Africa.
But animals do move around, especially over millions of years. While apes originated in Africa 26 million years ago, climatic shifts meant that for millions of years, they were more widespread and diverse in Eurasia, before largely moving back to Africa later on. A minority of researchers claim that European apes had signs of bipedal walking as early as 11.6 million years ago. There are also hominin-like footprints on the Greek island of Trachilos, which are 6.05 million years old – about on a par with Orrorin and a million years younger than Sahelanthropus. For added variety, a study from February claimed a key role in the story for Lufengpithecus, apes that lived in what is now China around 6 million years ago.
The evidence for bipedality evolving in Eurasia rather than Africa is strongly contested, because it’s based on incomplete and even fragmentary skeletons. But so is the idea that Sahelanthropus was a biped. Again, this is why I describe this whole period as nebulous.

As for how and why bipedalism evolved, we don’t know. Not that this has stopped people coming up with ideas. A paper from March suggested that the last common ancestor of hominins and other African apes lived in Eurasia, but that a dramatic event separated the population into two, which then evolved independently.
What dramatic event? Why, the Zanclean Megaflood of course. If you don’t know, there was a period between about 6 million and 5.3 million years ago when the Mediterranean almost entirely dried out. The Strait of Gibraltar, which connects the Mediterranean to the wider Atlantic, closed – and the sea gradually evaporated, leaving hypersaline lakes. This was the Messinian Salinity Crisis.
Then, around 5.3 million years ago, the Strait of Gibraltar reopened – and the waters of the Atlantic came rushing in. One reconstruction estimated that it took “from a few months to two years” to refill the Mediterranean basin, which, if not an apocalyptic mega-tsunami, is still pretty fast.
Supposedly, this Zanclean Megaflood cut off one population of apes/hominins on the Arabian peninsula, while others were able to reach Africa – creating an evolutionary split. In May, a separate group went further and linked the closure and reopening of the Mediterranean to changes in the behaviour of the Pacific tectonic plate. In this view, the evolution of bipedality and/or hominins was driven by geological processes on the largest scale.
You may be able to tell that I’m unconvinced by all of this. It seems to me there are far too many intermediate steps from the Pacific tectonic plate and the Zanclean Megaflood to hominins habitually walking upright, and we can’t be sure about any of them. We don’t even know the timing of the origin of bipedality. If either Sahelanthropus or Orrorin was bipedal, the behaviour evolved well before the megaflood.
So, much as I want to link the origin of hominins to the biggest flood of the past 10 million years, I think we probably ought to find some more fossils first.

Topics:human evolution More