Humans

Archaeologists have gathered evidence from hundreds of Bronze Age sites in western Turkey that could be remnants of a civilisation that has been largely overlooked More

Scientists have long tried to uncover the perilous journey humans took to reach the ancient land mass that now makes up Australia. Now, a genetic study has edged us closer to understanding how and when they achieved this More

Hotter temperatures and a series of droughts in what is now Pakistan and India fragmented one of the world’s major early civilisations, providing a “warning shot” for today More

The moai statues on Easter IslandMaurizio De Mattei/Shutterstock
Easter Island’s monumental stone statues may have been created through a decentralised artistic and spiritual tradition, with many different communities making their own carved stone giants, rather than a unified effort coordinated by powerful rulers. That is the finding of an attempt to definitively map the island’s main stone quarry.
Also known as Rapa Nui, Easter Island, in the Pacific Ocean, is thought to have been inhabited by Polynesian seafarers since around AD 1200.
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Archaeological evidence suggests that the Rapa Nui people were not politically unified, but there is debate over whether the hundreds of stone statues known as moai were coordinated by a centralised authority.
The island had only one quarry supplying the volcanic rock from which the statues were carved, a site called Rano Raraku.
Carl Lipo at Binghamton University in New York and his colleagues used drones and high-tech mapping equipment to create the first 3D map of the quarry, which contains many unfinished moai. Previous studies have come to varying conclusions about the number of moai that remain in the quarry, says Lipo.

Lipo and his colleagues recorded 426 features representing moai at various stages of completion, 341 trenches cut to outline blocks for carving, 133 quarried voids where statues were successfully removed, and five bollards that probably served as anchor points for lowering moai down slopes.
They also found the quarry was divided into 30 work areas that each appeared to be separate from the others and featured different carving techniques, says Lipo.
Combined with previous evidence showing that small crews could have moved the moai, and that groups marked out separate territories at freshwater sources, Lipo says it appears the statue carving was not the result of a centralised political authority.
“The monumentality represents competitive display between peer communities rather than top-down mobilisation,” he says.
There has been debate among historians about the supposed decline of the Rapa Nui people, with some claiming that overexploitation of resources led to a devastating societal collapse, but others question that narrative.
Lipo says the collapse story assumes centralised leaders drove the construction of the monuments and this led to deforestation and societal failure. “But if monumentality were decentralised, and that emerged from community-level competition rather than chiefly aggrandisement, then the island’s deforestation could not be blamed on megalomaniacal leadership,” says Lipo.

However, other researchers are not so sure this interpretation is correct. Dale Simpson at the University of Illinois Urbana-Champaign agrees there was not one overarching chief as there were in other Polynesian cultures such as Hawaii or Tonga. But, he says, the clans were not as separate and decentralised as Lipo and his colleagues have proposed, and there must have been collaboration between groups.
“I just wonder if they’re drinking a little too much Kool-Aid and not really thinking about the limitation factors on a small place like Rapa Nui where stone is king and if you’re not interacting and sharing that stone you can’t carve moai just inside one clan,” he says.
Jo Anne Van Tilburg at the University of California, Los Angeles, says further research is underway to clarify how the Rapa Nui people used Rano Raraku and Lipo’s team’s conclusions are “premature and overstated”.

Machu Picchu and the science of the Inca: Peru

Immerse yourself in the Inca civilisation’s most important archaeological sites, including visiting Machu Picchu twice as you discover how the story of the Inca is so much more than just one site.

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The ancient human foot bones have been a mystery since they were discovered by scientists in 2009Yohannes Haile-Selassie
The provenance of 3.4-million-year-old foot bones in Ethiopia may have finally been solved – and could prompt a rethink into how our various ancient human ancestors coexisted.
In 2009, Yohannes Haile-Selassie at Arizona State University and his colleagues found eight hominin bones, that once made up a right foot, at a site known as Burtele in the Afar region of north-eastern Ethiopia.

The find, christened the Burtele foot, included a gorilla-like opposable big toe, suggesting that whichever species it belonged to was able to climb trees.
Although another ancient hominin species, Australopithecus afarensis, was known to live nearby – most famously represented by the fossil Lucy, also found in the Afar region – the Burtele foot seemed to be from a different one. “We knew from the very beginning that it didn’t belong to Lucy’s species,” says Haile-Selassie.
The two main possibilities that gnawed at Haile-Selassie were whether the foot belonged to another species within the genus Australopithecus or a much older, more primitive one called Ardipithecus, which inhabited Ethiopia more than a million years earlier, but also had an opposable big toe.

In the meantime, the recovery of jaw and teeth remains from the same locality led the researchers to announce the discovery of a new-to-science hominin species in 2015, which they named Australopithecus deyiremeda. They suspected that the mysterious foot bones belonged to A. deyiremeda, but these were a different age to the jaw and teeth remains, so the team couldn’t be sure.
But the next year, the researchers found an A. deyiremeda’s lower jawbone within 300 metres of where the foot was recovered, with both remains being the same geological age. Based on this, the team has concluded that the foot bones belonged to A. deyiremeda.
The Burtele foot (left) and the bones embedded in an outline of a gorilla foot (right), which was similar to that of Australopithecus deyiremedaYohannes Haile-Selassie
In another part of the experiment, where the researchers studied the carbon isotopes of the A. deyiremeda teeth, they determined that the species mostly consumed material from trees and shrubs, whereas teeth of A. afarensis indicate a diet much richer in grasses.
The discoveries prove that two species of hominin lived together in the same environment, says Haile-Selassie. The groups weren’t competing for food, so it is possible they coexisted peacefully, he says.
“They must have seen each other, spent time in the same area doing their own things,” he says. “One may have seen members of Australopithecus deyiremeda in the trees while members of A. afarensis were roaming in the grasslands nearby.”

The findings also expand our knowledge of human evolution. “Some had argued that there was only one hominin species at any given time giving rise to a newer form,” says Haile-Selassie. “Now, we know that our evolution was not linear. There were multiple closely related hominin species living at the same time even in close geographic proximity and living in harmony, suggesting that coexistence is deep in our ancestry.”
Carrie Mongle at Stony Brook University in New York says it is “exciting we are starting to get a better understanding of hominin diversity in the Pliocene [around 3 million years ago]”.

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Cereal farming produced excess food that could be stored and taxedLUIS MONTANYA/MARTA MONTANYA/SCIENCE PHOTO LIBRARY
The cultivation of cereal grains probably led to the emergence of the first states – which operated mafia-like protection rackets − and to the adoption of writing for the purposes of recording taxes.
There is wide debate over how the first large human societies emerged. Some scholars see agriculture as the root of civilisation, while others see it as an invention born of necessity when the traditional hunter-gathering life became untenable. But many propose that the intensification of agriculture provided a surplus which could be stored and taxed, and that this enabled the formation of states.

“By using fertilisation and irrigation, [early farming societies] could hugely increase the output and, therefore, there was this surplus that was available for the construction of the state,” says Kit Opie at the University of Bristol, UK.
However, the timeline for these developments doesn’t quite match up. Our first evidence of agriculture popping up is from about 9000 years ago, and it was invented at least 11 separate times on four continents. But large-scale societies didn’t emerge until about 4000 years later, first in Mesopotamia, then in Egypt, China and Mesoamerica.
To look for more evidence, Opie and Quentin Atkinson at the University of Auckland in New Zealand turned to a set of family trees mapping out the evolution of the world’s languages, representing the relationships between cultures, and borrowed statistical methods from phylogenetics, the study of evolutionary relationships.

The pair used the language data in conjunction with information from anthropological databases on hundreds of pre-industrial societies to assess the probability that events such as the emergence of a state, taxation, writing, intense agriculture and the cultivation of cereal grains emerged in a specific order.
They found that the use of intensive agriculture was indeed coupled with the emergence of states, but the relationship wasn’t straightforward. “It looked more likely that it was the states causing the intensification, rather than the intensification causing the states,” says Opie.
A previous study of Austronesian societies also found that political complexity was more likely to have driven intensive agriculture than to have been a result of it.
“It makes sense that once you’ve got a state with money and people at its disposal, it can start doing irrigation,” says Opie.
But he and Atkinson also found that states were very unlikely to emerge in societies that didn’t already have widespread production of cereal grains such as wheat, barley, rice and maize, whereas they were very likely to emerge in societies with cereal grains as their main crop.
The results show that grain production and taxation were often associated, and taxation was less likely to arise in societies without grain.

This is because cereal grains have great taxable potential, says Opie. They can be easily assessed because they are grown in fixed fields, above ground, ripen at predictable times and can be stored for long periods. “Root crops like cassava or potatoes were hopeless for taxation,” he says. “The argument is that states, or protection rackets, would defend these fields from external states in exchange for tax.”
When it came to writing, Opie and Atkinson found that the practice was very unlikely to be adopted in societies without a tax system but very likely in those that did have one. Opie suggests that writing was invented and adopted to record those taxes. The elites of societies who raked in the taxes then created institutions and laws, maintaining the emerging hierarchical social structure.
The results also indicate that once formed, states were more likely to stop producing non-grain crops than non-states. “I would argue that we find strong evidence that they actually got rid of roots, tubers and fruit trees so that all the possible fields could be used for grain because none of the other things were good for taxation,” says Opie. “People were forced into using these kinds of crops, and it had a bad effect on us and, I would argue, still does.”
Although the move towards cereal cultivation was associated with a population boost in the Neolithic period, it also led to a decline in overall health, height and dental health.
“Applying phylogenetic methods to cultural evolution is innovative, but it may oversimplify the complexity of human history,” says Laura Dietrich at the Austrian Archaeological Institute in Vienna. Archaeological evidence shows that in south-west Asia, intensified agriculture in prehistoric times culminated in sustained state formation, whereas in Europe it didn’t, she says. To her the crucial question is why these regions diverge so markedly.
David Wengrow at University College London says that “from an archaeological perspective, it has been clear for decades that there was no single ‘prime mover’ for the emergence of early states in different parts of the world”. In Egypt, for example, he says, the first stirrings of bureaucracy seem to be linked more closely to the logistical organisation of royal rituals than to routine needs of taxation.

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Romantic kissing may go a long way back in our evolutionary pastATHVisions/Getty Images
Early humans like Neanderthals probably kissed, and our ape ancestors could have done so as far back as 21 million years ago.
There is wide debate over when humans began kissing romantically. Ancient texts hint that sexual kissing was practised in ancient Mesopotamia and Egypt at least 4500 years ago, but because such kissing has been documented in only about 46 per cent of human cultures, some argue it is a cultural phenomenon that emerged relatively recently in human history.

However, there are hints that Neanderthals exchanged oral bacteria with Homo sapiens, and chimpanzees, bonobos and orangutans have all been observed kissing. So it is possible that the behaviour goes back far further than historical texts reveal.
To look for answers, Matilda Brindle at the University of Oxford and her colleagues have attempted to work out the evolutionary history of kissing. “Kissing seems a bit of an evolutionary paradox, she says. “It probably doesn’t aid survival and could even be risky in terms of helping pathogen transmission.”
The researchers first came up with a definition of kissing that would work across many species, settling on mouth-to-mouth contact that is non-antagonistic and involves movement of the lips, but not the transfer of food.

This leads to many smooches being excluded, including kisses elsewhere on the body. “If you kiss someone on the cheek, then I would say that is a kiss, but by our definition, it isn’t kissing,” says Brindle. “Humans take kissing to a new level.”
The team then searched the scientific literature and contacted primate researchers to seek out reports of kissing in modern monkeys and apes that evolved in Africa, Europe and Asia.
To estimate the likelihood that various ancestral species also engaged in kissing, Brindle and her colleagues mapped out this information in a family tree of primates and ran a statistical approach called Bayesian modelling 10 million times to simulate different evolution scenarios.
They found that kissing probably evolved in ancestral apes some 21.5 million to 16.9 million years ago and there is an 84 per cent chance that our extinct human relatives, Neanderthals, engaged in kissing too.
“Obviously, that’s just Neanderthals kissing; we don’t know who they’re kissing,” says Brindle. “But together with the evidence that humans and Neanderthals had a similar oral microbiome and that most humans of non-African descent have some Neanderthal DNA, we would argue they were probably kissing each other, which definitely puts a much more romantic spin on human-Neanderthal relations.”

There isn’t enough data yet to tell why kissing evolved, says Brindle, but she does suggest two hypotheses.
“In terms of sexual kissing, it could enhance reproductive success by letting animals assess mate quality. If someone has bad breath, then you can choose not to reproduce with them,” she says.
Sexual kissing could also help with post-copulation success by promoting arousal, she says, which can speed up ejaculation and change the vaginal pH to make it more hospitable to sperm.
The other main idea is that non-sexual kissing developed from grooming and is useful for strengthening bonding and mitigating social tension. “Chimpanzees will literally kiss and make up after a fight,” says Brindle.
“I think from the evidence that they have, kissing definitely has this affiliative function,” says Zanna Clay at Durham University, UK. “We know, for example, in chimps that it does seem to form this important role in repairing social relationships. But to me, the sexual aspect is a little bit of a question mark.”
As to the issue of whether kissing is an evolved behaviour or a cultural invention, “I think our results show very clearly that kissing has evolved,” says Brindle.
Troels Pank Arbøll at the University of Copenhagen in Denmark, who traced early records of kissing in cuneiform writing from ancient Mesopotamia, agrees. “This provides a more well-developed basis to argue that kissing has been with humans for a long time,” he says.
But that is unlikely to be the whole story, given that many groups of people don’t kiss. “I’m sure there’s a strong cultural element to it and it’s probably come and gone with different cultural preferences,” says Clay.

Ancient caves, human origins: Northern Spain

Discover some of the world’s oldest known cave paintings in this idyllic part of Northern Spain. Travel back 40,000 years to explore how our ancestors lived, played and worked. From ancient Paleolithic art to awe-inspiring geological formations, each cave tells a unique story that transcends time.

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An ancient skull has finally shown us what the Denisovans looked like. Now it turns out they, not Neanderthals, might be our closest relatives, redrawing our family tree and transforming the hunt for Ancestor X.

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