̽��ֱ�� of Cambridge - prehistory

Revealed: face of 75,000-year-old female Neanderthal from cave where species buried their dead

fpjl2 — Thu, 02 May 2024 06:46:45 +0000

A new documentary has recreated the face of a 75,000-year-old female Neanderthal whose flattened skull was discovered and rebuilt from hundreds of bone fragments by a team of archaeologists and conservators led by the ̽��ֱ�� of Cambridge.

Parasites from feasting at Stonehenge found in prehistoric faeces

fpjl2 — Fri, 20 May 2022 09:07:24 +0000

A study of ancient faeces uncovered at a settlement thought to have housed builders of Stonehenge suggests that parasites got consumed via badly-cooked cow offal during epic winter feasts.

Shanidar Z: what did Neanderthals do with their dead?

fpjl2 — Tue, 18 Feb 2020 12:11:16 +0000

Archaeologists have unearthed a Neanderthal skeleton in a famous cave in Iraqi Kurdistan.

Direct genetic evidence of founding population reveals story of first Native Americans

tdk25 — Wed, 03 Jan 2018 18:00:05 +0000

̽��ֱ��data, which came from archaeological finds in Alaska, also points to the existence of a previously unknown Native American population, whom academics have named “Ancient Beringians”.

̽��ֱ��findings are being published in the journal Nature and present possible answers to a series of long-standing questions about how the Americas were first populated.

It is widely accepted that the earliest settlers crossed from what is now Russia into Alaska via an ancient land bridge spanning the Bering Strait which was submerged at the end of the last Ice Age. Issues such as whether there was one founding group or several, when they arrived, and what happened next, are the subject of extensive debate, however.

In the new study, an international team of researchers led by academics from the Universities of Cambridge and Copenhagen sequenced the full genome of an infant – a girl named Xach'itee'aanenh t'eede gay, or Sunrise Child-girl, by the local Native community - whose remains were found at the Upward Sun River archaeological site in Alaska in 2013.

To their surprise, they found that although the child had lived around 11,500 years ago, long after people first arrived in the region, her genetic information did not match either of the two recognised branches of early Native Americans, which are referred to as Northern and Southern. Instead, she appeared to have belonged to an entirely distinct Native American population, which they called Ancient Beringians.

Further analyses then revealed that the Ancient Beringians were an offshoot of the same ancestor population as the Northern and Southern Native American groups, but that they separated from that population earlier in its history. This timeline allowed the researchers to construct a picture of how and when the continent might have been settled by a common, founding population of ancestral Native Americans, that gradually divided into these different sub-groupings.

̽��ֱ��study was led by Professor Eske Willerslev, who holds positions both at St John’s College, ̽��ֱ�� of Cambridge, and the ̽��ֱ�� of Copenhagen in Denmark.

“ ̽��ֱ��Ancient Beringians diversified from other Native Americans before any ancient or living Native American population sequenced to date. It’s basically a relict population of an ancestral group which was common to all Native Americans, so the sequenced genetic data gave us enormous potential in terms of answering questions relating to the early peopling of the Americas,” he said.

“We were able to show that people probably entered Alaska before 20,000 years ago. It’s the first time that we have had direct genomic evidence that all Native Americans can be traced back to one source population, via a single, founding migration event.”

̽��ֱ��study compared data from the Upward Sun River remains with both ancient genomes, and those of numerous present-day populations. This allowed the researchers first to establish that the Ancient Beringian group was more closely related to early Native Americans than their Asian and Eurasian ancestors, and then to determine the precise nature of that relationship and how, over time, they split into distinct populations.

Until now, the existence of two separate Northern and Southern branches of early Native Americans has divided academic opinion regarding how the continent was populated. Researchers have disagreed over whether these two branches split after humans entered Alaska, or whether they represent separate migrations.

̽��ֱ��Upward Sun River genome shows that Ancient Beringians were isolated from the common, ancestral Native American population, both before the Northern and Southern divide, and after the ancestral source population was itself isolated from other groups in Asia. ̽��ֱ��researchers say that this means it is likely there was one wave of migration into the Americas, with all subdivisions taking place thereafter.

According to the researchers’ timeline, the ancestral population first emerged as a separate group around 36,000 years ago, probably somewhere in northeast Asia. Constant contact with Asian populations continued until around 25,000 years ago, when the gene flow between the two groups ceased. This cessation was probably caused by brutal changes in the climate, which isolated the Native American ancestors. “It therefore probably indicates the point when people first started moving into Alaska,” Willerslev said.

Around the same time, there was a level of genetic exchange with an ancient North Eurasian population. Previous research by Willerslev has shown that a relatively specific, localised level of contact between this group, and East Asians, led to the emergence of a distinctive ancestral Native American population.

Ancient Beringians themselves then separated from the ancestral group earlier than either the Northern or Southern branches around 20,000 years ago. Genetic contact continued with their Native American cousins, however, at least until the Upward Sun River girl was born in Alaska around 8,500 years later.

̽��ֱ��geographical proximity required for ongoing contact of this sort led the researchers to conclude that the initial migration into the Americas had probably already taken place when the Ancient Beringians broke away from the main ancestral line. José Víctor Moreno-Mayar, from the ̽��ֱ�� of Copenhagen, said: “It looks as though this Ancient Beringian population was up there, in Alaska, from 20,000 years ago until 11,500 years ago, but they were already distinct from the wider Native American group.”

Finally, the researchers established that the Northern and Southern Native American branches only split between 17,000 and 14,000 years ago which, based on the wider evidence, indicates that they must have already been on the American continent south of the glacial ice.

̽��ֱ��divide probably occurred after their ancestors had passed through, or around, the Laurentide and Cordilleran ice sheets – two vast glaciers which covered what is now Canada and parts of the northern United States, but began to thaw at around this time.

̽��ֱ��continued existence of this ice sheet across much of the north of the continent would have isolated the southbound travellers from the Ancient Beringians in Alaska, who were eventually replaced or absorbed by other Native American populations. Although modern populations in both Alaska and northern Canada belong to the Northern Native American branch, the analysis shows that these derive from a later “back” migration north, long after the initial migration events.

“One significant aspect of this research is that some people have claimed the presence of humans in the Americas dates back earlier – to 30,000 years, 40,000 years, or even more,” Willerslev added. “We cannot prove that those claims are not true, but what we are saying, is that if they are correct, they could not possibly have been the direct ancestors to contemporary Native Americans.”

Reference:

Willerslev, E, et al. Terminal Pleistocene Alaskan genome reveals first founding population of Native Americans. Nature. 3 Jan 2018. DOI: 10.1038/nature25173

Direct genetic traces of the earliest Native Americans have been identified for the first time in a new study. ̽��ֱ��genetic evidence suggests that people may have entered the continent in a single migratory wave, perhaps arriving more than 20,000 years ago.

It’s the first time that we have had direct genomic evidence that all Native Americans can be traced back to one source population, via a single, founding migration event

Eske Willerslev

Ben Potter.

Excavations at the Upward Sun River archaeological site in Alaska. ̽��ֱ��new study shows that the remains found there belonged to members of a previously unknown Native American population, whom academics have named “Ancient Beringians”.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Prehistoric women’s manual work was tougher than rowing in today’s elite boat crews

fpjl2 — Wed, 29 Nov 2017 19:01:03 +0000

A new study comparing the bones of Central European women that lived during the first 6,000 years of farming with those of modern athletes has shown that the average prehistoric agricultural woman had stronger upper arms than living female rowing champions.

Researchers from the ̽��ֱ�� of Cambridge’s Department of Archaeology say this physical prowess was likely obtained through tilling soil and harvesting crops by hand, as well as the grinding of grain for as much as five hours a day to make flour.

Until now, bioarchaeological investigations of past behaviour have interpreted women’s bones solely through direct comparison to those of men. However, male bones respond to strain in a more visibly dramatic way than female bones.

̽��ֱ��Cambridge scientists say this has resulted in the systematic underestimation of the nature and scale of the physical demands borne by women in prehistory.

“This is the first study to actually compare prehistoric female bones to those of living women,” said Dr Alison Macintosh, lead author of the study published today in the journal Science Advances.

“By interpreting women’s bones in a female-specific context we can start to see how intensive, variable and laborious their behaviours were, hinting at a hidden history of women’s work over thousands of years.”

̽��ֱ��study, part of the European Research Council-funded ADaPt (Adaption, Dispersals and Phenotype) Project, used a small CT scanner in Cambridge’s PAVE laboratory to analyse the arm (humerus) and leg (tibia) bones of living women who engage in a range of physical activity: from runners, rowers and footballers to those with more sedentary lifestyles.

̽��ֱ��bones strengths of modern women were compared to those of women from early Neolithic agricultural eras through to farming communities of the Middle Ages.

“It can be easy to forget that bone is a living tissue, one that responds to the rigours we put our bodies through. Physical impact and muscle activity both put strain on bone, called loading. ̽��ֱ��bone reacts by changing in shape, curvature, thickness and density over time to accommodate repeated strain,” said Macintosh.

“By analysing the bone characteristics of living people whose regular physical exertion is known, and comparing them to the characteristics of ancient bones, we can start to interpret the kinds of labour our ancestors were performing in prehistory.”

Over three weeks during trial season, Macintosh scanned the limb bones of the Open- and Lightweight squads of the Cambridge ̽��ֱ�� Women’s Boat Club, who ended up winning this year’s Boat Race and breaking the course record. These women, most in their early twenties, were training twice a day and rowing an average of 120km a week at the time.

̽��ֱ��Neolithic women analysed in the study (from 7400-7000 years ago) had similar leg bone strength to modern rowers, but their arm bones were 11-16% stronger for their size than the rowers, and almost 30% stronger than typical Cambridge students.

̽��ֱ��loading of the upper limbs was even more dominant in the study’s Bronze Age women (from 4300-3500 years ago), who had 9-13% stronger arm bones than the rowers but 12% weaker leg bones.

A possible explanation for this fierce arm strength is the grinding of grain. “We can’t say specifically what behaviours were causing the bone loading we found. However, a major activity in early agriculture was converting grain into flour, and this was likely performed by women,” said Macintosh.

“For millennia, grain would have been ground by hand between two large stones called a saddle quern. In the few remaining societies that still use saddle querns, women grind grain for up to five hours a day.

“ ̽��ֱ��repetitive arm action of grinding these stones together for hours may have loaded women's arm bones in a similar way to the laborious back-and-forth motion of rowing.”

However, Macintosh suspects that women’s labour was hardly likely to have been limited to this one behaviour.

“Prior to the invention of the plough, subsistence farming involved manually planting, tilling and harvesting all crops,” said Macintosh. “Women were also likely to have been fetching food and water for domestic livestock, processing milk and meat, and converting hides and wool into textiles.

“ ̽��ֱ��variation in bone loading found in prehistoric women suggests that a wide range of behaviours were occurring during early agriculture. In fact, we believe it may be the wide variety of women’s work that in part makes it so difficult to identify signatures of any one specific behaviour from their bones.”

Dr Jay Stock, senior study author and head of the ADaPt Project, added: “Our findings suggest that for thousands of years, the rigorous manual labour of women was a crucial driver of early farming economies. ̽��ֱ��research demonstrates what we can learn about the human past through better understanding of human variation today.”

̽��ֱ��first study to compare ancient and living female bones shows that women from early agricultural eras had stronger arms than the rowers of Cambridge ̽��ֱ��’s famously competitive boat club. Researchers say the findings suggest a “hidden history” of gruelling manual labour performed by women that stretched across millennia.

By interpreting women’s bones in a female-specific context we can start to see how intensive, variable and laborious their behaviours were

Alison Macintosh

Prehistoric women’s manual work was tougher than rowing in today’s elite boat crews

Alastair Fyfe for the ̽��ֱ�� of Cambridge

Cambridge ̽��ֱ�� Women’s Boat Club Openweight crew rowing during the 2017 Boat Race on the river Thames in London. ̽��ֱ��Cambridge women’s crew beat Oxford in the race. ̽��ֱ��members of this crew were among those analysed in the study.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Prehistoric humans are likely to have formed mating networks to avoid inbreeding

tdk25 — Thu, 05 Oct 2017 18:00:13 +0000

̽��ֱ��study, reported in the journal Science, examined genetic information from the remains of anatomically modern humans who lived during the Upper Palaeolithic, a period when modern humans from Africa first colonised western Eurasia. ̽��ֱ��results suggest that people deliberately sought partners beyond their immediate family, and that they were probably connected to a wider network of groups from within which mates were chosen, in order to avoid becoming inbred.

This suggests that our distant ancestors are likely to have been aware of the dangers of inbreeding, and purposely avoided it at a surprisingly early stage in prehistory.

̽��ֱ��symbolism, complexity and time invested in the objects and jewellery found buried with the remains also suggests that it is possible that they developed rules, ceremonies and rituals to accompany the exchange of mates between groups, which perhaps foreshadowed modern marriage ceremonies, and may have been similar to those still practised by hunter-gatherer communities in parts of the world today.

̽��ֱ��study’s authors also hint that the early development of more complex mating systems may at least partly explain why anatomically modern humans proved successful while other species, such as Neanderthals, did not. However, more ancient genomic information from both early humans and Neanderthals is needed to test this idea.

̽��ֱ��research was carried out by an international team of academics, led by the ̽��ֱ�� of Cambridge, UK, and the ̽��ֱ�� of Copenhagen, Denmark. They sequenced the genomes of four individuals from Sunghir, a famous Upper Palaeolithic site in Russia, which is believed to have been inhabited about 34,000 years ago.

̽��ֱ��human fossils buried at Sunghir represent a rare and highly valuable source of information because, very unusually for finds from this period, the people buried there appear to have lived at the same time and were buried together. To the researchers’ surprise, however, these individuals were not closely related in genetic terms; at the very most, they were second cousins. This is true even in the case of two children who were buried head-to-head in the same grave.

Professor Eske Willerslev, a Fellow at St John’s College, Cambridge, Prince Philip Professor of Ecology and Evolution in the Department of Zoology, and a Professor at the ̽��ֱ�� of Copenhagen, was the senior author on the study. “What this means is that even people in the Upper Palaeolithic, who were living in tiny groups, understood the importance of avoiding inbreeding,” he said. “ ̽��ֱ��data that we have suggest that it was being purposely avoided.”

“This means that they must have developed a system for this purpose. If small hunter–gatherer bands were mixing at random, we would see much greater evidence of inbreeding than we have here.”

Early humans and other hominins such as Neanderthals appear to have lived in small family units. ̽��ֱ��small population size made inbreeding likely, but among anatomically modern humans it eventually ceased to be commonplace; when this happened, however, is unclear.

“Small family bands are likely to have interconnected with larger networks, facilitating the exchange of people between groups in order to maintain diversity,” Professor Martin Sikora, from the Centre for GeoGenetics at the ̽��ֱ�� of Copenhagen, said.

Sunghir contains the burials of one adult male and two younger individuals, accompanied by the symbolically-modified incomplete remains of another adult, as well as a spectacular array of grave goods. ̽��ֱ��researchers were able to sequence the complete genomes of the four individuals, all of whom were probably living on the site at the same time. These data were compared with information from a large number of both modern and ancient human genomes.

They found that the four individuals studied were genetically no closer than second cousins, while an adult femur filled with red ochre found in the children’s’ grave would have belonged to an individual no closer than great-great grandfather of the boys. “This goes against what many would have predicted,” Willerslev said. “I think many researchers had assumed that the people of Sunghir were very closely related, especially the two youngsters from the same grave.”

̽��ֱ��people at Sunghir may have been part of a network similar to that of modern day hunter-gatherers, such as Aboriginal Australians and some historical Native American societies. Like their Upper Palaeolithic ancestors, these people live in fairly small groups of around 25 people, but they are also less directly connected to a larger community of perhaps 200 people, within which there are rules governing with whom individuals can form partnerships.

“Most non-human primate societies are organised around single-sex kin where one of the sexes remains resident and the other migrates to another group, minimising inbreeding,” Professor Marta Mirazón Lahr, from the Leverhulme Centre for Human Evolutionary Studies at the ̽��ֱ�� of Cambridge, said. “At some point, early human societies changed their mating system into one in which a large number of the individuals that form small hunter-gatherer units are non-kin. ̽��ֱ��results from Sunghir show that Upper Palaeolithic human groups could use sophisticated cultural systems to sustain very small group sizes by embedding them in a wide social network of other groups.”

By comparison, genomic sequencing of a Neanderthal individual from the Altai Mountains who lived around 50,000 years ago indicates that inbreeding was not avoided. This leads the researchers to speculate that an early, systematic approach to preventing inbreeding may have helped anatomically modern humans to thrive, compared with other hominins.

This should be treated with caution, however: “We don’t know why the Altai Neanderthal groups were inbred,” Sikora said. “Maybe they were isolated and that was the only option; or maybe they really did fail to develop an available network of connections. We will need more genomic data of diverse Neanderthal populations to be sure.”

Willerslev also highlights a possible link with the unusual sophistication of the ornaments and cultural objects found at Sunghir. Group-specific cultural expressions may have been used to establish distinctions between bands of early humans, providing a means of identifying who to mate with and who to avoid as partners.

“ ̽��ֱ��ornamentation is incredible and there is no evidence of anything like that with Neanderthals and other archaic humans,” Willerslev added. “When you put the evidence together, it seems to be speaking to us about the really big questions; what made these people who they were as a species, and who we are as a result.”

̽��ֱ��research paper, Ancient genomes show social and reproductive behaviour of early Upper Paleolithic foragers, is published in the October 5 issue of Science.

Early humans seem to have recognised the dangers of inbreeding at least 34,000 years ago, and developed surprisingly sophisticated social and mating networks to avoid it, new research has found.

When you put the evidence together, it seems to be speaking to us about the really big questions; what made these people who they were as a species, and who we are as a result

Eske Willerslev

José-Manuel Benito Álvarez via Wikimedia Commons

Detail of one of the burials from Sunghir, in Russia.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Licence type:

Public Domain

Ancient DNA reveals 'genetic continuity’ between Stone Age and modern populations in East Asia

fpjl2 — Wed, 01 Feb 2017 19:04:57 +0000

Researchers working on ancient DNA extracted from human remains interred almost 8,000 years ago in a cave in the Russian Far East have found that the genetic makeup of certain modern East Asian populations closely resemble that of their hunter-gatherer ancestors.

̽��ֱ��study, published today in the journal Science Advances, is the first to obtain nuclear genome data from ancient mainland East Asia and compare the results to modern populations.

̽��ֱ��findings indicate that there was no major migratory interruption, or “population turnover”, for well over seven millennia. Consequently, some contemporary ethnic groups share a remarkable genetic similarity to Stone Age hunters that once roamed the same region.

̽��ֱ��high “genetic continuity” in East Asia is in stark contrast to most of Western Europe, where sustained migrations of early farmers from the Levant overwhelmed hunter-gatherer populations. This was followed by a wave of horse riders from Central Asia during the Bronze Age. These events were likely driven by the success of emerging technologies such as agriculture and metallurgy

̽��ֱ��new research shows that, at least for part of East Asia, the story differs – with little genetic disruption in populations since the early Neolithic period.

Despite being separated by a vast expanse of history, this has allowed an exceptional genetic proximity between the Ulchi people of the Amur Basin, near where Russia borders China and North Korea, and the ancient hunter-gatherers laid to rest in a cave close to the Ulchi’s native land.

̽��ֱ��researchers suggest that the sheer scale of East Asia and dramatic variations in its climate may have prevented the sweeping influence of Neolithic agriculture and the accompanying migrations that replaced hunter-gatherers across much of Europe. They note that the Ulchi retained their hunter-fisher-gatherer lifestyle until recent times.

“Genetically speaking, the populations across northern East Asia have changed very little for around eight millennia,” said senior author Andrea Manica from the ̽��ֱ�� of Cambridge, who conducted the work with an international team, including colleagues from Ulsan National Institute of Science and Technology in Korea, and Trinity College Dublin and ̽��ֱ�� College Dublin in Ireland.

“Once we accounted for some local intermingling, the Ulchi and the ancient hunter-gatherers appeared to be almost the same population from a genetic point of view, even though there are thousands of years between them.”

̽��ֱ��new study also provides further support for the ‘dual origin’ theory of modern Japanese populations: that they descend from a combination of hunter-gatherers and agriculturalists that eventually brought wet rice farming from southern China. A similar pattern is also found in neighbouring Koreans, who are genetically very close to Japanese.

However, Manica says that much more DNA data from Neolithic China is required to pinpoint the origin of the agriculturalists involved in this mixture.

̽��ֱ��team from Trinity College Dublin were responsible for extracting DNA from the remains, which were found in a cave known as Devil’s Gate. Situated in a mountainous area close to the far eastern coast of Russia that faces northern Japan, the cave was first excavated by a soviet team in 1973.

Along with hundreds of stone and bone tools, the carbonised wood of a former dwelling, and woven wild grass that is one of the earliest examples of a textile, were the incomplete bodies of five humans.

If ancient DNA can be found in sufficiently preserved remains, sequencing it involves sifting through the contamination of millennia. ̽��ֱ��best samples for analysis from Devil’s Gate were obtained from the skulls of two females: one in her early twenties, the other close to fifty. ̽��ֱ��site itself dates back over 9,000 years, but the two women are estimated to have died around 7,700 years ago.

Researchers were able to glean the most from the middle-aged woman. Her DNA revealed she likely had brown eyes and thick, straight hair. She almost certainly lacked the ability to tolerate lactose, but was unlikely to have suffered from ‘alcohol flush’: the skin reaction to alcohol now common across East Asia.

While the Devil’s Gate samples show high genetic affinity to the Ulchi, fishermen from the same area who speak the Tungusic language, they are also close to other Tungusic-speaking populations in present day China, such as the Oroqen and Hezhen.

“These are ethnic groups with traditional societies and deep roots across eastern Russia and China, whose culture, language and populations are rapidly dwindling,” added lead author Veronika Siska, also from Cambridge.

“Our work suggests that these groups form a strong genetic lineage descending directly from the early Neolithic hunter-gatherers who inhabited the same region thousands of years previously.”

In contrast to Western Europeans, new research finds contemporary East Asians are genetically much closer to the ancient hunter-gatherers that lived in the same region eight thousand years previously.

̽��ֱ��Ulchi and the ancient hunter-gatherers appeared to be almost the same population from a genetic point of view, even though there are thousands of years between them

Andrea Manica

Elizaveta Veselovskaya/Yuriy Chernyavskiy

Right: Exterior of Devil’s Gate, the cave in the Primorye region near the far eastern coast of Russia. Left: One of the skulls found in the Devil’s Gate cave from which ancient DNA used in the study was extracted.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Bag-like sea creature was humans’ oldest known ancestor

tdk25 — Mon, 30 Jan 2017 08:57:51 +0000

Researchers have identified traces of what they believe is the earliest known prehistoric ancestor of humans – a microscopic, bag-like sea creature, which lived about 540 million years ago.

Named Saccorhytus, after the sack-like features created by its elliptical body and large mouth, the species is new to science and was identified from microfossils found in China. It is thought to be the most primitive example of a so-called 'deuterostome' – a broad biological category that encompasses a number of sub-groups, including the vertebrates.

If the conclusions of the study, published in the journal Nature, are correct, then Saccorhytus was the common ancestor of a huge range of species, and the earliest step yet discovered on the evolutionary path that eventually led to humans, hundreds of millions of years later.

Modern humans are, however, unlikely to perceive much by way of a family resemblance. Saccorhytus was about one millimetre in size, and probably lived between grains of sand on the seabed. Its features were spectacularly preserved in the fossil record – and intriguingly, the researchers were unable to find any evidence that the animal had an anus.

̽��ֱ��study was carried out by an international team of academics, including researchers from Cambridge in the UK and Northwest ̽��ֱ�� in Xi’an China, with support from other colleagues at institutions in China and Germany.

Simon Conway Morris, Professor of Evolutionary Palaeobiology and a Fellow of St John’s College, ̽��ֱ�� of Cambridge, said: “We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves. To the naked eye, the fossils we studied look like tiny black grains, but under the microscope the level of detail is jaw-dropping. All deuterostomes had a common ancestor, and we think that is what we are looking at here.”

Degan Shu, from Northwest ̽��ֱ��, added: “Our team has notched up some important discoveries in the past, including the earliest fish and a remarkable variety of other early deuterostomes. Saccorhytus now gives us remarkable insights into the very first stages of the evolution of a group that led to the fish, and ultimately, to us.”

Most other early deuterostome groups are from about 510 to 520 million years ago, when they had already begun to diversify into not just the vertebrates, but the sea squirts, echinoderms (animals such as starfish and sea urchins) and hemichordates (a group including things like acorn worms). This level of diversity has made it extremely difficult to work out what an earlier, common ancestor might have looked like.

̽��ֱ��Saccorhytus microfossils were found in Shaanxi Province, in central China, and pre-date all other known deuterostomes. By isolating the fossils from the surrounding rock, and then studying them both under an electron microscope and using a CT scan, the team were able to build up a picture of how Saccorhytus might have looked and lived. This revealed features and characteristics consistent with current assumptions about primitive deuterostomes.

Dr Jian Han, of Northwest ̽��ֱ��, said: “We had to process enormous volumes of limestone – about three tonnes – to get to the fossils, but a steady stream of new finds allowed us to tackle some key questions: was this a very early echinoderm, or something even more primitive? ̽��ֱ��latter now seems to be the correct answer.”

In the early Cambrian period, the region would have been a shallow sea. Saccorhytus was so small that it probably lived in between individual grains of sediment on the sea bed.

̽��ֱ��study suggests that its body was bilaterally symmetrical – a characteristic inherited by many of its descendants, including humans – and was covered with a thin, relatively flexible skin. This in turn suggests that it had some sort of musculature, leading the researchers to conclude that it could have made contractile movements, and got around by wriggling.

Perhaps its most striking feature, however, was its rather primitive means of eating food and then dispensing with the resulting waste. Saccorhytus had a large mouth, relative to the rest of its body, and probably ate by engulfing food particles, or even other creatures.

A crucial observation are small conical structures on its body. These may have allowed the water that it swallowed to escape and so were perhaps the evolutionary precursor of the gills we now see in fish. But the researchers were unable to find any evidence that the creature had an anus. “If that was the case, then any waste material would simply have been taken out back through the mouth, which from our perspective sounds rather unappealing,” Conway Morris said.

̽��ֱ��findings also provide evidence in support of a theory explaining the long-standing mismatch between fossil evidence of prehistoric life, and the record provided by biomolecular data, known as the 'molecular clock'.

Technically, it is possible to estimate roughly when species diverged by looking at differences in their genetic information. In principle, the longer two groups have evolved separately, the greater the biomolecular difference between them should be, and there are reasons to think this process is more or less clock-like.

Unfortunately, before a point corresponding roughly to the time at which Saccorhytus was wriggling in the mud, there are scarcely any fossils available to match the molecular clock’s predictions. Some researchers have theorised that this is because before a certain point, many of the creatures they are searching for were simply too small to leave much of a fossil record. ̽��ֱ��microscopic scale of Saccorhytus, combined with the fact that it is probably the most primitive deuterostome yet discovered, appears to back this up.

̽��ֱ��findings are published in Nature. Reference: Jian Han, Simon Conway Morris, Qiang Ou, Degan Shu and Hai Huang. Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China). DOI: 10.1038/nature21072.

Inset image: Photographs of the fossils show the spectacularly detailed levels of preservation which allowed researchers to identify and study the creature. Credit: Jian Han.

A tiny sea creature identified from fossils found in China may be the earliest known step on an evolutionary path that eventually led to the emergence of humans

We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves

Simon Conway Morris

Jian Han

Artist’s reconstruction of Saccorhytus coronarius, based on the original fossil finds. ̽��ֱ��actual creature was probably no more than a millimetre in size

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes