Neanderthals and modern humans diverged at least 800,000 years ago

Neanderthals and modern humans diverged at least 800,000 years ago

Neanderthals and modern humans diverged at least 800,000 years ago, substantially earlier than indicated by most DNA-based estimates, according to new research by a UCL academic.

Neanderthals diverged teeth
Dental morphology. Credit: Aida Gómez-Robles

The research, published in Science Advances, analysed dental evolutionary rates across different hominin species, focusing on early Neanderthals. It shows that the teeth of hominins from Sima de los Huesos, Spain - ancestors of the Neanderthals - diverged from the modern human lineage earlier than previously assumed.

Sima de los Huesos is a cave site in Atapuerca Mountains, Spain, where archaeologists have recovered fossils of almost 30 people. Previous studies date the site to around 430,000 years ago (Middle Pleistocene), making it one of the oldest and largest collections of human remains discovered to date.

Dr Aida Gomez-Robles (UCL Anthropology), said: "Any divergence time between Neanderthals and modern humans younger than 800,000 years ago would have entailed an unexpectedly fast dental evolution in the early Neanderthals from Sima de los Huesos."

"There are different factors that could potentially explain these results, including strong selection to change the teeth of these hominins or their isolation from other Neanderthals found in mainland Europe. However, the simplest explanation is that the divergence between Neanderthals and modern humans was older than 800,000 years. This would make the evolutionary rates of the early Neanderthals from Sima de los Huesos roughly comparable to those found in other species."

Modern humans share a common ancestor with Neanderthals, the extinct species that were our closest prehistoric relatives. However, the details on when and how they diverged are a matter of intense debate within the anthropological community.

Ancient DNA analyses have generally indicated that both lineages diverged around 300,000 to 500,000 years ago, which has strongly influenced the interpretation of the hominin fossil record.

This divergence time, however, is not compatible with the anatomical and genetic Neanderthal similarities observed in the hominins from Sima de los Huesos. The Sima fossils are considered likely Neanderthal ancestors based on both anatomical features and DNA analysis.

Dr Gomez-Robles said: "Sima de los Huesos hominins are characterised by very small posterior teeth (premolars and molars) that show multiple similarities with classic Neanderthals. It is likely that the small and Neanderthal-looking teeth of these hominins evolved from the larger and more primitive teeth present in the last common ancestor of Neanderthals and modern humans."

Dental shape has evolved at very similar rates across all hominin species, including those with very expanded and very reduced teeth. This new study examined the time at which Neanderthals and modern humans should have diverged to make the evolutionary rate of the early Neanderthals from Sima de los Huesos similar to those observed in other hominins.

The research used quantitative data to measure the evolution of dental shape across hominin species assuming different divergent times between Neanderthals and modern humans, and accounting for the uncertainty about the evolutionary relationships between different hominin species.

"The Sima people's teeth are very different from those that we would expect to find in their last common ancestral species with modern humans, suggesting that they evolved separately over a long period of time to develop such stark differences."

The study has significant implications for the identification of Homo sapiens last common ancestral species with Neanderthals, as it allows ruling out all the groups postdating 800,000 year ago.

Neanderthals diverged teeth
Hominin teeth. Credit: Aida Gómez-Robles

Press release from University College London


Traces of crawling in Italian cave give clues to ancient humans' social behavior

Traces of crawling in Italian cave give clues to ancient humans' social behavior

Using multiple methods of analysis, researchers have identified the movements of a group of humans as they explored an Italian cave system during the late Stone Age

The video shows a virtual exploration of the Bàsura cave, with a reconstruction of the group of ancient humans that proceeded via the 'Corridoio delle Impronte' to reach the inner rooms. Credit: MUSE - Isabella Salvador and Filippo Menolli

cave of Bàsura Toirano Liguria
In the cave of Bàsura, a preliminary survey of fossil traces is carried out on glossy sheets as a reference for more detailed analyses. Credit: Isabella Salvador

Evidence of crawling in an Italian cave system sheds new light on how late Stone Age humans behaved as a group, especially when exploring new grounds, says a study published today in eLife.

The cave of Bàsura at Toirano and its human and animal fossil traces have been known since the 1950s, with the first studies conducted by Italian archaeologist Virginia Chiappella. In the current study, promoted by the Archaeological Heritage Office of Liguria, researchers from Italy, Argentina and South Africa used multiple approaches to analyse the human traces and identified for the first time crawling behaviours from around 14,000 years ago.

"In our study, we wanted to see how ancient humans explored this fascinating cave system," says first author Marco Romano, Postdoctoral Fellow at the University of the Witwatersrand, South Africa. "Specifically, we set out to discover how many people entered the cave, whether they explored as individuals or as a group, their age, gender and what kind of route they took once inside the cave."

To answer these questions, the multidisciplinary team studied 180 tracks from within the cave, including foot and handprints on the clay-rich floor. They applied various modern dating methods, software that analyses the structure of the tracks, and different types of 3D modelling. "Together, these approaches allowed us to construct a narrative of how the humans entered and exited the cave, and their activities once they were inside," Romano explains.

The team determined that five individuals, including two adults, an adolescent of about 11 years old, and two children of three and six years old, entered the cave barefoot and illuminated the way using wooden sticks. This suggests that young children were active group members during the late Stone Age, even when carrying out apparently dangerous activities.

The researchers reported the first evidence of crawling in footprints from a low tunnel - a route that was taken to access the inner part of the cave. Anatomical details in the footprints suggest that the explorers went bare-legged as they navigated this pathway.

When analysing the various handprints, the team found that some of them appear 'unintentional' and relate to exploring the cave only, while others are more 'intentional' and suggest that social or symbolic activities took place within the inner chambers. "Hunter-gatherers may therefore have been driven by fun activities during exploration, as well as simply the need to find food," Romano adds.

"Together, our results show how a varied approach to studying our ancestors' tracks can provide detailed insights on their behaviour," concludes senior author Marco Avanzini, head of the geology department at MUSE - Trento Museum of Science, Italy. "We hope our approach will be useful for painting similar pictures of how humans behaved in other parts of the world and during different periods of time."

cave of Bàsura Toirano Liguria
These are ancient human footprints impressed on different surfaces in the cave of Bàsura. Credit: Marco Avanzini

###

Reference

The paper 'A multidisciplinary approach to a unique Palaeolithic human ichnological record from Italy (Bàsura Cave)' can be freely accessed online at https://doi.org/10.7554/eLife.45204.

Press release from eLife


birch bark chewing gums

Chewing gums reveal the oldest Scandinavian human DNA

Chewing gums reveal the oldest Scandinavian human DNA

birch bark chewing gums
This is an excavation of the site in the 1990's. Credit: Per Persson/Stockholm University

The first humans who settled in Scandinavia more than 10,000 years ago left their DNA behind in ancient chewing gums, which are masticated lumps made from birch bark pitch. This is shown in a new study conducted at Stockholm University and published in Communications Biology.

There are few human bones of this age, close to 10 000 years old, in Scandinavia, and not all of them have preserved enough DNA for archaeogenetic studies. In fact, the DNA from these newly examined chewing gums is the oldest human DNA sequenced from this area so far. The DNA derived from three individuals, two females and one male, creates an exciting link between material culture and human genetics.

Ancient chewing gums are as of now an alternative source for human DNA and possibly a good proxy for human bones in archaeogenetic studies. The investigated pieces come from Huseby-Klev, an early Mesolithic hunter-fisher site on the Swedish west coast. The sites excavation was done in the early 1990's, but at this time it was not possible to analyse ancient human DNA at all, let alone from non-human tissue. The masticates were made out of birch bark tar and used as glue in tool production and other types of technology during the Stone Age.

"When Per Persson and Mikael Maininen proposed to look for hunter-gatherer DNA in these chewing gums from Huseby Klev we were hesitant but really impressed that archaeologists took care during the excavations and preserved such fragile material", says Natalija Kashuba, who was affiliated to The Museum of Cultural History in Oslo when she performed the experiments in cooperation with Stockholm University.

"It took some work before the results overwhelmed us, as we understood that we stumbled into this almost 'forensic research', sequencing DNA from these mastic lumps, which were spat out at the site some 10 000 years ago!" says Natalija Kashuba. Today Natalija is a Ph.D. student at Uppsala University.

Exciting link between material culture and human genetics

The results show that, genetically, the individuals whose DNA was found share close genetic affinity to other hunter-gatherers in Sweden and to early Mesolithic populations from Ice Age Europe. However, the tools produced at the site were a part of lithic technology brought to Scandinavia from the East European Plain, modern day Russia. This scenario of a culture and genetic influx into Scandinavia from two routes was proposed in earlier studies, and these ancient chewing gums provides an exciting link directly between the tools and materials used and human genetics.

Emrah Kirdök at Stockholm University conducted the computational analyses of the DNA. "Demography analysis suggests that the genetic composition of Huseby Klev individuals show more similarity to western hunter-gatherer populations than eastern hunter-gatherers", he says.

"DNA from these ancient chewing gums have an enormous potential not only for tracing the origin and movement of peoples long time ago, but also for providing insights in their social relations, diseases and food.", says Per Persson at the Museum of Cultural History in Oslo. "Much of our history is visible in the DNA we carry with us, so we try to look for DNA where ever we believe we can find it", says Anders Götherström, at the Archaeological Research Laboratory at Stockholm University, where the work was conducted. The study is published in Communications Biology.

birch bark chewing gums
This is a masticate being examined. Credit: Natalija Kashuba/Stockholm University

Press release from Stockholm University


Uralic languages Siberia

Ancient DNA suggests that some Northern Europeans got their languages from Siberia

Ancient DNA suggests that some Northern Europeans got their languages from Siberia

Uralic languages Siberia
Estonian Grammar by Heinrich Stahl, published 1637 in Reval (Tallinn). Public Domain

Most Europeans descend from a combination of European hunter-gatherers, Anatolian early farmers, and Steppe herders. But only European speakers of Uralic languages like Estonian and Finnish also have DNA from ancient Siberians. Now, with the help of ancient DNA samples, researchers reporting in Current Biology on May 9 suggest that these languages may have arrived from Siberia by the beginning of the Iron Age, about 2,500 years ago, rather than evolving in Northern Europe.

The findings highlight the way in which a combination of genetic, archaeological, and linguistic data can converge to tell the same story about what happened in particular areas in the distant past.

"Since the transition from Bronze to Iron Age coincides with the diversification and arrival time of Finnic languages in the Eastern Baltic proposed by linguists, it is plausible that the people who brought Siberian ancestry to the region also brought Uralic languages with them," says Lehti Saag of University of Tartu, Estonia.

Although researchers knew that the Uralic-speaking people share common Siberian ancestry, its arrival time in the Eastern Baltic had remained uncertain. To characterize the genetic ancestry of people from the as-yet-unstudied cultural layers, Saag along with Kristiina Tambets and colleagues extracted DNA from the tooth roots of 56 individuals, 33 of which yielded enough DNA to include in the analysis.

"Studying ancient DNA makes it possible to pinpoint the moment in time when the genetic components that we see in modern populations reached the area since, instead of predicting past events based on modern genomes, we are analyzing the DNA of individuals who actually lived in a particular time in the past," Saag explains.

Their data suggest that the Siberian ancestry reached the coasts of the Baltic Sea no later than the mid-first millennium BC--around the time of the diversification of west Uralic/Finnic languages. It also indicates an influx of people from regions with strong Western hunter-gatherer characteristics in the Bronze Age, including many traits we now associate with modern Northern Europeans, like pale skins, blue eyes, and lactose tolerance.

"The Bronze Age individuals from the Eastern Baltic show an increase in hunter-gatherer ancestry compared to Late Neolithic people and also in the frequency of light eyes, hair, and skin and lactose tolerance," Tambets says, noting that those characteristics continue amongst present-day Northern Europeans.

The researchers are now expanding their study to better understand the Iron Age migration processes in Europe. They say they will also "move forward in time and focus on the genetic structure of the medieval time period."

Read more


freshwater mussel shells mother-of-pearl

Freshwater mussel shells were material of choice for prehistoric craftsmen

Freshwater mussel shells were material of choice for prehistoric craftsmen

A new study suggests that 6000-years-ago people across Europe shared a cultural tradition of using freshwater mussel shells to craft ornaments.

freshwater mussel shells mother-of-pearl
These are prehistoric shell ornaments made with freshwater mother-of-pearl. Credit: Jérôme Thomas (UMR CNRS 6282 Biogeosciences, University of Burgundy-Franche-Comté)

An international team of researchers, including academics from the University of York, extracted ancient proteins from prehistoric shell ornaments - which look remarkably similar despite being found at distant locations in Denmark, Romania and Germany - and discovered they were all made using the mother-of-pearl of freshwater mussels.

The ornaments were made between 4200 and 3800 BC and were even found in areas on the coast where plenty of other shells would have been available.

Archaeological evidence suggests the ornaments, known as "double-buttons", may have been pressed into leather to decorate armbands or belts.

Cross-cultural tradition

Senior author of the study, Dr Beatrice Demarchi, from the Department of Archaeology at the University of York and the University of Turin (Italy), said: "We were surprised to discover that the ornaments were all made from freshwater mussels because it implies that this material was highly regarded by prehistoric craftsmen, wherever they were in Europe and whatever cultural group they belonged to. Our study suggests the existence of a European-wide cross-cultural tradition for the manufacture of these double-buttons".

Freshwater molluscs have often been overlooked as a source of raw material in prehistory (despite the strength and resilience of mother-of-pearl) because many archaeologists believed that their local origin made them less "prestigious" than exotic marine shells.

Co-author of the paper, Dr André Colonese, from the Department of Archaeology at the University of York, said: "The ornaments are associated with the Late Mesolithic, Late Neolithic and Copper Age cultures. Some of these groups were still living as hunter gatherers, but in the south they were farmers with switching to a more settled lifestyle.

"The fact that these ornaments look consistently similar and are made from the same material suggests there may have been some kind of interaction between these distinct groups of people at this time.

"They may have had a shared knowledge or tradition for how to manufacture these ornaments and clearly had a sophisticated understanding of the natural environment and which resources to use."

Evolution

Mollusc shells contain a very small proportion of proteins compared to other bio-mineralised tissues, such as bone, making them difficult to analyse.

The researchers are now working on extracting proteins from fossilised molluscs, a method which they have dubbed "palaeoshellomics". These new techniques could offer fresh insights into some of the earliest forms of life on earth, enhancing our knowledge of evolution.

Dr Demarchi added: "This is the first time researchers have been able to retrieve ancient protein sequences from prehistoric shell ornaments in order to identify the type of mollusc they are made from.

"This research is an important step towards understanding how molluscs and other invertebrates evolved. We hope that using these techniques we will eventually be able to track an evolutionary process which began at least 550 million years ago."

###

"Palaeoshellomics" reveals the use of freshwater mother-of-pearl in prehistory is published in the journal eLife.

The research was carried out by researchers at the University of York, University of Turin and Ca' Foscari University (Italy), Universities of Burgundy-Franche-Comté and Lille (France), the University of Bradford (UK), the Moesgaard Museum (Denmark), the Landesamt für Denkmalpflege im Regierungspräsidium Stuttgart and the Niedersächsisches Landesamt für Denkmalpflege (Germany).

 

Press release from University of York


horse genetic history

A genomic tour-de-force reveals the last 5,000 years of horse history

A genomic tour-de-force reveals the last 5,000 years of horse history

horse genetic history
This image shows a herd of Kazakh horses in the Pavlodar region of Kazakhstan in August 2016. Credit: Ludovic Orlando

Each year on the first Saturday in May, Thoroughbred horses reach speeds of over 40 miles per hour as they compete to win the Kentucky Derby. But the domestic horse wasn't always bred for speed. In fact, an international team now has evidence to suggest that the modern horse is genetically quite different from the horses of even just a few hundred years ago.

Their work, appearing May 2 in the journal Cell, constructs the genetic history of the domestic horse across the world over the last 5,000 years by using the largest genome collection ever generated for a non-human organism. The findings identify two new horse lineages that are now extinct and suggest that familiar traits such as speed were only selected for more recently in their history.

"The horse has impacted human history like no other animal," says Ludovic Orlando (@LudovicLorlando), a research director with CNRS and the University of Toulouse and a Professor of Molecular Archaeology at the University of Copenhagen. "If you look at the historical record from the Bronze Age onward, horses are always part of the equation up until very recent times, connecting civilizations and impacting transportation, warfare, and agriculture. Our goal was to understand how humans and their activities transformed the horse throughout history to fit their purposes--and how these changes in biology influenced human history."

The team responsible for this project consisted of 121 collaborators, including geneticists, archaeologists, and evolutionary biologists from 85 institutions around the world, and examined genome-scale data from 278 horse specimens from across Eurasia over the last 42,000 years.

"Such a large collection of data means that we can build a much more precise understanding of horse domestication and management through space and time," Orlando says. "But it was truly an interdisciplinary effort because of course it takes a lot more than just DNA to understand such a story. We had to integrate all these social, historical, and geographical aspects."

This graphical abstract summarizes horse genetic history over the last 5,000 years. Credit: Fages et al./Cell

Overall, the team's findings suggest that equine history was much more complex than was previously realized. Today, there are only two known lineages of horses, the domestic horse and the Przewalski's horse. But the researchers here identified two additional now-extinct lineages of horses, one from the Iberian Peninsula and one from Siberia, both of which still existed 4,000-4,500 years ago. "We found two lineages of horses at the far ends of Eurasia that are not related to what we call the domestic horse today, nor to the Przewalski's horse. They are a sort of horse equivalent of what Neanderthals are to modern humans," Orlando says.

The researchers also found a major shift in the genetic makeup of horses in Europe and Central Asia in the 7th to 9th centuries and say this shift probably corresponds to Islamic expansions. The horses common in Europe before that time are now only found in regions such as Iceland; the new European horses after that time were much more similar to horses found in Persia during the Sassanid Empire. When the team performed a scan to identify genes that had been selected for in these Persian horses, they found evidence of selection in genes associated with body shape.

"It was a moment in history that reshaped the landscape of horses in Europe. If you look at what we today call Arabian horses, you know that they have a different shape--and we know how popular this anatomy has been throughout history, including in racing horses. Based on the genomic evidence, we propose that this horse was so successful and influential because it brought a new anatomy and perhaps other favorable traits," he says.

The researchers found that there have been additional significant and recent changes in the domestic horse. Similar selection scans indicate that only in the last 1,500 years did traits such as ambling and speed over short distances become more actively sought. And when they looked at the overall genetic diversity of the domestic horse, the researchers found a sharp decline in the last 200 to 300 years. They believe this decline corresponds with new breeding practices that were introduced with the rise of the concept of "pure" breeds.

"What we picture as a horse today and what we picture as a horse from a thousand years ago or two thousand years ago was likely actually very different. Some of those traits that we are most familiar with are only a modern invention, and in the last few hundred years, we have actually impacted the horse genome a lot more than in the previous 4,000 years of domestication," says Orlando.

This map shows the locations of the archaeological sites where horse remains were found. Credit: Fages et al./Cell

He believes that this research can tell us a lot about both the past and the present. "Our findings show that the past is a lot more diverse than we thought it was and that it cannot be imagined or inferred through modern-day variation. But ancient DNA tells us a lot about today as well, because it teaches us about the consequences of some shifts in breeding practices," he says. And that, he believes, can also affect the way we think about conservation and modern agricultural practices.

Of course, our understanding of the domestic horse's history is far from complete. Orlando acknowledges that there are geographic and temporal gaps in his story. Perhaps mostly glaringly, we still don't know when and or where the horse was domesticated. "Horse domestication is central to human history, and in 2019, we still don't understand where it started. That's mind-blowing," he says.

He looks forward to filling in those blanks. "Whenever I'm asked about what finding I'm most excited about, I always say, the next one. Because this research opens the door for so many possibilities to be studied now."

Read more


Genome analysis of yams reveals new cradle of crop domestication in West Africa

Genome analysis of yams reveals new cradle of crop domestication in West Africa

Yam genomics supports West Africa as a major cradle of crop domestication

yams
Wild yams, photo credits: Marco Schmidt [1], CC BY-SA 2.5
Yams as seen today in West Africa descended from a forest species, a new study finds. The results challenge the hypothesis that domestication of sub-Saharan African plants mostly arose in tropical savannahs. Critically, they also advance researchers' understanding of West African crops' domestication history, helping to identify a major cradle of domestication around the Niger River. One of the best-known domestication cradles in the world is the Fertile Crescent in the Middle East, where wheat, barley, oat, lentil and chickpea, among other crops, first appeared in the archaeological records.

The history of crop domestication is much less documented in sub-Saharan Africa, in part because archaeological studies are largely fragmentary. Previous studies of domestication in Africa suggest an origin encompassing a large area from Senegal to Somalia, while more recent studies have challenged this hypothesis - proposing a more restricted domestication origin near the Niger River Basin. To assess whether areas near the Niger Basin could be considered major hotspots of domestication, Nora Scarcelli and colleagues investigated the domestication of yam, a major staple crop originating from Africa. They used genome re-sequencing to analyze 167 "wild" and domesticated yam species from the country.

Their analysis, which included sophisticated statistical modeling, suggests that that cultivated yam was domesticated from a forest species, D. praehensilis, starting in the Niger River basin. Its domestication process involved adaptations to the open field environment and human selection that increased tuber size and starch content in the cultivated yam. The study further suggests that the Niger River region played a major role in African agriculture, comparable to the Fertile Crescent in the Near East.

 

Press release from the American Association for the Advancement of Science


imitation amber pine resin Iberian peninsula

First examples of Iberian prehistoric 'imitation amber' beads at gravesites

First examples of Iberian prehistoric 'imitation amber' beads at gravesites

Unscrupulous traders might have cheated rich customers with fake amber beads

imitation amber beads pine resin Iberian peninsula
These are amber bead samples studied in this paper. Credit: Odriozola et al., 2019, CC BY

Prehistoric Iberians created "imitation amber" by repeatedly coating bead cores with tree resins, according to a study published May 1, 2019 in the open-access journal PLOS ONE by Carlos Odriozola from Universidad de Sevilla, Spain, and colleagues.

Many studies have confirmed the ornamental and symbolic importance of amber to European prehistoric peoples. This study is the first to discuss potential prehistoric Iberian "imitation amber" beads made using the application of repeated resinite coatings on top of a bead core.

The authors obtained beads from two prehistoric sites in Spain: two from a cave tomb at the La Molina site in Sevilla, dating from the 3rd millennium BC, and four from a burial site in Cova del Gegant near Barcelona, dating from the 2nd millennium BC. Using infrared spectroscopy, an electron microscope probe, x-ray diffraction, and spectroscopy, the authors were able to study the chemical composition and structure of all six bead cores and coatings.

The beads from Cova del Gegant had a mollusk shell core, covered by a multilayered coating made up of tree resins, most likely pine. The beads were covered by a calcium-containing white deposit, which likely precipitated post-burial from the bone tissue of buried individuals. The beads from La Molina were also composed of a core covered by an amber-like resin, as well as two topmost layers of cinnabar and calcite which probably coated the beads post-burial.

The authors speculate these coating technologies were used to imitate amber's translucence, shine, and color, since during this prehistoric period, amber was relatively rare and highly in demand. However, both tomb sites contained other exotic materials such as ivory, gold and cinnabar, so it's not clear why individuals able to obtain these rare goods would use amber alternatives. The authors speculate that, especially in the Cova del Gegant where "imitation amber" was found directly alongside true amber beads, unscrupulous traders may have substituted low-cost fake amber to cheat their buyers. The authors also suggest chemical analysis of apparent "amber" artifacts could prevent erroneous amber identification in future studies of such Iberian sites.

###

Citation: Odriozola CP, Garrido Cordero JÁ, Daura J, Sanz M, Martínez-Blanes JM, Avilés MÁ (2019) Amber imitation? Two unusual cases of Pinus resin-coated beads in Iberian Late Prehistory (3rd and 2nd millennia BC). PLoS ONE 14(5): e0215469. https://doi.org/10.1371/journal.pone.0215469

Funding: This research was funded by the MINECO/AEI/FEDER -EU under contract HAR2012-34620 and HAR2017-83474-P. José Ángel Garrido Cordero acknowledges the University of Seville for a PhD grant under the V Plan Propio de Investigación de la Universidad de Sevilla. Montserrat Sanz acknowledges the program Juan de la Cierva for a postdoctoral grant (FJCI-2014-21386). Daura holds a postdoctoral grant (SFRH/BPD/ 100507/2014?) from the Portuguese Fundação para a Ciência e a Tecnologia using funding from the FSE/POPH.

Competing Interests: The authors have declared that no competing interests exist.

 

Press release from the Public Library of Sciences (PLOS)


Denisovans Tibetan Plateau Baishiya Karst Cave Xiahe mandible

First hominins on the Tibetan Plateau were Denisovans

First hominins on the Tibetan Plateau were Denisovans

Denisovan mandible likely represents the earliest hominin fossil on the Tibetan Plateau

Denisovans Tibetan Plateau Baishiya Karst Cave Xiahe mandible
The Xiahe mandible, only represented by its right half, was found in 1980 in Baishiya Karst Cave. Credit: © Dongju Zhang, Lanzhou University

So far Denisovans were only known from a small collection of fossil fragments from Denisova Cave in Siberia. A research team led by Fahu Chen from the Institute of Tibetan Plateau Research, CAS, Dongju Zhang from Lanzhou University and Jean-Jacques Hublin from the Max Planck Institute for Evolutionary Anthropology now describes a 160,000-year-old hominin mandible from Xiahe in China. Using ancient protein analysis the researchers found that the mandible’s owner belonged to a population that was closely related to the Denisovans from Siberia. This population occupied the Tibetan Plateau in the Middle Pleistocene and was adapted to this low-oxygen environment long before Homo sapiens arrived in the region.

Denisovans - an extinct sister group of Neandertals - were discovered in 2010, when a research team led by Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) sequenced the genome of a fossil finger bone found at Denisova Cave in Russia and showed that it belonged to a hominin group that was genetically distinct from Neandertals. "Traces of Denisovan DNA are found in present-day Asian, Australian and Melanesian populations, suggesting that these ancient hominins may have once been widespread," says Jean-Jacques Hublin, director of the Department of Human Evolution at the MPI-EVA. "Yet so far the only fossils representing this ancient hominin group were identified at Denisova Cave."

Mandible from Baishiya Karst Cave

In their new study, the researchers now describe a hominin lower mandible that was found on the Tibetan Plateau in Baishiya Karst Cave in Xiahe, China. The fossil was originally discovered in 1980 by a local monk who donated it to the 6th Gung-Thang Living Buddha who then passed it on to Lanzhou University. Since 2010, researchers Fahu Chen and Dongju Zhang from Lanzhou University have been studying the area of the discovery and the cave site from where the mandible originated. In 2016, they initiated a collaboration with the Department of Human Evolution at the MPI-EVA and have since been jointly analysing the fossil.

While the researchers could not find any traces of DNA preserved in this fossil, they managed to extract proteins from one of the molars, which they then analysed applying ancient protein analysis. "The ancient proteins in the mandible are highly degraded and clearly distinguishable from modern proteins that may contaminate a sample," says Frido Welker of the MPI-EVA and the University of Copenhagen. "Our protein analysis shows that the Xiahe mandible belonged to a hominin population that was closely related to the Denisovans from Denisova Cave."

Primitive shape and large molars

The researchers found the mandible to be well-preserved. Its robust primitive shape and the very large molars still attached to it suggest that this mandible once belonged to a Middle Pleistocene hominin sharing anatomical features with Neandertals and specimens from the Denisova Cave. Attached to the mandible was a heavy carbonate crust, and by applying U-series dating to the crust the researchers found that the Xiahe mandible is at least 160,000 years old. Chuan-Chou Shen from the Department of Geosciences at National Taiwan University, who conducted the dating, says: "This minimum age equals that of the oldest specimens from the Denisova Cave".

"The Xiahe mandible likely represents the earliest hominin fossil on the Tibetan Plateau," says Fahu Chen, director of the Institute of Tibetan Research, CAS. These people had already adapted to living in this high-altitude low-oxygen environment long before Homo sapiens even arrived in the region. Previous genetic studies found present-day Himalayan populations to carry the EPAS1 allele in their genome, passed on to them by Denisovans, which helps them to adapt to their specific environment.

"Archaic hominins occupied the Tibetan Plateau in the Middle Pleistocene and successfully adapted to high-altitude low-oxygen environments long before the regional arrival of modern Homo sapiens," says Dongju Zhang. According to Hublin, similarities with other Chinese specimens confirm the presence of Denisovans among the current Asian fossil record. "Our analyses pave the way towards a better understanding of the evolutionary history of Middle Pleistocene hominins in East Asia."

 

 

Press release from the Max Planck Institute for Evolutionary Anthropology / Max-Planck-Institut für evolutionäre Anthropologie in Leipzig 

Tibetan plateau first occupied by middle Pleistocene Denisovans

Baishiya Karst Cave
Fieldwork in the Baishiya Karst Cave and surrounding regions. Credit: ITP

The Tibetan Plateau, as Earth's "Third Pole," was reported to be first occupied by modern humans probably armed with blade technology as early as 40 ka BP. However, no earlier hominin groups had been found or reported on the Tibetan Plateau until a recent study was published by Chinese researchers.

A joint research team led by CHEN Fahu from the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences and ZHANG Dongju from the Lanzhou University reported their studies on a human mandible found in Xiahe, on the Northeastern Tibetan Plateau. The findings were published in Nature.

The researchers found that the mandible came from an individual who belonged to a population closely related to the Denisovans first found in Siberia. This population occupied the Tibetan Plateau in the Middle Pleistocene and adapted to this low-oxygen environment long before the arrival of modern Homo sapiens in the region.

So far, Denisovans are only known from a small collection of fossil fragments from Denisova Cave in Siberia. Traces of Denisovan DNA are found in present-day Asian, Australian and Melanesian populations, suggesting that these ancient hominins may have once been widespread.

This study confirms for the first time that Denisovans not only lived in East Asia but also on the high-altitude Tibetan Plateau. It also indicates that the previously found possible introgression of Denisovan DNA (EPAS1) into modern Tibetans and Sherpas, who mainly live on the high-altitude Tibetan Plateau and surrounding regions today, is probably derived or inherited locally on Tibetan Plateau from Xiahe hominin represented by this Xiahe mandible.

The reported Xiahe mandible was found on the Tibetan Plateau in the Baishiya Karst Cave in Xiahe, China. Researchers managed to extract collagen from one of the molars, which they then analysed using ancient protein analysis. Ancient protein data showed that the Xiahe mandible belonged to a hominin population closely related to the Denisovans from Denisova Cave.

The robust primitive shape of the mandible and the very large molars still attached to it suggest that this mandible once belonged to a Middle Pleistocene hominin sharing anatomical features with Neandertals and specimens from the Denisova Cave.

Attached to the mandible was a heavy carbonate crust. By applying U-series dating to the crust, the researchers found that the Xiahe mandible is at least 160,000 years old, representing a minimum age of human presence on the Tibetan Plateau.

The similarities between the Xiahe mandible and other Chinese specimens confirm the presence of Denisovans among the current Asian fossil record. The current study paves the way towards a better understanding of the evolutionary history of Middle Pleistocene hominins in East Asia.

 

Press release from the Chinese Academy of Sciences


brain fossils neuroanatomy

Brain, shape and fossils

Brain, shape and fossils

Emiliano Bruner has just published a paper on the shape of the brain over human evolution, which reviews the evolutionary relationship between humans and the other primates, as well as the most recent methods for comparing the principal variations between brain and cranium

brain fossils neuroanatomy
Credit: Emiliano Bruner

Emiliano Bruner, a paleoneurologist at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), has just published an overview article in the Journal of Comparative Neurology, on studies of changes in brain shape over the course of human evolution, which considers the evolutionary relationship between humans and the other primates.

Evolutionary neuroanatomy must integrate two different sources of information: fossils and living species. The fossils furnish data on the process of evolution, while living species do the same for the product of evolution. Unfortunately, the fossil record is incomplete and fragmented, and often cannot support validations for specific evolutionary hypotheses. Extant species can offer more comprehensive indications, but they do not represent ancestral groups or primitive forms.

Specifically, this paper reviews the limitations on studies of evolutionary neuroanatomy and the different contributions made by analyses of living primates and extinct hominins. For instance, the great apes are still interpreted as primitive biological models, even though these are species that have evolved independently of the path traced by the human genus. “Macaques or chimpanzees are frequently used as proxy for human ancestral conditions, despite the fact they are divergent and specialized lineages, with their own biological features”, says Bruner.

With regard to the fossils, these can furnish more direct information about the evolutionary process, but the limitations of the samples often do not allow scientific testing of our hypotheses, leading to a lot of guesswork. In fact, as Bruner explains, “independent lineages, such as the Neanderthals, ought not to be confused with ancestral modern human stages”.

Endocranial molds
The paper also introduces the most recent methods for computed morphometrics and biomedical image analysis, describing the principal variations in brains and endocranial molds (endocasts) for modern humans and extinct hominins, in addition to the spatial relationship between brain and cranium in the human genus.

Finally, it proposes integrating anatomical and cultural information with what is known in neurobiology when formulating hypotheses about cognitive evolution. One example would be the evolution of the parietal cortex and its schemes of cerebral connections.

This paper, entitled Human paleoneurology: shaping cortical evolution in fossil hominids, has been published in a volume dedicated to the evolution of the cerebral cortex, edited by Verónica Martínez-Cerdeño and Stephen Noctor, of the University of California at Davis (USA).

 

Full bibliographic information

 

"Human paleoneurology: shaping cortical evolution in fossil hominids", edited by Verónica Martínez-Cerdeño and Stephen Noctor Journal of Comparative Neurology (0). doi: 10.1002/cne.24591

Press release from the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) / ES