Ancient DNA sheds light on Arctic hunter-gatherer migration to North America ~5,000 years ago

Ancient DNA sheds light on Arctic hunter-gatherer migration to North America ~5,000 years ago

An ancient population of Arctic hunter-gatherers, known as Paleo-Eskimos, made a significant genetic contribution to populations living in Arctic North America today

New research reveals the profound impact of Arctic hunter-gathers who moved from Siberia to North America about 5000 years ago on present-day Native Americans. Although this group is well-known from archaeology and ancient DNA, previous genetic studies suggested that they may have been largely replaced by the groups that gave rise to present-day Arctic peoples such as the Inuit, Yup’ik, and Aleuts. The present study proves that many present-day North Americans derive significant heritage from this ancient population.

The first humans in North America arrived from Asia some time before 14,500 years ago. The next major stream of gene flow came about 5000 years ago, and is known to archaeologists as Paleo-Eskimos. About 800 years ago, the ancestors of the present-day Inuit and Yup'ik people replaced this population across the Arctic. By about 700 years ago, the archaeological evidence for the Paleo-Eskimo culture disappeared. Their genetic legacy in living populations has been contentious, with several genetic studies arguing that they made little contribution to later North Americans.

In the current study, researchers generated genome-wide data from 48 ancient individuals and 93 modern individuals from Siberia, Alaska, the Aleutian Islands and Canada, and compared this with previously published data. The researchers used novel analysis methods to create a comprehensive model of population history that included many ancient and modern groups to determine how they might be related to each other. "Our study is unique, not only in that it greatly expands the number of ancient genomes from this region, but because it is the first study to comprehensively describe all of these populations in one single coherent model," states Stephan Schiffels of the Max Planck Institute for the Science of Human History.

Paleo-Eskimos
An ancient population of Arctic hunter-gatherers, known as Paleo-Eskimos, made a significant genetic contribution to populations living in Arctic North America today. Credit: Illustration by Kerttu Majander, Design by Michelle O'Reilly

Paleo-Eskimos left a lasting legacy that extends across North America

The researchers were able to show that a substantial proportion of the genetic heritage of all ancient and modern American Arctic and Chukotkan populations comes from Paleo-Eskimos. This includes people speaking Eskimo-Aleut languages, such as the Yup'ik, Inuit and Aleuts, and groups speaking Na-Dene languages, such as Athabaskan and Tlingit speakers, in Canada, Alaska, and the lower 48 states of the United States.

Based on the researchers' analysis, Paleo-Eskimos interbred with people with ancestry similar to more southern Native peoples shortly after their arrival to Alaska, between 5,000 and 4,000 years ago. The ancestors of Aleutian Islanders and Athabaskans derive their genetic heritage directly from the ancient mixture between these two groups. The researchers also found that the ancestors of the Inuit and Yup'ik people crossed the Bering Strait at least three times: first as Paleo-Eskimos to Alaska, second as predecessors of the Old Bering Sea archaeological culture back to Chukotka, and third to Alaska again as bearers of the Thule culture. During their stay in Chukotka that likely lasted for more than 1000 years, Yupik and Inuit ancestors also admixed with local groups related to present-day Chukchi and local peoples from Kamchatka.

Paleo-Eskimo ancestry is particularly widespread today in Na-Dene language speakers, which includes Athabaskan and Tlingit communities from Alaska and northern Canada, the West Coast of the United States, and the southwest United States.

"For the last seven years, there has been a debate about whether Paleo-Eskimos contributed genetically to people living in North America today; our study resolves this debate and furthermore supports the theory that Paleo-Eskimos spread Na-Dene languages," explains David Reich of Harvard Medical School and the Howard Hughes Medical Institute. "One of the most striking case examples from our study is the ancient DNA we generated from the ancient Athabaskan site of Tochak McGrath in interior Alaska, where we worked in consultation with the local community to obtain data from three approximately seven hundred year old individuals. We found that these individuals, who lived after the time when the Paleo-Eskimo archaeological culture disappeared across North America, are well modeled as a mixture of the same two ancestry components as those found in Athabaskans today, and derived more than 40% of their ancestry from Paleo-Eskimos.

The excavation of the Middle Dorset individual from the Buchanan site on southeastern Victoria Island, Nunavut, Central Canadian Arctic. Credit: T. Max Friesen

A case example for how genetics can be combined with archaeology to shed new light on the past

The researchers hope that the paper will provide an example of the value of genetic data, in the context of archaeological knowledge, to resolve long-standing questions.

"Determining what happened to this population was not possible from the archaeological record alone," explains Pavel Flegontov of the University of Ostrava. "By analyzing genetic data in concert with the archaeological data, we can meaningfully improve our understanding of the prehistory of peoples of this region. We faced challenging analytical problems due to the complex sequence of gene flows that have shaped ancestries of peoples on both sides of the Bering Strait. Reconstructing this sequence of events required new modelling approaches that we hope may be useful for solving similar problems in other regions of the world."

Attu Island, Aleutian Islands, Alaska. Credit: Jason Rogers

Press release from the Max Planck Institute for the Science of Human History / Max-Planck-Instituts für Menschheitsgeschichte

 


DNA from 31,000-year-old milk teeth leads to discovery of new group of ancient Siberians

DNA from 31,000-year-old milk teeth leads to discovery of new group of ancient Siberians

The two 31,000-year-old milk teeth found at the Yana Rhinoceros Horn Site in Russia which led to the discovery of a new group of ancient Siberians. Credit: Russian Academy of Sciences

Two children's milk teeth buried deep in a remote archaeological site in north eastern Siberia have revealed a previously unknown group of people lived there during the last Ice Age.

The finding was part of a wider study which also discovered 10,000 year-old human remains in another site in Siberia are genetically related to Native Americans - the first time such close genetic links have been discovered outside of the US.

The international team of scientists, led by Professor Eske Willerslev who holds positions at St John's College, University of Cambridge, and is director of The Lundbeck Foundation Centre for GeoGenetics at the University of Copenhagen, have named the new people group the 'Ancient North Siberians' and described their existence as 'a significant part of human history'.

The DNA was recovered from the only human remains discovered from the era - two tiny milk teeth - that were found in a large archaeological site found in Russia near the Yana River. The site, known as Yana Rhinoceros Horn Site (RHS), was found in 2001 and features more than 2,500 artefacts of animal bones and ivory along with stone tools and evidence of human habitation.

The discovery is published today (June 5 2019) as part of a wider study in Nature and shows the Ancient North Siberians endured extreme conditions in the region 31,000 years ago and survived by hunting woolly mammoths, woolly rhinoceroses, and bison.

Professor Willerslev said: "These people were a significant part of human history, they diversified almost at the same time as the ancestors of modern day Asians and Europeans and it's likely that at one point they occupied large regions of the northern hemisphere."

Dr Martin Sikora, of The Lundbeck Foundation Centre for GeoGenetics and first author of the study, added: "They adapted to extreme environments very quickly, and were highly mobile. These findings have changed a lot of what we thought we knew about the population history of north eastern Siberia but also what we know about the history of human migration as a whole."

Researchers estimate that the population numbers at the site would have been around 40 people with a wider population of around 500. Genetic analysis of the milk teeth revealed the two individuals sequenced showed no evidence of inbreeding which was occurring in the declining Neanderthal populations at the time.

Siberia milk teeth America
Alla Mashezerskaya maps the artefacts in the area where two 31,000-year-old milk teeth were found. Credit: Elena Pavlova

The complex population dynamics during this period and genetic comparisons to other people groups, both ancient and recent, are documented as part of the wider study which analysed 34 samples of human genomes found in ancient archaeological sites across northern Siberia and central Russia.

Professor Laurent Excoffier from the University of Bern, Switzerland, said: "Remarkably, the Ancient North Siberians people are more closely related to Europeans than Asians and seem to have migrated all the way from Western Eurasia soon after the divergence between Europeans and Asians."

Scientists found the Ancient North Siberians generated the mosaic genetic make-up of contemporary people who inhabit a vast area across northern Eurasia and the Americas - providing the 'missing link' of understanding the genetics of Native American ancestry.

It is widely accepted that humans first made their way to the Americas from Siberia into Alaska via a land bridge spanning the Bering Strait which was submerged at the end of the last Ice Age. The researchers were able to pinpoint some of these ancestors as Asian people groups who mixed with the Ancient North Siberians.

Professor David Meltzer, Southern Methodist University, Dallas, one of the paper's authors, explained: "We gained important insight into population isolation and admixture that took place during the depths of the Last Glacial Maximum - the coldest and harshest time of the Ice Age - and ultimately the ancestry of the peoples who would emerge from that time as the ancestors of the indigenous people of the Americas."

This discovery was based on the DNA analysis of a 10,000 year-old male remains found at a site near the Kolyma River in Siberia. The individual derives his ancestry from a mixture of Ancient North Siberian DNA and East Asian DNA, which is very similar to that found in Native Americans. It is the first time human remains this closely related to the Native American populations have been discovered outside of the US.

Professor Willerslev added: "The remains are genetically very close to the ancestors of Paleo-Siberian speakers and close to the ancestors of Native Americans. It is an important piece in the puzzle of understanding the ancestry of Native Americans as you can see the Kolyma signature in the Native Americans and Paleo-Siberians. This individual is the missing link of Native American ancestry."

 

Press release from the St John's College, University of Cambridge

 


Ancient feces reveal parasites in 8,000-year-old village of Çatalhöyük

Ancient feces reveal parasites in 8,000-year-old village of Çatalhöyük

parasites whipworm Çatalhöyük
South area excavation of Çatalhöyük, Turkey, in 2003. Author: Ziggurat, CC BY-SA 3.0

New research published today in the journal Antiquity reveals that ancient faeces from the prehistoric village of Çatalhöyük have provided the earliest archaeological evidence for intestinal parasite infection in the mainland Near East.

People first gave up hunting and gathering and turned to farming in the Near East, around 10,000 years ago. The settlement of Çatalhöyük is famous for being an incredibly well preserved early village founded around 7,100 BC. The population of Çatalhöyük were early farmers, growing crops such as wheat and barley, and herding sheep and goats.

"It has been suggested that this change in lifestyle resulted in a similar change in the types of diseases that affected them. As the village is one of the largest and most densely populated of its time, this study at Çatalhöyük helps us to understand that process better," says study lead Dr Piers Mitchell of Cambridge's Department of Archaeology.

The toilet was first invented in the 4th millennium BC in Mesopotamia, 3000 years later than when Çatalhöyük flourished. It is thought the people living at Çatalhöyük either went to the rubbish tip (midden) to open their bowels, or carried their faeces from their houses to the midden in a vessel or basket to dispose of them.

"We would expect this to have put the population at risk of diseases spread by contact with human faeces, and explains why they were vulnerable to contracting whipworm," says the study first author Marissa Ledger.

"As writing was only invented 3000 years after the time of Çatalhöyük, the people were unable to record what happened to them during their lives. This research enables us for the first time to imagine the symptoms felt by some of the prehistoric people living at Çatalhöyük who were infected by this parasite."

To look for the eggs of intestinal parasites, Cambridge researchers Mitchell, Ledger and Evilena Anastasiou used microscopy to study preserved pieces of human faeces (coprolites) from a rubbish tip, and soil formed from decomposed faeces recovered from the pelvic region of burials. The samples dated from 7,100-6150 BC.

To determine whether the coprolites excavated from the midden were from human or animal faeces, they were analysed for sterols and bile acids at the University of Bristol Mass Spectrometry Facility by Helen Mackay, Lisa Marie Shillito, and Ian Bull. This analysis demonstrated that the coprolites were of human origin.

Further microscopic analysis showed that eggs of whipworm were present in two of the coprolites, demonstrating that people from the prehistoric village were infected by this intestinal parasite.

"It was a special moment to identify parasite eggs over 8000 years old," said study co-author Evilena Anastasiou.

Whipworms are 3-5cm in length, and live on the lining of the intestines of the large bowel. Adult worms can live for 5 years. Male and female worms mate and their eggs are mixed in with the faeces. Whipworm is spread by the contamination of food or drink from human faeces that contain the worm eggs. A heavy infection with whipworm can lead to anaemia, diarrhoea, stunted growth and reduced intelligence in children.

"Now we need to find ancient faecal material from prehistoric hunter gathers in the Near East, to help us understand how this change in lifestyle affected their diseases." added Mitchell.

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East Africa

Ancient DNA tells the story of the first herders and farmers in east Africa

Ancient DNA tells the story of the first herders and farmers in east Africa

A collaborative study that includes a SLU-Madrid archaeologist provides new insights on early human interaction

East Africa
Herders move goats through the Engaruka Basin in northern Tanzania's Rift Valley. Ancient DNA shows that this way of life spread to East Africa through multiple population movements. Credit: Katherine Grillo

ST. LOUIS, MO (May 30, 2019) - A collaborative study led by archaeologists, geneticists and museum curators is providing answers to previously unsolved questions about life in sub-Saharan Africa thousands of years ago. The results were published online in the journal Science Thursday, May 30.

Researchers from North American, European and African institutions analyzed ancient DNA from 41 human skeletons curated in the National Museums of Kenya and Tanzania, and the Livingstone Museum in Zambia.

"The origins of food producers in East Africa have remained elusive because of gaps in the archaeological record," said co-first author Mary Prendergast, Ph.D., professor of anthropology and chair of humanities at Saint Louis University's campus in Madrid, Spain.

"This study uses DNA to answer previously unresolvable questions about how people were moving and interacting," added Prendergast.

The research provides a look at the origins and movements of early African food producers.

The first form of food production to spread through most of Africa was the herding of cattle, sheep and goats. This way of life continues to support millions of people living on the arid grasslands that cover much of sub-Saharan Africa.

"Today, East Africa is one of the most genetically, linguistically, and culturally diverse places in the world," explains Elizabeth Sawchuk, Ph.D., a bioarchaeologist at Stony Brook University and co-first author of the study. "Our findings trace the roots of this mosaic back several millennia. Distinct peoples have coexisted in the Rift Valley for a very long time."

Previous archaeological research shows that the Great Rift Valley of Kenya and Tanzania was a key site for the transition from foraging to herding. Herders of livestock first appeared in northern Kenya around 5000 years ago, associated with elaborate monumental cemeteries, and then spread south into the Rift Valley, where Pastoral Neolithic cultures developed.

The new genetic results reveal that this spread of herding into Kenya and Tanzania involved groups with ancestry derived from northeast Africa, who appeared in East Africa and mixed with local foragers there between about 4500-3500 years ago. Previously, the origins and timing of these population shifts were unclear, and some archaeologists hypothesized that domestic animals spread through exchange networks, rather than by movement of people.

After around 3500 years ago, herders and foragers became genetically isolated in East Africa, even though they continued to live side by side. Archaeologists have hypothesized substantial interaction among foraging and herding groups, but the new results reveal that there were strong and persistent social barriers that lasted long after the initial encounters.

Another major genetic shift occurred during the Iron Age around 1200 years ago, with movement into the region of additional peoples from both northeastern and western Africa. These groups contributed to ancient ancestry profiles similar to those of many East Africans today. This genetic shift parallels two major cultural changes: farming and iron-working.

The study provided insight into the history of East Africa as an independent center of evolution of lactase persistence, which enables people to digest milk into adulthood. This genetic adaptation is found in high proportions among Kenyan and Tanzanian herders today.

Co-first author Mary Prendergast, Ph.D., is a professor of anthropology and chair of humanities at Saint Louis University's campus in Madrid, Spain. Credit: Mary Prendergast

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flint tools

Early humans deliberately recycled flint to create tiny, sharp tools

Early humans deliberately recycled flint to create tiny, sharp tools

Exceptional conditions at Israel's Qesem Cave preserved 400,000-year-old 'tool kit,' Tel Aviv University researchers say

flint tools
Experimental activity of cutting tubers with a small recycled flake and a close-up of its prehension (inset). Credit: Flavia Venditti/AFTAU

A new Tel Aviv University study finds that prehistoric humans "recycled" discarded or broken flint tools 400,000 years ago to create small, sharp utensils with specific functions. These recycled tools were then used with great precision and accuracy to perform specific tasks involved in the processing of animal products and vegetal materials.

The site of Qesem Cave, located just outside Tel Aviv, was discovered during a road construction project in 2000. It has since offered up countless insights into life in the region hundreds of thousands of years ago.

In collaboration with Prof. Cristina Lemorini of Sapienza University of Rome, the research was led jointly by postdoctoral fellow Dr. Flavia Venditti in collaboration with Profs. Ran Barkai and Avi Gopher. All three are members of TAU's Department of Archaeology and Ancient Near Eastern Cultures. It was published on April 11 in the Journal of Human Evolution.

In recent years, archaeologists working in caves in Spain and North Africa and digs in Italy and Israel have unearthed evidence that prehistoric people recycled objects they used in daily life. Just as we recycle materials such as paper and plastic to manufacture new items today, early hominids collected discarded or broken tools made of flint to create new utensils for specific purposes hundreds of thousands of years ago.

"Recycling was a way of life for these people," Prof. Barkai says. "It has long been a part of human evolution and culture. Now, for the first time, we are discovering the specific uses of the recycled 'tool kit' at Qesem Cave."

Exceptional conditions in the cave allowed for the immaculate preservation of the materials, including micro residue on the surface of the flint tools.

"We used microscopic and chemical analyses to discover that these small and sharp recycled tools were specifically produced to process animal resources like meat, hide, fat and bones," Venditti explains. "We also found evidence of plant and tuber processing, which demonstrated that they were also part of the hominids' diet and subsistence strategies."

According to the study, signs of use were found on the outer edges of the tiny objects, indicating targeted cutting activities related to the consumption of food: butchery activities and tuber, hide and bone processing. The researchers used two different and independent spectroscopic chemical techniques: Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX).

"The meticulous analysis we conducted allowed us to demonstrate that the small recycled flakes were used in tandem with other types of utensils. They therefore constituted a larger, more diversified tool kit in which each tool was designed for specific objectives," Venditti says.

She adds, "The research also demonstrates that the Qesem inhabitants practiced various activities in different parts of the cave: The fireplace and the area surrounding it were eventually a central area of activity devoted to the consumption of the hunted animal and collected vegetal resources, while the so-called 'shelf area' was used to process animal and vegetal materials to obtain different by-products."

"This research highlights two debated topics in the field of Paleolithic archaeology: the meaning of recycling and the functional role of small tools," Prof. Barkai observes. "The data from the unique, well-preserved and investigated Qesem Cave serve to enrich the discussion of these phenomena in the scientific community."

"Our data shows that lithic recycling at Qesem Cave was not occasional and not provoked by the scarcity of flint," Venditti concludes. "On the contrary, it was a conscious behavior which allowed early humans to quickly obtain tiny sharp tools to be used in tasks where precision and accuracy were essential."

The researchers are continuing to investigate prehistoric recycling by applying their analysis to other sites in Africa, Europe and Asia.

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Neanderthal extinction

Declining fertility rates may explain Neanderthal extinction, suggests new model

Declining fertility rates may explain Neanderthal extinction, suggests new model

Population modelling shows population could have dwindled to extinction due to demographics, not catastrophe

Neanderthal extinction
Spatial distribution and location of the 3 Neanderthal subpopulations.
Southern Europe (labeled A in green), Northern Europe (labelled B in yellow), and Eastern Europe (labeled C in purple) according to [61]. The full demographic model we used to simulate Neanderthal population dynamics was composed of three sub-models corresponding to each of the identified sub-populations. We included a migration parameter (noted ψ) to allow for individuals to move from a sub-population to another. Copyright: © 2019 Degioanni et al.
A new hypothesis for Neanderthal extinction supported by population modelling is put forward in a new study by Anna Degioanni from Aix Marseille Université, France and colleagues, published May 29, 2019 in the open-access journal PLOS ONE.

The lack of empirical data allowing testing of hypotheses is one of the biggest challenges for researchers studying Neanderthal extinction. Many hypotheses involve catastrophic events such as disease or climate change. In order to test alternative hypothetical extinction scenarios, Degioanni and colleagues created a Neanderthal population model allowing them to explore demographic factors which might have resulted in declining populations and population extinction over a period of 4,000-10,000 years (a time frame compatible with known Neanderthal history). The researchers created baseline demographic parameters for their Neanderthal extinction model (e.g. survival, migration, and fertility rates) based on observational data on modern hunter-gatherer groups and extant large apes, as well as available Neanderthal paleo-genetic and empirical data from earlier studies. The authors defined populations as extinct when they fell below 5,000 individuals.

The authors saw that in their model, extinction would have been possible within 10,000 years with a decrease in fertility rates of young (<20 year-old) Neanderthal women of just 2.7 percent; if the fertility rate decreased by 8 percent, extinction occurred within 4,000 years. If this decrease in fertility was amplified by a reduction in survival of infants (children less than one year old), a decrease in survival of just 0.4 percent could have led to extinction in 10,000 years.

The authors intended to explore possible Neanderthal extinction scenarios rather than to posit any definitive explanation. However, the researchers note that this study is the first to use empirical data to suggest that relatively minor demographic changes, such as a reduction in fertility or an increase in infant mortality, might have led to Neanderthal extinction. The authors note that modelling can be a useful tool in studying Neanderthals.

The authors add: "This study of the disappearance of the Neanderthals published today in PLOS ONE does not attempt to explain "why" the Neanderthals disappeared, but to identify "how" their demise may have taken place. This original approach is made on the basis of demographic modeling. The results suggest that a very small reduction in fertility may account for the disappearance of the Neanderthal population. According to this research, this decrease did not concern all female Neanderthals, but only the youngest (less than 20 years old)."

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Unexpected potential paths for the spread of Homo Sapiens across Asia in Late Pleistocene

Humans used northern migration routes to reach eastern Asia

New article suggests wetter climates may have allowed Homo sapiens to expand across the deserts of Central Asia by 50-30,000 years ago

 

Northern and Central Asia have been neglected in studies of early human migration, with deserts and mountains being considered uncompromising barriers. However, a new study by an international team argues that humans may have moved through these extreme settings in the past under wetter conditions. We must now reconsider where we look for the earliest traces of our species in northern Asia, as well as the zones of potential interaction with other hominins such as Neanderthals and Denisovans.

Archaeologists and palaeoanthropologists are increasingly interested in discovering the environments facing the earliest members of our species, Homo sapiens, as it moved into new parts of Eurasia in the Late Pleistocene (125,000-12,000 years ago). Much attention has focused on a 'southern' route around the Indian Ocean, with Northern and Central Asia being somewhat neglected. However, in a paper published in PLOS ONE, scientists of the Max Planck Institute for the History of Human Science in Jena, Germany, and colleagues at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, argue that climate change may have made this a particularly dynamic region of hominin dispersal, interaction, and adaptation, and a crucial corridor for movement.

'Heading North' Out of Africa and into Asia

"Archaeological discussions of the migration routes of Pleistocene Homo sapiens have often focused on a 'coastal' route from Africa to Australia, skirting around India and Southeast Asia," says Professor Michael Petraglia of the Max Planck Institute for the Science of Human History, a co-author of the new study. "In the context of northern Asia, a route into Siberia has been preferred, avoiding deserts such as the Gobi." Yet over the past ten years, a variety of evidence has emerged that has suggested that areas considered inhospitable today might not have always been so in the past.

"Our previous work in Saudi Arabia, and work in the Thar Desert of India, has been key in highlighting that survey work in previously neglected regions can yield new insights into human routes and adaptations," says Petraglia. Indeed, if Homo sapiens could cross what is now the Arabian Deserts then what would have stopped it crossing other currently arid regions such as the Gobi Desert, the Junggar Basin, and the Taklamakan Desert at different points in the past? Similarly, the Altai Mountains, the Tien Shan and the Tibetan Plateau represent a potentially new high altitude window into human evolution, especially given the recent Denisovan findings from Denisova Cave in Russia and at the Baishiya Karst Cave in China.

Nevertheless, traditional research areas, a density of archaeological sites, and assumptions about the persistence of environmental 'extremes' in the past has led to a focus on Siberia, rather than the potential for interior routes of human movement across northern Asia.

A "Green Gobi"?

The sand dunes of Mongol Els jutting out of the steppe in Mongolia. Many of these desert barriers only appeared after the Last Glacial Maximum (~20,000 years ago). Credit: Nils Vanwezer

Indeed, palaeoclimatic research in Central Asia has increasingly accumulated evidence of past lake extents, past records of changing precipitation amounts, and changing glacial extents in mountain regions, which suggest that environments could have varied dramatically in this part of the world over the course of the Pleistocene. However, the dating of many of these environmental transitions has remained broad in scale, and these records have not yet been incorporated into archaeological discussions of human arrival in northern and Central Asia.

"We factored in climate records and geographical features into GIS models for glacials (periods during which the polar ice caps were at their greatest extent) and interstadials (periods during the retreat of these ice caps) to test whether the direction of past human movement would vary, based on the presence of these environmental barriers," says Nils Vanwezer, PhD student at the Max Planck Institute for the Science of Human History and a joint lead-author of the study.

"We found that while during 'glacial' conditions humans would indeed likely have been forced to travel via a northern arc through southern Siberia, during wetter conditions a number of alternative pathways would have been possible, including across a 'green' Gobi Desert," he continues. Comparisons with the available palaeoenvironmental records confirm that local and regional conditions would have been very different in these parts of Asia in the past, making these 'route' models a definite possibility for human movement.

Where did you come from, where did you go?

Ancient lake landforms around Biger Nuur, Mongolia, which is evidence of larger lake sizes in the past. Credit: Nils Vanwezer

"We should emphasize that these routes are not 'real', definite pathways of Pleistocene human movement. However, they do suggest that we should look for human presence, migration, and interaction with other hominins in new parts of Asia that have been neglected as static voids of archaeology," says Dr. Patrick Roberts also of the Max Planck Institute for the Science of Human History, co-author of the study. "Given what we are increasingly discovering about the flexibility of our species, it would be of no surprise if we were to find early Homo sapiens in the middle of modern deserts or mountainous glacial sheets."

"These models will stimulate new survey and fieldwork in previously forgotten regions of northern and Central Asia," says Professor Nicole Boivin, Director of the Department of Archaeology at the Max Planck Institute for the Science of Human History, and co-author of the study. "Our next task is to undertake this work, which we will be doing in the next few years with an aim to test these new potential models of human arrival in these parts of Asia."

 

Press release from the Max Planck Institute for the Science of Human History / Max-Planck-Instituts für Menschheitsgeschichte

 

Homo sapiens may have had several routes of dispersal across Asia in the Late Pleistocene

A new model identifies unexpected potential paths for the spread of human culture and technology

Eastern Asia Central Homo Sapiens migrations
Illustrated dispersal routes from the results of the Least Cost Path analysis: The three routes from the "wet" simulations and the single route from the "dry" simulation are presented together in conjunction with palaeoclimatic extents (glaciers and palaeolakes). Sites: 4. Obi-Rakhmat, 5. Shugnou, 8. Denisova, 9. Ust-Karakol, 10. Kara-Tenesh, 11. Kara-Bom, 12. Luotuoshi, 14. Gouxi, 15. Lenghu 1, 17. Chikhen Agui, 18. Tsagaan Agui, 19. Tolbor 4, 20. Kharganyn Gol 5, 21. Orkhon 1 & 7, 22. Makarovo 4, 23. Kandabaevo, 24. Varvarina Gora, 25. Tolbaga, 27. Shuidonggou 1, 28. Shuidonggou 9, 42. Yushuwan, 70. Shibazhan (75075). I. 'Altai' Route, II. 'Tian Shan' Route, III. 'Tarim' Route, IV. "Revised Overland' Route. Base map raster is from naturalearthdata.com. Credit: Li et al, 2019

Homo sapiens may have had a variety of routes to choose from while dispersing across Asia during the Late Pleistocene Epoch, according to a study released May 29, 2019 in the open-access journal PLOS ONE by Feng Li of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and colleagues.

After leaving Africa, Homo sapiens dispersed across the Asian continent during the Late Pleistocene, but it isn't known exactly what routes our species followed. Most models assume that the Gobi Desert and Altai Mountain chains of North and Central Asia formed impassable barriers on the way to the east, so archaeological exploration has tended to neglect those regions in favor of seemingly more likely paths farther north and south.

In this study, Li and colleagues use Geographic Information Systems (GIS) software alongside archaeological and paleoclimate data to reconstruct the conditions of North and Central Asia over the Late Pleistocene and to identify possible routes of travel. Their data suggest that the desert and mountain regions were likely impassable during cold and dry glacial periods, but that during warmer and wetter interglacial times it would have been possible for human populations to traverse these regions via at least three routes following ancient lake and river systems.

The authors caution that these data do not demonstrate definite routes of dispersal and that more detailed models should be constructed to test these results. However, these models do identify specific routes that may be good candidates for future archaeological exploration. Understanding the timing and tempo of Homo sapiens dispersal across Asia will be crucial for determining how culture and technology spread and developed, as well as how our species interacted with our extinct cousins, the Neanderthals and Denisovans.

Roberts adds: "Our modelling of the available geographic and past climate data suggest that archaeologists and anthropologists should look for early human presence, migration, and interaction with other hominins in new parts of Asia that have been neglected as static voids. Given what we are increasingly discovering about the flexibility of our species, it would be of no surprise if we were to find early Homo sapiens in the middle of modern deserts or mountainous glacial sheets all across Asia. Indeed, it may be here that the key to our species' uniqueness lies".

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Citation: Li F, Vanwezer N, Boivin N, Gao X, Ott F, Petraglia M, et al. (2019) Heading north: Late Pleistocene environments and human dispersals in central and eastern Asia. PLoS ONE 14(5): e0216433. https://doi.org/10.1371/journal.pone.0216433

Funding: This study was funded by Max-Planck-Gesellschaft (DE) to Nicole Boivin, Strategic Priority Research Program of Chinese Academy of Sciences grant XDB26000000 to Feng Li, and Youth Innovation Promotion Association of the Chinese Academy of Sciences grant 2017102 to Feng Li. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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

 

Press release from the Public Library of Sciences


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Exploring the origins of the apple

Exploring the origins of the apple

Apples originally evolved in the wild to entice ancient megafauna to disperse their seeds; more recently, humans began spreading the trees along the Silk Road with other familiar crops; dispersing the apple trees led to their domestication

wild horses apple
Horses eating wild apples in the Tien Shan Mountains. These domesticated horses demonstrate the process of seed dispersal that wild apple trees evolved to support millions of years ago, when large monogastric mammals such as these were prominent across Eurasia. Credit: Artur Stroscherer

Recent archaeological finds of ancient preserved apple seeds across Europe and West Asia combined with historical, paleontological, and recently published genetic data are presenting a fascinating new narrative for one of our most familiar fruits. In this study, Robert Spengler of the Max Planck Institute for the Science of Human History traces the history of the apple from its wild origins, noting that it was originally spread by ancient megafauna and later as a process of trade along the Silk Road. These processes allowed for the development of the varieties that we know today.

The apple is, arguably, the most familiar fruit in the world. It is grown in temperate environments around the globe and its history is deeply intertwined with humanity. Depictions of large red fruits in Classical art demonstrate that domesticated apples were present in southern Europe over two millennia ago, and ancient seeds from archaeological sites attest to the fact that people have been collecting wild apples across Europe and West Asia for more than ten thousand years. While it is clear that people have closely maintained wild apple populations for millennia, the process of domestication, or evolutionary change under human cultivation, in these trees is not clear.

Several recent genetic studies have demonstrated that the modern apple is a hybrid of at least four wild apple populations, and researchers have hypothesized that the Silk Road trade routes were responsible for bringing these fruits together and causing their hybridization. Archaeological remains of apples in the form of preserved seeds have been recovered from sites across Eurasia, and these discoveries support the idea that fruit and nut trees were among the commodities that moved on these early trade routes. Spengler recently summarized the archaeobotanical and historical evidence for cultivated crops on the Silk Road in a book titled Fruit from the Sands, published with the University of California Press. The apple holds a deep connection with the Silk Road - much of the genetic material for the modern apple originated at the heart of the ancient trade routes in the Tien Shan Mountains of Kazakhstan. Furthermore, the process of exchange caused the hybridization events that gave rise to the large red sweet fruits in our produce markets.

Understanding how and when apple trees evolved to produce larger fruits is an important question for researchers, because fruit trees do not appear to have followed the same path towards domestication as other, better-understood crops, such as cereals or legumes. Many different wild and anthropogenic forces apply selective pressure on the crops in our fields, it is not always easy to reconstruct what pressures caused which evolutionary changes. Therefore, looking at evolutionary processing in modern and fossil plants can help scholars interpret the process of domestication. Fleshy sweet fruits evolve to attract animals to eat then and spread their seeds; large fruits specifically evolve to attract large animals to disperse them.

apple
The wild apples in the Tien Shan Mountains represent the main ancestral population for our modern apple. These trees produce large fruits, which are often red when ripe and have a varying array of flavors. These were the ancestors of the trees that people first started to cultivate and spread along the Silk Road. Credit: Prof. Dr. Martin R. Stuchtey

Large fruits evolved to attract ancient megafauna

While most scholars studying domestication focus on the period when humans first start cultivating a plant, in this study Spengler explores the processes in the wild that set the stage for domestication. Spengler suggests that understanding the process of evolution of large fruits in the wild will help us understand the process of their domestication. "Seeing that fruits are evolutionary adaptations for seed dispersal, the key to understanding fruit evolution rests in understanding what animals were eating the fruits in the past," he explains.

Many fruiting plants in the apple family (Rosaceae) have small fruits, such as cherries, raspberries, and roses. These small fruits are easily swallowed by birds, which then disperse their seeds. However, certain trees in the family, such as apples, pears, quince, and peaches, evolved in the wild to be too large for a bird to disperse their seeds. Fossil and genetic evidence demonstrate that these large fruits evolved several million years before humans started cultivating them. So who did these large fruits evolve to attract?

The evidence suggests that large fruits are an evolutionary adaptation to attract large animals that can eat the fruits and spread the seeds. Certain large mammals, such as bears and domesticated horses, eat apples and spread the seeds today. However, prior to the end of the last Ice Age, there were many more large mammals on the European landscape, such as wild horses and large deer. Evidence suggests that seed dispersal in the large-fruiting wild relatives of the apple has been weak during the past ten thousand years, since many of these animals went extinct. The fact that wild apple populations appear to map over glacial refugial zones of the Ice Age further suggests that these plants have not been moving over long distances or colonizing new areas in the absence of their original seed-spreaders.

Trade along the Silk Road likely enabled the development of the apple we know today

Silk Road apple
Venders in every Central Asian bazaar sell a diverse array of apples. This women in the Bukhara bazaar is selling a variety of small sweet yellow apples, which she locally cultivated in Uzbekistan. Some of the fruits sold in these markets today travel great distances, similar to how they would have during the peak of the Silk Road. Credit: Robert Spengler

Wild apple tree populations were isolated after the end of the last Ice Age, until humans started moving the fruits across Eurasia, in particular along the Silk Road. Once humans brought these tree lineages back into contact with each other again, bees and other pollinators did the rest of the work. The resulting hybrid offspring had larger fruits, a common result of hybridization. Humans noticed the larger fruiting trees and fixed this trait in place through grafting and by planting cuttings of the most favored trees. Thus, the apples we know today were primarily not developed through a long process of the selection and propagation of seeds from the most favored trees, but rather through hybridization and grafting. This process may have been relatively rapid and parts of it were likely unintentional. The fact that apple trees are hybrids and not "properly" domesticated is why we often end up with a crabapple tree when we plant an apple seed.

This study challenges the definition of "domestication"' and demonstrates that there is no one-shoe-fits-all model to explain plant evolution under human cultivation. For some plants, domestication took millennia of cultivation and human-induced selective pressure - for other plants, hybridization caused rapid morphological change. "The domestication process is not the same for all plants, and we still do not know much about the process in long-generation trees," notes Spengler. "It is important that we look past annual grasses, such as wheat and rice, when we study plant domestication. There are hundreds of other domesticated plants on the planet, many of which took different pathways toward domestication." Ultimately, the apple in your kitchen appears to owe its existence to extinct megafaunal browsers and Silk Road merchants.

 

 

Press release from the Max Planck Institute for the Science of Human History / Max-Planck-Institut für Menschheitsgeschichte


Iron Age shield bark Everards Meadows

Unique Iron Age shield gives insight into prehistoric technology

Unique Iron Age shield gives insight into prehistoric technology

 

A unique bark shield, thought to have been constructed with wooden laths during the Iron Age, has provided new insight into the construction and design of prehistoric weaponry.

Iron Age shield bark Everards Meadows
The unique find has given new insight into prehistoric technology

The only one of its kind ever found in Europe, the shield was found south of Leicester on the Everards Meadows site, in what is believed to have been a livestock watering hole.

Following analysis of the construction of the shield by Michael Bamforth at the University of York, it became apparent that the shield had been carefully constructed with wooden laths to stiffen the structure, a wooden edging rim, and a woven boss to protect the wooden handle.

Although prior evidence has shown that prehistoric people used bark to make bowls and boxes, this is the first time researchers have seen the material used for a weapon of war.

Severe damage

The outside of the shield has been painted and scored in red chequerboard decoration. Radiocarbon dating has revealed that the shield was made between 395 and 255 BC.

The shield was severely damaged before being deposited in the ground, with some of the damage likely to have been caused by the pointed tips of spears. Further analysis is planned to help understand if this occurred in battle or as an act of ritual destruction.

Prehistoric technology

Michael Bamforth, from the University of York’s Department of Archaeology, said: “This truly astonishing and unparalleled artefact has given us an insight into prehistoric technology that we could never have guessed at.

“Although we know that bark has many uses, including making boxes and containers it doesn't survive well in the archaeological record. Initially we didn't think bark could be strong enough to use as a shield to defend against spears and swords and we wondered if it could be for ceremonial use.

"It was only through experimentation that we realised it could be tough enough to protect against blows from metal weapons. Although a bark shield is not as strong as one made from wood or metal, it would be much lighter allowing the user much more freedom of movement."

CT scanning

The shield was first discovered by archaeologists at the University of Leicester's Archaeoligical Services in 2015 at an Iron Age site within a farming landscape known to have been used and managed by Iron Age communities, with the Fosse Way Roman road running close by.

Many cutting-edge analytical techniques have been used to understand the construction of the object, including CT scanning and 3D printing.

Dr Rachel Crellin, Lecturer in later Prehistory at the University of Leicester, who assessed the evidence for impact damage, said: “The first time I saw the shield I was absolutely awed by it: the complex structure, the careful decorations, and the beautiful boss.

“I must admit I was initially sceptical about whether the shield would have functioned effectively, however the experimental work showed that the shield would have worked very effectively, and analysis of the surface of the object has identified evidence of use.”

Craft practices

The shield has now been conserved by York Archaeological Trust and will be deposited with the British Museum on behalf of Everards of Leicestershire, who funded and supported the project.

Dr Julia Farley, Curator of British and European Iron Age Collections at the British Museum, said: “This is an absolutely phenomenal object, one of the most marvelous, internationally important finds that I've encountered in my career.

“Bark and basketry objects were probably commonplace in ancient Britain, but they seldom survive, so to be able to study this shield is a great privilege. It holds a rich store of information about Iron Age society and craft practices.”

 

Press release from the University of York.


Earliest evidence of the cooking and eating of starch

Earliest evidence of the cooking and eating of starch

Early human beings who lived around 120,000 years ago in South Africa were 'ecological geniuses' who were able to exploit their environment intelligently for suitable food and medicines

starch Klasies River Cave South Africa
The Klasies River cave in the southern Cape of South Africa. Credit: Wits University

New discoveries made at the Klasies River Cave in South Africa's southern Cape, where charred food remains from hearths were found, provide the first archaeological evidence that anatomically modern humans were roasting and eating plant starches, such as those from tubers and rhizomes, as early as 120,000 years ago.

The new research by an international team of archaeologists, published in the Journal of Human Evolution, provides archaeological evidence that has previously been lacking to support the hypothesis that the duplication of the starch digestion genes is an adaptive response to an increased starch diet.

"This is very exciting. The genetic and biological evidence previously suggested that early humans would have been eating starches, but this research had not been done before," says Lead author Cynthia Larbey of the Department of Archaeology at the University of Cambridge. The work is part of a systemic multidisciplinary investigation into the role that plants and fire played in the lives of Middle Stone Age communities.

The interdisciplinary team searched for and analysed undisturbed hearths at the Klasies River archaeological site.

"Our results showed that these small ashy hearths were used for cooking food and starchy roots and tubers were clearly part of their diet, from the earliest levels at around 120,000 years ago through to 65,000 years ago," says Larbey. "Despite changes in hunting strategies and stone tool technologies, they were still cooking roots and tubers."

starch Klasies River Cave South Africa
Cynthia Larbey points to an area where parenchyma were found in 65,000 year old hearths at Klasies River Cave. Credit: Wits University

Professor Sarah Wurz from the School of Geography, Archaeology and Environmental Studies at the University of the Witwatersrand in Johannesburg, South Africa (Wits University) and principal investigator of the site says the research shows that "early human beings followed a balanced diet and that they were ecological geniuses, able to exploit their environments intelligently for suitable foods and perhaps medicines".

By combining cooked roots and tubers as a staple with protein and fats from shellfish, fish, small and large fauna, these communities were able to optimally adapt to their environment, indicating great ecological intelligence as early as 120 000 years ago.

"Starch diet isn't something that happens when we started farming, but rather, is as old as humans themselves," says Larbey. Farming in Africa only started in the last 10 000 years of human existence.

Humans living in South Africa 120 000 years ago formed and lived in small bands.

"Evidence from Klasies River, where several human skull fragments and two maxillary fragments dating 120 000 years ago occur, show that humans living in that time period looked like modern humans of today. However, they were somewhat more robust," says Wurz.

Klasies River is a very famous early human occupation site on the Cape coast of South Africa excavated by Wurz, who, along with Susan Mentzer of the Senckenberg Institute and Eberhard Karls Universität Tübingen, investigated the small (c. 30cm in diameter) hearths.

The research to look for the plant materials in the hearths was inspired by Prof Hilary Deacon, who passed on the Directorship of the Klasies River site on to Wurz. Deacon has done groundbreaking work at the site and in the 1990's pointed out that there would be plant material in and around the hearths. However, at the time, the micro methods were not available to test this hypothesis.

The Klasies River cave in the southern Cape of South Africa. Credit: Wits University

Press release from the University of the Witwatersrand