̽��ֱ�� of Cambridge - C.L Scheib

Prehistoric roots of cold sore virus traced through ancient DNA

fpjl2 — Wed, 27 Jul 2022 15:03:19 +0000

First ancient herpes genomes to be sequenced suggest a Bronze Age flourishing linked to migrations into Europe and possibly the emergence of kissing.

First Peoples: two ancient ancestries ‘reconverged’ with settling of South America

fpjl2 — Thu, 31 May 2018 18:01:52 +0000

Recent research has suggested that the first people to enter the Americas split into two ancestral branches, the northern and southern, and that the “southern branch” gave rise to all populations in Central and South America.

Now, a study shows for the first time that, deep in their genetic history, the majority – if not all – of the Indigenous peoples of the southern continent retain at least some DNA from the “northern branch”: the direct ancestors of many Native communities living today in the Canadian east.

̽��ֱ��latest findings, published today in the journal Science, reveal that, while these two populations may have remained separate for millennia – long enough for distinct genetic ancestries to emerge – they came back together before or during the expansion of people into South America.

̽��ֱ��new analyses of 91 ancient genomes from sites in California and Canada also provide further evidence that the first peoples separated into two populations between 18,000 and 15,000 years ago. This would have been during or after migrating across the now-submerged land bridge from Siberia along the coast.

Ancient genomes from sites in Southwest Ontario show that, after the split, Indigenous ancestors representing the northern branch migrated eastwards to the great lakes region. This population may have followed the retreating glacial edges as the Ice Age began to thaw, say researchers.

̽��ֱ��study also adds to evidence that the prehistoric people associated with Clovis culture – named for 13,000-year-old stone tools found near Clovis, New Mexico, and once believed to be ancestral to all Native Americans – originated from ancient peoples representing the southern branch.

This southern population likely continued down the Pacific coast, inhabiting islands along the way. Ancient DNA from the Californian Channel Islands shows that initial populations were closely related to the Clovis people.

Yet contemporary Central and South American genomes reveal a “reconvergence” of these two branches deep in time. ̽��ֱ��scientific team, led by the universities of Cambridge, UK, and Illinois Urbana-Champaign, US, say there must have been one or a number of “admixture” events between the two populations around 13,000 years ago.

They say that the blending of lineages occurred either in North America prior to expansion south, or as people migrated ever deeper into the southern continent, most likely following the western coast down.

“It was previously thought that South Americans, and indeed most Native Americans, derived from one ancestry related to the Clovis people,” said Dr Toomas Kivisild, co-senior author of the study from Cambridge’s Department of Archaeology.

“We now find that all native populations in North, Central and South America also draw genetic ancestry from a northern branch most closely related to Indigenous peoples of eastern Canada. This cannot be explained by activity in the last few thousand years. It is something altogether more ancient,” he said.

Dr Ripan S. Malhi, co-senior author from Illinois Urbana-Champaign, said: “Working in partnership with Indigenous communities, we can now learn more about the intricacies of ancestral histories in the Americas through advances in paleogenomic technologies. We are starting to see that previous models of ancient populations were unrealistically simple.”

Present day Central and South American populations analysed in the study were found to have a genetic contribution from the northern branch ranging between 42% to as high as 71% of the genome.

Surprisingly, the highest proportion of northern branch genetics in South America was found way down in southern Chile, in the same area as the Monte Verde archeological site – one of the oldest known human settlements in the Americas (over 14,500 years old).

“It’s certainly an intriguing finding, although currently circumstantial – we don’t have ancient DNA to corroborate how early this northern ancestral branch arrived,” said Dr Christiana Scheib, first author of the study, who conducted the work while at the ̽��ֱ�� of Cambridge.

“It could be evidence for a vanguard population from the northern branch deep in the southern continent that became isolated for a long time – preserving a genetic continuity.

“Prior to 13,000 years ago, expansion into the tip of South America would have been difficult due to massive ice sheets blocking the way. However, the area in Chile where the Monte Verde site is located was not covered in ice at this time,” she said.

“In populations living today across both continents we see much higher genetic proportions of the southern, Clovis-related branch. Perhaps they had some technology or cultural practice that allowed for faster expansion. This may have pushed the northern branch to the edges of the landmass, as well as leading to admixture encounters.”

While consultation efforts varied in this study from community-based partnerships to more limited engagement, the researchers argue that more must be done to include Indigenous communities in ancient DNA studies in the Americas.

̽��ֱ��researchers say that genomic analysis of ancient people can have adverse consequences for linked Indigenous communities. Engagement work can help avoid unintended harm to the community and ensure that Indigenous peoples have a voice in research.

“ ̽��ֱ��lab-based science should only be a part of the research. We need to work with Indigenous communities in a more holistic way,” added Schieb, who has recently joined the ̽��ֱ�� of Tartu’s Institute of Genomics, where Kivisild also holds an affiliation.

“From the analysis of a single tooth, paleogenomics research can now offer information on ancient diet and disease as well as migration. By developing partnerships that incorporate ideas from Native communities, we can potentially generate results that are of direct interest and use to the Indigenous peoples involved,” she said.

New research using ancient DNA finds that a population split after people first arrived in North America was maintained for millennia before mixing again before or during the expansion of humans into the southern continent.

̽��ֱ��lab-based science should only be a part of the research. We need to work with Indigenous communities in a more holistic way

Dr Christiana Scheib

Scheib/Kivisild/Mahli

Two of the four possible combinations of ancient admixture highlighted by the researchers.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Genetic study suggests present-day Lebanese descend from biblical Canaanites

fpjl2 — Thu, 27 Jul 2017 16:02:17 +0000

Scientist have sequenced the entire genomes of 4,000-year-old Canaanite individuals who inhabited the Near East region during the Bronze Age, and compared these to other ancient and present-day populations. ̽��ֱ��results, published in the American Journal of Human Genetics, suggest that present-day Lebanese are direct descendants of the ancient Canaanites.

̽��ֱ��Near East is often described as the cradle of civilisation. ̽��ֱ��Bronze Age Canaanites, later known as the Phoenicians, introduced many aspects of society that we know today - they created the first alphabet, established colonies throughout the Mediterranean and were mentioned several times in the Bible.

However, historical records of the Canaanites are limited. They were mentioned in ancient Greek and Egyptian texts, and the Bible which reports widespread destruction of Canaanite settlements and annihilation of the communities. Experts have long debated who the Canaanites were genetically, what happened to them, who their ancestors were and if they had any descendants today.

In the first study of its kind, an international team of scientists have uncovered the genetics of the Canaanite people and a firm link with people living in Lebanon today. ̽��ֱ��team discovered that more than 90 per cent of present-day Lebanese ancestry is likely to be from the Canaanites, with an additional small proportion of ancestry coming from a different Eurasian population.

̽��ֱ��team, including researchers from Cambridge ̽��ֱ��’s Department of Archaeology and Anthropology, and led by the Wellcome Trust Sanger Institute, estimate that new Eurasian people mixed with the Canaanite population about 2,200 to 3,800 years ago at a time when there were many conquests of the region from outside.

̽��ֱ��analysis of ancient DNA also revealed that the Canaanites themselves were a mixture of local people who settled in farming villages during the Neolithic period and eastern migrants who arrived in the area around 5,000 years ago.

"Ancient DNA is becoming an indispensable tool for understanding population movements of the past. This study in particular provides previously inaccessible information about a group of people known only by surviving written accounts and interpretations of archaeological findings,” said Dr. C L Scheib, one of two Cambridge co-authors, along with Dr Toomas Kivisild.

“ ̽��ֱ��fact that we can retrieve whole genomes from conditions not considered ideal for DNA preservation also shows how far the field has advanced technically," she said.

In the study, researchers sequenced whole genomes of five Canaanite individuals who lived 4,000 years ago in a city known as Sidon in present-day Lebanon. Scientists also sequenced the genomes of 99 present-day Lebanese and analysed the genetic relationship between the ancient Canaanites and modern Lebanese.

Dr Marc Haber, first author from the Sanger Institute, said: “It was a pleasant surprise to be able to extract and analyse DNA from 4,000-year-old human remains found in a hot environment, which is not known for preserving DNA well. We overcame this challenge by taking samples from the petrous bone in the skull, which is a very tough bone with a high density of ancient DNA.”

Dr Claude Doumet-Serhal, co-author and Director of the Sidon excavation site in Lebanon, said: “For the first time we have genetic evidence for substantial continuity in the region, from the Bronze Age Canaanite population through to the present day. These results agree with the continuity seen by archaeologists.

“Collaborations between archaeologists and geneticists greatly enrich both fields of study and can answer questions about ancestry in ways that experts in neither field can answer alone.”

Adapted from a Wellcome Trust press release.

Researchers analysed DNA extracted from 4,000-year-old human remains to reveal that more than 90% of Lebanese ancestry is from ancient Canaanite populations.

̽��ֱ��fact that we can retrieve whole genomes from conditions not considered ideal for DNA preservation also shows how far the field has advanced technically

C.L Scheib

Wellcome Genome Campus Public Engagement

Cambridge co-author C.L Scheib conducting ancient bone analysis at the Wellcome Genome Campus.

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

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