Digging ancient signals out of modern human genomes

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With new genome analysis tools, scientists have made significant advances in our understanding of modern humans' origins and ancient migrations.

But trying to find ancient DNA, let alone prove that the ancient DNA is ancestral to a population living today is extremely challenging.

A new study in Molecular Biology and Evolution (MBE) adds to this understanding by reconstructing artificial genomes with the analyses of the of 565 contemporary South Asian individuals to extract ancient signals that recapitulate the long history of human migration and admixture in the region.

"All in all, our results provide a proof-of-principle for the feasibility of retrieving ancient genetic signals from contemporary human subjects, as if they were genomes from the past embedded in amber," said Luca Pagani, the research coordinator of the study.

The study was led by Burak Yelmen and Mayukh Mondal from the Institute of Genomics of the University of Tartu, Estonia and coordinated by Luca Pagani from the same institution and from the University of Padova, Italy.

"The genetic components we managed to extract from modern genomes are invaluable, given the shortage of ancient DNA available from South Asian human remains, and allow us to elucidate the genetic composition of the ancient populations that inhabited the area," said Burak Yelmen, co-first author of the study.

While studying the mixing events that brought ancient human populations to form contemporary South Asians, the researchers also noted that some portion of the genomes had not mixed as expected, as if the genetic variants that evolved in South Asia or the ones that arrived from West Eurasia were important for adapting to the local lifestyle through admixture.

"Among these variants, we found genes important for immunity and for dietary changes, as one may expect for human populations adapting to new sets of pathogens or food," said Mayukh Mondal, joint first author of this work.

The human evolution of also revealed many genetic variants for the population studied.

"Intriguingly we also noted that some genetic variants implicated in the skin pigmentation of West Eurasians were under opposite selective forces, some becoming highly frequent and others being almost lost after the admixture events. Skin pigmentation is surely a fascinating and complex subject and we are still trying to understand what, if any, would be the adaptive implications of the signal we detected."

The study will add to the growing picture of the diversity of South Asians, and future studies of modern human origins.

"These signals can complement the picture emerging from the booming field of ancient DNA by providing high quality genomic sequences especially for areas of the world where archaeological human remains are scarce or poorly preserved."

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More information: Burak Yelmen et al, Ancestry-specific analyses reveal differential demographic histories and opposite selective pressures in modern South Asian populations, Molecular Biology and Evolution (2019). DOI: 10.1093/molbev/msz037
Journal information: Molecular Biology and Evolution

Citation: Digging ancient signals out of modern human genomes (2019, April 6) retrieved 20 October 2019 from https://phys.org/news/2019-04-ancient-modern-human-genomes.html
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Apr 06, 2019
Your speculations about people thousands of years ago are not nearly as important as the lives of people living on the Earth today. Take your educations and your skills and your equipment and your funds and start solving problems and curing diseases of people who are alive right now. This is such a waste of resources!

You have been distracted from what is really important - living, breathing persons here and now.

Apr 07, 2019
This is such a waste of resources! You have been distracted from what is really important - living, breathing persons here and now.

Your *comment* is a waste.

It is wrong in details, as you would have seen if you bothered to read the article you are supposed to comment the science on: ""Among these variants, we found genes important for immunity and for dietary changes,". Useful to help people now.

It is also wrong generally, since basic research always return more on investment than targeted research, you cannot do the latter without the former.

And that gets us to the smear of hard working scientists, a smear uttered without showing that you bother to help people now in any way. In fact, the smear detracts from such efforts.

It is of course okay to ask if and how population studies help modern (as well as archaeological) study. It is not okay to make an uninformed opinion that is inflammatory and possibly damaging (if people accept the buffoonery).

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