May 3, 2012
(CORDIS) — Researchers in Denmark and Sweden have discovered that immigrant Stone Age farmers made a significant impact on the genetic variation of today’s Europeans. Their findings, presented in the journal Science, provide fresh insight into hypotheses about the transition from hunter-gatherer to agricultural societies in Europe. In a nutshell, agriculture spread from southern Europe to northern Europe, through migration.
The study was led by Uppsala University in Sweden, in cooperation with researchers from Stockholm University and Karolinska Institutet in Sweden, and the University of Copenhagen in Denmark.
‘We have been able to show that the genetic variation of today’s Europeans was strongly affected by immigrant Stone Age farmers, though a number of hunter-gatherer genes remain,’ said one of the authors of the study, Professor Anders Götherström from the Department of Evolutionary Biology at Uppsala’s Evolutionary Biology Centre.
Added Mattias Jakobsson, a professor at Uppsala University and one of the authors: ‘What is interesting and surprising is that Stone Age farmers and hunter-gatherers from the same time had entirely different genetic backgrounds and lived side by side for more than a thousand years, to finally interbreed.’
Researchers said agriculture developed in the Middle East around 11 000 years ago, reaching most of Continental Europe about 5 000 years ago. But little information was available about how agriculture spread and influenced Europeans, puzzling researchers for almost 100 years. The main question was whether agriculture was an idea that spread across the continent or a method a group of migrants transferred to various parts of the continent.
Past research studies focused primarily on small amounts of genetic data.
Professor Götherström said: ‘Many attempts, including using genetics, have been made to come to terms with the problem since the significance of the spread of agriculture was established almost 100 years ago. Our success in carrying out this study depended on access to good material, modern laboratory methods and a high level of analytical expertise.’
For this study, the team used advanced deoxyribonucleic acid (DNA) to characterise nearly 250 million base pairs from 4 skeletons of humans who lived during the Stone Age around 5 000 years ago: 3 were hunter-gatherers and 1 was from an agricultural society.
According to the researchers, the Stone Age farmer was representative of his time and group. This farmer died in the area where he was born and reared.
‘The Stone Age farmer’s genetic profile matched that of people currently living in the vicinity of the Mediterranean, on Cyprus, for example,’ said lead author Pontus Skoglund, an Uppsala University doctoral student who developed new analytical methods used in the study. ‘The three hunter-gatherers from the same time most resembled northern Europeans, without exactly matching any particular group.’
The results add weight to the theory that people who migrated from southern Europe helped fuel the agricultural revolution.
‘The process appears in the end to have had the result that nobody today has the same genetic profile as the original hunter-gatherers, although they continue to be represented in the genetic heritage of today’s Europeans,’ Mr Skoglund said.
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