Ancient DNA charts human migration

A study of ancient DNA from eight people who lived in Europe three to five thousand years ago challenges the simple model of human social transition from hunter-gathers to farmers.

It also shatters another assumption: Spain's Basques are not direct descendants from hunter-gatherers of 10,000 years ago. Instead, they have more recent genetic links to early farmers of Iberia in southern Europe.

La Trobe archaeologist, Dr Cristina Valdiosera, is joint lead author of the study published in the latest issue of the US Proceedings of the National Academy of Sciences.

The study sequenced the DNA of early farmers found in the Portalón cave at the world-famous site of Atapuerca in northern Spain. 

It found that farmers from Iberia are from the same group of people who migrated through the south of Europe and then populated Scandinavia and most of Europe.

Game-changing collaboration

'We noticed that although they share similarities with other early European farmers, early Iberians had their own particularities.  

'It was interesting to see that farmers in Iberia had interbred with local hunter-gatherers for thousands of years – but what was more surprising was that this mixing became greater through time.

'It appears that the longer farming was practiced, the more mixing took place. Genetically people look increasingly like native hunter-gatherers and more distant from the original incoming farmers,' Dr Valdiosera said.

She said this game-changing international collaboration between 19 archaeologists, anthropologists and geneticists from Sweden, Spain and Australia has shed a lot of new light on demographic processes in Europe and Iberia.

Basis of all modern societies

Dr Valdiosera straddles all three participating nations. She is a research fellow at La Trobe, a guest researcher at Uppsala University in Sweden and an active member of the Atapuerca team in Spain.

'I think these are exciting times,' she said. 'There are many groups working on this subject, and it is only a matter of time before we have a nearly complete genetic landscape of the Neolithic in Europe, a period characterised as the basis of all modern societies, and the world as we know it today.'

Dr Valdiosera was also a lead researcher of a recent study published in Science which dealt with early migration and ancestry in the Americas.

Significance of Basque findings

Explaining the significance of the Basque finding, La Trobe head of biomolecular archaeology, Dr Colin Smith, said Basques have long been considered European outliers because of cultural differences.

'For example, their language is a complete isolate from the Indo-European languages and they show genetic distinctiveness from other Iberian populations,' he said.

'It has even been suggested Basques are a modern extension of a local Palaeolithic population from 10,000 years ago. But we now know that their closest ancestors are found in the Neolithic – and therefore are not that ancient,' Dr Smith said.

See also: Putting together the Neolithic Puzzle

Gene study uncovers America's ancestors

Ancient Americans migrated in a single wave from Siberia

Caption: Dr Valdiosera at La Trobe's archaeology lab.

Media Contact: Ernest Raetz, Tel: (03) 9479 2315 or 041 226 1919.



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