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Stone Age hunter-gatherers in Anatolia laid the foundation for Europe’s population

2016-09-01

Woman with unborn baby discovered in Boncuklu, Anatolia.

The population of Europe consists largely of a mixture of groups that came from the south to the continent almost 8,000 years ago, and groups that had been living in Europe previously. Researchers from Stockholm and Uppsala universities and from Turkey now present a new picture of the demographic developments at the time of the first appearance of farming in Anatolia, before agriculture reached Europe.

In her PhD thesis, Ayca Omrak, doctoral student at the Department of Archaeology and Classical Studies at Stockholm University, has produced data forming the basis for the new findings. DNA from two archaeologically significant areas in Anatolia (the Asian part of modern-day Turkey) shows that the early agricultural population evolved over thousands of years in a dynamic process in Anatolia, eventually leading to the mass migration that brings agriculture to Europe.

The region’s transition to an agrarian society, neolithisation, takes place around central Anatolia, including at Boncuklu, in a hunter-gather population that gradually turns to farming. The changes in subsistence appear before we can discern signs of population growth and higher population density. The population at Boncuklu shows a low degree of genetic diversity – a clear sign of a limited population size. The population was comparable to the hunter-gatherer populations in Europe of the same period, which also showed low diversity, and stood in stark contrast to the somewhat later neolithic groups who spread agriculture to Europe.

However, about 1,500 years later, we see a greater genetic variation in Anatolia in places like Tepecik-Ҫiftlik, where agriculture and animal husbandry have now taken a dominant role in subsistence. There is greater genetic variation here and clear signs of a population increase. This demographic development is also related to an increased mobility from south to east, which is supported by the archaeological evidence that points to contact over large areas.

The findings, which are now being published in the leading journal Current Biology, were the result of a collaboration between Stockholm University, Uppsala University, and the Middle East Technical University in Ankara.

Anders Götherström with the Archaeological Research Laboratory at Stockholm University is one of the researchers behind the study.

‘For half a decade, we’ve been working to trace the genetics of the first European farmers back to their origins in the Fertile Crescent,’ says Anders. ‘Now that we’ve gone the whole way, it’s incredibly exciting to see how dynamic and innovative the earliest stage of agriculture in Anatolia was.’

The Fertile Crescent that Anders refers to is an area in the Middle East surrounding the Euphrates, Tigris, Jordan, Orontes and Karun rivers. The northern part of this area extends a bit into Anatolia.

‘This is a period,’ Anders continues, ‘in which the earliest farmers experiment with different aspects of agriculture and settled life and also expand their groups to include people with whom previous exchanges were not as intimate.’

‘We’ve been able to demonstrate that the groups who spread agriculture to Europe have their origins in Anatolia and not in the southern and eastern parts of the Fertile Crescent – modern-day Iran, Syria and Israel – despite the fact that agriculture developed in all of these areas,’ says Mattias Jakobsson of Uppsala University, and continues.

‘The material we work with is old, in some cases around 10,000 years old, and from an area with a warm climate. There isn’t a lot of DNA preserved in this type of material, but we have been able to produce a surprisingly large amount of DNA and information from some of our oldest samples.

Like Anders Götherström and Mattias Jakobsson, Jan Storå with the Osteoarchaeological Research Laboratory at Stockholm University has been involved in many of the studies tracking the path of agriculture from Anatolia and out into Europe.

‘It’s extremely valuable that we now have a clearer picture of the demographic development and link to the appearance of agriculture in the peripheral extremes of Europe, like Spain and Sweden,’ says Jan, ‘and now even within the areas of origin, where a dynamic population development with complex contact networks within large regions can be seen as early as 10,000 years ago. This study links the demographic history and the agricultural history across all of Europe.’


Results in brief:
The initial stage of neolithisation in Anatolia, which appears in the subsistence strategies at Boncuklu, takes place within the hunter-gatherer populations. The changes in subsistence appear before it is possible in the demographic development to distinguish the signs of population growth and increased population density – which would have resulted in increased genetic variation. The population at Boncuklu shows the same degree of genetic variation as the contemporary hunter-gatherer populations that were studied. About 1,500 years later, however, a greater genetic variation is seen in Anatolia in places like Tepecik-Ҫiftlik, where agriculture and animal husbandry have now taken a dominant role in subsistence. Clear signs of a greater genetic variation are evident here, indicating population growth and immigration. This demographic development is related to an increased mobility from the south and east, which is supported by the archaeological evidence indicating contact over large areas, such as among the population of Tepecik-Ҫiftlik.

 

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