DNA Research

16 Mar 2019

After spending the last couple of days ploughing through David Reich, 'Who We Are and How We Got Here; ancient DNA and the new science of the human past' Oxford University Press:2018, I came upon a press release on an article published in Science journal (March 2019) on the DNA of people in the Iberian peninsular (Spain and Portugal) and found the authors were pre-empted by Reich in his book. It seems that Y chromosomes (the male line) were upended by a large amount, virtually replaced in the Bronze Age by people with an origin in central Europe  see https://phys.org/print471768767.html. It seems that Reich was part of the research as he pops up in the press release, and the same story is actually repeated in his book. Starting in around 2500BC - and bear in mind that Intcal 2013 has recalibrated older dates and what is now 2500BC was formerly 2300BC - and until 2000BC, a lot of comings and goings around that period reshaped the paternal ancestry (Y chromosomes). In other words, an invasion by a new people that ultimately had an origin on the steppes according to Reich. They appear to have arrived in eastern and central Europe at some point around 3000BC so we are talking about a secondary expansion - after they had mixed with the farmers already living in Europe. Is this the origin of the Celts in Iberia one may ask. Alice Roberts, in her book 'The Celts' (2015) (also a TV series with Neil Oliver) proposed that the Celts (an Indo Euro speaking group) represented the group of farmers that made their way from the Near East through the Mediterranean basin to Iberia, and eventually to Britanny and the western side of the British Isles. She suggested that via trade and migration Celts moved into central Europe and brought metallurgy and various cultural traits into what is now the Danube valley, and at a later stage these people became the Celts recorded by the Greeks and Romans. Reich and colleagues appear to be saying something quite different. An invasion of steppe people (from the kurgan culture north of the Black Sea) mingled and ruled over farming communities in central and eastern Europe, bringing the Indo Euro language with them - and subsequently, some 500 years later, taking it into Iberia. Now, Reich is a geneticist rather than a lingualist so we may take the language bit with a pinch of salt. Colin Renfrew has previously suggested the Indo Euro language was spread by farmers with an origin in the Fertile Crescent. However, farmers came out of Anatolia 8000 years ago and spread through the Balkans into eastern, central and northern Europe over the following couple of thousand years. Some of these farmers moved into Bulgaria (where a lot of EU funded archaeology is currently revealing a complicated history where steppe culture and agriculture appears to have developed a composite semi mobile way of life in the Ukraine and southern Russia). In other words, it is still possible the Indo Euro languages were spread by farmers initially, but were adopted on the steppes by other cultures and redistributed to India in one direction and Europe in the other.

The article also details genetic variation among among ancient hunters (Late Palaeolithic and Mesolithic) in Iberia which appears to show admixture with people from North Africa and the Mediterranean basin. It also provides an explanation for why modern Basques have a distinctive language and culture, ancestrally different from other Iberians. It seems Reich was involved in the study and Inigo Olade, a post doctoral fellow in his laboratory at Harvard, wrote up the study.

At https://phys.org/print471781825.html ... we have a similar story - this time on the diversity of hunter gatherers in Europe - published in Current Biology (March,2019). This also concerns Iberia which was a refugia during the Late Glacial Maximum. DNA research on skeletal material has found an additional Palaeolithic lineage going back to the Ice Age. One of them was the foreunners of the Magdalenians who went on to colonise France, Britain, and southern Scandinavia after the ice retreated. The new group are also know from Italy ((a refuge population). They appear to have mixed with incoming farmers during the Neolithic as their genetic signature is also present in early European farmers who expanded across Europe from Anatolia (including Italy and Spain).

At https://phys.org/print471780053.html ... patterns and diet of the late Neandertals were similar to early modern humans (of the Late Palaeolithic) according to a new study in Scientific Reports (March 2019).