Unravelling the genetic diversity of Europeans

New information from a pooled analysis of ancient DNA sheds light on the genetic history of Europe's population over the past 15,000 years. The widespread notion of a single origin of Europeans has been proven wrong. It has also become clear who brought different diseases to the continent and during which era.

There were three waves of migration to Europe. About 45,000 years ago, when the last glaciation disappeared, the first anatomically modern humans arrived on the continent - primitive hunter-gatherers. Then, about 11 000 years ago, tribes arrived from the Middle East who had already mastered agriculture. And five thousand years ago, nomadic pastoralists from the steppes of western Asia and the northern Black Sea coast, travelling by ox carts - representatives of the Yamna culture - invaded the continent.

For a long time it was impossible to understand in detail the ethnogenesis of Europeans due to poor preservation of ancient DNA and imperfect analytical methods. Historians and archaeologists have traditionally believed that migration waves were uniform across the continent, ethnic groups gradually replaced each other, and populations of different regions acquired certain phenotypic traits depending on the degree of mixing or as a result of adaptation to local living conditions.

Recently, in the journal. Nature recently published four articles summarising the results of a large comprehensive study. The project involved 175 scientists from various countries, including Russia, led by Professors Eske Villerslev of the University of Cambridge, Thomas Verghe of the University of Copenhagen and Rasmus Nielsen of the University of California at Berkeley. Most of the work was carried out at the Centre for Geogenetics at the University of Copenhagen.

Samples were provided by numerous museums and scientific organizations in Europe and Asia.

Using the latest genome sequencing techniques, scientists analysed the DNA of almost five thousand people who lived in Europe and western Asia from the Late Palaeolithic (34,000 years ago) to the Viking Age, compared ancient DNA with genetic samples of hundreds of thousands of modern people held in the UK Biobank, and constructed historical maps of the distribution of characteristic genes as well as associated diseases.

The results have made it possible, among other things, to determine when in different parts of Europe the most important event in ancient human history occurred - the transition from hunting and gathering to agriculture, also called the Neolithic Revolution because it marked the end of the Mesolithic and the beginning of the Neolithic.

Around 11 500 years ago in the Middle East, in the region known as the Fertile Crescent, people moved from a nomadic existence based on hunting and gathering wild fruits to a settled way of life. This led to the establishment of permanent settlements and an agricultural culture. From here, the Neolithic Revolution spread north into Anatolia (present-day Turkey) and Europe.

New evidence suggests that the transition to agriculture began in the south and west of the continent 11,000 years ago. The arrival of Anatolian farmers affected the DNA of the population. Europeans acquired genes responsible for tolerance to vegetables and lactose - the ability to digest large quantities of plant foods and dairy products. Native hunter-gatherers did not have these qualities.

The genes for lactose tolerance were thought to have been passed on to Europeans from the Yanomami, the third wave of pastoralists who brought with them herds of domestic animals. In fact, they were Anatolian, and by the time the Yanomami arrived, Europeans were already ready to use dairy foods.

For the Eastern Europeans, these changes occurred three millennia later, and in the north, generally speaking, only a thousand years before the migration of the steppe peoples.

The "yam" genes appeared in all the inhabitants of the continent almost simultaneously - about five thousand years ago. From that moment on, the "genetic border" between the southwest and the northeast was erased and a genetically unified "European nation" emerged.

Surprisingly, almost nothing of the indigenous hunter-gatherer Europeans of the Upper Paleolithic remained in the genome even then. And they have traditionally been considered the main ancestors, giving a secondary role to foreign peoples. It appeared that the main population had completely dissolved or been wiped out by the outsiders. This means that today's Europeans can be called a 'nation of migrants'.

The phenotypical characteristics of the inhabitants of the different parts of the continent are determined above all by the routes of migration of peoples. As the farmers from the Middle East headed primarily for the southern and western parts of Europe, the population there is characterized by short stature and dark hair. The steppe pastoralists migrated north, from them came the taller stature, fair skin, eyes, and hair of the Scandinavians.

In a separate article, scientists have broken down the process of ethnogenesis using the Danes as an example. In the territory of Denmark and Great Britain, where the Neolithic Revolution reached late, until the IV millennium BC the primitive way of life was preserved. Then, 5,900 years ago, farmers coming from the south quickly, literally within a few generations, displaced the indigenous population.

Tall, fair-haired, warlike nomads with brazen weapons, moving with swift carts, simply annihilated the Scandinavian natives. Their genetic traces practically disappeared in the DNA of Danes, Swedes and Norwegians four and a half thousand years ago.

"The aliens did not drive out the natives and mingle with them, but most likely killed them all," the authors of the paper believe.

This is how the Scandinavian Viking ethnicity was formed.

"For the most part, the genetic history of Europeans was set outside Europe," Cambridge University said in a press release. "But once migrants settled in geographically isolated areas of the continent, their traits became entrenched in local populations."/BGNES