Moving to Iberia to survive the Ice Age
Investigation examines the migrations of Ice Age hunter-gatherers over a period of 30,000 years – they took shelter in Western Europe
WITH the largest dataset of prehistoric European huntergatherer genomes ever generated, an international research team has rewritten the genetic history of our ancestors, according to the universities involved in the project.
An Alicante university (UA) professor took part in the study into the migrations of huntergatherers.
The team analysed the genomes (the complete set of DNA in an organism) of 356 prehistoric people from different archaeological cultures – including new data sets of 116 individuals from 14 different European and Central Asian countries.
A UA spokeswoman explained that modern humans began to spread across Eurasia around 45,000 years ago but previous research showed that the first modern humans that arrived in Europe did not contribute to later populations.
This new study focused on the people who lived between 35,000 and 5,000 years ago and that are, ‘at least partially’, the ancestors of the present-day population of Western Eurasia, including – for the first time – the genomes of people who lived during the Last Glacial Maximum (LGM), the coldest phase of the last Ice Age, around 25,000 years ago.
“Surprisingly, the research team found that populations from different regions associated with the Gravettian culture, which was widespread across the European continent between 32,000 and 24,000 years ago, were not closely related to each other,” said the spokeswoman.
And this, despite the fact, that they were linked by a common archaeological culture,
using similar weapons and producing similar art.
Genetically, the populations from western and southwestern Europe – today’s France, Spain and Portugal – differed from contemporaneous populations from central and southern Europe (today’s Czech Republic and Italy).
Furthermore, the gene pool of the western Gravettian populations is found continuously for at least 20,000 years: their descendants stayed in southwestern Europe during the coldest period of the last Ice Age (between 25,000 and 19,000 years ago) and later spread north-eastward to the rest of Europe.
“With these findings, we can for the first time directly support the hypothesis that during the Last Glacial Maximum people found refuge in the climatically more favourable region of southwestern Europe,” said Professor Cosimo Posth from the University of Tübingen.
The Italian peninsula was previously considered to be another climatic refuge for humans during the LGM.
However, the research team found no evidence for this, on the contrary, hunter-gatherer populations associated with the Gravettian culture and living in central and southern Europe are no longer genetically detectable after the LGM.
People with a new gene pool settled in these areas, instead.
‘Presumably’, these people came from the Balkans, arrived first in northern Italy around the time of the glacial maximum and spread all the way south to Sicily.
The analysed genomes also show that the descendants of these inhabitants of the Italian peninsula spread across the rest of Europe about 14,000 years ago. The research team describes a large-scale genetic replacement that may have been caused, in part, by climatic changes that forced people to migrate.
“At that time, the climate warmed up quickly and considerably and forests spread across the European continent,” said Johannes Krause, the study’s senior author. “This may have prompted people from the south to expand their habitat. The previous inhabitants may have migrated to the north as their habitat, the ‘mammoth’ steppe, dwindled.”
Interactions between people from central and eastern Europe can only be detected again from 8,000 years ago.
“At that time, hunter-gatherers with distinct ancestries and appearances started to mix with each other,” noted He Yu from Peking University.
“They were different in many aspects, including their skin and eye colour.”
During this time agriculture and a sedentary lifestyle spread from Anatolia to Europe.
“It is possible that the migration of early farmers into
Europe triggered the retreat of hunter-gatherer populations to the northern edge of Europe,” added professor Krause.
“At the same time, these two groups started mixing with each other, and continued to do so for around 3,000 years.”
Alicante input
Javier Fernández López de Pablo, from the archaeology and heritage institute (INAPH) at Alicante university, explained that his department analysed human remains which had been unearthed at the Casa Corona dig site in Villena in 2008.
Sr Fernández explained that it was thanks to the international study that they were able to extract fossil DNA from the remains, ‘something that is particularly difficult in these latitudes’.
This allowed them to ‘better understand’ the population in the area at that time in relation to the movements of others living on the Iberian Peninsula and in Western Eurasia.
“The data that we have obtained reveals the existence of processes of interaction between different populations of hunter-gathers which inhabited Western Eurasia from the last Ice Age,” he said.
Further research needed
“The data we gained from this study provides us with astonishingly detailed insights into the developments and encounters of West Eurasian hunter-gatherer groups,” concluded Professor Cosimo Posth.
“Further interdisciplinary research will clarify which exact processes were responsible for the genetic replacements of entire Ice Age populations.”