The genetic map of western and central Eurasia changed significantly after the last glacial maximum about 20,000 years ago. Geneticists, together with anthropologists and archaeologists, studied the complete human genome of 356 individuals who lived 50,000–5,000 BCE. The study, published in Nature, also examined remains from the well-known triple burial at the Dolni Vestonice site, which were analysed by experts from the Institute of Archaeology of the Czech Academy of Sciences in Brno.
The analysis of archaic DNA is still yielding new insights. Currently, researchers centred around Cosimo Postha and Svante Päabo, Nobel laureate in paleogenetics, are focusing on how the distribution of populations and their genetic profile changed after the Last Glacial Maximum (LGM), a climatic event that occurred during the ice age about 24,000 to 20,000 years ago (the last peak of the last ice age). Researchers worked with sketches of the “genetic history” of Europe from a previous study of theirs. Now, thanks to new sampling methods, they were able to obtain more complete samples and significantly expand the European genetic tree.
“The Last Glacial Maximum represented a critical bottleneck for European populations. A part of Europe was covered by glaciers and permafrost was encroaching on the territory of present-day Czech Republic, the climate had cooled considerably, and there was greater drought. Groups of hunters-gatherers were changing and moving around while also developing further – perhaps even with new genes,” explains Jiří Svoboda from the Institute of Archaeology of the Czech Academy of Sciences in Brno, who has been involved in the study of fossil finds from Dolni Vestonice, Pavlov, and other studies for the past three decades.
The triple burial excavation site at Dolni Vestonice (1986). Photo: Jiří Svoboda, Archive of the Institute of Archeology of the CAS in Brno.
The Vestonice “cluster” disappeared
It was the remains of three men from the Dolni Vestonice II site that proved to be a missing piece in the genetic map of Europe. A complete analysis of their genomes and comparison with other remains in the new extensive study showed that the genetic trace of our hunters from Dolni Vestonice and Pavlov disappeared after the Last Glacial Maximum.
“The dominant hypothesis we are currently working with is an ecological one – due to the Last Glacial Maximum, the vegetation on the territory of the present-day Czech Republic was thinning and animal herds were migrating, which meant that sources of food were diminishing. It is not yet possible to prove whether other populations were involved as well,” Svoboda adds.
And while traces of the Vestonice cluster disappeared, other populations thrived.
“Their gene pool expanded into northern and north-eastern Europe after the LGM,” Svoboda explains.
Distinguishing between Western and Eastern European hunter-gatherers
Another significant genetic change was discovered by researchers in southern Europe, where migrations and local replacements within human groups, i.e., the exchange and differentiation of genes, were still occurring during the Last Glacial Maximum.
“In the last phase of the research, more analysis was done on samples from Italy, where there are also a lot of anthropological findings. This resulted in the ‘finer-grained’ view of population movements in the Mediterranean,” Svoboda explains.
Overall, the researchers were able to distinguish between Western and Eastern European hunter-gatherers thanks to the more detailed data.
Withstanding the ravages of time and archaeologists alike
When collecting archaic DNA, researchers struggle with the damage to the remains over thousands of years as well as contamination from more recent DNA that can be transferred onto the finds during handling. This must then be separated in the subsequent analyses.
“Additional samples from our fossils were taken in 2017 from the petrous part of the temporal bone, which is the hardest bone of the skull and its internal structure is best protected against the effects of the external environment,” says Sandra Sázelová from the Institute of Archaeology of the CAS in Brno, also a co-author of the international study.
The bones are very valuable, and each sample collection is a destructive process. It is therefore essential to take samples for genetic analysis in a completely clean environment and in as minimum a scope as possible.