Around 45,000 years ago, modern humans spread across Europe and Asia. However, it was still unclear what climatic conditions prevailed. A pollen analysis now provides information about the vegetation around Lake Baikal in Siberia at the time and thus indirectly about the prevailing climate. Combined with archaeological traces of early Homo sapiens in the region, the results suggest that warming temperatures favored human migration to northern regions of Eurasia.
How exactly Homo sapiens colonized Europe and Asia is one of the big questions in paleontology. According to the prevailing model, a warm phase during the Ice Age caused our ancestors to migrate north from Africa. A cold snap that followed a little later is said to have significantly weakened the populations of Neanderthals, who had previously predominated in Eurasia, which further promoted the spread of Homo sapiens. However, some studies also suggest that Homo sapiens opened up new areas in Eurasia during a cold phase.
Warm climate on Lake Baikal
As a contribution to this discussion, a team led by Koji Shichi from the Research Institute for Forestry and Forest Products in Kochi, Japan, has now shed light on the climatic conditions around Lake Baikal in Siberia. To do this, the researchers analyzed pollen data from sediment samples from the lake and its surroundings. “This research addresses long-standing debates about the environmental conditions experienced by early Homo sapiens during their migration to Europe and Asia about 40,000 to 50,000 years ago,” said co-author Ted Goebel of the University of Kansas. “Our results provide important insights into the environmental conditions on Lake Baikal.”
During their analysis, the researchers found that pollen from trees was initially only present in very small quantities compared to herbs and shrubs, but increased over time. Pollen from conifers made up a large proportion. “The expansion of conifers suggests remarkably wet conditions,” the team writes. Various grass pollens were also found. Together, this suggests a rather mild climate: “The pollen analyzes indicate a surprising level of warmth during this time,” says Goebel.
Combination of pollen analyzes and fossils
The researchers combined the pollen data with archaeological finds of human remains. “There is a human fossil from Siberia, but it was not found on Lake Baikal, but further west, in a place called Ust'-Ishim,” explains Goebel. In addition, tools and art objects indicate that groups of Homo sapiens lived in the region. Stone tools with long, slender blades, bone needles with eyelets and the first ivory carvings are typical of early modern humans.
“The key factor here is accurate dating, not only of human fossils and animal bones associated with the archeology of these people, but also of environmental data, including pollen,” says Goebel. “What we have presented is a solid chronology of environmental changes at Lake Baikal during this period, supplemented by a well-dated archaeological record of the presence of Homo sapiens in the region.”
Good conditions for hunters and gatherers
When Homo sapiens came to Siberia, the landscape was probably characterized by coniferous forests and grasslands and offered good opportunities for foraging and hunting. “This contradicts some recent archaeological findings in Europe,” says Goebel. “At least in the Baikal region, our results suggest that a milder climate and the emergence of forests facilitated the spread of Homo sapiens into an otherwise cold and dry region. “Our study also contributes to our understanding of the adaptability of early Homo sapiens, which spread into diverse environments in Europe and Asia.”
Source: Koji Shichi (Forestry and Forest Products Research Institute, Kochi, Japan) et al., Science Advances, doi: 10.1126/sciadv.adi0189