The first groups of Homo sapiens reached Europe around 45,000 years ago. Until now it was assumed that our ancestors could only colonize the new continent because the climate there became milder. But now isotope analyzes of animal teeth from the Bacho Kiro cave in Bulgaria show that this is probably not the case. At the time when the first representatives of Homo sapiens lived in this cave, the temperatures there were 10 to 15 degrees below today’s, as the researchers have determined. The climate was therefore as cold as it is today in northern Scandinavia and Russia. This suggests that our ancestors were more resistant to the cold and more adaptable than previously thought.
The great upheaval in Europe began around 45,000 years ago: The Neanderthals, who had dominated for hundreds of thousands of years, gradually disappeared, instead the newly immigrated Homo sapiens from Africa and the Middle East – our ancestor – spread. The earliest evidence of these newcomers to date was discovered by researchers led by Jean-Jacques Hublin from the Max Planck Institute for Evolutionary Anthropology in Leipzig in 2020 in the Bacho Kiro Cave in Bulgaria. Finds of human bones, tools and animal bones prove that Homo sapiens stayed in this cave located around 70 kilometers south of the Danube at the beginning of the Upper Paleolithic (IUD). Comparative DNA analyzes, however, revealed that this Homo sapiens group was apparently unable to establish itself and reproduce: they have left no traces in today’s European genome.
Climate reconstructed 45,000 years ago
Now Hublin’s team has brought more information about these first immigrants to Europe and their time. To learn more about the climate of that time, the researchers examined the bones and teeth of the animals that were deposited in this cave around 45,000 years ago. In addition to cold-tolerant animals such as mammoths and reindeer, these include animals whose descendants are found in more moderate climates today, including bison and wild horses. For their study, the scientists took samples from the enamel of bison and wild horses, which were found in the same layer as the relics of Homo sapiens, and examined them for their ratio of the oxygen isotopes O16 and O18. This allows conclusions to be drawn about the temperatures prevailing at the time.
“This time-consuming analysis, which comprised a total of 179 samples, made it possible to produce a very detailed record of past temperatures, including estimates of summer, winter and annual mean temperatures for people in the cave over a period of more than 7,000 Years, ”reports Hublin’s colleague, first author Sarah Pederzani. This study is the first to determine climatic data from the beginning of the Upper Paleolithic using finds from the site of human relics. So far, ice cores from Greenland or sediment cores from the Eifel, among others, have mostly been used for the reconstruction of the climate history.
As cold as in northern Scandinavia
The analyzes showed that the climate in Bacho Kiro around 45,000 years ago was cooler than previously assumed. The temperatures were on average 10 to 15 degrees below the usual there today and the winters in particular were very cold and severe. “The oxygen isotope values and reconstructed temperatures suggest that the climatic conditions at the time of settlement of the Bacho-Kiro Cave corresponded to those in what is now northern Scandinavia and Russia,” the team writes. “Our reconstructions demonstrate that the animals analyzed here – and the people who hunted them – lived under conditions that corresponded to those of the millennia-long cold periods known from other climate records from south-east Europe.” This contradicts earlier assessments made by the first representatives des Homo sapiens came to Europe in an interglacial period with mild temperatures.
The new results suggest that our ancestors may have been more cold-tolerant and adaptable than previously thought. “We were able to prove that these groups of people were more flexible with regard to the environments they used and more adaptable to different climatic conditions than previously assumed,” says Pederzani. This could mean that Homo sapiens did not have to rely on warm phases during its early colonization of the continents. “On the basis of these new findings, new models for the spread of our species across Eurasia must now be created, which take into account their greater climatic flexibility,” adds Hublin.
Source: Sarah Pederzani (Max Planck Institute for Evolutionary Anthropology, Leipzig) et al., Science Advances, doi: 10.1126 / sciadv.abi464