The first groups of Homo sapiens in Europe faced subarctic climates

Using the analysis of stable oxygen isotopes of the tooth enamel of animals massacred by humans at the Bacho Kiro cave site in Bulgaria, Max Planck researchers show that human groups belonging to at a first wave of dispersal of our species in Europe were faced with very cold climatic conditions while they occupied the cave about 46,000 to 43,000 years ago. The archaeological remains of the Bacho Kiro cave currently represent the oldest known remains of Homo sapiens from the Upper Paleolithic in Europe, and thus open a unique window on the time when our species began to emerge from the Levant and settle in through mid-latitudes of Eurasia as part of an archaeological phenomenon called the Early Upper Paleolithic.

The process by which our species dispersed to new environments during this time represents an important evolutionary turning point that ultimately led to Homo sapiens populating all continents and a great diversity of climatic zones and environments. The mechanisms that facilitated the initial waves of expansion remain debated, but a majority of models based on the correlation of archaeological sites with spatially distant climate records have so far indicated that human groups have relied on warmer climatic conditions for them. spread to new, more northerly environments.

Using evidence directly from the archaeological layers of the Bacho Kiro cave, Max Planck’s team have now been able to show that humans have endured very cold climatic conditions, similar to those typical of present-day northern Scandinavia, for several thousand years. “Our evidence shows that these human groups were more flexible about the environments they used and more adaptable to different climatic conditions than previously thought,” says lead author Sarah Pederzani, researcher at the Max Planck Institute for Evolutionary Anthropology and at the University of Aberdeen. Jean-Jacques Hublin, director of the Department of Human Evolution at the Max Planck Institute, adds: “Thanks to this new knowledge, new models for the propagation of our species across Eurasia will now have to be constructed, taking into account of their higher degree of climatic flexibility. “

Archaeological material from Bacho Kiro cave in Bulgaria

By directly using archaeological materials, such as the remains of human-slaughtered herbivores, to generate climate data, the paleoclimate research team, led by Pederzani and Kate Britton, also a researcher at the Max Planck Institute for Evolutionary Anthropology and the University of Aberdeen, was able to establish a very solid record of local climatic conditions that relate specifically to the time when humans inhabited the Bacho Kiro cave.

“This technique allows for a more secure attribution of the local climatic context compared to the more commonly used chronological correlation between archaeological data and climate records from different localities which have formed the basis of much of the existing research on adaptability. human climate – it really does give us a glimpse of what life was like ‘on the ground’, ”says Britton. remains of particular animals, studies of oxygen isotopes or other means of generating climate data directly from archaeological sites remain scarce during the period when Homo sapiens first spread across Eurasia, ”Pederzani adds. Indeed, this study by Max Planck is the first study carried out in the context of the initial Upper Paleolithic and could therefore give such surprising results.

Highly resolved record of past temperatures spanning over 7,000 years

Pederzani spent a year conducting laboratory work from series of drilling small samples of animal teeth to wet chemical preparation and stable isotope ratio mass spectrometry to obtain all the data needed. “Through this intensive analysis which included a total of 179 samples, it was possible to obtain a very highly resolved record of past temperatures, including estimates of summer, winter and annual temperatures averaged for human occupancies spanning over over 7,000 years old, ”Pederzani explains.

New excavations in the Bacho Kiro cave carried out by an international team led by researchers Max Planck Jean-Jacques Hublin, Tsenka Tsanova and Shannon McPherron, and Nikolay Sirakov from the National Institute of Archeology with Museum of the Bulgarian Academy of sciences in Sofia, Bulgaria, began in 2015 and have provided a rich archaeological record of human activity in the cave, including remains of occupations which represent the earliest known occurrence of the Upper Paleolithic Homo sapiens in Europe. The deposits in the lower part of the site contained a large number of animal bones, stone tools, pendants, and even human fossils and formed the basis of the climate study to study the environmental conditions that humans became known when they first spread to South-Eastern Europe from the Levant. .

The study is published in Scientists progress.