To understand how climate change affected hunter-gatherer groups in Europe between 47,000 and 7,000 years ago, researchers from Germany, Italy and the United States analyzed morphological features of fossil teeth. The study, published in the journal Science Advances, made use of the largest dataset of human fossils from Ice Age Europe to date.
The researchers examined various tooth features, such as the number and shape of crown cusps, the pattern of ridges and grooves on the chewing surface, and the presence of wisdom teeth. These features are heritable, allowing scientists to trace genetic relationships between Ice Age humans without relying on well-preserved ancient DNA.
“The fact that these features are heritable means that we can use them to trace genetic relationships between Ice Age humans without the need for well-preserved ancient DNA,” explains lead researcher Dr. Hannes Rassmann from the Senckenberg Center for Human Evolution and Paleoenvironment at the University of Tübingen.
Rasmann, in collaboration with colleagues from the University of Tübingen, the University of Ferrara in Italy, and New York University in the United States, developed a new method for analyzing fossils based on machine learning algorithms.
“Our new method, called Pheno-ABC, allows us to reconstruct complex prehistoric demographic events using morphological data. To our knowledge, this has never been done before,” said co-first author Dr. Maria Teresa Vizzari of the University of Ferrara, who played a key role in the development of the algorithm.
The study shows that populations in Western and Eastern Europe were genetically closely connected between 47,000 and 28,000 years ago. This period coincides with the last Ice Age, when the first modern humans arrived in Europe, marking the beginning of the so-called Upper Paleolithic.
“This finding is consistent with previous archaeological studies that have found broad similarities in stone tools, hunting weapons and portable art from different regions,” explains co-author Dr. Judith Beier of the DFG Advanced Research Center “Words, Bones, Genes, Tools” at the University of Tübingen.
However, during the Late Glacial Period, between 28,000 and 14,700 years ago, the researchers observed a significant decrease in population size and genetic diversity, with no genetic links between Western and Eastern Europe.
“This dramatic demographic shift was most likely caused by severe climate change: temperatures during this period dropped to their lowest values of the entire Palaeolithic and peaked during the Last Glacial Age, when ice sheets covered much of northern and central Europe,” said Lassmann.
“The climate deterioration caused a transformation of steppe to tundra landscapes, affecting the habitats of prey animals and, in turn, the hunter-gatherers who depended on them for their livelihoods.”
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