AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)—A new approach* to map the spread of humans in the Paleolithic era relies on dental features rather than traces of DNA, the latter of which so rarely found in ancient remains. Scientists validated the technique by creating demographic models based on fossilized teeth from 450 Homo sapiens specimens in Europe that lived throughout the Last Ice Age. “This opens up the exciting possibility to [investigate] archaeological time depths or regions where obtaining ancient DNA is not feasible, and where skeletal phenotypic data is the only source of information available,” Hannes Rathmann and colleagues write. Modern H. sapiens established an enduring foothold in Europe around 50 to 45 thousand years ago (kya) during the Last Ice Age. This migration coincided with the Upper Paleolithic, an age marked by sophisticated stone tool use. Yet, little is known about how Upper Paleolithic populations spread across Europe. Here, Rathmann et al. have modified an existing machine learning-based statistical framework to map European Ice Age population dynamics over time. The technique typically uses DNA to create demographic models, which researchers then compare with archaeological data. The newly adapted method instead assesses dental traits, such as the shape of tooth roots and fissure formations on dental crowns. As a test, researchers used it to catalog 20 dental features in 450 European specimens from 47 to 7 kya in age. While doing so, the model chronologically grouped specimens according to three climate periods: the Middle Pleniglacial (47 to 28 kya), the Late Pleniglacial (28 to 14.7 kya), and the Late Glacial to Early Holocene (14.7 to 7 kya). It also sorted populations into a Western group that spanned Portugal to Germany and an Eastern group that ranged from Italy to Russia. The framework developed 14 demographic models, and one – model 5 – aligned most consistently with established archaeological theories of population movement in Europe. In this scenario, Western and Eastern populations remained connected throughout the entire Middle Pleniglacial. Then, as the Late Pleniglacial began, groups in the East pushed westward, causing extinction events in West populations. As the world cooled further in the Late Pleniglacial, leading into the coldest stage of the Ice Age called the Last Glacial Maximum (LGM; 26.5 to 19 kya), East and West became geographically and genetically isolated. Once the LGM ended, migration and genetic exchange resumed.
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Article Source: AAAS news release.
*Human population dynamics in Upper Paleolithic Europe inferred from fossil dental phenotypes, Science Advances, 16-Aug-2024. www.science.org/doi/10.1126/sciadv.adn8129
Cover Image, Top Left: Tooth. LionFive, Pixabay
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