Study of ancient skulls reveals human-Neanderthal interbreeding

Study of ancient skulls reveals human-Neanderthal interbreeding

Neanderthal adult male. Reconstruction based on Shanidar 1 by John Gurche for the NMNH’s Human Origins Program. Credit: Chip Clark.

Research has shown traces of Neanderthal DNA in the modern human genome. Now, an exploratory study assessing the facial structure of prehistoric skulls is providing new insights and supporting the hypothesis that much of this interbreeding occurred in the Near East — a region from North Africa to Iraq.

“Ancient DNA sparked a revolution in how we think about human evolution,” said study co-author Steven Churchill, a professor of evolutionary anthropology at Duke University. “We often think of evolution as the branches on a tree, and researchers have spent a lot of time trying to trace the path that led to us, Homo sapiens. But we’re now starting to understand that it’s not a tree – it’s more of a series at multiple points Converging and diverging streams.”

“Our work here gives us a deeper understanding of where these streams converge,” said Ann Ross, the study’s corresponding author and a professor of biological sciences at North Carolina State University.

“The situation is really complicated,” Churchill said. “We know there is interbreeding. Modern Asian populations seem to have more Neanderthal DNA than modern European populations, which is odd – because Neanderthals lived in what is now Europe. This suggests that Neanderthals were closely related to Present-day humans left Africa as our prehistoric ancestors hybridized, but before spreading to Asia. Our goal with this study was to see what we can do about it by assessing the facial structures of prehistoric humans and Neanderthals Additional understanding.”

“By assessing facial morphology, we can track how crowds move and interact over time,” explains Ross. “The evidence shows us that the Near East is an important crossroads, both geographically and in the context of human evolution.”

In this study, researchers collected data on craniofacial morphology from published literature. This eventually resulted in a dataset that included 13 Neanderthals, 233 prehistoric Homo sapiens, and 83 modern humans.

The researchers focused on repeatable standard craniofacial measurements and used these measurements to assess the size and shape of key facial structures. This then allowed the researchers to conduct in-depth analyses to determine whether and to what extent specific populations were likely to interbreed with Neanderthal populations.

“Neanderthals had big faces,” Churchill said. “But size alone doesn’t establish any genetic link between humans and Neanderthals. Our work here involves a more robust analysis of facial structure.”

The researchers also considered environmental variables associated with changes in human facial features to determine the likelihood that the links they made between Neanderthals and humans were the result of hybridization and not other factors.

“We found that the facial features we focused on were not strongly influenced by climate, which made it easier to identify possible genetic influences,” Ross said. “We also found that face shape is a more useful variable for tracking the effects of Neanderthal interbreeding on human populations over time. Neanderthals were larger than humans. Over time, human face The size became smaller after several generations of mating with Neanderthals. But the actual shape of certain facial features retains evidence of interbreeding with Neanderthals.”

“This is an exploratory study,” Churchill said. “And, to be honest, I’m not sure that this method actually works — we had a relatively small sample size, and we didn’t have as much facial structure data as we would like. But, in the end, what we got was really Very convincing.

“Building on this, we hope to include measurements from larger populations, such as the Natu women who lived in the Mediterranean region more than 11,000 years ago, now Israel, Jordan and Syria.”

Paper published in biology.

Genomes of five late Neanderthals offer insights into Neanderthal population history

More information:
Steven E. Churchill et al., Midfacial Morphology and Neanderthal-Modern Human Hybridization, biology (2022). DOI: 10.3390/biology 11081163

Courtesy of North Carolina State University

Citation: Study of Ancient Skulls Reveals Human-Neanderthal Interbreeding (23 Aug 2022) Retrieved 24 Aug 2022 from skulls-human-interbreeding-neandertals.html

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