Neanderthal Interbreeding Potentially Essential for Modern Human Survival

Modern humans faced numerous extinctions after their departure from Africa before successfully populating the globe, according to recent studies. This new DNA research also illuminates the significant role played by our Neanderthal relatives in our eventual success. While these early European hominins were previously thought to have been successfully overcome by us after our migration from Africa, current studies indicate that only human populations that interbred with Neanderthals managed to flourish, while other lineages perished. Indeed, Neanderthal genetic material might have been vital for our survival by offering protection against novel diseases previously unknown to us. For the first time, this research identifies a brief period 48,000 years ago when Homo sapiens engaged in interbreeding with Neanderthals following their exit from Africa, after which they proceeded to expand globally. Although Homo sapiens had previously migrated from the African continent, the new findings reveal that these earlier populations, prior to the interbreeding phase, did not endure. Professor Johannes Krause from Germany’s Max Planck Institute of Evolutionary Biology informed BBC News that the narrative of modern human history will now require revision. “We see modern humans as a big story of success, coming out of Africa 60,000 years ago and expanding into all ecosystems to become the most successful mammal on the planet,” he stated. “But early on we were not, we went extinct multiple times.” For an extended period, understanding the evolution of the sole surviving human species relied on examining the morphology of fossilized remains of our ancestors from hundreds of thousands of years ago and observing subtle anatomical shifts over time. These ancient remains were scarce and frequently damaged. However, the capability to extract and analyze genetic code from bones thousands of years old has unveiled insights into our enigmatic past. The DNA within these fossils recounts the history of individuals, their familial connections, and their migratory patterns. Even following our successful interbreeding with Neanderthals, the establishment of our population in Europe encountered difficulties. The initial modern humans who had interbred with Neanderthals and coexisted with them completely died out in Europe 40,000 years ago, but not before their descendants had dispersed further across the world. It was the progeny of these early global pioneers who eventually returned to Europe to inhabit it. The research also offers a fresh perspective on the rapid disappearance of Neanderthals shortly after modern humans arrived from Africa. The precise reason remains unknown, but the new evidence challenges theories suggesting our species hunted them to extinction or that we possessed inherent physical or intellectual superiority. Instead, Professor Krause suggests that environmental factors are a more likely explanation. “Both humans and Neanderthals go extinct in Europe at this time,” he remarked. “If we as a successful species died out in the region then it is not a big surprise that Neanderthals, who had an even smaller population went extinct.” The climate during that era was exceptionally volatile, capable of shifting from conditions nearly as warm as today to intensely cold, sometimes within a single lifetime, according to Professor Chris Stringer of the Natural History Museum in London, who was not involved in the new research. “The study shows that near the end of their time on the planet, Neanderthals were very low in numbers, less genetically diverse than the modern human counterparts they lived alongside, and it may not have taken much to tip them over the edge to extinction,” he commented. A separate DNA investigation, published in the journal Science, indicates that modern humans retained certain crucial genetic characteristics from Neanderthals that might have conferred an evolutionary advantage. One such trait pertains to their immune system. Upon emerging from Africa, humans were highly vulnerable to new diseases they had never encountered. Interbreeding with Neanderthals provided their offspring with protection. “Perhaps getting Neanderthal DNA was part of the success because it gave us better adaptive capabilities outside of Africa,” Professor Stringer stated. “We had evolved in Africa, whereas the Neanderthals had evolved outside of Africa.” He added, “By interbreeding with the Neanderthals we got a quick fix to our immune systems.” Follow Pallab on Blue Sky and X Copyright 2024 BBC. All rights reserved. The BBC is not responsible for the content of external sites. Read about our approach to external linking.