Human origins appear increasingly intertwined with genes and fossil discoveries

Human origins depict our ancestors as lovers, not fighters

Written by Daniel Vergano

At the heart of scientific questions about human origins lie questions about human nature. teeth homo sapiens Lover or fighter in nature, predator or prey, lucky survivor or inevitable conqueror?

More and more friendly answers to these questions are coming, as evidenced by a series of genetic discoveries and recent fossil discoveries. They also highlight how difficult life was for our prehistoric ancestors. There are 8 billion people on Earth today, and that number continues to grow, but for most of human history, survival was the only victory.

Not everyone was like that. Just 200,000 years ago, our ancestors lived on a planet teeming with various human relatives. Neanderthals lived in Europe and the Middle East. The following Denisovans are known today: bone fragments, teeth, DNAlive all over Asia and probably Even in the Pacific. “The Hobbit” homo floresiensis, A small species that lives in Indonesia. Another short breedcalled Homo luzonensis, did in the philippines. flat homo erectusthe grandparents of the earliest human species were still running around until recently. 112,000 years ago.

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Now they are all gone. except for our genes. Denisovans interbred with Neanderthals, and both interbred with modern humans. Gene from “” unknown humans in africa” also marks the genome of modern humans. The first discovery of these admixtures was Since 2010which shook the common sense of the past. “Out of Africa” ​​painting A small, unique group of human ancestors developed language, which then replaced all other ancestors around the world within the past 100,000 years.

Rather, the new picture of our origins is less a family tree. more tangled shrubswhose winding branches connected different human groups to form today’s broader human population. Today’s humans arose primarily from the interbreeding of modern-looking humans living in Africa with disparate human populations scattered throughout the wider world. African migrants themselves initially came from scattered and intermittently mixed populations. found throughout the continent.

Neanderthal genes reveal the extent of this admixture. Modern humans and Neanderthals coexisted rather than fighting a war of extinction for at least 10,000 years in Europe and Asia about 50,000 years ago. Or maybe there’s evidence to suggest it sooner. homo sapiens lived in greece 210,000 years agothen ceded Europe to the Neanderthals. Genetic studies suggest this Gene exchange peaked twiceabout 200,000 years ago, and again 50,000 years ago. Even some of them bacteria in our mouthwhen you think about it, it seems to have Neanderthal origins. Thanks to its early admixture, Neanderthal itself was averaged 2.5 to 3.7 percent homo sapiens DNA, a contribution that later confounded family trees.

The demise of Neanderthals, who disappeared from the fossil record after 40,000 years ago, appears to be more of a demographic issue. in 2021 surveythe field of paleoanthropology largely agreed that Neanderthals’ small population size caused their extinction. A scientific report this summer confirms this. For their study, Princeton University researchers looked at: Repetitive gene flow Relationships between humans and Neanderthals over the past 200,000 years. They found that there were 20 percent fewer Neanderthals running around than expected. There weren’t that many. They interbred and integrated into larger groups of modern humans arriving from Africa.

Neanderthal numbers also took a hit This is because their larger prey, woolly mammoths, bison, and woolly rhinos, declined during the Ice Age. September report of 100,000-year-old Neanderthals from France Commonly known as “Thorin” Our cousins ​​were less likely to migrate than modern humans, suggesting they were more vulnerable to changes in climate and landscape. Thorin was the descendant of a population that remained genetically isolated for tens of thousands of years, even though he lived near other Neanderthals who likely later interbred with modern humans.

A similar situation of shuffled genes and small populations is forming for Denisovans and other peoples. ancient human species. This genetic shuffling has left humanity itself looking a little disorganized. July 2021 analysis For example, “Only 1.5 to 7 [percent] The genome of modern humans is unique to humans. ”

It’s not that much. Scientists including Chris Stringer of the Natural History Museum in London are once champions as they look back at humanity’s scattered genetic history. strict out of africa We considered the origins of humanity and examined the patchwork of humans, ancient fossils, and genes. stringer and colleagues I concluded with nature in 2021 “The specific point in time at which modern human ancestry was restricted to a limited number of birthplaces cannot currently be determined.”

Our origins therefore appear to be not particularly orderly, but complex, with much hybridization across time and space. We were more wanderers and potential stepparents in our new territory than conquerors. Something to consider the next time you hear someone talking about their family history or how the other person is an unwanted outsider.

This is an opinion and analysis article and the views expressed by the author are not necessarily those of the author. scientific american.