Scientists have long known that humans outside Africa owe 2 to 3 percent of their genomes to Neanderthal ancestors. But now, two separate studies using the oldest modern human DNA ever analyzed show that this ancestor was born in a single period that occurred between 45,000 and 49,000 years ago. It turns out that this can be traced back to the sudden increase in mixed-race people.
Neanderthal (homo neanderthalensis) and modern humans (homo sapiens) has been encountered many times over tens of thousands of years. Modern human DNA has been found in Neanderthals who lived more than 200,000 years ago, and some human populations have further intermixed with Neanderthals and Neanderthals, with the latter species dating back 39,000 years. Extinct. However, not all of these interactions left a common mark on all non-Africans today. The moment that left this near-global genetic fingerprint occurred over thousands of years between Neanderthals who settled in Europe and humans who newly arrived in their territory.
“We think the peak of this interaction was 47,000 years ago. This also gives us a rough estimate of when this migration out of Africa occurred,” said Professor of Evolutionary Genetics at Max Planck University. says postdoctoral researcher Leonardo Yasi. Institute for Evolutionary Anthropology in Leipzig, Germany, and lead author of one of the studies published Thursday. science. He is also a co-author of other papers published at the same time. nature.
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Multiple waves of humans left Africa, homo The genus originally evolved over thousands of years and established populations in the Near East and Europe. There they met and sometimes interbred with Neanderthals, descendants of human ancestors who left Africa hundreds of thousands of years ago. The last common ancestor of Neanderthals and modern humans remains unknown, but the species likely lived between 650,000 and 500,000 years ago. Researchers still can’t say for sure where Two new studies significantly narrow down the question of when Neanderthals and humans intermingled.
in nature In this study, biochemist Johannes Krauss, archaeogeneticist Kay Plüfer, doctoral student Alev Schumer and colleagues from the Max Planck Institute for Evolutionary Anthropology investigated the discovery in Ranis, Germany. six people, Zlaty Kring;ňňňňňncaron;ňncaron;ncaron;ncaron;ncaron;ncaron;ňncaron;ncaron;ň We sequenced the genomes of six people discovered in the United States. Czech Republic site. These people lived between 49,000 and 42,000 years ago and contained some of the oldest modern human genomes ever sequenced. They also turned out to include the oldest known modern human family, Schumer said. The inhabitants of Ranis included mothers and young daughters, as well as women from the same extended family. Even more surprising, the person Zlatý kň (a woman known from her skull) was a more distant relative of this Ranis family.
Spread across central Europe, these linked populations probably consisted of only about 300 members and also shared 2.9 percent Neanderthal ancestry. By examining the length of these Neanderthal gene segments in the human genome, researchers were able to determine when Neanderthal ancestors were introduced. (The longer segments are recent additions, because there was no chance to scramble them through genetic recombination; the shorter segments originate from more distant interbreeding events.) Scientists believe that these central European found that it was removed in about 80 generations, or between 1,500 and 1,000 generations. Several years have passed since our ancestors interbred with Neanderthals.
in science In this study, the researchers examined a large dataset of 59 ancient human genomes dating from 45,000 to 2,200 years ago, as well as the genomes of a diverse group of 275 modern humans. Priya Muajani, a population geneticist at the University of California, Berkeley, said: “We are trying to estimate when Neanderthal ancestry occurred, and to see whether it happened over a short period of time or over a long period of time. “I was interested,” he and Benjamin said. Peter from the Max Planck Institute for Evolutionary Anthropology was co-senior author of the paper. (Peter is also a co-author of this book) nature paper. )
Like Krauss’ team, Moorjani and his colleagues found evidence that a single pulse of Neanderthal genetics entered the human genome between about 50,500 and 43,500 years ago. Scientists also found evidence of natural selection in these genes. Within about 100 generations, the human genome became very similar to the one we have today, in which parts it contained many Neanderthal genes and which parts had very few. For example, there are very few Neanderthal genes on the modern X chromosome.
Joshua Akey, a Princeton University genomicist who was not involved in the study, says the genetic changes are fascinating. That’s because it points to places in the human genome where Neanderthal genes could have promoted survival and reproduction, become permanently integrated, or caused harm. And then it disappeared. “Everyone is inherently fascinated by what makes us potentially different from other types of humans that have ever existed,” Akey says. “And if there are genetic substrates that define the differences, they are located somewhere on the genome.”
The researchers also found that the Ranis and Zlati Klinkalon people left no descendants, despite connections with populations outside Africa that spread throughout the world. “Currently, we have identified multiple lineages that have not contributed to modern humans,” Kraus says. We too became extinct. ”
Additionally, these findings raise new questions about the dispersal of modern humans and how humans gradually replaced Neanderthals as Europe’s dominant species, said the French National Center for Scientific Research (CNRS) and Bordeaux. said university paleoanthropologist Isabelle Crèvecoeur. France was not involved in the new study. “The big challenge for us as paleoanthropologists and prehistorians is to try to understand and connect genetic results with cultural or archaeological data,” she says.
