Home / Science / The history of human migration outside of Africa has just been rewritten

The history of human migration outside of Africa has just been rewritten



For anyone trying to trace the roots of the human family tree, it would have been very convenient if our ancestors had left Africa in a great exodus, initiating the global takeover of humanity with a single inaugural blow. And the first time we look at the fossils left by our ancestors, that seems to be the case. Like a series of Foursquare check-ins, the ages of the bones seemed to represent a long human journey out of Africa, through Asia, and into Australia that began 60,000 years ago.

<p class = "canvas-atom canvas- text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "But in recent years, scientists They look back at ancient fossils with new techniques that have revealed discrepancies in history – evidence of much older humans ending up in regions they were not supposed to reach for thousands of years, or DNA that is not as human as we originally thought A review published on Thursday in Science compiles and analyzes all these deviations from the "Out of Africa" ​​(OoA) narrative, concluding that it is time for a rewrite. " data-reactid = "12"> But in recent years, scientists looking back at ancient fossils with new techniques have revealed discrepancies in history: evidence that many older humans end up in regions that were not supposed to reach for thousands of years, or DNA that is not as human as we thought at first. A review published on Thursday in Science compiles and analyzes all these deviations from the "Out of Africa" ​​(OoA) narrative, concluding that it is time for a rewrite.

Doing that was a big break with the old "smart" theory, says lead author and anthropologist Christopher Bae, Ph.D., of the University of Hawai'i in Manoa, but evidence that he and Their team discovered they were not left with another option.

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "" My co-authors and I work in different areas from Asia, and when we sat down and started to compare notes, we still found evidence (between 120 ka and 60 ka) of the previous modern human dispersions OoA, "he says Reverse in an email." data-reactid = "14"> "My co-authors and I worked in different areas of Asia, and when we sat down and began to compare notes, we still found evidence (between 120 ka and 60 ka) of the first modern human dispersions OoA," He says inverse in an email.

"So, what we imagine is that, although a higher OoA dispersion between 60 ka and 50 ka was likely, which may or may not be due to paleoenvironmental fluctuations, there were waves of earlier dispersions by modern humans as well, although these earlier populations they were smaller. "

Map of postulated migratory routes and sites associated with modern humans that disperse through Asia during the Late Pleistocene.

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "Bae and his team came to this conclusion after of reviewing multiple recent studies showing that humans traveled beyond what we would have expected given the OoA timeframe One showed Homo Sap iens fossils in China that were between 70,000 and 120,000 years old. Another discovered a fossil as far away as Australia dating back 60,000 years, which, according to OoA's theory, was when humans were preparing to leave for the first time.All of these aberrant findings, taken together, suggested that the original explanation was incorrect. "Data-reactid =" 24 "> Bae and his team came to this conclusion after reviewing multiple recent studies that show that humans traveled beyond what we would have expected. the OoA time frame. One showed Homo sapiens fossils in China that were between 70,000 and 120,000 years old. Another found a fossil as far away as Australia dating back 60,000 years – which, according to OoA's theory, was when humans were preparing to leave for the first time. All these aberrant findings, taken together, suggested that the original explanation was incorrect.

The main explanation for how these humans arrived in China and Australia tens of thousands of years before the theory predicted they would do so is that humans began to leave Africa much earlier than expected, the researchers write. His new model proposes that there were multiple diasporas in Africa, the first of them. that could have happened 120,000 years ago.

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "That does not mean that the original theory of OoA is now completely debatable. Leaving aside the new models, there is still a preponderance of fossils dating back to the 60,000-year mark, suggesting that there was a massive dispersion at that time, it was simply not the only one . ] ". = "26"> That does not mean that the original theory of OoA is now totally debatable. Leaving aside the new models, there is still a preponderance of fossils dating back to 60,000 years, which suggests that there was a massive dispersion at that time. it just was not the only .

"The first dispersions outside of Africa before 60,000 years were likely by small groups of gatherers, and at least some of these initial dispersions left low-level genetic traces in modern human populations," said Max Planck Institute anthropologist. Michael Petraglia, Ph.D., co-author of the study, in a statement.

Neanderthal DNA still runs in our genomes, complicating the history of our origins.

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "Another complication in the history of the origins human is the fact that some of the Homo sapiens fossils that the scientists have excavated above were, unexpectedly, not quite human.We had assumed for a long time that Homo sapiens branched out from the hominid tree very early and remained forever separated from our closest cousins, the Neandertals and the Denisovans, but now, genomic analysis in many studies has revealed that the DNA of Homo neanderthalensis and Homo sapiens ssp Denisova (it is not yet clear whether it is a different species or simply a subspecies) traverses the genomes of many modern humans, suggesting that the ancient humans who left Africa many years ago were a "hybrid" species or completely modern human beings who connected with other species throughout their travels, reintroducing those strange genes. "data-reactid =" 38 "> To further complicate the history of human origins, some of the Homo sapiens fossils Scientists have unearthed, unexpectedly, not quite human, we assumed for a long time that Homo sapiens branched from the hominid tree very early and remained forever separated from our closest cousins, the Neandertals and the Denisovans, but now, genomic analysis in many studies has revealed that the DNA of Homo neanderthalensis and Homo sapiens ssp Denisova (it is not yet clear whether it is a different species or simply a subspecies) traverses the genomes of many modern humans, suggesting that ancient humans who left Africa many years ago were a "hybrid" species or completely modern human beings who connected with other species along their journeys, reintroducing those genes. [19] 659009] For now, researchers say, the data we have suggests that all current non-African populations can trace their bloodlines to a single group of humans that separated from the family tree about 60,000 years ago, which probably represents the great OoA migration that for a long time scientists believed was our only movement to leave our ancestral home. But as researchers continue to uncover evidence of our ancestors in previously unexplored regions, such as Asia, there is still much we can learn about people who dared to leave Africa before that, and who their descendants are today. Bae notes that, already, scientists have discovered that two percent of the genome of Papua New Guinea contains evidence of modern human dispersions dating back 60,000 years.

"[With] the growing evidence of a modern human presence in Asia, possibility that these earlier dispersions can be detected in modern human genomes increases," he says.

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – -sm" type = "text" content = " Photos via Bae et al., 2017. On the origin of modern humans: Asian perspectives, Science, Image by: Katerina Douka and Michelle O & # 39; Reilly, Flickr / p_a_h, Wikimedia "data-reactid =" 41 "> Photos through Bae et al. 2017. On the origin of modern humans: Asian perspectives. Science. Image by: Katerina Douka and Michelle O & # 39; Reilly, Flickr / p_a_h, Wikimedia

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm "type =" text "content =" Photos through Bae et al. 2017. On the origin of modern humans: Asian perspectives Science: Image by: Katerina Douka and Michelle O & # 39; Reilly, Flickr / p_a_h, Wikimedia "data-reactid =" 42 "> Photos through Bae et al. 2017. On the origin of modern humans: Asian perspectives. Science. Image by: Katerina Douka and Michelle O & # 39; Reilly, Flickr / p_a_h, Wikimedia

Written by Yasmin Tayag

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