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In the 1980s, scientists learned that all humans living today descend from a woman, nicknamed "Eve" Mitochondrial ", which lived in Africa between 150,000 and 200,000 years ago. since. This discovery, along with other evidence, suggested that humans evolved from a single ancestral population – an interpretation that does not stand the test of time. The history of human evolution, as the latest research suggests, is more complicated than that.
A new comment published today in Trends in Ecology & Evolution calls into question the prevailing view that our species, Homo sapiens is derived from a single population ancestral and only one geographical region in Africa. By examining some of the latest archaeological, fossil, genetic and environmental discoveries, an international expert team led by Eleanor Scerri of the Oxford School of Archeology presented an alternative history of l & # 39; Human evolution, showing that our species emerged from isolated populations scattered across Africa, which sometimes met to cross each other. Little by little, this mixture of genetic characteristics has produced our species.
Indeed, the origin of Homo sapiens is not as neat and orderly as we have been led to believe
"While" mitochondrial Eve "was a no real person, she was not the only ancestor at the time, and would not have come from the only population around, "Scerri told Gizmodo. "She was just the woman that all living beings inherited today their mitochondrial genetic code."
No doubt, mitochondrial Eve, like other humans, featured a rich genetic lineage, and the history of its kind, as this new paper illustrates, has not begun and does not end with she or the immediate population to which she belonged.
"The idea that humans have emerged from a population and progressed in a straightforward linear manner towards a modern physical appearance is attractive, but unfortunately does not fit very well with the information available" said Scerri. "On the contrary, it seems that humans have emerged within a complex set of populations scattered across Africa."
The reality, as suggested by this latest research, is that human ancestors were distributed in Africa, separated by diverse habitats and environmental boundaries, such as forests and deserts. These extended periods of isolation have given rise to a surprising variety of human forms and a diverse range of adaptive traits. When stratified groups are crossed, they retain the best features that evolution has to offer. Therefore, the authors say that terms like "archaic humans" and "anatomically modern humans" are increasingly problematic given the evidence.
Scerri said that occasional crossover episodes between these different semi-isolated populations have created a diverse "metapopulation" of humans in Africa, hence our species has emerged for a very long time. Our Species, Homo sapiens appeared about 300,000 years ago, but some features, such as a round brain, a pronounced chin, and a small face, only appeared together in a single individual 100,000 years ago before. , and maybe not until 40,000 years ago – long before genetics and other archaeological evidence told us that our species already existed. Isolated populations have come together to exchange genes and cultures – two interdependent processes that have shaped our species, Scerri explained.
The new paper, instead of providing new evidence, provides a comprehensive review and analysis of what the latest scientific literature tells us about human evolution, about 300,000 years ago. The researchers found that human fossils from different parts of Africa all exhibited a varied mix of modern and more "archaic" physical characteristics. The oldest are 300,000 to 250,000 years old and come from opposite ends of Africa, extending from the southern tip of the continent to its northernmost points. Many of these fossils have been found with sophisticated archaeological objects associated with our species, including specialized tools mounted on wooden handles and handles, and often using different bindings and glues. These artifacts, like the various fossils, appeared across Africa at about the same time, and studies of their distribution suggest that they belonged to distinct groups. At the same time, genetic data indicate the presence of multiple populations
"From a methodological point of view, we can also see that inferences of genetic information that do not take into account subdivisions between populations can also generate very misleading information "says Scerri.
By studying changes in rivers, deserts, forests, and other physical barriers, researchers were able to chronicle geographic shifts in Africa that facilitated migration, introducing opportunities for contact between previously separated groups. These groups, after long periods of isolation, were able to interact and intersect, sometimes separating and experiencing further periods of prolonged isolation.
"There is growing evidence that the emergence of" modern humans "has not occurred in a small cradle in sub-Saharan Africa and at a specific time."
"The most surprising aspect of our research is that for most of our prehistory, human populations were largely isolated from each other," Scerri told Gizmodo. "This is very different from the way people live today and in the recent past. The effect of agriculture has had a phenomenal effect on our way of life, which has allowed the human population to become huge and create the conditions for different types of interaction because we are become attached to the earth. "
Scerri the species is more physically similar today than our ancestors were.
"This is a fascinating paper and I largely agree with the main premise that we must look at the evolution of Homo sapiens in a plus" Andy Cohen, environmentalist and evolutionary biologist at the University of Arizona, who was not involved in the new study, says Gizmodo. "The growing range of fossils and stone tools from all over the world. Africa and evidence of extremely variable climate change between regions of Africa – which would have been the backdrop of adaptation – make this article timely. "
Jean-Jacques Hublin, a scientist from The Max Planck Institute for Evolutionary Anthropology who was not involved in the new study, said the new commentary presents what is rapidly becoming the prevailing opinion on this topic. [19659004] evidence that the emergence of so-called "modern humans" does not occur is not produced in a small cradle in sub-Saharan Africa and at a specific time, "Hublin told Gizmodo. "On the contrary, it involved several populations across the continent and was a fundamentally progressive process."
Importantly, Hublin said, the more we fill the fossils, the harder it will be to distinguish "anatomically modern humans" from more archaic forms among the different bands of Homo sapiens . For the future, Hublin said the new document should encourage scientists to document this evolution in parts of Africa, including those in which this story is indeed empty. He said geneticists also need to revise their "over-simplified models" to explain the genetic mix. "According to this new model, gene flow extends advantageous mutations from one population to another when climatic conditions allow contact between populations." Hublin said. "Most likely, a similar process is involved that explains the spread of some technical or even social innovations."
That's the great thing about science. New discoveries lead to new interpretations, which in turn lead to new suggestions about what scientists should study next. There is still much to learn about our species and the extraordinary story of how we came to dominate the Earth.
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