Early humans still had ape-like brains, according to a new study that found modern humans evolved to have between 1.7 million and 1.5 million of our more recently “advanced” cognitive organs. Last year
That means that the unique brain of modern humans (transvestite) Developed over 1 million years after transvestite The genus arises and after the first time Standing man Emigrated from Africa, according to a study published online Thursday (April 7) in the journal. science.
The discovery overturned a previously held view that the human frontal lobe, part of the brain That process complex cognitive tasks, including social thinking, tool use, and language, which evolved as the transition from Ostralopitecus To transvestiteThat happened about 2.8 million to 2.5 million years ago, the researchers said.
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This is because the brain is made of soft tissue that is not fossilInstead, the researchers examined fossil endocasts, or cranial regions, to determine how the organ changed over time.
In doing so, the scientists compared the structure of the “primitive” or “primitive” brain with the modern human brain, based on the endocasts of human’s closest living relative. Great monkeyThis included 81 chimpanzees, 27 bonobos, 43 gorillas and 32 orangutans, along with 110 modern human endocasts. They then analyzed the almost ancient human skull endocasts. 40 pieces including from Australopithecus sediba, Standing man and Naledi maleAnd consider how “primitive” their brains are, or how advanced by comparison with great apes and the endocasts of modern humans.
When researchers came up with this research project in the late 1990s, the work was impossible to achieve because there was no method for interpreting brain structures from endocasts, co-author Marcia Ponce de León, a paleontologist at the university. Zurich told Live Science by email, but then the progress in Computed tomography (CT) scan And other imaging technologies, enabling researchers to “Find the number of brain-endocasts relationships in living organisms,” she said. If it was possible to identify brain structures from the organism’s endocasts, her team was, of course, able to infer brain structures in scans. CT of the fossil skull, she thought.
The researchers found that detailed endocasts revealed long-missing brain gyri and salsis imprints, or folds and furrows, as well as the structures of blood vessels surrounding the brain. This is a difficult job. “That’s a tough job and it takes a lot.Gray matter“Participation,” joked co-lead researcher Christoph Zollikofer, a paleontologist and neurobiologist at the University of Zurich.
As the team slowly walked through the fossilized endocasts, they saw evolutionary changes spread, such as a distant area to the back of the brain over time. “For example, the sulcus precentral backward shift during evolution indicates reliably that the Broca region in front of it expanded during human evolution,” Zollikofer said. It is special because in modern humans they are involved in the production of speech and other higher cognitive abilities.
After comparing the endocast fossils with great apes and modern humans, the team’s analysis revealed that the earliest members of transvestite Have a brain with a monkey-like frontal lobe
“The oldest population in our family transvestite They have primeval monkey-like brains, like their Australian ancestors, ”says Ponce de León, which includes some of the fossils involved. transvestite And early Standing manThe researchers said..
Related: Photos: The earliest human fossils discovered.
When did Homo’s brain become ‘modern’?
Fastest transvestite Remain In the fossil record from Ledi-Geraru in Ethiopia, it was 2.8 million years ago, but they did not preserve the brain for the next 1 million years. transvestite Endocast, according to Amélie Beaudet, a paleontologist at the University of Cambridge in the UK, who was not involved in the study. But I have written opinions about it in the journal. science.
When did this 1-million-year gap aggravate the mystery? transvestiteAdvanced brain development But the analysis of Standing man Researchers said the skull helped unlock the discovery. Especially the fifth group Standing man The skull, known as the Dmanisi individual, named after an archaeological site in Dmanisi, Georgia, is the key. The skull, approximately 1.8 million years old, is very well preserved and belongs to individuals who have died between adolescence and old age.
“Manici fossils are very important because they show us that about 1.8 million years ago, in the early transvestite Has a primitive brain similar to Ostralopitecus And a big monkey, ”Zollikofer told Live Science by email.
But having a monkey-like frontal lobe didn’t stop. Standing man With an extraordinary life, “these primitive brain-stricken people were able to leave Africa, cope with the harsh Eurasia climate, produce a wide range of tools, contribute to meat supply and provide support. A member of the elderly group, “Zollikofer said.
Dmanisi individuals are considered to be one of the earliest populations of transvestite That left Africa about 1.7 million years ago in that Africa transvestiteThe researchers said that the brain’s complex lobe began to form, which found evidence of a reorganized brain region in transvestite Skulls from Africa and Southeast Asia that are 1.5 million years ago and younger, for example. Standing man A person who lived less than 1.5 million years ago, whose remains were found in Southeast Asia, had the endocast indicating modernization. transvestite The researchers said that the front forehead
This discovery suggests that the complex frontal lobe “At one time, it was a hallmark of the early days. transvestite In Africa… evolution was rather slow, ”and was not necessary for the early spread of humans out of Africa, the researchers wrote in the study.
The findings are “interesting and important, but … not necessarily contradictory,” said Fred Spoor, a paleontologist at the Center for Human Evolution Research at the Museum of Natural History in London, who was not involved in the study.
Focus on the strong polarization between our ‘genera’ transvestite And the previous ancestors (such as Ostralopitecus Such as ‘Lucy’ from Ethiopia) is a remnant from a time with fewer fossils, and human evolution is seen as a simple linear process from early ancestors to modern humans, ” Spoor told Live Science in an email. “In that context, the origins of the genus transvestite It was seen as a revolution in biology that involved making stone tools and having bigger and more complex brains. ”
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The researchers learned that “Stone tools were built as early as 3.3 million years ago. (Previously expected to have origin transvestite) And the type and example of the genus transvestite A smaller brain has been discovered, ”Spoor said.“ The truth is, aspects that indicate that we are modern humans arise at different times and are not necessarily delicately packaged over time. Special
Why did the brain of the transvestite change?
Still a mystery why transvestite The brain was developed with a complex frontal lobe. But scientists have some ideas. Perhaps this is an example of the so-called “Baldwin effect” when the ability to learn new behaviors can drive change. Genetics And the phenotypes or appearance, Zollikofer said, in this case it is possible that the brain structures responsible for language and other complex cognitive tasks have grown in an environment that promotes and requires proto-language communication. He said
“we hypothesis “We do not know how these early language constructs for the early languages were” in place “about 1.5 million years ago. transvestite Populations have languages that are similar to modern humans, ”he said, but early humans often had“ some proto-language ”that – in terms of the mutual evolution of brain cultures – contributed to the evolution of these brain structures and these brain structures. Favorite The evolution of proto language “
Originally published in Live Science.