Early humans are still apes, according to a new study that discovered that modern humans evolved relatively recently to have our “advanced” thinking organs 1.7 to 1.5 million years ago. I had a brain.
This is the unique brain of modern people (Homo) Developed over a million years later Homo Genus occurs, after the first Homo erectus According to a survey, they emigrated from Africa and were published online in the journal on Thursday (April 7th). Science..
This discovery overturns the previously held view of the human frontal lobe — brain Handles complex cognitive tasks such as social thinking, tool use, and language. Australopithecus To Homo, That happened about 2.8 to 2.5 million years ago, the researchers said.
Because the brain is made of soft tissue that is not. FossilizationInstead, researchers examined fossilized endocasts, or skull areas that housed the brain, to determine how organs changed over time.
To do this, scientists compared the structure of the “primitive” or “early” brain to that of the modern human brain, examining the endcasts of humans’ closest living relatives. ApesIncludes 81 chimpanzees, 27 bonobos, 43 gorillas, 32 orangutans, and 110 modern human endcasts. Next, they analyzed the endocasts of nearly 40 ancient human skulls. Australopithecus sediva, Homo erectus And Homo naledi, And by comparing them with apes and modern human endcasts, we determined how likely their brains were “primitive” or advanced.
When researchers came up with this research project in the late 1990s, they felt that this task could not be achieved because there was no objective way to interpret the structure of the brain from the endcast. Zurich emailed Live Science. But then Computed tomography (CT) And other imaging techniques have allowed researchers to “quantify the relationship between the brain and endcasts of living species,” she said. She thought that if the endocast of a living species could determine the structure of the brain, her team could infer the structure of the brain with a CT scan of a fossilized skull.
Researchers have found that detailed endocast revealed the gyrus and sulcus of the ancient brain, or traces of folds and sulcus, and the vascular structure surrounding the brain. Analyzing these traces was a daunting task. “It was a tough job, and it needed a lot.”gray matter“Involvement,” joked Christoph Zorikofer, a paleoanthropologist and neurobiologist at the University of Zurich.
As the team slowly progressed through the fossil endcast, we saw evolutionary changes unfolding over time, with one region further inching towards the back of the brain. “For example, the backward shift over the precentral gyrus evolution time certainly shows that the previous Broca’s area expanded during human evolution,” Zorikofer said. “This area and its surroundings are of particular interest because modern humans are involved in speech synthesis and other higher cognitive abilities.”
After comparing the fossil endcast with the ape and modern endcast, the team’s analysis revealed that Homo It had a brain with an ape-like frontal lobe.
“The earliest population of our genus Homo It had a very primitive ape-like brain, like its ancestor Australopithecus. ” Homo habilis And early on Homo erectus, The researcher said..
When did the homo brain become “modern”?
The· Oldest Homo Remaining On record, the fossil of Ledi-Geraru in Ethiopia is 2.8 million years old, but the brain case is not preserved.Nothing has been preserved for the next million years Homo An endcast, according to Amelie Bode, a paleoanthropologist at the University of Cambridge, England, who was not involved in the study but wrote an opinion piece about it in the journal. Science..
This one million year gap has strengthened the mystery of when HomoAdvanced brain has developed.But the analysis of Homo erectus The skull helped unleash this finding, the researchers said.Especially a group of 5 people Homo erectus The key was the skull known as the Dmanisi individual, named after the ruins of Dmanisi, Georgia. Approximately 1.8 million years ago, the skull was well preserved and belonged to an individual who died between adolescence and old age.
“Dmanisi fossils are very important, because in the early days, about 1.8 million years ago. Homo Had a primitive brain similar to that of Australopithecus Of apes. ”
But it didn’t stop having ape-like frontal lobes Homo erectus From an extraordinary being. “People with these primitive brains can leave Africa, cope with the harsh climatic conditions of Eurasia, produce a variety of tools, engage in meat sourcing and assist members of the elderly group. “It was,” said Zorikofer.
Individuals of Dmanisi Homo It left Africa. In Africa, it was about 1.7 million years ago. HomoComplex frontal lobes are likely to have begun to form, according to researchers who found evidence of reorganized brain regions. Homo Skulls in Africa and Southeast Asia less than 1.5 million years ago. For example Homo erectus An individual who lived less than 1.5 million years ago and whose body was found in Southeast Asia had an endcast showing the present age. Homo Frontal lobe, the researcher said.
This finding indicates that the complex frontal lobe was “once considered the earliest feature.” Homo In Africa … evolution is relatively slow, “and it was not necessary for the early dispersal of humans from Africa, the researchers wrote in the study.
The discovery is “interesting and important, but not necessarily controversial,” said Fred Spour, a paleontologist at the Center for Human Evolution at the Natural History Museum in London, who was not involved in the study.
“Focus on a strong dichotomy between” our “genus Homo And previous ancestors (eg Australopithecus (Like Ethiopia’s “Lucy”) was a remnant of an era when few fossils were available, and human evolution was seen as a simple linear process from various early ancestors to modern humans. ..Its context, the origin of the genus Homo It was regarded as a biological revolution associated with making stone tools and having a larger and more complex brain. ”
Researchers have since learned that “stone tools were made as early as 3.3 million years ago (long before their expected origin). Homo) And genus species and specimens Homo It was discovered that the brain was small, “Spoor said. “In reality, the different aspects that characterize us as modern humans have emerged at different times, not necessarily as neat packages in” special moments. ” “
Why did the homo brain change?
Why it remains a mystery Homo The brain has evolved and sophisticated frontal lobes, but scientists have some ideas.Perhaps it is an instance of the so-called “Baldwin effect”, and the ability to learn new behaviors can drive change. Genetics Said phenotype, or appearance, Zorikofer. In this case, he said, the structure of the brain responsible for language and other complex cognitive tasks may have promoted proto-language-like communication and grew in the environment in which it was needed.
“we Make a hypothesis “Positive feedback between cultural innovation and evolutionary brain reorganization,” explained Zorikofer, even though the brain structure of early language was “organized” about 1.5 million years ago. I do not know. Homo The population had a modern human-like language, “he said. Instead, early humans probably “in the sense of co-evolution of the brain and culture, supported the evolution of these brain structures and had some sort of original language that supported these brain structures. . “
Originally published in Live Science.
First ‘Homo’ species left Africa with ape-like brains Source link First ‘Homo’ species left Africa with ape-like brains