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Early humans walked with monkey-like brains, a study found

One of Dmanisi's skulls at an exhibition in Leiden in 2009

One of Dmanisi’s skulls at an exhibition in Leiden in 2009.
Photo: VALERIE KUYPERS / AFP via Getty Images (Getty Images)

Humans can be distinguished from other apes in many ways, such as our total hairlessness, our upright bipeds, and, of course, our powerful brains. But it turns out that our cognitive abilities did not develop earlier than previously thought, according to a new study by an international team of researchers.

The findings of the team, published Today, Science magazine is based on five 1.8-million-year-old skulls from about 10 acres near the Georgian city of Dmanisi. The brain of these early arrivals in Europe and Asia—Hominin species that evolved long before homo sapiensthey were already known to be small, but in a recent inspection, researchers made endocasts of ancient skulls. In general, they have created topographic maps of brain cases that can reveal small differences in shape that give an idea of ​​the development of different regions of the long-decomposed brain. Understanding the ancient brain structures helps to clarify the genesis of our species; whether we have reached or sprinted to our modern morphology and what path we have taken to get here.

Endocasti of the five 1.8 million year old cranes from Dmanisi.

Endocasti of the five 1.8 million year old cranes from Dmanisi.
Image: M. Ponce de Leon and Ch. Zolikofer, University of Zurich

“These structures are extremely interesting because they represent the neural substrate for complex cognitive tasks, such as the development and use of tools, social knowledge and, most importantly, spoken language,” said study authors Marcia Ponce de Leon and Christophe Zolikofer, both paleoanthropologists. from the University of Zurich, in an email. “We don’t know if these hominins had language in the modern sense, but the brain structures were there and probably evolved along with language abilities.”

The saga of human origins is obscured by fragmentary fossil recordings, like an old book, so worn out over time that only a handful of sentences are used to guess the whole story. But I guess we do, and our accuracy improves with each newly discovered fossil and newly invented technology for analyzing them. The skulls examined in the new document were excavated between 1991 and 2008 and are housed in the Georgian National Museum in Tbilisi.

Comparison of Georgian Homo endocasts to units taken herem skulls of approximately the same age and younger than Africa and Indonesian island of Java, the team found that the brains of Georgian hominins look more similar to those of great apes than modern humans. This suggests that modern brain structures emerged from Africa at least 100,000 years later than early wanderers outside the continent.

“There must have been two ‘accelerations outside Africa’ in the beginning Homo: the first is documented by fossil evidence from Dmanisi’s site in present-day Georgia, “about 2 million years ago, the researchers said in an email. “These Homo populations had primitive brains. The second scattering is documented by the Java fossils; these populations had modern brains. “

Dmanisi specimen (left) compared to the more cognitively developed Homo erectus from Indonesia (right).

Sample from Dmanisi (left) compared to more cognitively developed A permanent person from Indonesia (right).
Image: M. Ponce de Leon and Ch. Zolikofer, University of Zurich

From the earliest fossils attributed to the genus Homo dating back nearly 3 million years, Georgian skulls mean at least some of the earliest humans there was a lack of developed brains, which we usually consider definiteof our kind. Researchers said it was a moment, “realizing that the emperor had no clothes,” clothes here as a reorganized brain.

Researchers have been particularly interested in the frontal lobes of individuals from Dmanisi, a region of the brain that probably played a vital role in early human endeavors for language development and instrument making. Both innovations were springboards for early humans who were able to do more than survive; at one point we began to communicate with nuances, to organize as larger groups, and to create tools that allowed us to hunt more efficiently, to live in greater comfort, and eventually to become the most dominant species of the planet (for better or worse).

“It doesn’t really change our understanding of homo sapiens, but it definitely changes the way we look at the early evolution of the human brain, ”said Amelie Bode, a paleoanthropologist at the University of Cambridge who is not involved in the recent study, in an email. B.eaudet noted that despite the knowledge of the primitive Australopithecin brain structure owned by Lucy, among others, and a more developed cranium of recent humans (dating back about half a million years ago), “we didn’t really know what happened between them. With this study, we have a better idea, even if there are still some gaps. “

More fossils always help to better understand our evolutionary arc, but instead of new discoveries, new technology tends to intensify. The gap in our knowledge of human cognitive development is narrowing. We should be grateful for the development of our predecessors, because now we have the brain to understand how it all happened.

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