Human evolution: more on timing brain development (Introduction)

by David Turell , Friday, April 09, 2021, 22:12 (1110 days ago) @ David Turell
edited by David Turell, Friday, April 09, 2021, 22:25

Our body upright posture developed well before our large brain appeared:

https://www.sciencenews.org/article/ancient-humans-brain-apelike-modern-africa-evolution

"Even after ancient humans took their first steps out of Africa, they still may have possessed brains more like those of great apes than modern humans, a new study suggests.

"For decades, scientists had thought modern humanlike organization of brain structures evolved soon after the human lineage Homo arose roughly 2.8 million years ago. But an analysis of fossilized human skulls that retain imprints of the brains they once held now suggests such brain development occurred much later. Modernlike brains may have emerged in an evolutionary sprint starting about 1.7 million years ago, researchers report in the April 9 Science.

"What sets modern humans apart most from our closest living relatives, the great apes, is most likely our brain. To learn more about how the modern human brain evolved, the researchers analyzed replicas of the brain’s convoluted outer surface, re-created from the oldest known fossils to preserve the inner surfaces of early human skulls. The 1.77-million to 1.85-million-year-old fossils are from the Dmanisi archaeological site in the modern-day nation of Georgia and were compared with bones from Africa and Southeast Asia ranging from roughly 2 million to 70,000 years old.

"The scientists focused on the brain’s frontal lobes, which are linked with complex mental tasks such as toolmaking and language. Early Homo from Dmanisi and Africa still apparently retained a great ape–like organization of the frontal lobe 1.8 million years ago, “a million or so years later than previously thought,” says paleoanthropologist Philipp Gunz at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who did not take part in this study. (my bold)

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"Future research can investigate what evolutionary pressures might have driven the emergence of modern human–like brain organization. Ultimately such research could reveal how brain reorganization is related to the evolution of language and symbolic thought, says study author Christoph Zollikofer, a paleoanthropologist at the University of Zurich. (my bold)

"But perhaps there were no such pressures, “and this reorganization was a by-product of changes in other areas,” says paleoanthropologist Amélie Beaudet at the University of Cambridge, who wrote a review of this study for the April 9 Science. The only way to answer this question “would be to study more fossils from the time period ranging between the earliest human representatives 2.8 million years ago and Homo after 1.8 million years ago and to reconstruct the contexts in which they were living and evolving.'”

Comment: This article, like dhw, looks for natural pressures to force evolution. Note my bolds: language and symbolic thought took 245,000 years to appear after sapiens first arrived on Earth, but it did appear because our brain was lying around waiting for the ability/use to be found. What makes perfect sense is the early timing: with freed arms and better hands the new hominid could learn to do many new things at the manual level, and later. when given a bigger frontal lobe with which to develop immaterial ideation (at 315,000 years ago), could invent more complex objects with more varied activities. God's planning is obvious.