Neanderthal and human brains similar shape at birth, research shows

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By Amina Khan, Los Angeles Times
November 13, 2010
Original article here

Human brains soon become more rounded, but those of the extinct species retained an elongated shape. The findings could help scientists determine the cognitive differences between the two species.

The shape-shift of human brains may be linked to some underlying structural changes in brain regions that account for emotional, social and language development. (CSIC, EPA / May 6, 2010)

The newborn brains of Neanderthals looked remarkably similar to human brains at birth and then began to diverge drastically over the first year of life, European scientists have reported. The findings, reported online Monday in the journal Current Biology, could help paleoanthropologists figure out the cognitive differences between modern humans and their extinct relatives — and when, exactly, those differences developed.

A team led by paleoanthropologist Philipp Gunz of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, scanned the skulls of several Neanderthals, including a newborn, and mapped out the shape of the brain cavity. Gunz said he decided to look at the differences between human and Neanderthal skulls after finding in an earlier study that chimpanzee and human brains have the same elongated shape at birth, but that the human baby’s brain quickly becomes more rounded.

Gunz wondered whether even though human and Neanderthal brains were roughly the same size, they would find a similar difference in shape between young humans and Neanderthals, who went extinct about 25,000 years ago.Human and Neanderthal brains were remarkably similar in shape right after birth, the scientists found — perhaps because of the common need to squeeze a baby’s head through its mother’s birth canal.

But differences set in during the first year. Human brains begin to morph from an elongated shape to a more rounded one. The Neanderthal brains, similar to chimpanzee brains, retained their oblong shape.

Although any inference about Neanderthals’ cognitive ability would be speculative at best, Gunz said, the shape-shift of human brains may be linked to some underlying structural changes in brain regions that account for emotional, social and language development.

“We think shape indicates a difference in the speed of development,” Gunz said, “because if you grow faster or slower, the brain shape changes differently…. We know from modern humans that the way you grow your brain affects the pattern of neural wiring.”

Steven Leigh, a biological anthropologist at the University of Illinois at Urbana-Champaign, said the findings were interesting. “There obviously has been a lot of debate about the evolution of the human brain and at what points the brain differs from other species, including Neanderthals,” he said. “They seem to be getting closer to the answer in this analysis.”

amina.khan@latimes.com

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