Human evolution; comparing sapiens and Neanderthal brains (Introduction)

by David Turell , Thursday, March 09, 2023, 19:04 (623 days ago) @ David Turell

Ours is smaller:

https://www.discovermagazine.com/the-sciences/brutes-and-brains-what-we-know-about-nean...

"Tradition says that Homo neanderthalensis and Homo sapiens were intellectually distinct. But archaeologists and anthropologists increasingly insist that the intellectual divide between the two species is shrinking.

"In fact, the traces of their ancient activities show more and more that the two species followed similar survival strategies. Residing in similar societies, they made similar sounds and manipulated similar tools. Apart from that, the most recent research shows that the two created similar art, too, signifying their shared taste for abstraction.

"But what about their brains? Was there anything in their anatomy that differentiated their thinking?

'Some specialists say yes. Working in the fields of paleontology, paleoneurology and paleogenetics, experts suspect that the slightest distinctions in the structure and development of the two species’ brains could’ve set their cognition apart in complex and consequential ways.

***

"Though the measurements aren’t always consistent and change over time, specialists say that the typical Neanderthal skull contained around 1500 cubic centimeters (or 51 ounces) of cerebral tissue, though the skulls of their more modern counterparts showed a smaller cranial capacity of only 1350 cubic centimeters (or 46 ounces).

"In addition to their size, Neanderthal brains and braincases were also slightly stretched, producing a strange, semi-spherical skull that terminated in a big bump toward the back. Termed the “occipital bun,” this bump was one of the first features of Neanderthal anatomy that experts discovered and described.

***

"Some studies suppose, for instance, that the structure of the Neanderthal skull meant that the H. neanderthalensis cerebellum was smaller than the H. sapiens cerebellum. A small cerebellum, these studies say, can cut a species’ capacity to learn and think logically, to process language, and to interact socially, which would all substantially impact its survival.

"Adding to this is an assortment of similar proposals about the peculiarities inside the Neanderthal mind. For instance, some paleontologists and paleoneurologists say that much more of the species’ brain was concentrated on controlling basic body movements, all thanks to the species’ bigger, bulkier bodies, which were more difficult to move than our own.

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"Genetic analyses add additional support to the idea that the development of the Neanderthal brain differed from our own. In fact, though specialists traditionally stick to skulls in their attempts to study Neanderthal smarts, the recent reconstruction of the Neanderthal genome is inspiring some to turn to the ancient genes that guide brain growth, instead, as a way to differentiate between H. neanderthalensis and H. sapiens thinking.

"In 2021, for instance, a team of geneticists investigated a gene called NOVA1, which directs the development of brain tissues in H. neanderthalensis and H. sapiens. Inserting two distinct forms of the gene into clusters of uncultured cells, the team discovered that the form of NOVA1 found in H. neanderthalensis created bumpier blobs of brain tissue when cultured, while the form of NOVA1 found in H. sapiens created smooth, spherical clumps.

"The following year, in 2022, a second team of geneticists followed a similar approach with a gene called TKTL1, which prompts neuron production. While the H. neanderthalensis form of TKTL1 fostered some neurons, the H. sapiens form fostered many more.

"Though these findings do demonstrate that the brains of H. neanderthalensis and H. sapiens developed differently, they don’t disclose all the details of this difference. Individual genes are only tiny threads in a greater genetic tapestry, specialists say, suggesting that a true appreciation of the influence of NOVA1 and TKTL1 on something as complex as cognition can only come in the context of a more complete genome."

Comment: not brutes, much like us, but phenotypically different