Big brain evolution: comparing chimp and brain organoids (Evolution)

by David Turell @, Saturday, February 09, 2019, 14:58 (191 days ago) @ dhw

QUOTES: "At some point during human evolution, a handful of genetic changes triggered a dramatic threefold expansion of the brain's neocortex, the wrinkly outermost layer of brain tissue responsible for everything from language to self-awareness to abstract thought. Identifying what drove this evolutionary shift is fundamental to understanding what makes us human,

"By looking for differences in gene activity between human organoids and chimp organoids (as well as reference tissue from another primate, the rhesus macaque monkey) Bhaduri identified several hundred genetic changes unique to the human lineage that could help explain the evolutionary origins of the distinctly human brain. (David’s bold)

DAVID: Note my bolds. Several hundred new genes are not a handful as described in the first paragraph. Yes it is, as if compared to all the genes we have, but as cooperative beneficial new genes created to affect this change it is not a handful, and clearly shows how the result of the study is propagandized to make it sound simple. This change requires design and a designer. This is the sort of hyperbole that I find constantly. Since it was not apparent to readers from my previous entries, I'll be more careful to point it out. It is misleading.

dhw: I have no doubt that in its proper place your attack on hyperbole is perfectly justified. It simply has no place in the discussion on cellular intelligence. By your admission this cause was championed long before the current grant issue, you initially quoted the article without any of these negative comments (and said two of the quotes expressed your own thoughts), and in any case I hope you are not including Shapiro in your blacklist of “fakers”.

I’m very happy with your expression “cooperative beneficial new genes”. This seems to me to sum up how the whole process works. I would suggest that the big leap from a handful to several hundred would coincide with the different stages in between our ape ancestors and H. sapiens. The brain expanded (= new cells/new genes), as existing cells cooperated to enable hominins to cope with changing conditions or to implement new ideas that required new skills. Today, as we noted in our very long discussions on this subject, the brain complexifies – and indeed that process has proved so efficient that there has even been a shrinkage.

Humans have five layers of neurons in the prefrontal cortex not at all present in chimps, in a highly complex wiring set of patterns that AI folks are trying to imitate. One must assume from the jumps in fossil cranial size these layers also appeared in jumps in complexity requiring design that a committee of neurons could not envision before they were wired properly. Each wire/axon grows out from the central body of the neuron and at a distance makes multiple connection branches to other neurons. Unless guided what one would get is a pile of spaghetti. Your fanciful cell committees are out of their league. Designer required.


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