Evolution and humans: big brain size uses energy (Evolution)

by David Turell @, Sunday, October 22, 2017, 20:03 (336 days ago) @ dhw

QUOTES: "'On an acute level, we have now demonstrated that when humans simultaneously experience extremes of physical and mental exertion, our internal trade-off preserves cognitive function as the body's priority."

"He points to examples of this trade-off in humans benefiting the brain. "The selfish nature of the brain has been observed in the unique preservation of brain mass as bodies waste away in people suffering from long-term malnutrition or starvation, as well as in children born with growth restriction.'"

dhw: David, perhaps you could explain to me how they know that, for example, a starving gorilla’s cognitive functions disappear before its body wastes away. The question should be particularly interesting for any dualist.

I’d be grateful for an answer to this question, if you happen to know.

I don't know of any studies of starving apes, but in the human condition, concentration camp survivors weighing 80 pounds fully preserved their thinking capacity. Think of Viktor Frankl's book. I would think apes have the same preservation mechanism.


DAVID’s comment: The findngs make perfect sense, and suggest the entire transition from trees to ground was a well-planned transition. I view God as in control.

dhw: I can see no such suggestion in the article or in the implications of the article. It makes equally perfect sense to argue that the transition from trees to ground (possibly due to local environmental conditions) resulted in new requirements, and the need to fulfil these requirements gave rise to the expansion of the brain, which in turn gave rise to the brain’s increased demand for energy. A logical sequence begun as a RESPONSE to new conditions, not planned in advance.

DAVID: Except the change to upright began 23 million years ago in a monkey. And the changes we see in the early hominins show loss of muscle before the brain growth. Opposite of your comment.

dhw:It doesn’t matter when the changes began. You have no way of knowing that they were not in response to local changes in the environment. I don’t understand the reference to “loss of muscle before the brain growth”. I suggest that early hominins underwent anatomical changes, including those to the brain, after and as a result of their descent from the trees (whereas you tell us your God preprogrammed or dabbled them BEFORE they descended). How can we know the sequence?

The fossils demonstrate loss of muscle while the brains are still small and they are bipedal. There is an obvious sequence. Environmental response does not affect the swquence I point out.


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