Evolution and humans: big brain size or use (Evolution)

by David Turell , Monday, May 29, 2017, 17:49 (2522 days ago) @ dhw

DAVID: Once and for all there is no gradualness, no 'if' about the stages. Yes, saltations, which I think come from God. And not much use until 50,000 years ago with advanced language, and 45,000 years ago with cave art. Not like the use of today, which was allowed 200,000 years ago, but not taken advantage of.

dhw: What do you mean by “not much use”? The first sapiens survived, didn’t they? And they used fire and tools and we don’t know what else in the way of language and other skills that enabled them to cope with their different environments.

There are two issues. 1) What caused the enlargement of the brain? 2) What caused all the advances humans have made over the last 200,000 years? You say we begin with an advanced form of God-given consciousness which you now agree uses the brain. According to the study you recommended, the brain changes according to the demands of consciousness. History: the brain grew larger by saltations. Implication: consciousness made demands…brain enlarged to cope with demands. Brain reached optimum size. Consciousness continued to come up with new concepts, and so the brain had to complexify in order to meet the new demands of consciousness. It could hardly be clearer, provided one believes in dualism and an afterlife as oneself.

Our brain arrived 200,000 years ago and in recent years has gotten a little smaller. That doesn't fit your concept of use driving a larger size, since in the past 10,000 years since agriculture arrived the use of the brain has tremendously expanded. The following study explains it:

https://www.sciencedaily.com/releases/2017/05/170526084524.htm

"Since it has been well-established that larger brain volume is associated with better cognitive performance, it was puzzling that cognitive performance shows a dramatic improvement from childhood to young adulthood at the same time that brain volume and cortical thickness decline.

"A new study ... may help resolve this puzzle, revealing that while volume indeed decreases from childhood to young adulthood, gray matter density actually increases. Their findings also show that while females have lower brain volume, proportionate to their smaller size, they have higher gray matter density than males, which could explain why their cognitive performance is comparable despite having lower brain volume. Thus, while adolescents lose brain volume, and females have lower brain volume than males, this is compensated for by increased density of gray matter.

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"'Our findings also emphasize the need to examine several measures of brain structure at the same time. Volume and cortical thickness have received the most attention in developmental studies in the past, but gray matter density may be as important for understanding how improved performance relates to brain development.'"

The brain has the ability to increase density. Our highly used sapiens brain is shrinking under enormous new uses. No question, size first, use second with each 200cc jump.

DAVID: Thank you. Of the brain's plastic abilities work intimately with consciousness.

dhw: The intimate work consists in the plastic brain responding to the requirements of consciousness: since that is what is demonstrated by the study, it makes perfect sense that it would also apply to the enlargement of the brain until it reached its optimum size. I presume your thanks denote agreement, so why have you spent the first part of this post disagreeing?

Because what I conclude from the studies is opposite from you conclusions, which do not explain the small shrinkage in our brain size in the past 50,000 years.