Brain complexity: more important than size (Introduction)

by David Turell , Tuesday, November 28, 2017, 15:54 (2552 days ago) @ dhw

DAVID: You insist that an urgency for implementation forces the size jump (evolutionary mechanism unknown). But history tells us the sapiens brain arrived 300,000 years ago, with most implementation in the past 10,000 years. If it was required by necessity, what took so long (290,000 years)?

dhw: You have already agreed that progress is made through individuals. I do not accept that there was no progress for 290,000 years, but 10,000 years ago there were some particularly bright individuals who came up with concepts that would have caused rapid change (complexification).

DAVID: My answer, sapiens had to learn to use the new capacity. And with complexification the brain and skull shrunk a little.

Added: That advance was in the very civilized parts of the world. But there are still parts of the world with isolated indigenous people. We all have the same brain size related to body size. The indigenous have still not learned to use all of it, wich is my point about jump in size and then learning to use it.

dhw: The new, optimum capacity was reached 300,000 years ago. Complexification had to take over, and was so efficient that the brain no longer needs quite as many cells as it had before.

Complexification involved more than cells. Connectivity with much more branching of axons is equally important.

DAVID: This tells us it was an early development in evolution in early hominins, because we see no tiny enlargements, but 200 cc jumps in size, with each stage not gradually enlarging, but complexifying at the same size achieved when the new hominin stage appeared.

dhw: 200 cc, you have told us, was the average, but I am quite happy to accept that there would have been a process of complexifying until the capacity was no longer adequate to cope with new demands. Then there would have had to be a jump. Then complexification within the new capacity would have sufficed until new concepts required another jump. 300,000 years ago complexification took over from jumps. What’s the problem?

Artifacts! What a brain can think of is evidence of the present concepts and the implementation it is capable of at its current size.

DAVID: Since I believe God speciates, He caused the necessary enlargements to occur.

dhw: Or he may have created the mechanism which enabled the necessary enlargements to occur. And in all this welter of repeated objections, you still haven’t answered my question: Do you or do you not accept the findings of modern science that the brain changes in response to concepts, and not in anticipation of them?

Once a new brain size is established, the new advanced level of hominin learns to use it. Each level responds by complexification at the same size. The brain change is within a given size as demonstrated by current science. You can't extrapolate otherwise.