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

by David Turell , Friday, November 03, 2017, 22:06 (2575 days ago) @ dhw

DAVID: No self-respecting ape type leaves the trees without a reason. There is evidence of upright posture alterations in the spine 23 million years ago, in preparation for the descent. If they came out of the trees as you propose, there should be more fossil evidence of the pelvic alterations required. There are none. The speciation gap exists.

dhw: And why should there be more fossils of pelvic alterations after descent than there are of pelvic alterations in anticipation of descent?

Lucy walked fully upright at the start with pelvic lumbar spine changes in place. Fossils are few and far between with early hominins. Lucy is the closest thing we have to an ape-human in-between. We don't know when Lucy in her forbears achieved her form. In trees or down.

DAVID: You keep skipping over in your reasoning the fact that shrinkage is only seen after a brain is enlarged, although you recognize the sequence. The cause of enlargement is not proven by that observation. A particular size is reached with gaps in the fossil story. It is not epigenetic, while the shrinkage is.

Dhw: You have quoted my answer! Once the brain had reached optimum size, complexity took over from enlargement. The efficiency of complexification would then eventually have led to less volume. Nobody knows the cause of enlargement (hence hypotheses concerning diet, upright posture, cooking, random mutations, divine dabbling), but since we KNOW that new concepts RESULT in rewiring/complexification, it is not unreasonable to suggest that in earlier times new concepts RESULTED in expansion.

It is unreasonable since the only event we have seen is shrinkage in an established size of brain in an large skull. How does the skull decided to enlarge if the brains says to itself I'm enlarging, so it tells the skull, "skull get bigger"? Note the need for advanced planning, which you like to forget. I repeat: shrinkage is epigenetic, enlargement must be speciation.

dhw: Why would it [the brain] expand/complexify in anticipation of ideas that have not yet been thought of?
DAVID: My point. Simply, the brain can't by itself. It needs God as an outside agent to do it.

dhw: So only God can expand the brain, but the brain can complexify of its own accord, or do you believe your God dabbled with the Indian women’s brains before they learned to read?

Brain complexification/shrinkage is epigenetic, obviously. The brain does it on its own.

DAVID: Speciation is planning in advance.
Dhw Speciation is major changes to the anatomy. It is you who insist that they must be planned in advance, as opposed to being responses to the challenges and opportunities offered by the conditions in which organisms find themselves.
DAVID: Yes I insist as well as my ID friends.

dhw: As a matter of interest, do your ID friends insist that their God fiddled with ape anatomy before apes left the trees, designed eight stages of pre-whales before they entered the water, and planned weaverbird’s nests, toxin-swallowing snakes and skull shrinking shrews in order to keep life going until he could produce Homo sapiens’ brain? A simple yes or no will do.

Generally, yes. They believe in planning and design.