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

by David Turell , Saturday, November 04, 2017, 19:31 (2574 days ago) @ dhw

DAVID: 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.

dhw: You were talking about a fossil from 23 million years ago with spinal changes which you think your God must have engineered "in preparation" before the ape descended from the trees. Now you tell me we don’t even know if the 3.2-million-year-old Lucy “achieved her form” before or after she descended, and you have not told me why there should be more fossils if the 23-million-year-old’s anatomy changed after it had descended from the trees. Yes indeed, fossils are few and far between. So how does that prove that your God must have dabbled BEFORE early hominins descended?

He obviously dabbled 23 million years ago. Lucy was a major change from an ape body structure. She used both land and trees. That involved many leg and pelvic changes structurally. Since she had the changes she probably used land more than trees. We don't have the fossils to tell us how it happened, but with the 23 million year old evidence, and since I believe God speciates, they were changed so they could then descend.

Dhw: 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.
DAVID: 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: If shrinkage is epigenetic (i.e. does not require a divine dabble), then the brain cells are cooperating to make the changes. (You agree that “the brain does it on its own”). The same process would apply with enlargement, as the different cell communities cooperate, just as they do whenever organisms adapt. I don’t “forget” the need for advanced planning: I challenge that whole assumption. In my hypothesis, adaptation and speciation follow the same course, and are often connected, as they RESPOND to challenges and opportunities. The skull adapts to contain the expanding brain it houses; the leg adapts to its new maritime environment and becomes a fin; the hominin spine adapts to the new demands of life on the ground. If God can create a mechanism that enables the brain to shrink on its own, why do you think the same mechanism is incapable of making the brain expand, and is incapable of making the skull adapt to the expansion?

First, you propose the early forms tried to think, and epigenetically forced an expansion of the brain. At a time when they did not know what they did not know, and lacked the capacity of imagining future possibilities. That is how I interpret what you have presented. But the skull as bone is a different type of cells. Did the brain cell committees tell the skull cell committees what to do? It is the same chicken and egg problem that I've presented with larger brains, larger skulls and the required larger maternal birth canal in a changed pelvis. Requires foresight and design planning, none of which is epigenetic. God makes these changes in new species.

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.
DAVID: Generally, yes. They believe in planning and design.

dhw: Of course intelligent design believers believe in planning and design. It’s the details of your divinely controlled evolutionary history I’m asking about. Do they insist, for instance, that their God dabbled with ape anatomy before apes left the trees?

It fits their theories.