Human evolution: savannah theory fading; big brain (Introduction)

by dhw, Tuesday, March 18, 2025, 11:39 (16 days ago) @ David Turell

The human brain

DAVID: God guided brain enlargement and complexity as needed by the new environmental changes.bbb (dhw’s bold)

dhw: At least you now agree once more that complexity and enlargement occur IN RESPONSE to environmental changes, and not in anticipation. How does one “guide” enlargement and complexification? Did your God pop round to each pre-sapiens in the group with his X-Ray machine and scalpel, making sure the cells were arranging themselves in the right order?

As usual, you have ignored my question.

DAVID: Just because I didn't mention anticipation our 315,000 brain shows just that.

“As needed by the new changes” does not mean “as will be needed by changes that will not happen until two or three thousand years later”. You have agreed that your God does NOT guide complexification, and all past brains would have continued to complexify until new requirements exceeded their capacity for complexification. The enlarged brain in all cases, including our own, would have been a response to new requirements, as would subsequent complexifications. Once more: A response to new requirements does not entail anticipation.

dhw: (under “origin of language”) This still allows for your God as the inventor of the mechanism that runs the process.

DAVID: And that is our difference. I see an active God designer. You prefer your usual second-hand design by instructed cells.

Thank you for dropping the "anticipation" argument. When will you stop pretending that a God who designs autonomous thinking is not an active God designer? You have him designing humans to think for themselves, so does your theory make him inactive? You even acknowledge that the behaviour of cells “looks” intelligent, but you just happen to know that it’s not. This is what Shapiro calls “large organisms chauvinism”.

The savannah theory
DAVID: The savannah theory was a phantasy based on one finding.

dhw: […] It is generally agreed that we are descended from tree-dwellers. No one knows exactly where, when or why we first descended. The savannah theory offers a logical explanation for why. You will claim that your God’s surgery on a sleeping group (groups) is more logical.

DAVID: Look at the current evidence of hominin/homo activity in every climate/geography. The savannah theory is logical but now not supported. As you say, we just don't know.

What we do now is totally irrelevant to the question of how sapiens originated! No theory is supported – we just don’t know. But the savannah theory is as logical as any other theory you can produce – e.g. your God operating on the legs, brains and pelvises of a group or groups of our ancestors.

Theoretical origin of life
DAVID: A novel way precursor chemicals might have appeared, but it still is giant steps to life itself. I still favor ocean vents as the likeliest origin spots.

dhw: I agree completely that both theories are still a long way from providing us with the fine-tuning necessary for the appearance of life itself. [...] And those “giant steps” are what you have dismissed as “secondary” in your efforts to prove that the entire universe is fine-tuned for life even without them.

DAVID: Your confusion is obvious. The way this universe is formed allows life anywhere. That you wish to add habitability is the next required step.

This universe only allows life where there is habitability!!! That means it does NOT allow life anywhere else. Your confusion becomes more and more obvious. See the other thread.