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

by David Turell , Monday, March 17, 2025, 20:21 (16 days ago) @ dhw

The human brain

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.

What is a “single theory”? Humans are found everywhere because they migrated everywhere. “Quite early” leads us back earlier and earlier, until finally we come to the fact that we don’t know where, when or how the first sapiens came into existence. How does that invalidate the savannah theory, or validate your theory about God’s surgery on sleeping pre-sapiens?

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.

DAVID: God guided brain enlargement and complexity as needed by the new environmental changes.

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?

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

Neanderthal sapiens mix in the Levant

DAVID: I follow Adler's theory that only a highly intelligent agent could produce humans.

dhw: The same argument can be used for the production of elephants, eagles and octopuses. I don’t recall you saying that Adler thought your God had operated on legs, pelvises and brains in order to produce sapiens.

DAVID: He just discussed the logic of God rather than naturally occurring evolution.

dhw: So please stop alluding to him as if he supported all your wacky ideas.

Adler is distilled into my thinking.

Theoretical origin of life

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.

DAVID: Yes.

dhw: 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.

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

Origin of language

DAVID: I'll stick with my prepared in advance theory, our 315,000 year-old brain as proof.

dhw: You have agreed that our entire brain has been in use from the beginning, that the brain RESPONDS to new requirements, and in our case it does so through complexification, which you agree takes place without your God’s intervention. Our disagreement is that you insist your God performed brain surgery on a sleeping group or groups in order to enlarge their brains, whereas I propose that our brains expanded in response to new requirements, and complexified thereafter, again through responses. This still allows for your God as the inventor of the mechanism that runs the process.

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