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

by David Turell , Sunday, March 16, 2025, 17:57 (17 days ago) @ dhw

The human brain

DAVID: We departed from the primate line six million years ago. Apes and monkeys are unchanged. We went on to full bipedalism, intricate hand usages, bigger more complex brains etc. Did we push ourselves or was an agent doing it? I still favor God, the designer.

dhw: You have completely ignored my response above, and simply repeated your belief, which is that your God did it by popping in to operate on the brains of a group or groups of sleeping homos.

My belief trumps your beliefs in the power of chance, purposeless evolution.

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

dhw: What is the time frame for the unknown origin of sapiens? 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.

The savannah theory is no longer available as a single theory with the new findings of humans everywhere. Lucy shows us bipedalism came quite early.

Neanderthal sapiens mix in the Levant

dhw: The mystery deepens. We know that sapiens and Neanderthals interbred, and presumably this other unknown group did the same. Obviously they co-existed peacefully. And their shared cultures suggest sophisticated communication. The Neanderthal brain was at least as big as ours, so the big brain of sapiens is/was not unique. I wonder what was the brain size of the third homo.

DAVID: Brain size is a minor issue compared to neuron organization and complexification.

dhw: My answer at the start of this post was to your statement that “no natural need for our big brain has ever been demonstrated”. Neuron organization and complexification would have been the same in all the earlier brains, but they had to expand when requirements exceeded the capacity for reorganization and complexification, as explained above and formerly agreed by you.

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

DAVID: dhw's plea for origin places an emphasis on where did uprightness originate. Obviously in Africa before the great migrations into Europe and Asia. The levant was a major part of the route. The point of origin of bipedalism remains unknown. For those looking for a natural driving requirement living on savannahs is a reasonable but unsupported theory in view of all the new findings in other climates.

dhw: The new findings in other climates would relate to times when sapiens had already originated and migrated. I’m glad you recognize the logic behind the savannah theory .

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.

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

Theoretical origin of life

QUOTE: "The first molecules necessary for life on Earth could have been created when tiny flickers of “microlightning” between drops of water sparked the necessary chemical reactions.”

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.

Yes.