Introducing the brain: why so big? Part two (Introduction)

by David Turell , Sunday, July 14, 2024, 18:27 (96 days ago) @ dhw

Evolution of the brain

DAVID: Very distantly of course. No where near the current complexity.

dhw:c Of course early ancestors are “distant” and nowhere near current complexity. Thank you for now acknowledging that the vertebrate brain was not designed “de novo”, i.e. without predecessors.

Neurons had to be evolved and then used in minor ways. Our evolved brain is a giant jump from Planaria.

Why is our brain so big?

DAVID: The problem is you dodged with a just-so story. Was our huge complex brain necessary for survival, when their close cousins didn't need it. All living in the same African environment.

dhw: Africa is a huge continent, and all that is required is one local environment (perhaps even more than one) which necessitated the move from trees to land.

So, bipedalism demanded that the brain must appear? Did walking upright demand more survivability in brain capacity? Your just-so's raise more questions than answers.

DAVID: Lucy's bipedalism preceded brain growth, showing that she did not need a big brain.

dhw: Brain growth would only occur when the existing brain could not cope with new requirements. We have no idea what new requirements may have caused each stage of expansion, but no doubt new environments, new ideas (artefacts), new discoveries (fire) would all have played a part. All of these would have improved our ancestors’ chances of survival.

Yes, when we were in a stone age. But at that time we had a fully enlarged brain, mainly unused and unexplained under Darwinism.

dhw: There is no chance involved if cells have the autonomous ability (perhaps God-given) to changes themselves in order to cope with or exploit new conditions.

DAVID (repeated reply): Back-peddling to God.

dhw: You look at the complexities and back-pedal to your God designing every single one individually. I look at the complexities and acknowledge the possibility that your God might have invented the process that produced the complexities. What’s wrong with that?

Thank you for admitting the possibility of God.

DAVID: Our frontal lobe has no predecessor of size or complexity. And it fits no survival need.

dhw: All mammals have frontal lobes. Those of our ancestors would have functioned for survival. As sapiens’ activities expanded, the frontal lobe would also have expanded in order to respond to the new requirements. Expansion and enhanced complexity do not equal “de novo” creation.

Our very large and complex frontal lobes are a giant jump from ape brains>

DAVID: Sapiens activities expanded because they had big brains to use. Ours is 300,000 years old and when did we use it fully? In the past 10,000 years.

dhw: I don’t know how many times you want to repeat this discussion! The question is how our brains evolved. You have agreed over and over again that early sapiens used their big brains almost exclusively for survival (I say “almost”, because some of our ancestors are known to have produced art, decorations, rituals etc.) Your figures would be 290,000 years for survival. When the cultural “explosion” began, our big brains did not expand! They complexified. The original additional cells would not have simply hung around doing absolutely nothing for 290,000 years, but simply being passed on through thousands of generations! They were used for survival and then, according to you, for the last 10,000 years all new requirements have been met by complexification of existing cells, which has been so efficient that some of the existing cells were no longer needed (hence shrinkage). By insisting that the big brain was initially used only for survival, you have agreed that survivability was what drove the evolution of our brain, as per Darwin.

No agreement. Our 300,000-year-old brains were much too large for just survival needs when that brain appeared. It is just like a 1,000hp engine plugged into your Volkswagen