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

by dhw, Monday, July 15, 2024, 14:27 (129 days ago) @ David Turell

Evolution of the brain

dhw: Do you believe {...] that the planarian brain may have been the ancestor of the vertebrate brain?

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

dhw: 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.

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

Of course it is. All species are a giant jump from the first cells with which life began. And in between you have innumerable stages of development through 3.8 thousand million years in a process known as evolution.

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.

DAVID: So, bipedalism demanded that the brain must appear?

Not “appear”! The brain already existed. But the new way of life would have demanded changes to the existing brain.

DAVID: Did walking upright demand more survivability in brain capacity? Your just-so's raise more questions than answers.

Your question makes no sense. The new environment required new responses from brain and body if they were to survive, and these required increased brain capacity Bipedalism improved chances of survival. Why do you think your God made all the changes if they didn’t do the same? Increased brain capacity is a fact, whether your God did it or the cells did it! You just can’t believe that the cells did it in response to new conditions. You insist that your God had to look into his crystal ball and operate on our ancestors before they embarked on their new way of life.

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.

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

Stop obfuscating. “Mainly unused” is a massive distortion, as I explained as follows yesterday:

dhw: 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 […] 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,

DAVID: Our 300,000-year-old brains were much too large for just survival needs when that brain appeared.

For 290,000 years all the cells were used for survival. They were not just hanging around. When new conditions/ideas/discoveries triggered the cultural explosion, the existing cells complexified, presumably because further expansion would have caused problems for the rest of the human anatomy.

dhw: There is no chance involved if cells have the autonomous ability (perhaps God-given) to change 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?

DAVID: Thank you for admitting the possibility of God.

After 16 years you still didn’t know that agnosticism, unlike atheism, allows for the possibility of God! Now please explain what is wrong with the above.

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.

DAVID: Our very large and complex frontal lobes are a giant jump from ape brains.

That does not mean that our large and complex frontal lobes were created “de novo” by your God. Even in your theory, you have your God operating on existing brains.

The brain: a curious area found

DAVID: I think these views about human curiosity are overblown. All animals are very curious, but our very advanced consciousness enhances our curiosity.

A slightly surprising comment in view of your constant emphasis on the giant jump. But I agree completely that our fellow animals are very curious, and indeed have many other attributes in common with ours, which is why we should treat them with more respect..