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

by dhw, Tuesday, July 16, 2024, 11:19 (128 days ago) @ David Turell

Why is our brain so big?

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

dhw: 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: Yes, God designed for the future needs.

So he looked into his crystal ball, operated on a group of apes, and then told them to go walkies. I get it. I just think that common sense plus every known change throughout the history of life, right through to the present, suggest that bodies and brains make changes IN RESPONSE to new conditions and not IN ANTICIPATION of conditions that do not yet exist.

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

dhw: 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.

No response.

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.

dhw: 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.

No response.

DAVID: In your just-so brain how much is the speech area used, as an example? The music area? The working acting area for memorizing? The typing area? The early brain neurons are alive and firing, but not at our current level. The brain was obviously very over-sized for the survival requirements of shelter, food, and protection.

The early cells were alive and firing. They were not superfluous to the needs of the time. Hence the evolution of our brain led to its current size, and the subsequent usages you mention led to complexification, because (I suggest) further expansion would have created problems for the rest of the anatomy. The early cells were able to meet all new demands, and they did not hang around unused for 290,000 years.

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

dhw: 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.

DAVID: Yes, taking Lucy's brain and then enlarging and complexifying it in large steps.

Nothing “de novo”, then. Thank you for agreeing.