Introducing the brain: general (Introduction)

by David Turell , Sunday, February 27, 2022, 15:56 (1000 days ago) @ dhw

DAVID: Our brain has very limited ability to produce new neurons. I think God made all prior hominin/homo brains in the same form.

dhw: The fact that we generally do not produce new neurons can be attributed to the fact that complexification has taken over from production of new cells. We don’t know why, though at least I’m sure you will agree that our brain could hardly go on expanding indefinitely without dire repercussions on the rest of our anatomy. Imagine an elephant-sized head being carried around on your body. The time had to come when expansion would cease.

dhw: You have not responded to this explanation of why the brain ceased to expand, and you have not told us your own theory either.

Answered previously. Our current bodies could easily handle 200cc of more brain consistent with the last enlargement. My theory is that we are the endpoint of evolution. And the elephant skull is a debate trick known as taking an idea to an illogical extreme

dhw: The only difference between us is that you insist they had the extra cells BEFORE they needed them, whereas I propose that the additions were made in response to new requirements. And you still haven’t explained why your God could not have given them the same autonomy for expansion as for complexification.

DAVID: Answered many times. Our frontal cortex has a very different complex design involving specialized pyramidal neurons in five distinct layers, like nothing seen in apes/chimps.

dhw: And how does that come to mean that your God, who apparently gave our brain cells the autonomous ability to complexify, could not possibly have given the same cells the ability to add to their numbers?

Adding numbers of new neurons requires new design like our current design. God does His own designing. Your confusion about complexification continues. It is simply neurons reorganizing their dendritic connections to handle new work.

DAVID: Requires a designing mind. Neurons carry our thoughts, but can't design new network arrangements. Complexification simply means the ability of existing neurons to make new dendritic connections in existing circuits as necessary.

dhw: Neurons are able to make new connections but they are not able to make new network arrangements. I’m baffled.

Yes! You are confused. Existing neurons always can change connecting dendrites to make new complex arrangements between existing neurons. But our frontal pyramidal neuron arrangement is pure design, most likely new to the past brain designs.