Introducing the brain: general (Introduction)

by dhw, Monday, February 28, 2022, 11:15 (787 days ago) @ David Turell

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.

DAVID: 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

How much more could they handle? The process of expansion had to stop at some time. Your theory that we are the “endpoint”, by which you apparently mean the one and only purpose, does not explain why our brains have stopped expanding. Erectus was still erectus, even though his brain continued to expand.

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?

DAVID: 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.

The new neurons are added for the same reason as complexification: to handle new work. And I suggest that this is what species do generally: they reorganize themselves in order to handle new conditions. And if your God creates the mechanism for autonomous complexification, I continue to ask why you think he couldn’t have done the same for enlargement, which fulfils the same purpose as complexification.

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.

DAVID: 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.

You agree that our neurons make complex new arrangements, but apparently they are incapable of making a very complex new arrangement. God had to operate. But hey, you also had him operating to expand all the brains of all the hominins and homos before us. And you know as well as I do that other mammals have a frontal cortex, so did your God operate to create theirs as well as ours? And let’s not forget that you also have him operating on whale legs and blow holes, and giving courses to weaverbirds...No, I’m not being “facetious”. You've confirmed that this is what you believe. I’m merely suggesting that if your God was able to give autonomy to our neurons to design their own connections and form complex new arrangements, it is not beyond the bounds of possibility that he could have given autonomy to other cells/cell communities as well to enable them to do their own designing.