Introducing the brain: general (Introduction)

by David Turell , Monday, February 28, 2022, 18:58 (997 days ago) @ dhw

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

dhw: 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.

Which should mean to you our small expansion from Erectus to Sapiens, which you tout, contained more than just more neurons but a major new complexity, the five layer pyramidal neuron arrangement.

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.

dhw: 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.

Our brain has no real facility for enlargement. Your argument fails in that we see our current frontal lobe arrangement as a very complex design that neurons alone could not create. Our living predecessors don't show any of it.

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.

dhw: 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.

Worth repeating: "Our brain has no real facility for enlargement. Your argument fails in that we see our current frontal lobe arrangement as a very complex design that neurons alone could not create. Our living predecessors don't show any of it." Complexification is existing neurons adding dendritic connections, nothing more, and cannot imply existing neurons can design for future use.