Brain expansion (Evolution)

by dhw, Friday, June 19, 2020, 10:20 (1400 days ago) @ David Turell

DAVID: Only you think the brain can enlarge itself. All it can do from the evidence is complexify itself and shrink. How did your cell committees know to overly enlarge the sapiens brain so it could complexify?

My response is below, but I should have added that you have yourself stated that the pre-sapiens brain must also have complexified before expanding. And why on earth would the excessive enlargement have been necessary for complexification, if complexification was already taking place?

dhw: Am I really alone? The only alternative to the brain enlarging itself is your God preprogramming and/or dabbling the expansion, and not everybody believes in God. There are various theories (random mutations, diet, discovery of fire) – ask any atheist. The evidence does indeed show that the brain can complexify itself, and so it is not unreasonable to propose that the same autonomous mechanism also engineered expansion.

DAVID: A false analogy. Complexification comes from specific developments of use and is guided to change by the specific quality of that new usage, i.e., memorizing, repeated new muscular coordinated motions, developing new concepts, etc. In expansion what guides which areas are to enlarged as required for new circumstances and invented new uses? This requires foresight of what is intended. How would an autonomous mechanism know what to create? I see intentionality and you are still back at chance a la' Darwin.

You have involuntarily confirmed the "analogy". Expansion would have come from specific “developments of use”, i.e. developing new concepts, in the sense of implementing the new concepts invented by your dualist’s soul (or the thinking sections of the materialist’s brain). The areas which expanded would have been those areas that now complexify in implementing new concepts – or more accurately, in meeting new requirements. The autonomous mechanism which now responds to the demands of your dualist’s soul by complexifying would also have responded to the soul of our ancestors, but would have reinforced itself if its existing capacity was unable to cope with a particular new requirement. There is absolutely no chance involved. Nor is there any “foresight of what is intended”. The brain RESPONDS to the requirements of the soul; it does not anticipate them!

dhw: Your agreement that the brain RESPONDS to the new demands made by the dualist’s soul (as opposed to being changed in advance of new demands) is the breakthrough in our discussions.

DAVID: False assumption. My point is the overly large brain has a mechanism to adapt to new use, and then shrink as a result. What enlarged the brain primarily is at all explained by new complexification.

You wrote: “Briefly it gave the bigger brain much more flexibility of response to the soul's new demands.” How is my “assumption” false? Shrinkage, we have agreed ad nauseam, was due to the efficiency of complexification. How does that come to mean that the brain changes in advance of new requirements?

dhw: you still haven’t explained why you think your God made the sapiens brain bigger than necessary.

DAVID: I have. It allows for new usages and complexification for brain efficiency as it shrinks. It also introduces the reduction in energy required, since the brain uses so much energy.

But shrinkage did not allow for new uses! The brain shrank BECAUSE complexification was so efficient. If your God’s object in making the brain bigger than necessary was to save energy by shrinking it, why did he make it bigger than necessary in the first place?

dhw: I am suggesting that for a period of time, there would have been lots of casualties until the big pelvis WAS "simultaneous" with the big baby head! That is why I asked you whether you thought the switch to large pelvises happened overnight, and if not, how long you thought it might have taken. You still haven’t answered.

DAVID: Do you have any idea how long your weird catch-up theory would take? Both attempting dead mothers and dead babies and nothing else? Much easier to accept the theory that it all occurred through simultaneous design by God, the designer.

So you do think the switch to large pelvises happened overnight. A group of homos woke up one morning and found that their brains and skulls and pelvises had suddenly got bigger. I’m afraid I don’t find that “much easier to accept” than the theory that there was a period of transition. But no, I don’t know how long it would have taken. It’s a shame that we don’t have a continuous record of fossils to cover the hundreds of thousands of years between smaller and larger skulls.