Human evolution; savannah theory fading (Introduction)

by dhw, Saturday, August 06, 2022, 13:36 (838 days ago) @ David Turell

Brain expansion

DAVID: There are not enough fossils to answer all question, but brain shrinkage is accumpianed without skull case shrinkage.

dhw: Correct. So what makes you think that habilis and erectus began with “excess capacities”, as opposed to their having acquired new cells to meet new requirements when their existing capacity for complexification had been exhausted?

DAVID: Don't forget evolution is a process is which new processes build on earlier ones. Don't you think our brain is built from previous functioning brains, so why can't complexification be previously present?

You are repeating what I keep telling you! Previous brains complexified until their capacity for complexification could not cope with new requirements, and so they expanded. Ours followed the same process, but then it stopped expanding and complexification took over almost completely.

DAVID: I agree with your description of events but reject your intelligent cell theory.

dhw: So long as you agree with the theory that new cells were acquired when new conditions etc. demanded an increase in capacity, we can leave it open as to the nature of the mechanism. My objection is to your theory that new “excess” cells were acquired when they were not needed, purely in anticipation of future requirements that did not yet exist.

DAVID: A designer would logically design a brain for free usage which would implies shrinkage could occur as brain complexifies.

But past brains did not shrink, which implies that their powers of complexification had reached a limit, and so new cells were needed to cope with new requirements. Only in our case did the brain stop expanding.

dhw: […] you have not yet given us your own theory as to why our brain stopped expanding and reverted to enhanced complexification instead. Please tell us.

DAVID: You constantly fail to think as a designer would. God made our brain oversized so we could develop its use as we willed. Free will!!! It was so complete in its capacities further enlargement was never necessary. I view us as a finished endopint.

Why “oversized”? This is your theory that your God gave us “excess” cells, but a) they could hardly have been excessive if they served the purpose of giving us free will, and b) you have already agreed that habilis and erectus would also have had free will, i.e. WITHOUT those cells! But I can accept the logic that enhanced complexification made further expansion unnecessary, since that is clearly what happened. The question then is why and how cells became able to enhance their ability to complexify. Chicken and egg: were they forced to do so because further expansion would have presented problems, or did they do so spontaneously, thereby rendering expansion unnecessary? If your God intervened, as you believe, whichever answer you give will refute your claim that the extra cells were excessive, and one can only ask why he bothered with all the preceding stages of brain development if all he ever wanted was the brain we now have. But as you have told us repeatedly, you can’t find any reason for this, and it makes sense “only to God”. What WOULD explain the many stages is that your God gave cells the ability to design their own improvements - but you have closed your mind to this possibility,

Human evolution; new study says our brain did not shrink
QUOTE: "Multiple hypotheses on causes of reduction in modern human brain size need to be reassessed if human brains haven't actually changed in size since the arrival of our species."

DAVID: if true, this changes the whole tone of our discussion about modern humans. It means complexification occurs without shrinkage.

It makes no difference at all to the above arguments, but simply removes one area of discussion. We still have to explain why our brain stopped expanding.