Human evolution; savannah theory fading (Introduction)

by David Turell , Monday, August 22, 2022, 20:20 (822 days ago) @ dhw

Brain expansion

DAVID: So you finally agree with me. It came fully prepared for future use.

dhw: Of course we agree, since there has been no further increase in the number of cells. But we do not agree on your belief that your God operated on a group of sleeping hominins to insert the final collection of cells for the purpose of meeting requirements that would not exist for the next few thousand years. Once more: my proposal is that the new cells were added (by an autonomous mechanism, which may have been designed by your God – like that of complexification) to meet new requirements at that time. From then on, the capacity for complexification took over from expansion as cells continued to design their responses to new requirements, as they had always done.

Our only disagreeemnt is how the new enlargeed number of neurons arrived in sapeins. I'll stich woth a designer God. But we have agreed the extra cells arrived new and unused in preparation for the future use.

DAVID: Once again, complexification could work in handling new brain uses precisely because it had so many extra new neurons sitting around with little to do at first.

dhw: Complexification had always handled new brain uses until the existing capacity was inadequate to deal with a particular new requirement. And that process of complexification and enlargement would have continued through to ourselves. Extra neurons would not have “sat around with little to do”! They would have performed a specific function. If there was shrinkage, it was because complexification made previously necessary cells redundant; if there was no shrinkage, then all the cells, old and new, were necessary when the extra cells were added, and remained necessary. I don’t know why you think cells would be added simply to sit around until needed. And of course they were also used in the future! That, I suggest, is the basic principle behind all of evolution: changes (in this case extra cells) take place to respond to new current requirements, and if they prove to be useful, they survive for future use.

Lots of palaver about all those extra neurons 315,000 years ago, not used as they are now. Note in the caves there was little complicated for them to do. Certainly not reading, typing, deep concptualizing as we do in our discussions

Cerebellum

DAVID: our large cerebellum, compared to other organisms is finally studied. It arrived 315,000 years ago and performs its duties, and we are now trying to find out how much it does for us.

dhw: Yes, the brain is a community of cell communities, just like the rest of the body, and they work together. And – to get back to the major disagreement which has dogged this discussion – you still haven’t explained why your God, who you agree designed a mechanism for autonomous complexification, could not possibly have designed a mechanism for autonomous enlargement.

Same answer. You want secondhand design. Hands on design is more efficient, without question.

Prehistoric brains and pelvises

DAVID: Your theory is let them die until they figure it out.

dhw: Who “let them die”? I propose that the cells eventually “figured it out”, but a lot of mothers would have died until the new size became the norm. Your theory seems to be that God did his best to figure it out, but although he failed to the extent that some mothers died, there weren’t “a lot”, so my theory must be wrong. As I said, this is getting ridiculous. Shall we drop the subject?

DAVID: God set it up so new-sized infant heads fit into their mother's new-sized pelvises.

dhw: Two days ago, you said there would have been more deaths than in our time, because “obstetricians currently can solve more complications than cave folks back then. God did what he could to accommodate walking and big head birthing all at once.” Are you now saying there were no deaths at all? I suggest we drop this subject.

Total misinterpretation of my statement. All it says is we can solve things now than they couldn't then.

Genetic formation of our pelvis:

dhw: The question is why pelvises, brains and species underwent their changes in the first place. According to you, your God preprogrammed or dabbled them all BEFORE there was any need for the changes. My proposal is that they all took place as a RESPONSE to what were then current needs. Once they proved successful, of course they were then used in the future! (See above.)

DAVID: You have solved the issue of speciation. It is simply adaptation.

dhw: It depends what kind of speciation you mean. I would say that larger brains and pelvises were indeed adaptations. (It is believed that there was interbreeding between different types of homos, and the ability to reproduce is one criterion for “species”). But it is sometimes difficult to draw a precise borderline between adaptation and innovation (e.g. pre-whale legs turning to flippers). However, I keep pointing out that evolutionary changes may be in the form of coping with new conditions (adaptation) and exploiting them (through innovations), and I would say that generally it is the latter that create clear speciation.

While I think God designs all future forms for future use.