Human evolution; savannah theory fading (Introduction)

by dhw, Friday, August 19, 2022, 08:37 (610 days ago) @ David Turell

Brain expansion

DAVID: You can assume that possibility as pure unsubstantiated theory.

dhw: Nobody knows the truth, which is why we have different theories. However, since the hippocampus apparently has the autonomous ability to enlarge itself, we have evidence of brain cells being able to add autonomously to their numbers, and so the possibility that they were able to do so generally in the past is not entirely unsubstantiated. We also know that for unknown reasons expansion was made unnecessary by means of enhanced complexification, and so - sticking to theism – one might say that your God’s creation of such an autonomous expansion mechanism is at least as feasible as the theory that he kept on performing operations on sleeping hominins and homos in order to give them their new cells.

DAVID: Why is one of God's actions feasible (complexification) and brain enlargement not? Sticking to confused attempts at theism!!!

That is the question I keep asking you! My theistic proposal is that he gave cells the autonomous abilities to complexify and to multiply. You agree to the first, and reject the second! Why?

Prehistoric brains and pelvises

dhw: My answer to what you called the “pelvic problem” was that the cell communities would have adjusted themselves to accommodate the new sized skull, but no doubt there would initially have been a lot of deaths during childbirth. You pooh-poohed this possibility because God would have arranged it “so new heads fit into new sized brains all at once without all those messy deaths you prescribe”? Do you now accept the possibility that there would have been a lot of deaths during childbirth as a result of the new sized skull?

DAVID: My kind God provides for all required changes as He designs for future use.

dhw: But do you now accept the possibility that there would have been a lot of deaths in childbirth, as I proposed above?

DAVID: No. But more than ours now, yes.

So we return to my solution to the “pelvic problem”. It would have taken time for the relevant cell communities to adjust to the new sized baby skull, and no doubt this would have caused a lot of deaths in childbirth. Your objection is no longer that your God stepped in to ensure that there were no messy deaths, but God stepped in to ensure that there were fewer deaths than “a lot” of deaths.

Hemispherectomy

DAVID: He gave the brain the abilities we see. No stepping in.

dhw: Thank you for confirming my proposal that if God exists, he would have given cells the autonomous ability to change themselves in order to meet new requirements.

DAVID: All He gave the neurons is the ability to arrange new networks of connections in complexification.

dhw: That is all they need now, since expansion has ceased and complexification has taken over. But I’m happy with your conclusion, as you agree that brain cells are capable of changing themselves autonomously in order to meet new requirements. If brain cells can do this in the present, and we know for a fact that other cells can also make the minor changes necessary for adaptation, there is no reason to assume that other cell communities did not have the same autonomous capabilities in the past, when full speciation took place (as opposed to varieties, which we also call species). The current period of evolutionary stasis is very short compared to those of the past, and who knows what new species might be formed by the same autonomous mechanisms if (when?) our planet – or parts of it - undergoes radical changes? It is pleasing to see you gradually coming round to the fact that your God could and did give a degree of autonomous, creative intelligence to cell communities.

DAVID: Not evolutionary stasis. We are its endpoint under God's designs.

I’m pleased to see that you have no objections to my argument that past cells might have had the same autonomous abilities as present cells to make the changes needed to meet new requirements. Whether evolution has now finished is a question none of us can answer – unless you happen to have a reliable crystal ball to observe Planet Earth as it will be in, say, a billion years’ time.