Miscellany (General)

by dhw, Tuesday, May 11, 2021, 14:11 (1082 days ago) @ David Turell

BATS
dhw: You say you believe in common descent, and I’m asking why you think it’s impossible for bats to have descended from an earlier life form.

DAVID: Sudden appearance implies God might have dropped in an addition, as in the Cambrian.

dhw: I know what it suggests. I am asking why you, who believe in common descent, think it’s impossible for bats to have had an ancestor, and why you should take it for granted that every stage of speciation, going back hundreds or even thousands of millions of years, should have left us with a complete fossil record of itself.

DAVID: Incompleteness is a hopeful position after hundreds of years of searching for fossils.

No more hopeful than the belief that there is a God who decided one day not to use existing species as the basis for new species, but to specially design the bat de novo, even though his one and only purpose was to specially design H. sapiens. You see how difficult it is to accept your arguments in the light of your combined beliefs? And I would still ask if you honestly believe it is possible to have a complete fossil record of every life form for the last 3 thousand million years.

Seals
DAVID: Of course there is diversity, which Darwin tells us comes from random mutations

dhw: The article contains no reference to random mutations, so I don’t know why you tried to dismiss it as “typical Darwin think”, or why you objected to the statement that adaptation to new environments helps us to understand diversity.

DAVID: I view it as an empty observation.

Certainly no emptier than your dismissal of it as “typical Darwin think” when it never even mentions the “Darwin think” you objected to (random mutations). And in fact I would say the interaction between adaptation, innovation and the environment is of prime importance to our understanding of evolution.

The obstetric dilemma
DAVID: A total non-answer. How did the pelvic bony cells anticipate the bigger baby head? You just prefer non-thought in considering the obstetric dilemma. 'Respond' requires anticipation.

dhw: My proposal is that the cells did NOT anticipate the bigger head, and “respond” is exactly the opposite of “anticipate”! The process would be that the pelvis finds itself having to cope with a bigger head. Either it expands or it’s goodbye to mother and child. Initially, I have no doubt that the latter would have happened all too frequently. But in some cases the response would have enabled mother and child to live, and those are the cases which would have led eventually to the adapted form of pelvis surviving as the norm. Still not perfect by any means, but adequate for general survival. Do you really imagine that your God stepped in to provide a ready-made new pelvis, and therefore all Lucy-mothers survived?

DAVID: Yes. Your paragraph is wishful thinking. The pelvic required changes had to result from massive coordinated mutations.

Do you really believe that all Lucy-mothers survived childbirth in those early days? That’s what I would call wishful thinking. Yes, the pelvis required major adaptations to accommodate the larger heads, just as the pre-whale required major adaptations to adapt to marine life. But in both cases, I suggest there would have been a clear sequence: new conditions led to appropriate responses. It happens all the time.