Human organ evolution (Introduction)

by dhw, Saturday, April 21, 2018, 10:17 (2406 days ago) @ David Turell

DAVID: Deep divers have big spleens:
https://www.the-scientist.com/?articles.view/articleNo/52347/title/Free-Divers-From-Sou...

DAVID’s comment: This is an organ adaptation, not a change in the human species.

Yes indeed, but it confirms a pattern which runs through so many of these threads. Adaptation to the environment causes changes to the body, but we don’t know the extent to which the body can change itself. The divers didn’t tell their spleens to get bigger. Of course it may be that natural selection caused bigger spleens to outlive smaller spleens, but an alternative would be the process already observed elsewhere, i.e. that concentrated usage results in expansion of the organs used. With musicians and taxi drivers it’s parts of the brain, and with the divers it’s the spleen. One can envisage the same process occurring when land animals entered the water, and limbs became fins, or vice versa, with fish evolving legs out of fins. Not proven, of course, but there is a satisfying consistency in this hypothesis, and it still allows for your God as the inventor of the mechanism that makes it all possible.