Evolution: whale adaptive losses and changes (Evolution)

by David Turell , Friday, September 27, 2019, 22:50 (1882 days ago) @ dhw

QUOTE: “So the creatures of the cetacean stem lineage had to find a way to balance the need for sleep with the restriction of their new aquatic environment. As a result, they have a unique adaptation called ‘unihemispheric sleep’, which “allows one brain hemisphere to sleep while the awake hemisphere coordinates movement for surfacing.”
This adaptation was facilitated by the loss of several genes involved in the production and reception of the sleep hormone melatonin. This helped to “decouple sleep-wake patterns from daytime,” which, argue the researchers, “may have been a precondition to adopt unihemispheric sleep as the exclusive sleep pattern.[/b]” (DAVID’s bold)

DAVID: Interesting complex changes, and one can imagine some of these adaptations while learning to become aquatic, but note my bold. How does a whale learn to sleep with half a brain active while living in the water, without drowning during the process of adaptation? For me God prepared them.

dhw: Nobody knows, but I suggest that, as with every other adaptation, the cells worked out a solution to improve performance or to cope with new conditions. It’s not beyond the scope of reason that initially some whales did drown if they strayed too far away from land, and others swam till they found dry land to sleep on. Loss of melatonin would then be the result of training the body to do without sleep for long periods. But the eventual half and half compromise would be the solution that worked best and hence survived by natural selection. Certainly no more fanciful than your God preprogramming the first cells with the whole history of whale stages, bacteria solutions, monarch butterfly migration, weaverbird nesting etc., all to cover the time he’d decided to wait before pursuing his one and only goal!

Your explanation tells us some just-so stories. Finding dry land does not explain what God must have programmed. How did whales tell melatonin to go away? Same issue: why bother with whales in the first place? Answer, because they are a major part of of the ecosystem of the ocean