Different in degree or kind: Egnor's take; more on gaps (Introduction)

by dhw, Saturday, October 15, 2016, 13:53 (2752 days ago) @ David Turell

DAVID: Look at this article which discusses Tiktaalik:

https://blogs.scientificamerican.com/artful-amoeba/fish-out-of-water-are-actually-prett...

This is a real eye-opener. Thank you. Here again are the quotes you have highlighted:

"..the authors theorize, drying out is the real challenge: specifically, the problems posed by the dessication of gills, which must remain moist for most fish to breathe. Our ancestors, such as the early tetrapod Tiktaalik, seemed to have been pre-adapted to overcome this obstacle because they possessed, in addition to gills, a primitive lung. (David’s bold)

"Without this trait or something like it, the forays of fish onto land seem destined to remain a flirtation. Though free to frolic, they must ultimately remain tethered to the water whence they came." (David’s bold)

David’s comment: In regard to jumping gaps, note the bolds above. The Tiktaalik come with a pre-adaptive primative lung. It looks like a God saltation to me, allowing the ability to breathe on land while real legs are added in a further gap jump. Walking bass in Florida don't have any type of lung. Hypothesized tiny steps are not in the fossil record. Lets work from what we see in that record to derive a theory of evolution.

Here are two more quotes (my bold) that open up new insights, especially since no less than 33 “families” are known to have made the transition from water to land, albeit only briefly in most cases:
“Fish that live in water that is prone to heating also have been known to leave it because warmer water loses oxygen and may become suffocating. In such cases, air may present the better option[.” [/b]
And especially this one:

“Fish that live on the bottom of their body of water seem like they would also be better candidates for land-dwelling, because they already have adaptations that favor life on the ground. [These adaptations include a rounder, less vertically flattened body that makes walking easier and drying out less likely, and sometimes fins that are limb-like already.”

Plus one that you quoted: “Four of the families did have species that spent hours or days out of water: mudskippers, rockskippers, eels, and four-eyed blennies each come from separate families, implying that at least four times, significant amphibious behaviour has evolved on Earth, not including, of course, the crucial fifth instance that resulted in us.”

The reference to pre-adaptation becomes very clear once we realize that there have been so many instances of fish venturing out onto dry land, and being able to cope with the problems of movement and of breathing. Fish that live at the bottom of the sea or lake have fins that are “limb-like already”. We are not even talking of innovations here but of adaptations. I’m not going to downgrade the difficulty of explaining how all of this led to us (i.e. “the fifth instance that resulted in us”) but if the researchers say the transition from water to land “does not seem particularly hard” in the light of these adaptations, I’m not going to argue. We are left with the information that many water-based organisms have made the transition, and crucially the article makes it abundantly clear that the move was made for environmental reasons. Any “pre-adaptations” would have taken place for those same reasons: loss of oxygen, moving along the seabed, habitat alternating between wet and dry, or drying up altogether. The pattern is clear: need gives rise to change. It’s not change in preparation for need. Or do you think all the environmental changes as well as all these different family responses were dabbled or preprogrammed 3.7 billion years ago? Why so many if God only needed one? Ah, but you “don't believe God follows human logic in what He does.”