Freddy:
See above. That’s how evolution works. You must have known that…
If the environment didn’t change for billions of years, then nothing would change.
Change and Isolation — New England Complex Systems Institute
Okaaay, let me try another approach.
Let me know which point# you don’t agree with:
For a limb to function as a limb;
- The circulatory system has to be functioning
- The nervous system has to be functioning
- The skeletal system has to be ok
- The muscular system has to be ok
- A change in one of the above renders the animal sick and thus the physiology of the limb is less functional.
- For the limb to continue functioning under changes, all the systems must have a corresponding change.Example, the lengthening or shortening of skeletal tissues must be followed by physical changes in the blood supply, nerve endings, muscular connection e.t.c
Aha. Got you at 5.
The changes are incremental. I hope you don’t think that we go from fin-which-is-great-for-swimming-and-not-walking to fin-which-is-great-for-both.
Let’s say that my son, because of a genetic glitch, has slightly bigger leg muscles than me. And any of other of kids I might have. Now all things being equal, that would be a disadvantage because it makes him larger and therefore he requires a little more food to keep going. If food is hard to come by, you generally get people who are wiry rather than bulky.
But…if the environment changes from us picking berries (big leg muscles useless) to chasing down game (big leg muscles usefull) then he’s ahead of the game. So he might survive when one of his kin didn’t. So
his kids will tend to have the physical attributes that will help *them survive better.
Rinse and repeat.
So a fish that has a fin that is just a tiny bit stronger than other fish
if that’s an advantage will survive - all other things being equal - better than one which doesn’t. IF the environment requires it.
So saying that any changes are detrimental is nonsensical
unless you consider the environment. But in any case, just because my son might have slightly larger leg muscles wouldn’t ‘render the animal sick’ in any case.
Most changes
are detrimental so
eventually they are removed from the lineage. You don’t see them. They’re gone. But those that
aren’t detrimental continue on for quite some time. Until external changes (like the environment) prompt another direction.
If the environment in which the ‘walking fish’ lived changed so that the extra muscles and blood supply wasn’t required…became a negative characteristic rather than a positive one, then they’d go extinct.