How Fish Might Have Evolved Hands

[Sven Simonsen]

The problem with proving evolution by a study of evolving generations is a matter of scale. Evolution works with glacial speed over almost astronomical time frames before it gets to the kind of proof that the common sceptical person questioning evolution is asking for. It's almost as bad as demanding experimental proof for the workings of stars. "Why don't you just collect some helium and hydrogen and convince me that that is how it works?"

No one ever saw an electron power a computer. Science works via scrutiny of hypotheses that grow out of a working theory.

Extrapolating on evolution, scientists have made many predictions that turned out to be true and if they didn't found the wrong assumptions not to be that of evolution. If a theory has stood this kind of scrutiny as long as the theory of evolution has, I think we are allowed our exasperated reactions when someone dismissively calls it "just a theory" and then demands their hypothesis get the same recognition. And it better get it now and be taught at schools to boot.

 

[man-man]

Without wishing to get involved in creation vs evolution (seriously guys, that question is so far past settled it's not even fun to argue about any more. Evolution is entirely uncontroversial in every country that doesn't have a big group of religious literalists pretending they have good reasons to disbelieve it).

Just wanted to say that "Remember that the next time you order fish and chips you might be munching on your long lost relative", seems to kinda miss fact that every food item you eat, from beef to broccoli, is an immensely distant cousin. Not just the food either - the trees outside, those weird-lookin' deep sea fish, E.coli... all cousins of each other and of us.

 

[man-man]

Food on land is a powerful motivator to grow the leg and hand.

Food on land is a powerful selective advantage for any mutant fish able to crawl up and eat it. But no matter how motivated they are about it, they're not going to grow legs by pure force of will.

 

[man-man]

Hmmm... I don't really like this experiment. It doesn't really show anything. I mean, even if that hormone WAS what caused fish to grow limbs, what caused the fish to produce the hormone in excess? Maybe it's a small piece to the larger puzzle, but it's a very small piece indeed.

Assuming that fish produce the hormone at all (though I don't know if that's the case), producing an excessive amount of it would be a fairly small step - duplicate the gene that codes for it, break a regulatory mechanism that limits the amount produced, add some sort of promoter to up-regulate it... not too hard.

If they didn't previously have that specific hormone, they may well have had something similar - there's a whole family of "hox" genes that are involved in the development of body structure, and those are old genes, not a new development in fish. It produces some interesting results if you mess around with them in fruit flies - you can quite easily produce scrambled body plans, like extra pairs of wings where the legs should be. Or the same thing in flowers can have them growing petals/stamens in all the wrong places.

 

[Arakasi]

Food on land is a powerful motivator to grow the leg and hand.

Food on land is a powerful selective advantage for any mutant fish able to crawl up and eat it. But no matter how motivated they are about it, they're not going to grow legs by pure force of will.

I am aware of that, growing legs by pure force of will was not the meaning of my rhyme.

 

[Cryo84R]

It's a dangerous path someone walks when they are offended by science and reason, or perceive them to be an attack.

Also, when a person says theory and means hypothesis, a dictionary weeps somewhere.