I always wondered why the primitive legs of the coleocanth and lungfish evolved. As we all know, various stages of the eye are more useful than the stage before… but what point was a stronger legbone when fish could just swim?
It seems, for fish in shallow rivers, the ability to hold their head up was rather useful.
Interesting, and a useful point I never really considered before.
Admittedly, I put it in Great Debates because that’s where evolution related dialogues tend to wind up.
On the other hand, are there any other holes in the great web of evolution that starts with a single cell in the mud? Where are the parts where, when we look back to the point from where we came from, we say, “Hm. Wonder why that happened?”
Well, I’m far from an evolutionary expert, but I thought that mutations just happen with no real point. If they are neutral from a selection perspective or even only slightly negative sometimes they just continue on, dormant so to speak, neither helping nor hindering…until conditions arrise that make them useful. So, stronger ‘legbones’ could have simply been a mutation with no point at all, one that neither helped nor hindered the fish in question…until circumstances changed and certain fish began to become amphibians.
Yeah, the way teachers make evolution sound sometimes really bothers me. In all my biology classes through about freshman year of high school, we were taught that evolution happened for a purpose–like “the giraffe evolved the long neck so he could watch out for predators.” As if one day the giraffe just up and decided that he needed a larger neck. So he evolved one. :rolleyes:
Mutation is totally random and genetic lines that are unhelpful or detrimental to the species are phased out by nature.
Xtisme, that’s correct, completely. However, to be selected for, the stronger bones in the legs must have granted some evolutionary advantage, even before the feet developed from fins. I was simplifying, slightly.
Not necessarily. The mutation could have simply been neutral…i.e. it neither caused a detriment nor did it confer an initial advantage. In that case it could very well have been passed on until it DID confer an eventual advantage when the situation changed. There are plenty of examples of mutations or differences that confer no advantage being propagated in any given species but continue to be propagated because they don’t effect an individuals ability to pass on its genes. I’m simplifying greatly.