Mutations, bad not good (Introduction)

by dhw, Sunday, July 17, 2011, 22:43 (4878 days ago) @ Balance_Maintained

Tony and I have finally agreed on the comparative likelihood of the evolutionary process, as well as on a list of problems relating to the theory (innovations, time scales, gradualism and NS as a creative force). To this list, Tony has added the problem of speciation.-TONY: According to the earlier discussion, speciation is defined by the two species not being able to breed. Yet this article provides incontrovertible proof that Neanderthals, supposedly a different species, did breed with modern humans. So are they a different species, or not?-I don't know how familiar you are with Darwin's Origin, but he has some revealing things to say on the definition of "species". Here are a few quotes from Chapter II:-"No one definition has as yet satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species."- "Certainly no clear line of demarcation has as yet been drawn between species and sub-species [...] or, again, between sub-species and well-marked varieties, or between lesser varieties and individual differences."-"If a variety were to flourish so as to exceed in numbers the parent species, it would then rank as the species, and the species as the variety; or it might come to supplant and exterminate the parent species; or both might co-exist, and both rank as an independent species." (Interesting in the context of the Neanderthals.)-This is indeed another problem that has still not been solved, though it doesn't affect the discussion on how the mechanisms of evolution actually work.-DAVID: Since there are no fossil series that show Darwin's tiny gradual steps, I agree that PE is the main mechanism, whatever that means. -I don't see PE as a mechanism at all, but simply a historical description. There are long periods of equilibrium in which species remain relatively stable, and these are punctuated by bursts of activity, with extinctions, innovations etc. These bursts may be associated with major events affecting the environment. Tony questions "how fast these changes are actually able to happen" and wonders why we have not witnessed more of them, "particularly after the drastic changes man has made to the environment". Even the Cambrian Explosion took millions of years (though different sources give wildly varying figures of how many millions). How fast is "fast"? However, if there is a sudden event like, say, a massive eruption or a collision with a meteorite, I would have thought changes would be extremely rapid. Adaptation would certainly need to be swift, but adaptation need not lead to innovations and new species.
 
DAVID: In medicine, if we didn't understand a process, we gave it a name and everyone felt better.-A wonderful revelation! But actually it's a very serious point. By naming things, we give them authenticity, authority, and eventually perhaps even familiarity. Think of "random mutations", "dark energy", "multiverse", "God".