I’m going to go through the topic and give you my reactions to each section of this thread as I see it, starting with the title.
Humans Disrupt Evolution: No. To say that is to somehow hold us as being separate from the environment (because the process of evolution is one by which a population becomes more likely to reproduce over time within its environment). For the populations that we are changing, we are a part of their environment. So we are not ‘disrupting’ evolution, we are simply changing the evolutionary tract of a population.
@GarGleM0nster: Now your question has become a bit more apparent to me. It refers to the evolution of our own species. Yes, I think that medical advances will slow our genetic evolution… simply because we are increasing the reproductive ability of those who are less evolutionarily fit. But really, I think that’s a bad way to say it. Because really, we’re making them more evolutionarily fit. So, you’re right in that genetic variability should decrease in many ways… but our of the typical definition of evolutionary fitness – an organism’s fecundity - means that we are not decreasing the rate of evolution (or the movement towards greater fecundity within a population in a given environment), but rather we are cooperatively evolving (though not on the genetic level). Those are my initial thoughts on the question, anyway. I have to admit it is much more complex than I thought it would be simply based on the title of the article.
@sanddbox: No, evolution has very little to do with any individual surviving: it’s about populations surviving. Evolutionary fitness is determined by an organism’s ability to reproduce. A given fish may only survive for a few weeks, but if it makes thousands of offspring in that time it has a great evolutionary fitness.
@Goatboy: I agree, minus the survival part.
@r-ID: Evolution is more than mutations. This question pertains far more to natural selection than mutations.
@runninggee57: A couple hundred year sample can’t realistically constitute an argument for the evolution of decreased brain size (especially when that timespan will only realistically cover a few generations). But you’re right, it’s a very interesting and amazing fact that the rate of genetic mutation in humans has increase substantially over the past 10,000 or so years. Some biologists have suggested that we have “evolved to evolve”.
@Goatboy: But an ape that knows how to lure a fox with bait wins out every time, because he will be more well-nourished, and thus able to fight better, and thus able to attain a high status in the group, and thus able to mate with all the females (this topic is perfect for a Philosophy/Biology Major/Anthropology Minor to discuss!)
I also agree with you that things don’t evolve due to lack of use. Thus, we get vestigial organs.
@Yamman13: Totally interesting discussion. At this point survivability curves become important: just how many of the people in the developing countries are living to sexual maturity and actually reproducing? I don’t know the answer to this, but I would bet that it is not very much. I would disagree that that gets in the way of natural selection, though, because it’s still natural selection occurring – it’s just going in another direction. Also, to say that this is getting in the way of natural selection, you are assuming two things: that people in developing countries are substantially genetically different than those in developed countries and that there is some direction that natural selection should go. The former claim is almost certainly incorrect. As for the latter claim, without some sort of higher power or ultimate universal goal, I don’t see how this can really be the case. So, even if homo sapiens were evolving in a “direction” that you perceive to be unfavorable, that is a very subjective judgement.
@Vulpine: I agree… though I think that even if it were a “giant, controlled eugenics experiment” natural selection would still occur, because there is still an environment (the people choosing) which is determining the gene makeup of a population.
@Yamman13: I like your post, and I think you understand the distinction but I want to make sure everyone does. There is a big difference between ‘success’ as we generally refer to it and ‘evolutionary success’. Stephen Hawking has been marvelously successful, but as far as I know his currently evolutionary fitness value is 0 (assuming he doesn’t have kids). What I think this shows is that the success exhibited in human populations isn’t necessarily genetic.
@r-ID: Careful. Generally, biologists consider all living organisms to be equally evolved (they are all successful results of a giant evolutionary chain!) That same cockroach would perform terribly in the dolphin’s habitat one hundred feet below the ocean, or in a tiger’s battle with a lion. Also, I think you’ve presented us with a false dilemma: there are a few more options than those you have presented us with.
@acantho: I agree, it is in a way correct to say that evolution has stopped for humans. But only in a way. I don’t think that it is correct in the way biologists usually use the term evolve.
@chimchamcaru: Uh. Maybe to survive. But not to produce. That kinda person would be uuugggglly. I’m not going to let them have my babies.
These are my thoughts on the issue, and pretty much cover what I think of the answer to the question at this point. I am very open to having my opinion changed, so I look forward to your responses. I realize this post is very old, so some of the people whom I may have addressed may not be around. But I thought this would be the most holistic way to present my view and cover all my bases.