Op5, I want to reply to your thread here but I'm not sure exactly what you are saying or asking. Sooo I'll just write what I think!
I think the thing a lot of people don't know about evolution is that when chromosomes split to form gametes, and re-unite with the other parent's to form a zygote, the combination possibilities for each one are in the trillions. It's not like one day we wake up and bam, we have thumbs... we are the results of a countless number of possibilities. Once in awhile a weird combination happens between the two gametes, and something weird shows up - brachydatyly, or something. When DNA forms, a variation in a single base can form a life threatening disease - sickle cell anemia is a real common one. Some variations make us more or less able to reproduce (or likely to reproduce) and these things cause certain variations to be passed on... obviously if they are more in favor of us reproducing, those variations will become more pronounced within the population... and will continue to separate and reconnect with other variations ad nauseum. The problem that I feel now exists is that many of those things that before would have stopped a "bad" variation from being passed on, we have found ways to allow that person to live and reproduce. Thus there are a lot more "bad" or "counterproductive" genes floating around today than there were before (I say it in this way because I'm still dazed from a horrible night of non-sleep and I can't think of a better way to describe it.. sorry). Things which would have been sorted out by natural selection in the past. Now it seems that natural selection AND technology (and society) have a big say in gene pools, rather than just the former... so evolution today and from now on will always be different than it was in the past. That's something I think about a lot.
I often wonder where the variations come from, however. I mean, it's easy to look at something like a plant and see how you can have a homozygous "pure line" without variation - but when you get into people, it's a whole new ball game. I know that a tiny, tiny variation in one single base in the formation of DNA can have a huge consequence - but something so complex as the human body, everything works perfectly in tune (most of the time) - was there ever a time when any organism did not have any variations? I mean, if that were the case, do you think it might have meant we wouldn't be here? Is the purpose of DNA to "mess up" once in awhile so that we
have variations?
