Taking the example of my asthma... is it the case that ordinarily, the genes which cause my asthma would have dissappeared from my families bloodline, but as it is, it's still here and thriving, and my kids will likely inherit these genes.
And any asthma genes stick around because we have lessened their selective impact. This is biodiversity, which is evolutionary. I can't think of one off the top of my head, but if the environment was to change in a way that would favour asthmatics (hot and humid?), then the human race grows stronger.
I agree with you – our evolutionary bush is allowed to grow more wildly than it might otherwise. It is being tended to by a topiarist of sorts, but his tools have been slightly blunted (perhaps by an acidic secretion).
To keep the metaphor rolling, the topiarist is inevitably going to keep coming back with newer and better tools, and 'select' only the 'fittest' parts of the bush to survive. That'll probably happen when our population stops growing, or if someone decides to do the job of the topiarist themselves.
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