Just a little thought that struck me today: Couldn't it be possible that due to our advanced medicine and promiscuous use of it we're hampering evolution?
I mean, evolution works by letting individuals survive that are better adapted to their surroundings. By rescuing numerous people from their deaths who would otherwise die we do enable them to spread their genes and thus they have (almost) the same chances as healthier individuals of propagating their stage of evolution. Basically we're staying at one point of evolution and encourage stagnation.
This may be beneficial to the individual but possibly not for the whole species itself.
Who knows where we'd be today if it weren't for doctors, medicine and letting people survive who'd otherwise die? Maybe a few million/billion people less on Earth, resistances against epidemics?
Don't get me wrong. I hereby do not encourage euthanasia or similar ideas, it's just a play of thoughts what could be if. As I said, it is beneficial for the individual which seems to be the primary goal for most human beings. Very few choose to sacrifice themselves for the good of a species and I am possibly no exception.
Maybe we overcome this drawback with genetical engineering; maybe ethics stand too much in our way for that. We'll see ... :)