This is an interesting question. There comes a point in human evolution where cultural selection takes over from natural selection. Typically this is thought to be when the social structures of human groups hold more importance to the way people live that than the mechanisms of natural selection. Some people have suggested that for humans and their ancestors, cultural selection may have taken over as early as 500 thousand years ago, although I think it may be more like from c. 150 thousand years ago when we start to see evidence in the archaeological record for the creation of symbols and jewellery. So in that sense we have not been governed by natural selection process for quite some time. Modern medicine is certainly having an impact on us, such as an increased ageing population, and I’m not sure anyone is really clear on how humans will continue to evolve in the future. It is perhaps worth noting however that our human ancestors seem to have looked after the sick and injured for as long as perhaps 2 million years, often helping those people survive whilst their injuries heal.