Musings: Homo Evolitus

How should evolution and purposeful evolution be thought of in today's human world? We are not under the same evolutionary pressures as when we developed, but we also will not evolve at any reasonable speed (even for evolutionary change), because of our ability to help people live, and even reproduce, who would not have been able to before. We have eradicated so many diseases, that the only ones left are the kind that are very good at adapting, or allow reproduction before becoming fatal (if they ever get fatal). Many health problems (which I personally hesitate to call diseases, by my own definitions at least) actually result from what were historically adaptations. Should we then begin to change ourselves? Not just behaviorally, but at the genetic level? Homo Evolitus. And if we should, how do we tell if a trait has any benefit today? Ex. in Generosity, the 'happiness gene.' We know why the pattern of normal anxiety/stress and occasional peaks of happiness/ecstasy were useful historically, but are they still necessary today? And how can we tell without trying (and causing some humans, or at least animals, to take genetic risks?