adaptation based on behavior
I think that one of the criteria for evolution is technological development. Yes, there may be conditions that science is able to cure for those that may not be able to survive and reproduce in an enviornment with no medical science. But how have humans arrived at the top of the food chain?
It's our ability to pass on what we've learned in our generation and pass it on (through the ability to record information, have a common language that can be learned to access the information acquired by ancestors, whether the media be animal skins, rocks, paper, or computers.
So, because of our ability to modify our environment to ensure our survival, the criteria for natural selection changes. We still live as tribes (i.e. political boundaries). We are still hunters and gatherers -- we are successful because we've become more efficient at it.
However, the next phase is about to occur: we WILL run out of resources because we are able to save so many and they are able to procreate. This is why there is exponential global population growth. We remain hunters and gatherers but we need to seek out new terrains to ensure survival. Almost every terrain is occupied and in a couple of hundred years, we will deplete oursevles and there will be no way for the earth to sustain the bio load.
We come to a fork in the road: do we turn back now or do we march forward? To say that we should stop advancing medical science is backwards. We have the ability to change our environments to survive -- we cannot change from that -- to turn our backs on it and to say that we should live au-naturel and let those who cannot survive be eliminated from the survival game is to say that we ought to step backwards and go back to letting our environment control us when we have gone forward and grown beyond this. We cannot go back. We need to be stronger by breaking biological barriers that prevent us from going to new terrains. One of the factors contributing to the success of homo sapiens is that we are able to modify our environment to suit our purposes (of survival). This is the ONLY way it can be if we are to continue as a species. If we reduce our population numbers, it means that we'll need to enforce a quota on birth rate (there will be civil unrest because people cannot exercise their birthright to procreate).
We need to learn to terraform other planets to make them habitable. The earth is finite. An asteroid could come along and wipe everything off the face of the planet. So, staying here and enforcing a birth rate and renewing our resources will not ensure our survival. We need to socialize and have more brains working on more pressing problems (like how to make another planet habitable, how to detect and avoid large, planet-colliding objects). We can be great in numbers but success (in terms of our evolution) is a result of everyone working together as a tribe. Sounds corny but I can't see any other way for humans to progress any further.
Given current conditions right now, the bio capacity is nearing a point where it is possible, in a few centuries, for the earth to be overloaded. Either we let nature optimize our numbers (through plagues, lack of resources, lack of space, aggression due to overcrowding) or we can increase the amount of space and accessibility to resources to accommodate our growing numbers.
This problem will not go away over time and we still have enough resources to dedicate towards space exploration and finding new worlds to make homes in the future. I think that we might be at a point in civilization development where our numbers, living conditions, availability of resources, etc. facilitate a climb on Darwin's ladder. I suspect that the universe seems empty because very few species are able to make it of their planets, even though a countless species of anything and everything have occured, because such conditions exist once in an eon and (I can imagine) -- and even though the optimal conditions for the ability for space travel and colonizing of other worlds exists (in terms of resources), the species must also choose to work for the common good of giving descendents other homes in the stars. It is so so so possible ... we may even see it start in our lifetimes (because social and technological development undergoes an exponential ripple effect, too). It is almost within our grasp. So close, yet still so far.