The idea is that it is natural to have the weak replaced by the strong and beneficial in the long run. The main problem that I have is that there isn't anyone wise enough to judge which is better. Using that as an excuse to not give aid to people negates one of our most powerful abilities and that is to help out others in our social group. We gain by having a large diverse group of people solving problems. Some of our top scientists are disabled and couldn't survive in the wild so the comparison isn't appropriate to humans. Our goals in life include things beyond just having the best offspring to pass down the best genes. We can contribute in other ways.
We are a higher form of life and helping other humans makes the world a better place to live. The best thing from an evolutionary perspective is to have a very large proportion of the population die and to have everyone else struggle to survive. That wouldn't be an ideal way to spend your life. People often accomplish great things when they aren't forced to constantly think about survival. I am happy for the struggle our ancestors had to go through. They give us the luxury of expanding our minds beyond the daily requirements of gathering food.
There is some truth to social Darwinism. Giving things to people can make them dependent but that isn't really helping them. The problem is that many people don't know the difference between making someone dependent and actually helping them.
