From the simplest bacteria to apes, evolution's mechanic is the same: fittest survive and reproduce, weak fail. Thus the specie evolve and gets better in every generation. But humans turned out to be somewhat different from the rest of the biosphere.
We are much more complex than all the other species, even our closest relatives. We changed the rules of the game that is as old as the life itself.
Part of our complexity is our social nature. While the other species are fighting between themselves for survival and for better chances of reproduction, we are, more or less, supporting each other. We found out that as a group, we had, and still have, much better chances of surviving among other species and even among other groups of humans.
Other reason is that we are far beyond mere surviving and reproduction. And evolution is actually just about those two. As society, we support individuals that are great in something, be it art or science of something else we find valuable, but which would not save that individual of blind and harsh powers of the evolution.
illustration by Joel Ormsby
But there is also the other, darker, side in our motivation to help the weaker individual survive. Human society, since its early days, has the need for work power. These humans don't need to be great individuals. They need to drag the stones to the pyramid or work in the field. To do the hard and dirty job. So the weaker were not let to die but "saved". That was the beginning of the slavery.
For the first time in 3.7 billion years of life on Earth, the rules of the game of the evolution were changed.
Not only the strongest and most capable survive. Weak get their pass as well. Not the free pass though, their survival comes with the price tag attached, but they survive.
And, as the society grows, the need for the work force grows too. Society wants them to reproduce too, to make more and more slaves. So they are not only in the gene pool, they are very active there.
illustration by latvian
Things got even more complicated with buddhism, christianity and other ideologies that emphasize compassion and the value of human life. Now we don't support the less fit for survival because of their other values, nor because of their usability, but for no other reason than "just because".
We tricked the evolution, but we still haven't tricked the genetics. We systematically prevent mother nature from doing its job. As a result, we are the specie that rules the planet, despite our vulnerability, our bad adaptations skills and our weakness. We are the specie that continuously degenerate but still grows. And there's no turning back.