As humanity spread throughout space, it encountered environments which were increasingly more hostile towards our form and function. On occasion, we may have been able to adjust these environments to suit our frail needs, but as technology continued to advance, we soon discovered that it was far easier to simply adjust humanity to suit the environment. Thus, via genetic modification, new “genotypes” of humans began to rise and spread throughout the systems.
Humanity found that we required a boost in evolution in order to survive. We decided that we could not wait around for evolution, we thus took our mutations into our own, hopefully not incapable, hands.