IMHO, as I under stand it, in the animal kingdom any generic variations are ostracized and are either killed or don't usually get to mate. All of the animal shows I see on TV talk about this. A white wolf has problems. Even in humans we see this. Case in point, what if, and this is a big if, Down Syndrome is just a part of evolution. Abortion or sterilization is the norm for these special people. I don't believe basic animal/human instincts would allow evolution.
Good points. "Natural Selection is basically an agency of stasis and not change, and that is a major problem for evolutionists. Natural selection weeds out anything an iota to the left or right of the norm for a given species as you note. In the case of humans, abortion and sterilization might be the solution to such cases in fairly recent times; prior to recent times the solution was probably witchcraft trials.