Where do atheists get their morality from?

[Whateverist]

So evolution made a mistake? It seems to me the more pitiable-looking humans are the ones we're most likely to help--and they have bad genes.

Without intentionality it doesn't make a lot of sense to speak of 'making a mistake". In fact, evolution doesn't do anything at all -intentionally or otherwise- because evolution isn't that kind of 'thing'. Evolution is merely a description of the manner in which living things change over time in response to the way genetic variation and the occasional mutation either improve or worsen the fit between an organism and its environment.