Among these, the authors argue, was a very specific kind of religiosity which developed in all complex societies: the collective worship of gods concerned with morality. Belief in these kinds of gods was selected for, they maintain, because once we developed cities we had to deal with strangers—people who weren’t part of our extended family. By conceiving of a god who demanded moral behaviour towards other believers, people were compelled to cooperate with these strangers, meaning that large, highly cooperative groups could develop. ...If this is even partially correct, then it has a lot of implications.
And it is from here that the authors make the leap that has made SJW blood boil. Drawing on research by Michael Woodley of Menie and his team (see here and here) they argue that conditions of Darwinian selection have now massively weakened, leading to a huge rise in people with damaging mutations. This is evidenced in increasing rates of autism, schizophrenia, homosexuality, sex-dysmorphia, left-handedness, asymmetrical bodies and much else. These are all indicators of mutant genes.
Woodley suggests that weakened Darwinian selection would have led to the spread of “spiteful mutations” of the mind, which would help to destroy the increasingly physically and mentally sick group, even influencing the non-carriers to behave against their genetic interests, as carriers would help undermine the structures through which members learnt adaptive behaviour.
This is exactly what happened in the infamous Mouse Utopia experiment in the late 1960s, where a colony of mice was placed in conditions of zero Darwinian selection and eventually died out.
Humans do have the ability to cooperate with strangers, and no other species does. So presumably this ability evolved, is genetic, and is more prevalent in some groups than others.
Cooperating with strangers is a good feature for building a civilization, but many people seem to cooperate only with their own clan. With genetic diversity, you get many situations where A cooperates with B, but B does not cooperate with A. This seems unstable, unless A is willing to ostracize B.