Ask Marc Hauser discussion

Morality can also be based on the urge to nurture your genetic legacy. Oxytocin is released in the brain of mammals and affects trust in humans, while its sister chemical vasopressin has very strong effects on the creation of out-groups and violence against "the other". Partiality is a natural consequence of preferentially taking care of those closest to you.

it is interesting that you focus on partiality, as many theories of morality start by asking how you can be impartial with justice (e.g., rawls). what we ought to do is a different issue, right?