Evolution by group selection is accepted as important in all social animals,
and illustrated by examples. In-group and out-group psychology can be seen in young
infants, it is an old function of the old brain, it favours the in-group and devalues outgroups,
it is related to emotion, symbolism, loyalty, patriotism, honour, pride,
aggression, sacrifice, and war. It is involved in personal identity, sense of self, and
pride of place. It determines many beliefs.
Keywords: Belief, Child psychology, Evolution, In-group psychology, War.
