Or some of these customs, traditions and institutions evolved to combat it through unconscious group selection. The tribes/towns/cities/countries/groups that had superior civic norms (superior defined as those norms which promote harmony, prosperity, in-group cooperation, etc) tended to attract immigrants, be capable of dominating geo-politically, etc, and thus those cultural values become dominant through this process of selection.
Also, while I think that explains things to a certain extent, it's just part of the picture. Culture also come from (i) self-interest, (ii) power asymmetries, and (iii) an unintended by-product of our evolutionary psychology/emotions/personalty traits such as jealousy/disgust sensitivity among others. For example jealousy mediating a desire for taxation (this has been studied by psychologists, it is one of the three common motives), or disgust sensitivity mediating a desire for borders and authoritarian leaders.
Or some of these customs, traditions and institutions evolved to combat it through unconscious group selection. The tribes/towns/cities/countries/groups that had superior civic norms (superior defined as those norms which promote harmony, prosperity, in-group cooperation, etc) tended to attract immigrants, be capable of dominating geo-politically, etc, and thus those cultural values become dominant through this process of selection.
Also, while I think that explains things to a certain extent, it's just part of the picture. Culture also come from (i) self-interest, (ii) power asymmetries, and (iii) an unintended by-product of our evolutionary psychology/emotions/personalty traits such as jealousy/disgust sensitivity among others. For example jealousy mediating a desire for taxation (this has been studied by psychologists, it is one of the three common motives), or disgust sensitivity mediating a desire for borders and authoritarian leaders.