ABSTRACT
So far we have discussed the rewards of group life; we must also examine the costs. Finding that a given type of social structure is adaptive under a given set of conditions does not explain how that social structure was or could be realized. Our own species sufficiently demonstrates that not everything that is adaptive is also possible. Cultural develop ments, like other modifications, are restricted by the phylogenetic heritage of the species, and phylogenetic adaption itself proceeds slowly. Ecological conditions can put a pre mium on a certain type of society, but i t cannot tell the species how to create such a society. Discussions of adaptiveness sometimes leave us w i t h the impression that every trait observed in a species must by definition be ideally adap tive, whereas all we can say w i t h certainty is that i t must be tolerable since i t d id not lead to extinction. Evolution, after all, is not sorcery.
