ABSTRACT
Our experiences with the "cheating" and "non-cooperation" models suggest to us that the advantages of widespread generosity in sunay outweigh the advantages of cheating or ignoring those who are not one's kin. Groups practicing universal sunay should therefore thrive economically, relative to groups who practiced it more selectively. In other words, universal adherence to sunay, even if it includes giving good breeding stock to non-kin, can make it possible for one's children to pass on more animals to one's grandchildren. It does that by ensuring that there will be lots of other herds around from which the children and grandchildren can get sunay when they need it. One should seek to support and increase the herds of one's children, other close relatives, and perhaps more distantly related ayllu members. Among ayllu members, mutual aid is given freely because adherence to the principle of ayni is too universal for cheating to occur.
