B. Oztan, Douglas White

Paper #: 13-12-038

Stereotyped kinship behaviors are unrecognized as significant to the evolution of human cooperation. Joking relations reinforce cooperation through links with existing or close relatives (cross cousins, sibling’s spouses, spouse’s siblings). Avoidances reach out to connect non-relatives through marriage: parents-in-law and distant in-laws such as WiBrWi. The latter behaviors enhance cooperation in more extensive networks of in-laws and a variety of more distant kin. Low population densities, in a sample of 34 forager societies, show Joking dyads that are very frequent. They help to integrate societies of smaller scale and density, facilitating close marriages (e.g., wife’s sister). Avoidance relationships become more common at higher densities that require nucleation into localized communities of larger scale and integrate kinship networks at these larger scales. Study of kinship-behavior dyads and other coded variables in the SCCS reinforce the view that Avoidance is density dependent: as population density increases, along with higher jurisdictional levels, the commonality of parent-in-law Avoidances among larger-scale foragers and more complex societies peaks, declines, and eventually disappears. These relationships are shown here by a Network of Variable Analysis (NoVA) of SCCS societies using Dow-Eff software that corrects for autocorrelation and missing data. See Appendix 1: Murdock Kin Behavior Data Summary.
 A world sample of kinship-behavior dyads in 250 societies coded by Murdock (1971 and n.d.) shows 23 types of avoidances that fall into two categories: Parent-in-law (4 types) and another set of 19 other in-laws that forms an odd assortment of affinal and blood relatives (e.g., Br/Si, FaSi, MoBr, cross-sex cousins, HuSiHu, HuBrSo), of which WiBrWi, although scantily reported, forms the most generic superset. A formal concept lattice, carried out by Darmstadt mathematicians for the Birkoff festschrift (Baker, Birkoff and Wille 2007), identifies every superset, subset and intersection of types of avoidance and identifies all these intertwined subsets for subgroups of societies in this sample, and describes details of networks of avoidances for individual societies.