Evolution of mammalian social structure

Social groups may be viewed as collections of individuals exhibiting nonindependent behavior and organized in a cooperative manner. The evolutionary advantage of social behavior to individuals must be measured in its relativity to other potential behaviors, the scale of competitive interactions, and under a variety of environmental and genetic constraints. A primary tent of social evolution is that coancestry will promote the genes of related individuals. High values of coancestry, however, do not necessarily translate into evolutionary adventage unless the primary competetive interactions occur among the groups. Coancestry is affected by the breeding tactics within and rates of genetic exchange among social groups. Low rates of exchange among groups, regardless of breeding tactics, may result in high values for intragroup coancestry but may lend to inbreeding depression in progeny. Likewise, breedig tactics such as polygyny, may not impart any long-lasting evolutionary advantage if genetic exchange rates are high.