Inbreeding coefficients of the Ramah Navaho population. 1953.

Any discussion of inbreeding should distinguish two senses in which the term has been used: the social, and the biological. Socially speaking, we may refer to endogamie mating, that is, to mating which occurs within the limits of a socially-defined category, such as a community, a clan, a caste, or a class. Biologically speaking, inbreeding refers to the mating of individuals with one or more common biological ancestors. Inbred individuals are offspring of genetic relatives and inbreeding is the mating of genetically related individuals. The genetic consequences of inbreeding and endogamy may differ. Relatively small, endogamous and isolated human populations are not necessarily highly inbred. The degree of inbreeding in many natural and enduring local populations is slight compared to that characteristic of matings typical for some domestic and experimental animals. Throughout the remainder of this paper we shall be concerned with inbreeding in the biological sense, and not, except as noted, with endogamy in the social sense. This paper describes the types, and gives a measure of the degree, of inbreeding in the Ramah Navaho population as of September first 1948. A number of estimates of inbreeding coefficients based on various sorts of cousin marriages are available for human populations (see the summary in Neel, et al., 49). Measurements of inbreeding for relatives of all degrees, for a total human population seemingly have not been published heretofore.