ETHNOHISTORICAL EVIDENCE FOR INBREEDING AMONG THE PRE-HISPANIC MIXTECROYAL CASTE

Pre-Columbian Mixtec social organization was distinguished by the tigh t endogamy of the ruling class, which included many consanguineous mar riages. It was also characterized by a vigorous historical and genealo gical tradition. The historical documents, or codices, provide materia ls for the calculation of the levels of inbreeding present before the Spanish Conquest. A genealogical analysis of inbreeding was performed on the combined pedigree, which spanned the tenth through sixteenth ce nturies, of all individuals connected by ancestry, descent, or marriag e with Lord 8 Deer Jaguar Claw of Tilantongo (A.D. 1063-1115). Sixty o f the 217 couples (27.65%) were consanguineous. When only couples of w holly known grandparentage were considered (N = 39), F = 0.1051. The m ean F of all couples, even those where one spouse was of unknown paren tage, was 0.0243. Over the 550 years of the pedigree the maximum F in any 52-year period was 0.1324. This level of inbreeding is sufficient to produce noticeable effects on population structure and affinities o ver time.