Progenic isonymy among the Chamorro of Guam

Abstract

This study examines several methodological issues pertaining to the application of isonymy techniques to a historical population located on the island of Guam in Micronesia. Since European contact the indigenous Chamorro population of Guam has undergone a series of precipitous population declines. The Spanish colonial administration imposed a dual surname system on the Chamorro. The surname information was compiled into a demographic database representing approximately 39,000 persons traced from late 19th century vital records. Analysis using the methods of isonymy was conducted on lineages established from the four parental surnames. Values were calculated from the progeny in the database, in effect focusing on the effective breeding population. Comparisons were made with inbreeding values obtained using other methods of surname analysis both for single and dual surname systems. In contrast to the paternal lineage, the values for the other lineages were influenced by their shallow temporal depth. The non-paternal lineages showed patterns of assortative mating reflecting choices of mate selection that have the potential to influence levels of inbreeding in the population.