Fertility differentials within a subdivided population: a controlled comparison of four Sells Papago isolates
Smith, D.G.
Human Biology 52(2): 325-342
1980
ISSN/ISBN: 0018-7143 PMID: 7380430 DOI: 10.2307/41464537Document Number: 451545
4 ethnically, cultural-historically and linguistically distinct subsets of the Sells Reservation Papago population of southern Arizona are identified using ethnographic and demographic data. Breeding patterns of these 4 isolates are described and compared with fertility and mortality parameters. Isolates which experienced greater ethnic and isolate admixture were those less geographically remote from western influences; they showed greater fertility than those more endogamous and geographically remote isolates. It is argued that population-biological restraints on survival, high rates of emigration, and adverse economic conditions require that fertility rates be appropriate within narrow limits for continued survival of the reservation population. Subsistence farming and wage labor are the major occupations. Most occupations are off-reservation, although 50% of all Papago live on-reservation. Only 31% earn all or part of their income there. Hybrid matings were more fertile than the total reservation mean with birth rates of 4.80 and 4.45 respectively. Isolate exogamous matings produced an average parity of 5.03, while isolate endogamous matings averaged 3.85. Although exogamy itself can never alter gene frequencies, members of a breeding isolate will be distantly related even though they recognize no kinship ties, and intermarriage, when it occurs between these isolates, constitutes outbreeding which also theoretically leads to increased heterozygosity and heterosis.