International Union for Circumpolar Health Ministry of Public Health and Social Development of RF Russian Academy of Medical Sciences Siberian Branch of Russian Academy of Medical Sciences Siberian Branch of Russian Academy of Sciences Medical Polar Fund “Science” The Northern Forum

Abstracts

Genetics, demography, anthropology

Nganasans inhabit the central tundra zone of Taimyr Peninsula. The population has formed about 250 years ago as a result of assimilation of Paleoasian people by Samodians and Tunguses. Total size of Nganasan population has changed within 550-870 persons. It was 855 in 2000. Up to the late 1970s the population was characterized by high endogamy: 1976 – 83,8%; 1926 – 88,4%; 1976 – 74,3%. The main source of traditional marriage migration (preferentially female) was population of Entsy. The frequency of Nganasan-Entsy marriages was 16,2% in 1796 and 14,9% in 1926. Transition to settled way of life in 1960-1990-th has led to isolation of Nganasans from Entsy and the growth of total frequency of Nganasans-Dolgans and Nganasans-immigrants (non-aborigines) marriages up to 47,9 % in 1991. This year the frequency of Nganasans-immigrants marriages has reached 31,9 %, the relative number of metises in the age group of 0-10 years - 62,1%. In 1976-1991 Nganasan assimilation was biased with regard to sex: marriages with non-aborigine women was virtually absent. The analysis of family trees has confirmed the data on asymmetry of the mixed Nganasan marriage structure. Insignificant decrease of inbreeding coefficient on family trees from 0,0022 to 0,0016, and by isonymy - from 0,0614 to 0,0460 was shown. On a background of promptly increasing processes of assimilation it reflects the increasing contribution of the remote generations to inbreeding coefficient in previously isolated small Nganasan population and the rather low variety of Nganasan surnames. The increase in availability of medical care during transition of Nganasans on settled way of life (1976-1991)has led to decrease in prereproductive mortality in 2 and more times, including death rate till 1 year, and distribution of birth control practice. In result there was a decrease of Crow index of the opportunity for selection from 1,91 (highest in the Siberian populations) in 1976 to 0,92 in 1991. The component of differential fertility has increased twice (up to 0,44), and the component of differential mortality has decreased in 4 times - from 1,38 to 0,33. There is an open question: on what probable consequences of destruction of the adaptive gene complexes generated during natural selection, for descendants from Nganasans-immigrants marriages.

This study was supported by the Program of Presidium of the Russian Academy of Sciences «Dynamics of Plant, Animal, and Human Gene Pools».

Note. Abstracts are published in author's edition

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Last update: 06-Jul-2012 (11:52:05)