Demographic information is given and data on 25 genetic systems are reanalysed for six populations of Wapishana Indians living in northern Brazil. Despite 200 years of contact with non-Indians, the maximum amount of admixture that may be present in persons who claim 'pure' Indian ancestry is 3%. Historical sources mention considerable exchange with the Macushi, Taurepan and Atorai tribes, confirmed by our genealogies. Departures from the maximum amount of heterozygosity per locus are similar in putative 'full bloods' and admixed individuals, as well as among the first and members of other tribes. Demographically the Wapishana can be characterized as very mobile, with high fertility but moderate mortality for an agricultural group. The Index of Opportunity for Selection (0 x 57) is one of the lowest calculated so far among South American tribes. Despite the indicated high mobility, clustering of some alleles was observed in two localities.

Adolescent↗

PubMedDate not supplied

New studies on the Macushi Indians of northern Brazil.

Demographic data and genetic information concerning 40 genetic systems are reported for three populations of Macushi Indians, and have been compared to those already obtained for three other communities of this tribe. These are young populations (mean age, 19 years), with a low sex ratio (90), low percentages of non-Indian ancestry (1-2%) and of marriages between locally born persons (34). Intertribal unions (14%) are less frequent than among their neighbours, the Wapishana. Fertility is high (average of 8.2 children per woman who completed reproduction), but the variance in family size and the frequency of premature deaths relatively low for populations at this cultural level. This conditions the lowest Index of Opportunity for Selection (0.45) calculated thus far among South American Indians. No variation was observed in 20 genetic systems, limited variation in 3, and larger variability in the remaining 17. In 13 of the 29 comparisons (45%), the Macushi gene frequencies present values in the middle third of the range observed among South American Indians. The previously reported private genetic polymorphism of esterase A was encountered in one of the three villages. A comparison of the genetic distances between villages with and without this polymorphism, and a similar comparison for the villages of the neighbouring Wapishana, yields no clue as to the tribe in which this polymorphism originated.

Adolescent↗

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Frequency of spontaneous and induced "point" mutations in higher eukaryotes.

Data are presented on comparative mutation rates in Drosophila, mice, and humans, as derived from the study of both biochemical and morphological traits. There is a notable similarity in these rates, despite the large differences in average generation time, mean body temperature, and number of cell divisions intervening between fertilization of the egg and production of functional gametes. This suggests the evolution of superior genetic (DNA) repair strategies in (long-lived) humans. Evidence is reviewed that raises the possibility of higher mutation rates in mostly tropical-dwelling, tribal human populations than in temperate-dwelling civilized groups. The data suggesting that humans may be somewhat less sensitive to the genetic effects of radiation than mice are presented, and the question of whether this apparent difference is real or spurious is discussed. Finally, some possible new directions in the study of the mutation-selection balance are presented.

Animals↗

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Some ethical issues at the population level raised by 'soft' eugenics, euphenics, and isogenics.

It is argued that at the population level there are three central genetic developments raising ethical issues. The first is the emergence of 'soft' eugenics, due primarily to the increasing ability to detect carriers of genetic diseases, to monitor their pregnancies, and to provide the option to abort a fetus predisposed to major genetic disease. The second development is the recognition of the extent to which many serious diseases of adult life are due to a disturbance of ancient genetic homeostatic mechanisms due to changing life style, raising the question of whether a society that increasingly pays the medical bills should attempt to impose healthier standards of living on its members. Such an attempt at 'euphenics' may be thought of as the antithesis to eugenics. The third development relates to recognition of the need to regulate the size of the earth's population to numbers that can be indefinitely sustained; this regulation in a fashion (isogenic) that will preserve existing genetic diversity.

Bioethics↗

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The study of natural selection in primitive and civilized human populations. 1958.

Explore the source record for details and available documents.

Africa↗

PubMedDate not supplied

Frequency of polymorphisms for alleles encoding for liver proteins of domesticated mice.

Three different inbred strains of mice have been crossed with a lethal albino line (cch/c3H) and the liver polypeptides of the parents and offspring examined by two-dimensional polyacrylamide gel electrophoresis for evidences of protein polymorphisms, different alleles of which have gone to fixation in different strains. In the battery of polypeptides considered most favorable for scoring, 3.3 +/- 1.6 percent of the battery exhibited paired variants and 1.6 +/- 1.2 percent, unpaired. An adjustment for the fact the same allele of a biallelic polymorphism may go to fixation in two inbred lines of common ancestry leads to the suggestion that in the stock from which these inbred lines were ultimately derived, there were some 11.0 percent paired and 5.3 percent unpaired polymorphisms in the average mouse. This is about half the frequency of polymorphisms observed in wild European Mus musculus musculus and Mus musculus domesticus with one-dimensional electrophoresis of blood plasma and erythrocyte proteins. Three explanations were considered for the lower estimated frequency for liver protein polymorphisms: the difference is real, the apparent difference is due to the lower resolving power of two-dimensional gels, or the mouse strains from which the present inbred lines were drawn had already, lost through inbreeding, a considerable amount of their genetic variation before the inbreeding leading to the present strains commenced.

Alleles↗

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