Chronic problems in understanding tribal violence and warfare.

This paper discusses problems confronting researchers whose work addresses the nature, causes and functions of violence and warfare in contemporary tribal societies and the interpretation of evidence on these topics from archaeological records. A major problem is the paucity of reliable ethnographic evidence describing conflicts, causes of conflicts and numbers of casualties suffered. There are few first-hand studies of warring tribesmen and little uniformity in data collection methods or specific topics covered by the studies. A second problem is the wide range of theoretical opinion on ultimate versus proximate causes of conflict and often polemic insistence that some causes cannot even be admitted into the explanatory framework, as illustrated by the debate between cultural materialists and evolutionary anthropologists. A third problem is the widespread belief that pre-colonial conflict and warfare was either rare or did not exist at all and that where contemporary tribesmen are found to be in lethal contests this has been provoked by contact with European colonial expansion. Finally, a new problem is emerging: ethnographic descriptions of violence in tribal societies are increasingly opposed by politically correct academics who argue that it is detrimental to the goals of advocates of native cultural survival. The paper concludes with a summary of some of the main features of Yanomamö violence and warfare, based on the author's field research and publications up to 1990, and introduces new data and theoretical issues that are emerging from his most recent field studies since 1990.

The thyroid status of the Yanomamö Indians of southern Venezuela: 1992 update.

Previous reports described an apparent paradox in the clinical expression of endemic iodine deficiency in Amazonian Indians, who were severely iodine deficient but had no goiter and were clinically euthyroid. To confirm and explain this unique observation, we estimated the iodine intake and evaluated the functional and structural thyroid status of an isolated population of Yanomamö Indians (n = 104) in southern Venezuela. Twenty-six children, 32 adolescents, and 46 adults were studied with serum thyroid function tests, spot urinary iodide concentration determinations, and sonographic measurement of thyroid gland volume. A subset of adolescents and adults (n = 35) had 24-h fractional thyroidal 131I uptake determinations. No individual with goiter, clinical hypothyroidism, or cretinism was observed. Children had higher mean serum T4 (114.5 vs. 102.9 nmol/L; P < 0.02) and serum T3 (2.96 vs. 2.46 nmol/L; P < 0.02) concentrations than adults, with 2% and 50%, respectively, of children having levels more than 2 SD above the mean for a North American reference population. Serum TSH concentrations were also higher in children than adults (3.3 vs. 2.3 mU/L; P < 0.02), with 25% of the subjects above the reference range. Mean urinary iodide was 61 +/- 29 micrograms/L (range, 10-178 micrograms/L), reflecting borderline iodine sufficiency. Thyroidal 131I uptake values were 28 +/- 7%, with 33% above the upper limit of normal (30%). Compared to an iodine-replete Swedish population, the thyroid gland volume was above normal (> mean + 2 SD) in 71% of the study children. We conclude that the Yanomamö have borderline iodine deficiency, associated in children with predictably higher serum T3 and TSH concentrations and a high prevalence of small goiters. The basis for the apparent change in their dietary iodide intake over the past 30 yr is unclear, as is the explanation for their previously postulated resistance to goitrogenesis with more profound iodine deficiency.

Life histories, blood revenge, and warfare in a tribal population.

Blood revenge is one of the most commonly cited causes of violence and warfare in tribal societies, yet it is largely ignored in recent anthropological theories of primitive warfare. A theory of tribal violence is presented showing how homicide, revenge, kinship obligations, and warfare are linked and why reproductive variables must be included in explanations of tribal violence and warfare. Studies of the Yanomamö Indians of Amazonas during the past 23 years show that 44 percent of males estimated to be 25 or older have participated in the killing of someone, that approximately 30 percent of adult male dealths are due to violence, and that nearly 70 percent of all adults over an estimated 40 years of age have lost a close genetic relative due to violence. Demographic data indicate that men who have killed have more wives and offspring than men who have not killed.

Protein deficiency and tribal warfare in Amazonia: new data.

Increasing numbers of anthropological studies about native Amazonian warfare and demographic practices attempt to explain these phenomena as competition over or a response to scarce game animals and other sources of high-quality protein. Recently completed field research among the Yanomamö Indians living at the Venezuela-Brazil border indicates that their protein intake is comparable to that found in highly developed industrialized nations and as much as 200 percent more than many nutritional authorities recommend as daily allowances. Recent data on other Amazonian tribes likewise fails to indicate a correlation between protein intake and intensity of warfare patterns.

Chromosome aberrations among the Yanomamma Indians.

The chromosomes of leucocytes cultured from the peripheral blood of 49 primitive Yanomama Indians of Venezuela were studied to determine the types and frequencies of aberrations in a human population not exposed to the same exogenous agents as civilized man. In all but one instance, 100 cells per individual were scored. In 13 cases, we found one or more cells with multiple complex breaks and rearrangements, represented by tetracentric, tricentric, and numerous dicentric chromosomes. From the standpoint of chromosomal damage, these cells are among the most abnormal cells yet described in vivo in man, and were not seen in the controls. There was also a higher than expected frequency of cells with an isolated structural aberration in both Indians and controls. This may be the result of a 24- to 48-hour delay in the initiation of culture. The cause of the more extensive damage to some cells remains to be determined.