Stephen Beckerman

Life histories, blood revenge, and reproductive success among the Waorani of Ecuador

The Waorani may have the highest rate of homicide of any society known to anthropology. We interviewed 121 Waorani elders of both sexes to obtain genealogical information and recollections of raids in which they and their relatives participated. We also obtained complete raiding histories of 95 warriors. An analysis of the raiding histories, marital trajectories, and reproductive histories of these men reveals that more aggressive warriors have lower indices of reproductive success than their milder brethren. This result contrasts the findings of Chagnon [Chagnon N (1988) Science 239:985–992] for the Yanomamo. We suggest that the spacing of revenge raids may be involved in the explanation of why the consequences of aggressiveness differ between these 2 warlike lowland South American peoples.

Food Taboos, Diet, and Hunting Strategy: The Adaptation to Animals in Amazon Cultural Ecology [and Comments and Reply]

The issue of food prohibitions on such Amazonian game animals as deer is examined from an ecological perspective, in contrast to previous symbolic or structuralist views on this subject. Examined in conjunction with settlement pattern, technology, animal behavior, and habitat productivity, which together determine the food-extraction potential of a population, the avoidance of certain inherently edible species by characterizing them as inebible is seen as selective use of the environment to resolve the relative costs and benefits of alternative procurement options through a strategy of optimum yield. It is shown how the interaction of technoeconomic variables and the differential biotic potential of various species produces a particular set of cultural assumptions about the edibility of such animals and that such selectivity represents a cost-effective strategy of protein acquisition and not a merely metaphysical product.

Does the Swidden Ape the Jungle

Results of recent ethnographic research in indigenous agricultural systems in the South American tropical forests indicate that the Geertzian model of the highly intercropped swidden that mimics the tropical forest it replaces is not the appropriate description of the agricultural regimes of several rainforest peoples. A model is proposed relating degree of intercropping to amount of agricultural labor.

Living with Kin in Lowland Horticultural Societies

Postmarital residence patterns in traditional human societies figure prominently in models of hominid social evolution with arguments for patrilocal human bands similar in structure to female-dispersal systems in other African apes. However, considerable flexibility in hunter-gatherer cultures has led to their characterization as primarily multilocal. Horticulturalists are associated with larger, more sedentary social groups with more political inequality and intergroup conflict and may therefore provide additional insights into evolved human social structures. We analyze coresidence patterns of primary kin for 34 New World horticultural societies (6,833 adults living in 243 residential groupings) to show more uxorilocality (women live with more kin) than found for hunter-gatherers. Our findings further point to the uniqueness of human social structures and to considerable variation that is not fully described by traditional postmarital residence typologies. Sex biases in coresident kin can vary according to the scale of analysis (household vs. house cluster vs. village) and change across the life span, with women often living with more kin later in life. Headmen in large villages live with more close kin, primarily siblings, than do nonheadmen. Importantly, human marriage exchange and residence patterns create meta-group social structures, with alliances extending across multiple villages often united in competition against other large alliances at scales unparalleled by other species.

Carpe Diem: An Optimal Foraging Approach to Bari Fishing and Hunting

Publisher Summary This chapter discusses a feature of Bari protein foraging strategy that contradicts one of the central tenets of optimal foraging theory. The Bari are a group of tropical forest horticulturalists who live in the southwestern most lobe of the Marcaibo basin. The tenet of optimal foraging theory of interest posits that a forager should exploit a resource when he cannot, on the average, get a better return for his time by exploiting some other resource(s). The chapter provides an overview of the Bari, focusing on subsistence activities. The hypotheses claim that the information gathered in hunting informs decisions as to where and when fishing should take place, in seasons when good fishing spots are rare. The hypotheses claim that hunting is not needed during the dry season good fishing months because rewarding fishing spots are abundant and there is no need to spend time seeking them out.

Barí Swidden gardens: Crop Segregation patterns

The proposition that tropical forest swidden gardens mimic the extraordinary species diversity of the forest by the use of extensive intercropping is examined in the light of the field architecture of the Barí, a people of the Maracaibo basin. Barí fields manifest annular zonation rather than intercropping. It is concluded that Barí horticulture is an inversion of the jungle rather than an imitation of it.

Unbiased Sex Ratios Among the Bari: An Evolutionary Interpretation

We examine whether among the Barí sex ratios at birth or later ages deviate from the value of one expected by chance. We find no significant bias toward sons or daughters. We also examine whether the costs and benefits associated with sons and daughters are similar or if one sex is more expensive than the other. We contrast our results with predictions derived from Fishers and the Trivers-Willard hypotheses on sex ratios.

High Prevalence of Cleft Lip among the Barí Indians of Western Venezuela

Cleft lip with or without cleft palate (CL +/- P) is of high prevalence in an isolated, inbred indigenous population of the Venezuelan rain forest: 12 contemporary probands are known in a population of 1200. CL +/- P is familial in this population. One kindred contains four affected siblings and a total of eight probands. The mode of transmission of CL +/- P is under investigation through the collection and biological verification of genealogies and through screening for selected sequence-based polymorphisms. Polymerase chain reaction (PCR) assays were successfully applied to recover DNA from blood dried onto filter paper in the field. Eleven samples from probands and their first-degree relatives have been analyzed for DNA sequence-based polymorphisms for TGF-A and HOX7. No significant linkages for either locus were found. Evaluation of the distribution of probands in four genealogies indicates that CL +/- P could be transmitted as an autosomal recessive trait in this population. We believe this is the first report of this mode of transmission for nonsyndromic CL +/- P.

Risk sensitive foraging behavior among the Barí

Risksensitive behavior can be defined as the active choosing among probability distributions in an attempt to maximize expected utility of returns. An analysis of human foraging behavior is examined in terms of risk sensitivity. Foraging data collected from Barí hunting and fishing trips were tested according to the prediction that future foraging behavior will be dependent on or at least be sensitive to the success of the previous days trip. An analysis of protein foraging data yields statistically insignificant results, suggesting risk indifference on the part of the Barí.

Partible Paternity, the Secondary Sex Ratio, and a Possible Trivers-Willard Effect

Partible paternity, the belief that a child can have more than one biological father, is widespread in lowland South America. An analysis of demographic data sets from four lowland tribes (Aché, Barí, Ese Eja, and Surui) reveals a systematic variation in the sex ratios of live births with respect to the number of fathers to whom the births are attributed. Births attributed to only one father show a sex ratio that is unexceptional for South America; births with two fathers are highly male biased, while children with three or more fathers are female biased. This pattern may be a manifestation of a phenomenon predicted by the Trivers-Willard hypothesis, which proposes that, in many circumstances, females in good condition might bias their offspring toward males, whereas those in poor condition would produce a preponderance of females. If, as suggested below, a woman with a husband and a single extramarital lover tends to be better cared for before and during a pregnancy than other women, this difference might result in the improved maternal condition required by the Trivers-Willard hypothesis for excess males, whereas women who accept two or more lovers might be preponderantly those who are already in distress, thus tending to produce female-biased offspring.