Bram Tucker

Risk-Sensitive Adaptive Tactics: Models and Evidence from Subsistence Studies in Biology and Anthropology

Risk-sensitive analysis of subsistence adaptations is warranted when (i) outcomes are to some degree unpredictable and (ii) they have nonlinear consequences for fitness and/or utility. Both conditions are likely to be common among peoples studied by ecologicll anthropologists and archaeologists. We develop a general conceptual model of risk. We then review and summarize the extensive empirical literatures from biology and anthropology for methodological insights and for their comparative potential. Risk-sensitive adaptive tactics are diverse and they are taxonomically widespread. However, the anthropological literature rarely makes use of formal models of risk-sensitive adaptation, while the biological literature lacks naturalistic observations of risk-sensitive behavior. Both anthropology and biology could benefit from greater interdisciplinary exchange.

Applying Behavioral Ecology and Behavioral Economics to Conservation and Development Planning: An Example from the Mikea Forest, Madagascar

Governments and non-govermental organizations (NGOs) that plan projects to conserve the environment and alleviate poverty often attempt to modify rural livelihoods by halting activities they judge to be destructive or inefficient and encouraging alternatives. Project planners typically do so without understanding how rural people themselves judge the value of their activities. When the alternatives planners recommend do not replace the value of banned activities, alternatives are unlikely to be adopted, and local people will refuse to participate. Human behavioral ecology and behavioral economics may provide useful tools for generating and evaluating hypotheses for how people value economic activities in their portfolios and potential alternatives. This is demonstrated with a case example from southwestern Madagascar, where plans to create a Mikea Forest National Park began with the elimination of slash-and-burn maize agriculture and the encouragement to plant labor-intensive manioc instead. Future park plans could restrict access to wild tuber patches, hunting small game, and fishing. The value of these activities is considered using observational data informed by optimal foraging theory, and experimental data describing people’s time preference and covariation perception. Analyses suggest that manioc is not a suitable replacement for maize for many Mikea because the two crops differ in terms of labor requirements, delay-to-reward, and covariation with rainfall. Park planners should promote wild tuber foraging and stewardship of tuber patches and the anthropogenic landscapes in which they are found. To conserve small game, planners must provide alternative sources of protein and cash. Little effort should be spent protecting lemurs, as they are rarely eaten and never sold.

Do risk and time experimental choices represent individual strategies for coping with poverty or conformity to social norms?: evidence from rural Southwestern Madagascar

This study revisits a debate played out in Current Anthropology as to whether subsistence decisions are the result of individual strategy to cope with poverty and increase wealth (advanced by Kuznar in 2001 and 2002) or conformity to social norms (advanced by Henrich and McElreath in 2002)—a debate that mirrors discussions within the behavioral sciences about individual versus social learning and within the social sciences about agency versus structure. This study, set in southwestern Madagascar, goes beyond previous investigations by examining the influence on choices in simple risk and time preference experiments of multiple measures of income, wealth, status, and need, as well as conformity at three nested levels: ethnicity (Masikoro, Mikea, and Vezo), village, and clan. Logistic regression models found that both wealth and income variables and social group memberships predict choices, where the best-fit model, evaluated with the Akaike Information Criterion, combined income and either ethnicity or village. The coinfluence of strategy and conformity on economic decisions suggests that humans habitually balance individual goals against social pressures. Equating wealth effects with individual learning and rational choice or equating ethnic effects with social learning and bounded rationality erects a series of false dichotomies.

Perception of Interannual Covariation and Strategies for Risk Reduction among Mikea of Madagascar : Individual and Social Learning.

This paper begins with the hypothesis that Mikea, participants in a mixed foraging–fishing–farming–herding economy of southwestern Madagascar, may attempt to reduce interannual variance in food supply caused by unpredictable rainfall by following a simple rule-of-thumb: Practice an even mix of activities that covary positively with rainfall and activities that covary negatively with rainfall. Results from a historical matrix participatory exercise confirm that Mikea perceive that foraging and farming outcomes covary positively or negatively with rainfall. This paper further considers whether Mikea learn about covariation through personal observation and memory recall (individual learning) or through socially transmitted ethnotheory (social learning). Dual inheritance theory models by Boyd and Richerson (1988) predict that individual learning is more effective in spatially and temporally variable environments such as the Mikea Forest. In contrast, the psychological literature suggests that individuals judge covariation poorly when memory of past events is required, unless they share a socially learned theory that a covariation should exist (Nisbett and Ross 1980). Results suggest that Mikea rely heavily on shared ethnotheory when judging covariation, but individuals continually strive to improve their judgment through individual observation.

The Human Behavioral Ecology of Contemporary World Issues

Human behavioral ecology (HBE) began as an attempt to explain human economic, reproductive, and social behavior using neodarwinian theory in concert with theory from ecology and economics, and ethnographic methods. HBE has addressed subsistence decision-making, cooperation, life history trade-offs, parental investment, mate choice, and marriage strategies among hunter-gatherers, herders, peasants, and wage earners in rural and urban settings throughout the world. Despite our rich insights into human behavior, HBE has very rarely been used as a tool to help the people with whom we work. This article introduces a special issue of Human Nature which explores the application of HBE to significant world issues through the design and critique of public policy and international development projects. The articles by Tucker, Shenk, Leonetti et al., and Neil were presented at the 104th annual meeting of the American Anthropological Association (AAA) in Washington, D.C., in December 2005, in the first organized session of the nascent Evolutionary Anthropology Section (EAS). We conclude this introduction by summarizing some theoretical challenges to applying HBE, and ways in which evolutionary anthropologists can contribute to solving tough world issues.

Ecological and cosmological coexistence thinking in a hypervariable environment: causal models of economic success and failure among farmers, foragers, and fishermen of southwestern Madagascar

A fact of life for farmers, hunter-gatherers, and fishermen in the rural parts of the world are that crops fail, wild resources become scarce, and winds discourage fishing. In this article we approach subsistence risk from the perspective of “coexistence thinking,” the simultaneous application of natural and supernatural causal models to explain subsistence success and failure. In southwestern Madagascar, the ecological world is characterized by extreme variability and unpredictability, and the cosmological world is characterized by anxiety about supernatural dangers. Ecological and cosmological causes seem to point to different risk minimizing strategies: to avoid losses from drought, flood, or heavy winds, one should diversify activities and be flexible; but to avoid losses caused by disrespected spirits one should narrow one’s range of behaviors to follow the code of taboos and offerings. We address this paradox by investigating whether southwestern Malagasy understand natural and supernatural causes as occupying separate, contradictory explanatory systems (target dependence), whether they make no categorical distinction between natural and supernatural forces and combine them within a single explanatory system (synthetic thinking), or whether they have separate natural and supernatural categories of causes that are integrated into one explanatory system so that supernatural forces drive natural forces (integrative thinking). Results from three field studies suggest that (a) informants explain why crops, prey, and market activities succeed or fail with reference to natural causal forces like rainfall and pests, (b) they explain why individual persons experience success or failure primarily with supernatural factors like God and ancestors, and (c) they understand supernatural forces as driving natural forces, so that ecology and cosmology represent distinct sets of causes within a single explanatory framework. We expect that future cross-cultural analyses may find that this form of “integrative thinking” is common in unpredictable environments and is a cognitive strategy that accompanies economic diversification.

Do Risk and Time Experimental Choices Represent Individual Strategies for Coping with Poverty or Conformity to Social Norms

This study revisits a debate played out in Current Anthropology as to whether subsistence decisions are the result of individual strategy to cope with poverty and increase wealth (advanced by Kuznar in 2001 and 2002) or conformity to social norms (advanced by Henrich and McElreath in 2002)—a debate that mirrors discussions within the behavioral sciences about individual versus social learning and within the social sciences about agency versus structure. This study, set in southwestern Madagascar, goes beyond previous investigations by examining the influence on choices in simple risk and time preference experiments of multiple measures of income, wealth, status, and need, as well as conformity at three nested levels: ethnicity (Masikoro, Mikea, and Vezo), village, and clan. Logistic regression models found that both wealth and income variables and social group memberships predict choices, where the best-fit model, evaluated with the Akaike Information Criterion, combined income and either ethnicity or village. The coinfluence of strategy and conformity on economic decisions suggests that humans habitually balance individual goals against social pressures. Equating wealth effects with individual learning and rational choice or equating ethnic effects with social learning and bounded rationality erects a series of false dichotomies.

Rationality and the Green Revolution

Adaptation via differential success among competing individuals creates winners and losers. But adaptation via cultural group selection creates benefits that are shared among group members. During the twentieth century, evolutionary biologists and economists developed parallel theories of rationality, the gene’s eye view and rational choice theory, which imagine humans as self-interested individuals maximizing consumption of scarce resources. When rational choice theory was applied to agricultural development in the Green Revolution programs of the 1940s to the 1980s, it turned otherwise cooperative farmers into competitors for cash profits, resulting in a process akin to differential mortality, generating wealth for some but exacerbating poverty for many. I suggest that evolutionary biology may offer an alternative view of human rationality, one consistent with ethnographic evidence of farmers’ behavior. One emerging candidate for a “Rationality 2.0” assumes cultural inheritance, cultural group selection, strong reciprocity, and bounded rationality. Farmers make decisions that balance individual benefits with family and community well-being. While the new Alliance for a Green Revolution for Africa (AGRA) seeks technical solutions within its seeds, soils, policy, and markets programs, Rationality 2.0 suggests that AGRA should also promote community cohesion, autonomy, human capability, and reduced dependence on imported technology.

An ecosystem approach to explaining religious diversity: why, how, and what?

Gelfand, M. J., Raver, J. L., Nishii, L., Leslie, L. M., Lun, J., Lim, B. C.,... Yamaguchi, S. (2011). Differences between tight and loose cultures: A 33-nation study. Science, 332, 1100–1104. Gibbon, E. (1963). The decline and fall of the Roman empire. New York: Dell Publishing. Hall, N. R., & Crisp, R. J. (2005). Considering multiple criteria for social categorization can reduce intergroup bias. Personality and Social Psychology Bulletin, 31, 1345–1444. Jannoulatos, A. (1975, 11th printing in 2001) Islam. Athens: Porefthendes. Uz, I. (2015). The index of cultural tightness and looseness among 68 countries. Journal of Cross-Cultural Psychology, 46, 319–335.

From Risk and Time Preferences to Cultural Models of Causality: On the Challenges and Possibilities of Field Experiments, with Examples from Rural Southwestern Madagascar

Risk preference and time preference experiments have been conducted in field conditions in many rural and urban populations throughout the world, to evaluate how non-Western people subjectively trade off the value of reward amount, probability, and delay. My thesis is that it is difficult to quantitatively evaluate risk and time preferences with precision and that choice experiments have dubious internal validity (it is unclear whether the experiments evaluate the same thing—preferences—across all subjects and studies) and external validity (it is unclear how they relate to actual behavior). Probability and elapsing days preceding a reward are not necessarily the meaningful components of choice under risk and intertemporal choice for many people. I argue that if the goal of such work is to understand the cultural differences in thought and action related to risk and time, it may be more productive to examine how people in different cultures understand causal relationships linking natural, social, and supernatural factors to successful and unsuccessful outcomes. I illustrate my thesis by describing 13 risk and time preference choice experiments that I conducted among Masikoro farmers, Mikea hunter-gatherers, and Vezo fishermen in southwestern Madagascar from 2003 to 2008, contrasted with published risk and time preference studies from throughout the world. I find inconsistency in subjects’ choices across experiments and time, inconsistency in the determinants of choice, and a poor relationship between risk and time preferences and amount of time spent foraging and fishing. Then, I discuss some preliminary ethnographic and experimental attempts to understand the people’s causal models for risky economic outcomes. Preliminary evidence suggests that southwestern Malagasy understand activity risk as being caused primarily by natural factors and personal risk by supernatural factors.