🦍Biological Anthropology Unit 11 – Human Behavioral Ecology

Key Concepts and Definitions

• Human Behavioral Ecology (HBE) applies evolutionary principles to understand how ecological factors shape human behavior and decision-making
• Fitness refers to an individual's ability to survive and reproduce, passing on their genes to future generations
• Life history theory examines how organisms allocate resources to growth, maintenance, and reproduction throughout their lifespan
  • Includes trade-offs between current and future reproduction (somatic effort vs. reproductive effort)
• Optimal foraging theory predicts that individuals will make foraging decisions that maximize their net energy gain while minimizing costs (time, energy, risk)
• Inclusive fitness considers the reproductive success of an individual and their relatives, as shared genes can be passed on indirectly
• Phenotypic plasticity is the ability of an organism to alter its phenotype in response to environmental conditions
• Niche construction occurs when organisms modify their environment, which can influence the selection pressures acting on them and future generations

Evolutionary Foundations

• Natural selection is the process by which heritable traits that increase fitness become more common in a population over time
• Sexual selection arises from differences in reproductive success caused by competition for mates or mate choice
• Kin selection explains the evolution of altruistic behaviors towards relatives, as helping them can indirectly increase an individual's inclusive fitness
• Reciprocal altruism involves the exchange of beneficial acts between unrelated individuals, with the expectation of future reciprocation
• Evolutionary game theory models the evolution of strategies in populations, considering the costs and benefits of different behaviors
  • Includes concepts such as the prisoner's dilemma and the hawk-dove game
• Evolutionary mismatch occurs when traits that were adaptive in ancestral environments become maladaptive in modern contexts (obesity, addiction)
• Gene-culture coevolution recognizes that cultural practices can influence genetic evolution and vice versa (lactase persistence, sickle cell anemia)

Adaptive Strategies

• Subsistence strategies are the ways in which individuals and groups obtain food and other resources necessary for survival and reproduction
  • Includes foraging, horticulture, pastoralism, and agriculture
• Optimal diet breadth models predict that foragers will prioritize resources with high net energy returns and expand their diet to include lower-quality items when high-quality resources become scarce
• Patch choice models consider how long foragers should spend in a particular resource patch before moving to another
• Risk-sensitive foraging theory examines how individuals make foraging decisions under conditions of uncertainty, balancing the potential for high rewards with the risk of failure
• Behavioral adaptations to seasonal fluctuations in resource availability (migration, storage, social networks)
• Adaptive responses to environmental stressors such as altitude, temperature, and aridity (physiological acclimatization, cultural practices)
• Behavioral strategies for managing risk and uncertainty (diversification, reciprocity, social insurance)

Resource Acquisition and Allocation

• Optimal foraging models predict how individuals should allocate time and energy to different foraging activities to maximize net energy gain
• Central place foraging theory considers how the distance between a forager's home base and resource patches influences foraging decisions
• Marginal value theorem predicts when a forager should leave a resource patch based on the diminishing returns of continued foraging
• Parental investment theory examines how parents allocate resources to their offspring, considering factors such as offspring quality, birth order, and sex
  • Trivers-Willard hypothesis predicts that parents in good condition will bias investment towards sons, while those in poor condition will favor daughters
• Intergenerational resource transfers (inheritance, dowry, bridewealth) can influence reproductive success and social status
• Trade-offs between quantity and quality of offspring, as investing heavily in fewer offspring can increase their chances of survival and reproduction
• Resource sharing and reciprocal exchange networks (food sharing, alloparental care) can buffer against environmental variability and improve individual fitness

Mating and Reproductive Behavior

• Sexual selection theory explains how mate preferences and competition for mates can drive the evolution of traits that increase reproductive success
• Parental investment theory predicts that the sex investing more heavily in offspring (typically females) will be more selective in mate choice, while the sex investing less (typically males) will compete more intensely for access to mates
• Mating systems (monogamy, polygyny, polyandry) are influenced by factors such as resource distribution, parental care requirements, and adult sex ratios
• Mate choice criteria often include indicators of genetic quality, parental investment capacity, and compatibility
  • Examples include physical attractiveness, resource holding potential, and major histocompatibility complex (MHC) dissimilarity
• Reproductive strategies can vary based on individual condition, social context, and environmental factors (conditional strategies, alternative reproductive tactics)
• Fertility decisions are influenced by factors such as resource availability, offspring survival prospects, and cultural norms
• Menopause and post-reproductive lifespan in human females may have evolved due to the benefits of grandmothering and increased inclusive fitness

Social Interactions and Cooperation

• Kin selection theory explains the evolution of altruistic behavior towards relatives, as helping them can indirectly increase an individual's inclusive fitness
• Reciprocal altruism involves the exchange of beneficial acts between unrelated individuals, with the expectation of future reciprocation
  • Requires mechanisms to prevent cheating, such as repeated interactions, reputation, and punishment
• Cooperation can evolve through mechanisms such as mutualism, reciprocity, and group selection
• Social hierarchies and dominance relationships can influence access to resources, mates, and reproductive success
• Alliance formation and coalitionary behavior can help individuals compete for resources and mates, and defend against threats
• Costly signaling theory suggests that individuals may engage in behaviors that are costly to themselves but signal their quality to others (conspicuous consumption, altruistic acts)
• Conflict resolution strategies (negotiation, mediation, reconciliation) can help maintain social cohesion and cooperative relationships

Cultural Influences on Behavior

• Cultural norms and institutions can shape human behavior by establishing expectations, rewards, and punishments for different actions
• Gene-culture coevolution recognizes that cultural practices can influence genetic evolution and vice versa (lactase persistence, sickle cell anemia)
• Cultural transmission of knowledge, skills, and values can influence individual fitness and shape the selective environment for future generations
• Conformity bias and social learning can lead to the rapid spread of adaptive behaviors, but also the persistence of maladaptive practices
• Cultural group selection theory proposes that competition between groups can favor the spread of cooperative norms and institutions
• Behavioral variation across cultures can reflect adaptations to different ecological and social environments (marriage systems, subsistence strategies)
• Cultural evolution can be influenced by factors such as population size, migration, and innovation

Research Methods and Case Studies

• Observational studies of behavior in natural settings can provide insights into the ecological and social factors shaping human behavior
  • Examples include studies of foraging behavior among hunter-gatherers (Hadza, !Kung) and mating patterns in small-scale societies (Yanomamö, Tsimane)
• Experimental studies can test specific hypotheses about the factors influencing human behavior, such as the role of resource distribution on cooperation or the impact of mate choice criteria on partner preferences
• Comparative studies across species can shed light on the evolutionary origins and adaptive significance of human behaviors (parental care in mammals, cooperative breeding in birds)
• Ethnographic research provides detailed descriptions of cultural practices, social organization, and environmental adaptations in specific societies
• Historical and archaeological evidence can be used to reconstruct past behaviors and test hypotheses about the evolution of human social systems (division of labor, inequality)
• Genetic and physiological studies can investigate the biological basis of behavioral traits and the mechanisms underlying behavioral adaptations (stress response, immune function)
• Mathematical models and computer simulations can explore the dynamics of behavioral strategies and test the predictions of evolutionary theories (agent-based models, evolutionary game theory)