Human behavioral ecology
Human behavioral ecology (HBE) or human evolutionary ecology applies the principles of evolutionary theory and optimization to the study of human behavioral and cultural diversity. HBE examines the adaptive design of traits, behaviors, and life histories of humans in an ecological context. One aim of modern human behavioral ecology is to determine how ecological and social factors influence and shape behavioral flexibility within and between human populations. Among other things, HBE attempts to explain variation in human behavior as adaptive solutions to the competing life-history demands of growth, development, reproduction, parental care, and mate acquisition. HBE  overlaps with evolutionary psychology, human or cultural ecology, and decision theory. It is most prominent in disciplines such as anthropology and psychology where human evolution is considered relevant for a holistic understanding of human behavior or in economics where self-interest, methodological individualism, and maximization are key elements in modeling behavioral responses to various ecological factors. Evolutionary theory. Human behavioral ecology rests upon a foundation of evolutionary theory. This includes aspects of both general evolutionary theory and established middle-level evolutionary theories, as well. Aspects of general evolutionary theory include: Middle-level evolutionary theories used in HBE include: Basic principles . Ecological selectionism. Ecological selectionism refers to the assumption that humans are highly flexible in their behaviors. Furthermore, it assumes that various ecological forces select for various behaviors that optimize humans' inclusive fitness in their given ecological context. The piecemeal approach. The piecemeal approach refers to taking a reductionist approach as opposed to a holistic approach in studying human socioecological behavior. Human behavioral ecologists assume that by taking complex social phenomena, (e.g., marriage patterns, foraging behaviors, etc.), and then breaking them down into sets of components involving decisions and constraints that they are in a better position to create models and  make predictions involving human behavior. An example would be examining marriage systems by examining the ecological context, mate preferences, the distribution of particular characteristics within the population, and so forth. Conditional strategies. Human behavioral ecologists assume that what might be the most adaptive strategy in one environment might not be the most adaptive strategy in another environment. Conditional strategies, therefore, can be represented in the following statement: The phenotypic gambit. The phenotypic gambit refers to the simplifying assumption that complex traits, such as behavioural traits, can be modelled as if they were controlled by single distinct alleles, representing alternate strategies . In other words, the phenotypic gambit assumes that "selection will favour traits with high fitness ...irrespective of the particulars of inheritance." Modeling. Theoretical models that human behavioral ecologists employ include, but are not limited to: