Human Behavioral Ecology - Evolutionary Theory

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:

• Natural selection, the process by which individual organisms with favorable traits are more likely to survive and reproduce.
• Sexual selection, the theory that competition for mates between individuals of the same sex results in differential mating and reproduction.
• Kin selection, the changes in gene frequency across generations that are driven at least in part by interactions between related individuals, and
• Inclusive fitness, the sum of an individual's own reproductive success, (natural and sexual selection), plus the effects the individual's actions have on the reproductive success of that individual's kin, (kin selection).

Middle-level evolutionary theories used in HBE include:

• The theory of parental investment, which predicts that the sex making the largest investment in lactation, nurturing and protecting offspring will be more discriminating in mating and that the sex that invests less in offspring will compete for access to the higher investing sex.
• Parent-offspring conflict, which predicts that because the genetic interests of parents and offspring are not identical, offspring will be selected to manipulate their parents in order to ensure higher investment, and that, conversely, parents will be selected to manipulate their offspring.
• The theory of reciprocal altruism, a form of altruism in which one organism provides a benefit to another in the expectation of future reciprocation.
• The Trivers–Willard hypothesis, which proposes that parents should invest more in the sex that gives them the greatest reproductive payoff (grandchildren) with increasing or marginal investment.
• r/K selection theory, which, in ecology, relates to the selection of traits in organisms that allow success in particular environments. r-selected species - in unstable or unpredictable environments - produce many offspring, any individual one of which is unlikely to survive to adulthood, while K-selected species - in stable or predictable environments - invest more heavily in fewer offspring, each of which has a better chance of surviving to adulthood.
• Evolutionary game theory, the application of population genetics-inspired models of change in gene frequency in populations to game theory.
• Evolutionary stable strategy, which refers to a strategy, which if adopted by a population, cannot be invaded by any competing alternative strategy.