title: Historical perspectives and a focus on fitness.
authors: Department of Animal & Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK. b.hatchwell@sheffield.ac.uk
authors: Ben J
authors: BJ
authors: Hatchwell
mesh_terms: D000222:Adaptation, Physiological; D000533:Altruism; D000818:Animals; D001522:Behavior, Animal; D003299:Cooperative Behavior; D006379:Helping Behavior; D012098:Reproduction; D012641:Selection, Genetic; D012726:Sexual Behavior, Animal