title: Mother's little helpers: What we know (and don't know) about cooperative infant care in callitrichines.
abstract: Since Darwin (), scientists have been puzzled by how behaviors that impose fitness costs on helpers while benefiting their competitors could evolve through natural selection. Hamilton's () theory of inclusive fitness provided an explanation by showing how cooperative behaviors could be adaptive if directed at closely related kin. Recent studies, however, have begun to question whether kin selection is sufficient to explain cooperative behavior in some species (Bergmüller, Johnstone, Russell, & Bshary, ). Many researchers have instead emphasized the importance of direct fitness benefits for helpers in the evolution of cooperative breeding systems. Furthermore, individuals can vary in who, when, and how much they help, and the factors that affect this variation are poorly understood (Cockburn, ; Heinsohn, ). Cooperative breeders thus provide excellent models for the study of evolutionary theories of cooperation and conflict (Cant, ).
authors.affiliation: Department of Anthropology, Rutgers University, New Brunswick, New Jersey, 08901, USA.|The Center for Human Evolutionary Studies, Rutgers University, New Brunswick, New Jersey, 08901.
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Erb
authors.affiliation: Department of Anthropology, Northern Illinois University, Dekalb, Illinois, 08901.
authors.forename: Leila M
authors.initials: LM
authors.lastname: Porter
mesh_terms: D000818:Animals; D000885:Anthropology, Physical; D005075:Biological Evolution; D002143:Callitrichinae / Q000502:physiology*; D003299:Cooperative Behavior; D005260:Female; D008297:Male; D008425:Maternal Behavior; D012641:Selection, Genetic
keywords: allocare; cooperative breeding; kin selection; marmosets; tamarins