title: Kin-selected cooperation without lifetime monogamy: human insights and animal implications.
abstract: Recent phylogenetic analyses suggest that monogamy precedes the evolution of cooperative breeding involving non-breeding helpers. The rationale: only through monogamy can helper-recipient relatedness coefficients match those of parent-offspring. Given that humans are cooperative breeders, these studies imply a monogamy bottleneck during hominin evolution. However, evidence from multiple sources is not compelling. In reconciliation, we propose that selection against cooperative breeding under alternative mating patterns will be mitigated by: (i) kin discrimination, (ii) reduced birth-intervals, and (iii) constraints on independent breeding, particularly for premature and post-fertile individuals. We suggest that such alternatives require consideration to derive a complete picture of the selection pressures acting on the evolution of cooperative breeding in humans and other animals.
authors.affiliation: Department of Anthropology, University of Utah, Salt Lake City, UT 84112, USA; Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Kramer
authors.affiliation: Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9FE, UK. Electronic address: a.russell@exeter.ac.uk.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Russell
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003299:Cooperative Behavior; D015186:Hominidae; D006801:Humans; D010152:Pair Bond; D010802:Phylogeny; D012725:Sexual Behavior; D012726:Sexual Behavior, Animal; D012919:Social Behavior
keywords: alloparenting; interbirth intervals; juvenile helpers and grandmothers; kin discrimination; mating system; monogamy hypothesis