Ontogeny and phylogeny of mating behaviour: social heteroch rony in primates.

Based on the Recognition Concept of species, the specific-mate contact model posits that mating systems develop as combinations of two fundamental courtship strategies that we interpret here in terms of behavioural heterochrony: territorial mate-attraction evolved as an effect of peramorphosis whereas group-living mate-seeking evolved as an effect of paedomorphosis. We tested this hypothesis on primates in a phylogenetic and paleo-climatic context. Our results suggest that primate promiscuity (both males and females are mate-seekers) evolved with group-living from ancestral pair-living monogamy (both males and females are mate-attractors) in the Palaeogene, as the result of a slowdown in growth (neoteny) caused by increased environmental predictability. A secondary return to territorial monogamy probably evolved as the result of accelerated growth driven by seasonality (acceleration). Polygamy evolved in the Neogene during periods of forest fragmentation and environmental unpredictability. Small monogamous ancestors evolved seasonal polyandry (female attraction) as an effect of truncated development (progenesis). Large promiscuous, neotenic ancestors evolved non-seasonal polygyny (male attraction) as an effect of prolonged development (hypermorphosis) in males. We conclude that social heterochrony offers alternative explanations for the coevolution of life history and mating be-haviour; and we discuss the implications of our model for human social evolution.