Phylogeny of Sexually-Selected Infanticide

Roadside foraging only exists as a consequence of the encroachment of humans and their infrastructure on grizzly territory. Though roads are novel guests in nature and grizzlies have not nibbled beside them on an evolutionary timescale, we can more generally consider this behavior as a counterstrategy to adult male infanticide, or sexually selected infanticide (SSI). [16]

Ursidae phylogenetic tree (d)

SSI in Mammals

Male mammals of many species, particularly those where females mate with many males within a mating season and over the course of their lifetime [17], commit infanticide in order to further their own reproductive fitness (hence "sexually selected") [11]. While males do sometimes kill young conspecifics in order to reduce competition or for nutritive reasons, this seems less common. Restricting our consideration to species where loss of a female's litter induces estrus cycling (as in the grizzly bear), infanticidal behavior has been documented in a staggering 60 species (twenty of which are old-world monkeys) [17].