Life and death of a disabled wild capuchin monkey infant.

The evolutionary roots of care for injured, ill, and disabled group members remain unclear. The same can be said about care for dying and dead group members. Accumulating case reports in a variety of nonhuman primates can shed light on these origins. Here we provide a detailed account of interactions of a wild capuchin monkey mother and other group members with a disabled infant before and after its death. Limb disability caused the infant to be in unstable positions when carried, which appeared to increase the frequency of body readjustments by the adults and may have contributed to its death. After death, no adults other than the mother made contact with the corpse, but four immatures approached and touched it. The mother foraged only on flies surrounding the corpse while carrying it, stopped several times to set the corpse down on the branches, and let it finally fall as she leapt between trees. The difficulty of carrying disabled and dead individuals up in the trees may help to explain the scarcity of reports in platyrrhines, and suggests that terrestriality and increasing ease of bipedality may have contributed to the evolution of these behaviors in primates.