Another possibility would be for this behavior to come from grooming behavior in primates, during which (in many species?) lice and other stuff found on the skin seems to be eaten. In that case there is some clear advantage to eating the lice because it may otherwise infect another nearby individual.
Another possibility would be for this behavior to come from grooming behavior in primates, during which (in many species?) lice and other stuff found on the skin seems to be eaten. In that case there is some clear advantage to eating the lice because it may otherwise infect another nearby individual.