It's typically committed by males that take over a pride or pack and kill whatever babies are present to make room for the ones they plan to father. ... There must be plenty of males to do the protecting and provisioning, and there can't be too many other females with babies of their own that also require attention.

Why do mother monkeys hurt their babies?

Mother tamarins do not have an easy job. Gestation is long — about 150 days; they usually have twins, and those twins are usually big. ... In essence, mother mustached tamarin's kill their babies when they are unlikely to survive, due to a low number of helpers and the presence of another gestating female.

Why do macaque monkeys drag their babies?

The reason why monkeys kidnap other baby monkeys, is that many female monkeys are interested in new-born babies. They will try to groom the new-born, try to touch the baby or ultimately kidnap the baby from the mother. This happens a lot between high ranking female monkeys, and low-ranking mothers and their babies.