Whether male Dayak fruit bats actually suckle their young remains to been seen. However, the discovery by Kunz and his colleagues raises at least the possibility of a male mammal caring for its young single-handedly, a scenario that had previously been considered impossible. Conventional wisdom has long been that female mammals must necessarily care for their young by virtue of their mammary glands. But about five percent of mammal species exhibit at least some paternal care. Such behavior is most common among rodents, carnivores, and primates, and the lion's share of species with paternal care are monogamous, an arrangement that may give males a greater assurance of paternity.
Mammalian males can be very dedicated parents.
Among primates, New World monkeys exhibit the most extensive male care. The extensive parental care given by male prairie voles presumably helps females have litters in rapid succession, which benefits males by increasing their reproductive success. Unlike mammals, females in other classes of animals are not physiologically bound to care for their young. Even so, females usually provide what care there is in non-mammalian species. Most invertebrates simply lay huge numbers of eggs and trust that some of the young will survive long enough to reproduce.