The surprising reason female mongooses start wars - and what it reveals about group survival

"The banded mongoose lives in sub-Saharan Africa. It has a long, bulky body and a pointed face, kind of like a ferret on steroids. There are many species of mongoose, but this one has dark stripes across its lower back and haunches."

"In western Uganda, where University of Exeter evolutionary biologist Michael Cant studies them, the banded mongooses live in extended families of 10 to 20 adults, plus their children. These families are highly cooperative when it comes to raising the pups."

"Among other cooperatively breeding species, such as the marmosets and tamarins, it's common for a group to include an alpha female or couple, who do most or all of the breeding. Helpers aren't supposed to have babies. The enforcement of this policy can be brutal: Dominant meerkat females, for instance, may forcibly evict their sisters or daughters who become pregnant."

"But among the banded mongooses, any female can breed. The group's older females do sometimes kill pups that aren't their own. More often, though, the mongooses avoid this hazard with a neat trick they've evolved: They synchronize their births. In one study, 64 percent of the time, the mongooses managed it perfectly. No matter when they'd gotten pregnant, every female in the group gave birth on the same night."

Banded mongooses in sub-Saharan Africa live in extended families of 10 to 20 adults plus their children. These groups cooperate in raising pups. In many cooperatively breeding mammals, only an alpha pair breeds while helpers are prevented from reproducing, sometimes through harsh enforcement. Banded mongooses differ because any female can breed. Older females may kill unrelated pups, but the group often avoids this by synchronizing births. In one study, 64 percent of the time all females in a group gave birth on the same night, regardless of when they became pregnant. The mechanism is not fully known, but pheromones are likely involved, leaving mothers unable to identify their own offspring among multiple litters.

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