In dolphin “families”, positive social interactions are more than twice as important as good genes in determining successful reproduction.

Researchers have known for a long time that dolphins associate in something like human “mums’ clubs”. How important is this for successful reproduction compared with the importance of having good genes?

It turns out that both of them matter. Researchers found that the females who have successful relatives and successful “friends” are much better at producing calves than they would have expected from simply adding the effects of the relatives and the effects of their peer group.