Sibling cooperation & the evolution of family life

What is it about?

The evolution of family life requires net benefits for offspring. These benefits are commonly assumed to derive almost exclusively from parental care. However, an additional source of benefits for offspring is often overlooked: cooperative interactions among juvenile siblings. In this study, we used the European earwig to examine how sibling cooperation and parental care could jointly contribute to the early evolution of family life. We showed that higher levels of sibling cooperation (food transfer among juveniles) were associated with lower levels of maternal care (food provisioning) and negative effects on the production of the second and terminal clutch by the tending mothers. These findings indicate that sibling cooperation could mitigate the detrimental effects on offspring survival that result from being tended by low-quality mothers.

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Why is it important?

Sibling cooperation has long been neglected, despite its potential impact on the evolution of family life. Our results support the hypothesis that sibling cooperation is an ancestral behavior that could have complemented the benefits of early forms of parental care, and can be retained in contemporary species to compensate for insufficient levels of parental investment.

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