Core set of genes explain why some animals stick to one mate at a time

mimic poison frog

The mimic poison frog is monogamous

Anton Sorokin/Alamy

A common set of genes may determine whether all sorts of animals – from mice to fish – mate with one partner or many.

Rebecca Young and Hans Hofmann of the University of Texas at Austin and colleagues looked at which genes are turned on in the brains of males in five pairs of closely related species: two mice, two voles, two songbirds, two frogs and two cichlid fish. Each pair included one monogamous species and one non-monogamous species.

They analysed the patterns of gene expression to look for genes that …