Female cheating may be a byproduct of genetic variants that promote cheating in males, according to a new study on zebra finches. Paired-up male finches who tried cheating with other females had the same genetic variants as female finches who were more prone to cheating.
The researchers imply the findings may be relevant to humans. 'In humans, individual differences in attachment style, fidelity and sociosexuality are known to have a hereditary basis', says the study published in the Proceedings of the National Academy of Sciences.
A study by US researchers on university students last year found a genetic variant in the dopamine receptor gene, DRD4, was linked to higher rates of promiscuity.
The findings also tackle a puzzle that has perplexed scientists - why some paired-up female zebra finches mate with other males when there's no clear evolutionary benefit. Cheating can lead to sexually transmitted diseases and the cuckolded male neglecting the female's chicks.
According to the scientists who carried out the study: 'Individual zebra finches are known to differ markedly in their readiness to court unfamiliar females. These consistent individual differences in courtship rate are partly genetic and affect male success in obtaining extra-pair copulations, not because these males differ in their attractiveness to females, but because of individual differences in the number of extra-pair copulation attempts'.
Scientists working at the Max-Planck Institute in Germany observed over 1,500 zebra finches living in captivity over five generations. The finches were marked by different colour bands, allowing scientists to differentiate between individuals. By videoing the finches they could determine how successful sex in monogamous female birds was, both with their partner, 'within-pair', or with a different partner, 'extra-pair'.