A new study of a cooperative bird in the Kalahari Desert suggests that unequal sharing of workloads in societies could leave the most industrious individuals at higher risk of poor health and prone to accelerated ageing.
A team of scientists at the University of Exeter studied white-browed sparrow weavers, a social species in which all group members share offspring care duties, but the dominant male and female work hardest.
Dominants are the only birds that breed, with dominant males singing to attract a mate and dominant females producing all of the eggs and providing most of the care for nestlings.
Both dominants also invest most in fiercely defending the group's territory. In order to assess how these unequal workloads impact the health of the birds, the researchers measured the level of antioxidant protection in 93 sparrow weavers before and then again after a long breeding season.