Experimental administration of stress hormones to meerkat helpers does not affect their contributions to cooperative activities. Previous work on cooperative breeders suggested that levels of stress hormones are related to helping behavior. We tested this experimentally by injecting meerkat helpers with cortisol, whilst matched controls received a saline injection. This did not lead to changes in cooperative behaviour, but induced females, and not males, to spend more time near pups and less time foragin
