NEW RESEARCH finds that killer whale grandmothers who were no longer able to reproduce had the biggest beneficial impact on the survival chances of their grand-offspring. This may be because grandmothers without calves of their own are free to focus time and resources on the latest generation, the researchers suggest. The research team also found that grandmothers had a particularly important role in times of food scarcity, as the impact on a calf of losing a postmenopausal grandmother was highest in years when salmon was scarce. These benefits to the group may help to solve the long-standing mystery of why the menopause has evolved in some species of whales and in humans, the authors of the study say.
