HEalth Issue: Menopause origin

Whale study hints at menopause origin London: The evolutionary mystery of menopause is a step closer to being solved thanks to research on killer whales.        A study by Cambridge and Exeter universities has found a link between killer whales, pilot whales and humans, the only three known species where females stop breeding relatively early in their lifespan.       Despite very different social structures between the species, the study, byRufus Johnstone of the deparment of zoology at Cambridge and Michael Cant of Exeter, shows that in each case females become increasingly genetically related to those they live with as they get older.       Because of this, there is a motivation for older females to do what is best for the survival of those around them. This creates a "grand mother" role, where the success rate of breeding in the group can be helped by older females sharing parenting knowledge and stopping breeding to allow younger females easier access to resources.       The research, published in the proceedings of the Royal Society B, is the first to provide a plausible explanation as to why these species in particular are the only ones in which females finish reporduction while they still have decades left to live.        Cant, from the University of Exeter's school fo biosciences, said"Although the social behaviours of the three menopausal species are very different , there is a common link their social systems mean females become more relanted to those around them as they get older. This predisposes females. to the evolution of menopause and late-life helping."