Grandma, what a big and fickle metaphor you can be! For children, the name translates as 'the magnificent one with presents in her suitcase who thinks I'm a genius if I put my shoes on the right feet, and who stuffs me with cookies the moment my parents' backs are turned.' In news reports, to call a woman 'grandmotherly' is shorthand for 'kindly, frail, harmless, keeper of the family antimacassars, and operationally past tense.' For anthropologists and ethnographers of yore, grandmothers were crones, an impediment to 'real' research. The renowned ethnographer Charles William Merton Hart, who in the 1920's studied the Tiwi hunter-gatherers of Australia, described the elder females there as 'a terrible nuisance' and 'physically quite revolting' and in whose company he was distressed to find himself on occasion, yet whose activities did not merit recording or analyzing with anything like the attention he paid to the men, the young women, even the children. But for a growing number of evolutionary biologists and cultural anthropologists, grandmothers represent a key to understanding human prehistory, and the particulars of why we are as we are —slow to grow up and start breeding but remarkably fruitful once we get there, empathetic and generous as animals go, and family-focused to a degree hardly seen elsewhere in the primate order. As a result, biologists, evolutionary anthropologists, sociologists and demographers are starting to pay more attention to grandmothers: what they did in the past, whether and how they made a difference to their families' welfare, and what they are up to now in a sampling of cultures around the world. At a recent international conference —the first devoted to grandmothers —researchers concluded with something approaching a consensus that grandmothers in particular, and elder female kin in general, have been an underrated source of power and sway in our evolutionary heritage. Grandmothers, they said, are in a distinctive evolutionary category. They are no longer reproductively active themselves, as older males may struggle to be, but they often have many hale years ahead of them and as the existence of substantial proportions of older adults among even the most 'primitive' cultures indicates, such durability is nothing new. If, over the span of human evolution, postmenopausal women have not been using their Stalwart bodies for bearing babies, they very likely have been directing their considerable energies elsewhere. Say, over the river and through the woods. It turns out that there is a reason children are perpetually yearning for the flourdusted, mythical figure called grandma or granny or oma or abuelita. As a number of participants at the conference demonstrated, the presence or absence of a grandmother often spelled the difference in traditional subsistence cultures between life or death for the grandchildren. In fact, having a grandmother around sometimes improved a child's prospects to a far greater extent than did the presence of a father. Dr. Ruth Mace and Dr. Rebecca Sear of the department of anthropology at University College in London, for example, analyzed demographic information from rural Gambia that was collected from 1950 to 1974, when child mortality rates in the area were so high that even minor discrepancies in care could be all too readily tallied. The anthropologists found that for Gambian toddlers, weaned from the protective balm of breast milk but not yet possessing strength and immune vigor of their own, the presence of a grandmother cut their chances of dying in half. 'The surprising result to us was that if the father was alive or dead didn't matter,' Dr. Mace said in a telephone interview. 'If the grandmother dies, you notice it if the father does, you don't.' Importantly, this beneficent granny effect derived only from maternal grandmothers —the mother of one's mother. The p