Grandparental investment : a relic of the past or a resource for the future?

From changing diapers and minding the kids when school is out to providing support when they set fire to the carpet, grandparents can be invaluable to have around. What motivates grandparents to lend a hand? Several disciplines have offered answers. The most important accounts come from life-history theory and evolutionary psychology, sociology, and economics. These accounts exist side-by-side, but there is little theoretical integration among them. But regardless of whether grandparental investment is traced back to ancestral selection pressure or attributed to an individual grandparent’s values or norms, one important question is, What impact does it have in industrialized, low-fertility, low-mortality societies? We briefly review the initial evidence concerning the impact of grandparental investment in industrialized societies and conclude that in difficult circumstances, grandparents can provide the support that safeguards their grandchildren’s development. Additional cross-disciplinary research to examine the effects of intergenerational transfers in our evolutionarily unique environment of grandparenthood is needed.