Does paternal uncertainty explain discriminative grandparental solicitude? A cross-cultural study in Greece and Germany.

Recent research on kin investment as a reproductive strategy is based on the idea that differences in grandparental caregiving directly reflect degrees of differential grandpaternal versus grandmaternal certainty. In a cross-cultural study in Greece and Germany, 544 subjects (318 Greeks, 208 Germans, 18 of other origins) were asked for an assessment of their grandparents' (GPs') caregiving. In Germany and urban Greece (modern Western societies), the maternal GPs were rated as more intensive caregivers than the paternal GPs, but this was not the case in rural Greece, where paternal GPs provided more care. However, in all groups, grandmothers were more caring than grandfathers. Thus, contrary to previous theory and research, these two effects must be clearly distinguished, and may be explained by (1) more intense female caregiving in humans (as in other viviparous mammals) and (2) a socially engendered favoring of maternal relatives in Western industrial societies as opposed to the favoring of paternal GPs seen in the patrilateral culture of rural Greece.