Abstract:

Grandparenting which is an important part of alloparenting for the prolonged development of human children has been practiced in both traditional and modern societies. We review the relevant evolutionary psychology literature to highlight some of the characteristics of human grandparenting. Among some of the well observed characteristics are the lineage differences in grandparenting. Specifically, maternal grandparents seem to invest more than paternal grandparents, and female grandparents seem to invest more than male grandparents. This observation is in line with the paternity uncertainty hypothesis whereby paternal parenting is regulated by paternity doubt a male parent has over his offspring. Less widely observed are emerging evidence suggesting grandparental investment differences due to the grandchild’s sex. This observation is explained by the sex-chromosome hypothesis in that a woman is least related to her paternal grandson, equally related to her maternal grandson and granddaughter, and most related to her paternal granddaughter. Other variables such as residential proximity and patrilocality may also shape the grandparental investment. Future studies should take the intergenerational conflict perspective to investigate inclusive fitness of grandparents and their grandchildren.

Key words: grandparental investment, pertanity uncertainty, lineage bias, sex bias, parental investment theory, kin selection theory, evolutionary psychology