Asymmetric Caregiving by Grandparents,Aunts,and Uncles and the Theories of Kin Selection and Paternity Certainty: How Does Evolution Explain Human Behavior Toward Close Relatives?

Abstract

Evolutionary theories explain altruism between related individuals, not only for nonhuman animals but also humans themselves. In sociobiology and evolutionary psychology, the supposedly universally found stronger matrilineal kin caregiving by grandparents, aunts, and uncles is often explained by paternity uncertainty in the male descent line. The present article provides an overview of theories and results of the evolutionary research. I will focus, in particular, on the universal caregiving pattern as well as on cultural variety in kin caregiving, the role of actual paternity certainty in the society, theoretical inconsistencies, and nonconsanguineous step relationships. From the analysis of the empirical data, I will conclude that the paternity certainty hypothesis is in fact not a very suitable explanation for the asymmetric kin caregiving found in humans. I will discuss how human behavior toward relatives, in particular grandchildren, can be alternatively explained from an evolutionary perspective.