Journal of Biosocial Science

Articles

TESTING EVOLUTIONARY THEORIES OF DISCRIMINATIVE GRANDPARENTAL INVESTMENT

RALF KAPTIJNa1, FLEUR THOMESEa1, AART C. LIEFBROERa1a2 and MERRIL SILVERSTEINa3

a1 VU University Amsterdam, the Netherlands

a2 Netherlands Interdisciplinary Demographic Institute, The Hague, the Netherlands

a3 University of Southern California, Los Angeles, USA

Summary

This study tests two evolutionary hypotheses on grandparental investments differentiated by the child's sex: the paternity uncertainty hypothesis and the Trivers–Willard hypothesis. Data are from two culturally different countries: the Dutch Longitudinal Aging Study Amsterdam (n=2375) and the Chinese Anhui Survey (n=4026). In the Netherlands, grandparental investments are biased towards daughters' children, which is in accordance with the paternity uncertainty hypothesis. But in China, grandparental investments are biased towards sons' children, which is in conflict with the paternity uncertainty hypothesis. This study found no support for the Trivers–Willard hypothesis. These results raise doubts over the relevance of paternity uncertainty as an explanation of a grandparental investment bias towards daughters' children that is often found in Western populations. The results suggest that discriminative grandparental investments are better understood as the outcome of cultural prescriptions and economic motives.

(Online publication November 15 2012)

Metrics