Human kin investment as a function of genetic relatedness and lineage

Original article:

Human kin investment as a function of genetic relatedness and lineage

Evolutionary Psychology 2: 129-141 Gregory D. Webster, Department of Psychology, Campus Box 345, University of Colorado, Boulder, Colorado 80309-0345, USA, gwebster@psych.colorado.edu

Abstract

Two independent samples of students were asked to allocate fictional lotteries of varying dollar amounts to their blood relatives. In both studies, a reliable genetic relatedness by lineage interaction emerged, such that the genetic effect was a more positive predictor of percent of money allocated for relatives of a direct lineage (e.g., parents, grandparents) than it was for peripheral relatives (e.g., siblings, aunts and uncles). In a third study, this interaction was replicated in an archival analysis of wills. The implications of accounting for differences in relatives’ lineages in studies of kin investment are discussed.

Keywords

Altruism; Genetic relatedness; Inclusive fitness; Kin investment; Lineage; Multilevel modeling; Prosocial behavior; Resource allocation

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