An Evolutionary Perspective on Siblings: Rivals and Resources

Thomas V. Pollet and Ashley D. Hoben

in The Oxford Handbook of Evolutionary Family Psychology

Published in print May 2011 | ISBN: 9780195396690
Published online November 2012 | | DOI:

Series: Oxford Library of Psychology

An Evolutionary Perspective on Siblings: Rivals and Resources

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  • Psychology
  • Social Psychology
  • Developmental Psychology



In this chapter, we examine two important questions in evolutionary psychology pertaining to the study of sibling relationships. These questions are: Which mechanisms assist in the detection of kin generally, and siblings, in particular? And, which selection pressures played a key role in determining whether an individual helps or competes with a sibling? One area of biological literature views siblings as rivals, whereas another views them as important resources. Using the tools of kin selection theory, parent–offspring conflict theory, and parental investment theory, we review the evidence for the view that human sibling relationships can be typified in terms of rivalry or mutualism. We discuss important factors, such as birth spacing and gender, for example, which determine when siblings are rivals and when they are resources. Our conclusion is that, although sibling competition is widespread and can be fierce both during development and in adulthood, siblings are also an important resource throughout one’s life. Yet, the degree to which siblings are rivals or resources is dependent on many contextual factors, such as gender, birth order, and reproductive value. Finally, we conclude by discussing future directions for research on sibling relationships from an evolutionary point of view.

Keywords: Sibling ties; sibling rivalry; kin selection theory; helpers-at-the-nest; genetic relatedness

Article.  16368 words. 

Subjects: Psychology ; Social Psychology ; Developmental Psychology

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