Altruism

by

J. David Van Dyken

• LAST REVIEWED: 12 April 2023
• LAST MODIFIED: 13 January 2014
• DOI: 10.1093/obo/9780199941728-0017

Introduction

Darwin’s revolutionary insight was that evolution favors the spread of traits that increase the survival or reproduction of their bearer. Yet nature abounds in self-sacrifice. Altruism, the act of sacrificing one’s personal fitness (i.e., survival or reproduction) to increase the fitness of others, exists at all taxonomic scales, from prokaryotes to primates. Even more fundamentally, altruism is a force that creates biocomplexity. By facilitating the transition from one level of biological organization to another, such as the transition from unicellular species to metazoans, altruism is responsible for constructing the hierarchical structure of the living world. Fitting altruism into the Darwinian paradigm vexed Darwin himself, and it has challenged evolutionists for well over a century. How can the defensive sting of a worker bee, an act of suicide, help the bee survive and reproduce? How can a nature “red in tooth and claw” brook the existence of helping and self-sacrifice? Not until the work of W. D. Hamilton in the 1960s did we begin to comprehend the existence of self-sacrifice in a selfish world. Hamilton derived a succinct mathematical statement specifying the conditions necessary for altruism to spread in a population by natural selection. “Hamilton’s rule” states that altruism evolves provided that br – c > 0. That is, it evolves provided the fitness benefit, b, gained by recipients of an altruistic act, weighted by the relatedness, r, between altruist and recipient, exceeds the fitness cost to the altruist, c. The partitioning of fitness into direct (c) and indirect (br) components, as well as the introduction of relatedness as a central determinant of the rate and direction of social evolution, revolutionized evolutionary biology. Moreover, Hamilton’s analysis laid the foundation for all subsequent research on the evolution of altruism.

General Overviews

Hamilton’s original work on altruism evolution ignited an explosion of research, both theoretical and empirical, into the evolution of altruism. Despite the abundance of work in this field, general overviews of altruism evolution are difficult to find. Most books and reviews on the subject are fairly specialized, focusing on a single narrow perspective (see Conceptual Frameworks). Volume 1 of Hamilton 1998 is a compendium of Hamilton’s classic papers on altruism evolution intercalated with Hamilton’s autobiographical musings on his work, providing invaluable historical context. Several books provide an introduction to the conceptual and theoretical foundations of altruism evolution. McElreath and Boyd 2007 provides an accessible theoretical introduction to social evolution. Bourke 2011 provides an overview of inclusive fitness theory, while Sober and Wilson 1998 gives an introduction to group selection theory with application to human psychology. Bowles and Gintis 2011 reviews work on human altruism with a focus on the role of game theory in understanding sociality. A number of papers are also useful. Nowak 2006 gives a synthetic review of social evolution theory integrating a number of distinct mechanisms. West, et al. 2007 provides a conceptual and empirical overviews of altruism evolution, with a focus on inclusive fitness theory. Strassman and Queller 2011 provides an overview of major issues in altruism evolution from the perspective of a unicellular eukaryote, while Fehr and Fischbacher 2003 does the same for humans.

• Bourke, A. F. G. 2011. Principles of social evolution. New York: Oxford Univ. Press.

  This book provides a good overview of inclusive fitness theory, primarily through the lens of the major evolutionary transitions in organismal complexity.

• Bowles, S., and H. Gintis. 2011. A cooperative species: Human reciprocity and its evolution. Princeton, NJ: Princeton Univ. Press.

  An integrative book reviewing current research on the evolution of altruism in humans, seamlessly weaving together empirical and theoretical work from game theory, experimental economics, and anthropology.

• Fehr, E., and U. Fischbacher. 2003. The nature of human altruism. Nature 425.6960: 785–791.

  DOI: 10.1038/nature02043

  This article reviews experimental work on altruism in humans. It provides an overview of the various mechanisms of altruism evolution, including reciprocity, punishment, and gene-culture coevolution, and reviews empirical work on each front.

• Hamilton, W. D. 1998. Narrow roads of gene land. Vol. 1, Evolution of social behaviour. Basingstoke, UK: W. H. Freeman.

  This indispensable resource collects all of the major papers by Hamilton on the evolution of altruism, and includes introductions to each paper by the author.

• McElreath, R., and R. Boyd. 2007. Mathematical models of social evolution: A guide for the perplexed. Chicago: Univ. of Chicago Press.

  DOI: 10.7208/chicago/9780226558288.001.0001

  This book offers a clear, pedagogical introduction to the theory of social evolution that is appropriate for an audience ranging from advanced undergraduates up to practicing researchers. Problem sets with solutions make this an ideal teaching text.

• Nowak, M. A. 2006. Five rules for the evolution of cooperation. Science 314.5805: 1560–1563.

  DOI: 10.1126/science.1133755

  A synthetic review of social evolution theory, showing the connection between various mechanisms known to promote the evolution of cooperation, including relatedness, reciprocity and multilevel selection.

• Sober, E., and D. S. Wilson. 1998. Unto others: The evolution and psychology of unselfish behavior. Cambridge, MA: Harvard Univ. Press.

  This book provides a nice introduction to the history of the group selection controversy, as well as a thorough defense of group selection. The second half of the book is an application of the theoretical, biological, and evolutionary implications of altruism by group selection for our understanding of altruism in human psychology.

• Strassman, J. E., and D. C. Queller. 2011. Evolution of cooperation and control of cheating in a social microbe. Proceedings of the National Academy of Sciences of the United States of America 108:10855–10862.

  DOI: 10.1073/pnas.1102451108

  This paper reviews social behavior in the unicellular slime mold, Dictystelium discoideum, a model system for the study of altruism, providing a broad overview of research in altruism evolution.

• West, S. A., A. S. Griffin, and A. Gardner. 2007. Evolutionary explanations for cooperation. Current Biology 17.16: R661–R672.

  This paper reviews both theoretical and empirical work on the evolution of altruism, providing a succinct overview of the field from the perspective of inclusive fitness theory.