Andy Gardner*, Stuart A. West

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

224 Citations (Scopus)


Greenbeards are genes that can identify the presence of copies of themselves in other individuals, and cause their bearer to behave nepotistically toward those individuals. In recent years, a number of examples have been discovered, and it has been suggested that greenbeards represent one of the fundamental routes to social behaviors such as cooperation. However, despite their possible theoretical and empirical importance, many basic aspects of greenbeard biology are commonly misunderstood. Here, we distinguish between four different types of greenbeard, which differ in their evolutionary dynamics. We show that all four types exist, and that they differ in the ease with which they can be empirically detected. We clarify the inclusive fitness explanation of greenbeards, and show that they are not intragenomic outlaws. Finally, we argue that although greenbeards are likely to be most common and easiest to detect in microorganisms, they are unlikely to important in organisms such as humans.

Original languageEnglish
Pages (from-to)25-38
Number of pages14
Issue number1
Publication statusPublished - Jan 2010


  • Altruism
  • chloropogonology
  • Hamilton's rule
  • inclusive fitness
  • kin selection
  • relatedness
  • spite
  • Social evolution theory
  • Rock-paper-scissors
  • Strong reciprocity
  • Group selection
  • Viscous population
  • Green beard
  • Cytoplasmic incompatibility


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