Adaptive suicide: is a kin-selected driver of fatal behaviours likely?

Rosalind K. Humphreys*, Graeme D. Ruxton

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

2 Citations (Scopus)
6 Downloads (Pure)


While several manipulated host behaviours are accepted as extended phenotypes of parasites, there remains debate over whether other altered behaviours in hosts following parasitic invasion represent cases of parasite manipulation, host defence or the pathology of infection. One particularly controversial subject is 'suicidal behaviour' in infected hosts. The host-suicide hypothesis proposes that host death benefits hosts doomed to reduced direct fitness by protecting kin from parasitism and therefore increasing inclusive fitness. However, adaptive suicide has been difficult to demonstrate conclusively as a host adaptation in studies on social or clonal insects, for whom high relatedness should enable greater inclusive fitness benefits. Following discussion of empirical and theoretical works from a behavioural ecology perspective, this review finds that the most persuasive evidence for selection of adaptive suicide comes from bacteria. Despite a focus on parasites, driven by the existing literature, the potential for the evolution of adaptive suicidal behaviour in hosts is also considered to apply to cases of infection by pathogens, provided that the disease has a severe effect on direct fitness and that suicidal behaviour can affect pathogen transmission dynamics. Suggestions are made for future research and a broadening of the possible implications for coevolution between parasites and hosts.

Original languageEnglish
Article number20180823
JournalBiology Letters
Issue number2
Publication statusPublished - 27 Feb 2019


  • Adaptive suicide
  • Behavioural ecology
  • Evolution
  • Host suicide hypothesis
  • Inclusive fitness
  • Parasitism


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