Handicap principle

Photo of a peacock with its enormous tail
The peacock tail in flight, a classic example of what Amotz Zahavi proposed was a handicapped signal of male quality[1]

The handicap principle is a disputed hypothesis proposed by the Israeli biologist Amotz Zahavi in 1975. It is meant to explain how "signal selection" during mate choice may lead to "honest" or reliable signalling between male and female animals which have an obvious motivation to bluff or deceive each other.[2][3][4] The handicap principle suggests that secondary sexual characteristics are costly signals which must be reliable, as they cost the signaller resources that individuals with less of a particular trait could not afford. The handicap principle further proposes that animals of greater biological fitness signal this through handicapping behaviour, or morphology that effectively lowers overall fitness. The central idea is that sexually selected traits function like conspicuous consumption, signalling the ability to afford to squander a resource. Receivers then know that the signal indicates quality, because inferior-quality signallers are unable to produce such wastefully extravagant signals.[5][6][7][8][9]

The handicap principle is supported by game theory modelling representing situations such as nestlings begging for food, predator-deterrent signalling, and threat displays. However, honest signals are not necessarily costly, undermining the theoretical basis for the handicap principle, which remains unconfirmed by empirical evidence.

  1. ^ Cite error: The named reference Grafen 1990 was invoked but never defined (see the help page).
  2. ^ Zahavi, Amotz (1975). "Mate selection—A selection for a handicap". Journal of Theoretical Biology. 53 (1). Elsevier BV: 205–214. Bibcode:1975JThBi..53..205Z. doi:10.1016/0022-5193(75)90111-3. ISSN 0022-5193. PMID 1195756.
  3. ^ Zahavi, Amotz (1977). "The cost of honesty". Journal of Theoretical Biology. 67 (3). Elsevier BV: 603–605. Bibcode:1977JThBi..67..603Z. doi:10.1016/0022-5193(77)90061-3. ISSN 0022-5193. PMID 904334.
  4. ^ Zahavi, Amotz; Zahavi, Avishag (1997). The handicap principle: a missing piece of Darwin's puzzle (PDF). New York: Oxford University Press. ISBN 978-0-19-510035-8. OCLC 35360821.
  5. ^ Cite error: The named reference Davis 1976 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Eshel 1978 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Kirkpatrick 1986 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Pomiankowski 1987 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Maynard Smith 1976 was invoked but never defined (see the help page).