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Encyclopedia > Handicap principle
The Peacock's train, the classic example of a handicapped signal of male quality.

The handicap principle is a hypothesis originally proposed in 1975 by biologist Amotz Zahavi[1][2][3] to explain how evolution may lead to "honest" or reliable communication between animals who have an obvious motivation to bluff or deceive each other. The handicap principle suggests that reliable signals must be costly to the signaller, costing the signaller in the trait being signalled in a manner that an individual with less of that trait could not afford. For example, in the case of sexual selection, the theory suggests that animals of greater biological fitness communicate this status through handicapping behaviour or morphology that effectively lowers this quality. The central idea is that sexually selected traits function like conspicuous consumption, signalling the ability to afford to squander a resource simply by squandering it. Receivers know that the signal indicates quality because inferior quality signallers cannot afford to produce such wastefully extravagant signals. Image File history File links Download high-resolution version (1067x1600, 1092 KB) Peacock front view, Melbourne Zoo If you are a (commercial) publisher and you want me to write you an email or paper mail giving you an authorization to use my works in your products or a license with... Image File history File links Download high-resolution version (1067x1600, 1092 KB) Peacock front view, Melbourne Zoo If you are a (commercial) publisher and you want me to write you an email or paper mail giving you an authorization to use my works in your products or a license with... Look up Hypothesis in Wiktionary, the free dictionary. ... Year 1975 (MCMLXXV) was a common year starting on Wednesday (link will display full calendar) of the Gregorian calendar. ... For other uses, see Biology (disambiguation). ... Amotz Zahavi is an Israeli Evolutionary Biologist from Tel-Aviv University, and one of the founders of the Israeli Society for the Protection of Nature. ... This article is about evolution in biology. ... Animal communication is any behaviour on the part of one animal that has an effect on the current or future behaviour of another animal. ... Illustration from The Descent of Man and Selection in Relation to Sex by Charles Darwin showing the Tufted Coquette Lophornis ornatus, female on left, ornamented male on right. ... Fitness (often denoted in population genetics models) is a central concept in evolutionary theory. ... Within evolutionary biology, signalling theory refers to the scientific theory around how organisms signal their condition to others. ... This article does not cite any references or sources. ... The term morphology in biology refers to the outward appearance (shape, structure, colour, pattern) of an organism or taxon and its component parts. ... Illustration from The Descent of Man and Selection in Relation to Sex by Charles Darwin showing the Tufted Coquette Lophornis ornatus, female on left, ornamented male on right. ... Conspicuous consumption is a term used to describe the lavish spending on goods and services that are acquired mainly for the purpose of displaying income or wealth. ...


The generality of the phenomenon is the matter of some debate and disagreement, and Zahavi's views on the scope and importance of handicaps in biology remain outside the mainstream.[4] Nevertheless, the idea has been very influential,[5][6][7] with most researchers in the field believing that the theory explains some aspects of animal communication.

Contents

Handicap models

Johnstone's 1997[5] graphical representation of a Zahavian handicap. Where CL is cost to a low quality signaller and CH is cost to a high quality signaller. Optimal signalling levels are for a low quality signaller, and for a high quality signaller.

Though the idea was initially controversial[8][9][10][11] (John Maynard Smith being one notable early critic of Zahavi's ideas[12][13][14]) it has gained wider acceptance due to supporting game theoretic models, most notably Alan Grafen's signalling game model.[15] Grafen's model is essentially a rediscovery of Michael Spence's job market signalling model,[16] where the signalled trait was conceived as a courting male's quality, signalled by investment in an extravagant trait -such as the peacock's tail- rather than an employee signalling their quality by way of an expensive education. In both cases, it is the decreased cost to higher quality signallers of producing increased signal that stabilizes the reliability of the signal (Fig. 2). Further formal game theoretical signalling models demonstrated the evolutionary stability of handicapped signals in nestling begging calls[17] predator deterrent signals[18] and threat displays.[19][20] In the classic handicapped models of begging, all players are assumed to pay the same amount to produce a signal of a given level of intensity, but differ in the relative value of eliciting the desired response (donation) from the receiver (Fig. 3). Professor John Maynard Smith[1], F.R.S. (6 January 1920 – 19 April 2004) was a British evolutionary biologist and geneticist. ... For other uses, see Game theory (disambiguation) and Game (disambiguation). ... An extensive form representation of a signalling game Signaling games are dynamic games with two players, the sender (S) and the receiver (R). ... Michael Spence (born November 7, 1943) is an American-born, Canadian-raised economist and recipient of the 2001 Nobel Memorial Prize in Economics, along with George A. Akerlof and Joseph E. Stiglitz, for their work on the dynamics of information flows and market development. ... In economics, more precisely in contract theory, signaling is the idea that one party (termed the agent) conveys some meaningful information about itself to another party (the principal). ... Peacock re-directs here; for alternate uses see Peacock (disambiguation). ... In game theory, an evolutionarily stable strategy (or ESS; also evolutionary stable strategy) is a strategy which if adopted by a population cannot be invaded by any competing alternative strategy. ...

Johnstone's 1997[5] graphical representation of a handicapped signal of need. Where BL and BH are the benefits to Low and High motivated signallers. Optimal signalling levels are for a low motivation signaller, and for a high motivation signaller

Counter-examples to handicap models predate handicap models themselves. Models of signals, such as threat displays, without any handicapping costs show that conventional signalling may be evolutionarily stable in biological communication[21] Further, analysis of some begging models also shows that, in addition to the handicapped outcomes, non-communication strategies are not only evolutionarily stable, but lead to higher payoffs for both players.[22][23] Cheap Talk is a term used in Game Theory for pre-play communication which carries no cost. ...


Generality and empirical examples

The theory predicts that a sexual ornament, or any other signal, must be costly if it is to accurately advertise a trait of relevance to an individual with conflicting interests. Typical examples of handicapped signals include bird songs, the peacock's tail, courtship dances, bowerbird's bowers, or even possibly jewellery and humor. Jared Diamond has proposed that certain risky human behaviours, such as bungee jumping, may be expressions of instincts that have evolved through the operation of the handicap principle. Zahavi has invoked the potlatch ceremony as a human example of the handicap principle in action. This interpretation of potlatch can be traced to Thorstein Veblen's use of the ceremony in his book Theory of the Leisure Class as an example of "conspicuous consumption".[24] Illustration from The Descent of Man and Selection in Relation to Sex by Charles Darwin showing the Tufted Coquette Lophornis ornatus, female on left, ornamented male on right. ... Blackbird (Turdus merula), singing male. ... Peacock re-directs here; for alternate uses see Peacock (disambiguation). ... Genera Ailuroedus Archboldia Amblyornis Prionodura Sericulus Ptilonorhynchus Chlamydera The 19 bowerbirds and catbirds make up the family Ptilonorhynchidae. ... For the Korean music group, see Jewelry (group). ... Look up Humour in Wiktionary, the free dictionary. ... Jared Mason Diamond (b. ... Bungee Jump in Normandy, France (Souleuvre Viaduct) Bungee jumping (or bungy jumping) is the sport that originated from New Zealand and was created by maverick daredevil A J Hackett, and his original jump from a bridge in Greenhithe, Auckland. ... For other uses, see Potlatch (disambiguation). ... Thorstein Bunde Veblen (born Tosten Bunde Veblen July 30, 1857 – August 3, 1929) was a Norwegian-American sociologist and economist and a founder, along with John R. Commons, of the Institutional economics movement. ... The Theory of the Leisure Class is a book, first published in 1899, by the American economist Thorstein Veblen while he was a professor at the University of Chicago. ... Conspicuous consumption is a term used to describe the lavish spending on goods and services that are acquired mainly for the purpose of displaying income or wealth. ...


The handicap principle gains further support by providing interpretations for behaviours that fit into a single unifying gene-centered view of evolution and making earlier explanations based on group selection obsolete. A classic example is that of stotting in gazelles. This behaviour consists in the gazelle initially running slowly and jumping high when threatened by a predator such as a lion or cheetah. The explanation based on group selection was that such behaviour might be adapted to alerting other gazelle to a cheetah's presence or might be part of a collective behaviour pattern of the group of gazelle to confuse the cheetah. Instead, Zahavi proposed that each gazelle was communicating to the cheetah that it was a fitter individual than its fellows and that the predator should avoid chasing it. The gene-centered view of evolution, gene selection theory or selfish gene theory holds that natural selection acts through differential survival of competing genes, increasing the frequency of those alleles whose phenotypic effects successfully promote their own propagation. ... In evolutionary biology, group selection refers to the idea that alleles can become fixed or spread in a population because of the benefits they bestow on groups, regardless of the fitness of individuals within that group. ... Stotting is a behavior of gazelles, particularly Thomsons Gazelles, involving leaping straight up during pursuit by a predator, typically a cheetah or lion. ... This article does not cite any references or sources. ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... For other uses, see Lion (disambiguation). ... This article is about the animal. ...


Immunocompetence handicaps

The theory of immunocompetence handicaps suggests that androgen-mediated traits accurately signal condition due to the immunosuppressive effects of androgens[25]. This immunosuppression may be either because testosterone alters the allocation of limited resources between the development of ornamental traits and other tissues, including the immune system[26], or because heightened immune system activity has a propensity to launch autoimmune attacks against gametes, such that suppression of the immune system enhances fertility[27] Healthy individuals can afford to suppress their immune system by raising their testosterone levels, which also augments secondary sexual traits and displays. A review of empirical studies into the various aspects of this theory found weak support[28]. Immunocompetence is the ability of the body to produce a normal immune response (i. ... Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors. ... A peacock displays his long, colored feathers, an example of his secondary sexual characteristics. ...


Examples

Directed at members of the same species

Amotz Zahavi studied in particular the Arabian Babbler, a very social bird, with a life-length of 30 years, which was considered to have altruist behaviours. The helping-at-the-nest behavior often occurs among unrelated individuals, and therefore cannot be explained by kin selection. Zahavi reinterpreted these behaviours according to his signal theory and its correlative, the handicap principle. The altruistic act is costly to the donor, but may improve its attractiveness to potential mates. The evolution of this condition may be explained by competitive altruism. Amotz Zahavi is an Israeli Evolutionary Biologist from Tel-Aviv University, and one of the founders of the Israeli Society for the Protection of Nature. ... Binomial name (Cretzschmar, 1827) The Arabian Babbler (Turdoides squamiceps) is a passerine bird belonging to the genus Turdoides, a genus of Old World babblers. ... Altruism refers to both a practice or habit (in the view of many, a virtue) as well as an ethical doctrine. ...


The tail of a peacock makes the peacock more vulnerable to predators, and is therefore a handicap. But the message that the tail carries to the potential mate peahen is 'I have survived in spite of this huge tail, hence I am fitter and more attractive than others'. Peacock re-directs here; for alternate uses see Peacock (disambiguation). ...


An example in humans was suggested by Geoffrey Miller who expressed that Veblen goods such as luxury cars and other forms of conspicuous consumption are manifestations of the handicap principle, being used by men to advertise their "fitness" to women. Geoffrey Miller Geoffrey Miller is a widely recognised evolutionary psychologist, whose work is in the tradition of scientists such as Richard Dawkins, Daniel Dennett, and Steven Pinker. ... A commodity is a Veblen good if peoples preference for buying it increases as a direct function of its price. ... Conspicuous consumption is a term used to describe the lavish spending on goods and services that are acquired mainly for the purpose of displaying income or wealth. ...


Directed at other species

The signal receiver need not be a conspecific of the sender, however. Signals may also be directed at predators, with the function of showing that pursuit will probably be unprofitable. Stotting, for instance, is a sort of hopping that certain gazelles do when they sight a predator. As this behavior gives no evident benefit and would seem to waste resources, it was a puzzle until handicap theory offered an explanation. According to this analysis, the gazelle invests a bit of energy to show the predator that it had the fitness necessary to avoid capture, thus avoiding spending the energy required to evade actual pursuit. The lion might recognize that it could not catch this gazelle and so avoid a wasted pursuit. This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... Stotting is a behavior of gazelles, particularly Thomsons Gazelles, involving leaping straight up during pursuit by a predator, typically a cheetah or lion. ...


Another example is provided by larks, some of which discourage merlin by sending a similar message: they sing while being chased, telling their predator that they will be difficult to capture.[29] For other uses, see Lark (disambiguation). ... Binomial name Linnaeus, 1758 Subspecies 3-9, see text. ...


See also

The bright colours of this Yellow-winged Darter dragonfly serve as a warning to predators of its noxious taste. ...

References

  1. ^ Zahavi, A. (1975) Mate selection - a selection for a handicap. Journal of Theoretical Biology 53: 205-214.
  2. ^ Zahavi, A. (1977) The cost of honesty (Further remarks on the handicap principle). Journal of Theoretical Biology 67: 603-605.
  3. ^ Zahavi, A. and Zahavi, A. (1997) The handicap principle: a missing piece of Darwin's puzzle. Oxford University Press. Oxford. ISBN 0-19-510035-2
  4. ^ Andrew Pomiankowski, A. & Iwasa, Y. 1998. Handicap Signaling: Loud and True? Evolution, 52, 928-932
  5. ^ a b c Johnstone, R.A. (1995) Sexual selection, honest advertisement and the handicap principle: reviewing the evidence" Biological Reviews 70 1-65.
  6. ^ Johnstone, R.A. (1997) The evolution of animal signals, In Behavioural Ecology: an evolutionary approach 4th ed., J. R. Krebs and N. B. Davies, editors. Blackwell. Oxford, pp:155-178.
  7. ^ Maynard Smith, J. and Harper, D. (2003) Animal Signals. Oxford University Press. ISBN 0-19-852685-7.
  8. ^ Davis, J. W. F., & O’Donald, P. (1976). Sexual selection for a handicap: A critical analysis of Zahavi’s model. Journal of Theoretical Biology, 57, 345–354.
  9. ^ Eshel, I. (1978). On the handicap principle — a critical defence. Journal of Theoretical Biology, 70, 245–250
  10. ^ Kirkpatrick, M (1986) The handicap mechanism of sexual selection does not work. American Naturalist 127:222-240.
  11. ^ Pomiankowski, A. (1987). Sexual selection: The handicap principle does work sometimes. Proc. R. Soc. Lond., Series B, 231, 123–145.
  12. ^ Maynard Smith, J. (1976). Sexual selection and the handicap principle. Journal of Theoretical Biology, 57, 239–242
  13. ^ Maynard Smith, J. (1978). The handicap principle — a comment. Journal of Theoretical Biology,70, 251–252
  14. ^ Maynard Smith, J. (1985). Mini review: Sexual selection, handicaps and true fitness. Journal of Theoretical Biology, 115, 1–8.
  15. ^ Grafen, A. (1990) Biological signals as handicaps. Journal of Theoretical Biology 144:517-546.
  16. ^ Spence, A.M. (1973) Job Market Signaling. Quarterly Journal of Economics 87:355-374.
  17. ^ Godfray, H.C.J. 1991. Signalling of need by offspring to their parents, Nature 352 328-330.
  18. ^ Yachi, S. 1995. How can honest signalling evolve? The role of the handicap principle. Proceedings of the Royal Society of London, series B 262 283-288.
  19. ^ Adams, E.S. & Mesterton-Gibbons, M. 1995. The cost of threat displays and the stability of deceptive communication. Journal of Theoretical Biology 175 405-421.
  20. ^ Kim, Y-G. 1995. Status signalling games in animal contests. Journal of Theoretical Biology 176, 221-231.
  21. ^ Enquist, M. 1985. Communication during aggressive interactions with particular reference to variation in choice of behaviour. Animal Behaviour 33 1152-1161.
  22. ^ Rodriguez-Girones, M.A., Cotton, P.A. & Kacelnik, A. 1996. The evolution of begging: signaling and sibling competition. Proceedings of the National Academy of Sciences USA, 93:14637­-14641.
  23. ^ Lachmann, M. & Bergstrom, C.T. 1998. Signalling among relatives. II. Beyond the tower of babel. Theoretical Population Biology, 54:146-­160.
  24. ^ Bliege Bird, R. and Smith, E. A. (2005). Signalling theory, strategic interaction, and symbolic capital. Current Anthropology, 46(2), 221-248.
  25. ^ Folstad, I. & Karter, A.K. (1992) Parasites, bright males, and the immunocompetence handicap. American Naturalist 139:603-622.
  26. ^ Wedekind, C. and Folstad, I. (1994) Adaptive or non-adaptive immunosuppression by sex hormones? American Naturalist 143:936-38.
  27. ^ Folstad, I. & Sakrstein, F. (1996) Is male germ line control creating avenues for female choice? Behavioral Ecology 8:109-112
  28. ^ Roberts, M.L., Buchanan K.L., Evans, M.R. (2004). Testing the immunocompetence handicap hypothesis: a review of the evidence. Animal Behaviour. 68:227-239
  29. ^ For footage of this, see Attenborough, D. (1990) The Trials of Life, Episode 10. BBC.

Amotz Zahavi is an Israeli Evolutionary Biologist from Tel-Aviv University, and one of the founders of the Israeli Society for the Protection of Nature. ... Amotz Zahavi is an Israeli Evolutionary Biologist from Tel-Aviv University, and one of the founders of the Israeli Society for the Protection of Nature. ... Amotz Zahavi is an Israeli Evolutionary Biologist from Tel-Aviv University, and one of the founders of the Israeli Society for the Protection of Nature. ... Professor John Maynard Smith[1], F.R.S. (6 January 1920 – 19 April 2004) was a British evolutionary biologist and geneticist. ... The Proceedings of the National Academy of Sciences of the United States of America, usually referred to as PNAS, is the official journal of the United States National Academy of Sciences. ... Trials of Life is a BBC (in conjunction with The Australian Broadcasting Service and Turner Broadcasting System Inc. ...

External links

  • "The Theory of Honest Signaling"

  Results from FactBites:
 
The Theory of Honest Signaling - Examples from Biology (241 words)
Females which selected males with the most developed characters can be sure that they have selected from among the best genotypes of the male population.
Zahavi named his hypothesis "the handicap principle," and suggested that there is something about costly behaviors or physical features that make for inherently reliable signals.
In the following sections, we will start to answer this question by exploring some of the messages that animals send using costly signals.
  More results at FactBites »

 
 

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