Handicap principle

[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.[1] A series of papers by the American biologist Thomas Getty showed that Grafen's proof of the handicap principle depends on the critical, simplifying assumption that signallers trade off costs for benefits in an additive fashion, analogous to the way humans invest money to increase income in the same currency.[26][27] In the classic handicap models of begging in game theory, 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.Models of signals (such as threat displays) without any handicapping costs show that what biologists call cheap talk may be an evolutionarily stable form of communication.[38] Dustin J. Penn and Szabolcs Számadó stated in 2019 that there was still no empirical evidence for evolutionary pressure for wasteful biology or acts, and proposed that the handicap principle should be abandoned.[39] The handicap principle predicts that a sexual ornament, or any other signal such as visibly risky behavior, must be costly if it is to accurately advertise a trait of relevance to an individual with conflicting interests.American scientist 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.[41] 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.[42][43][44] French biologist Patrice David showed that in the stalk-eyed fly species Cyrtodiopsis dalmanni, genetic variation underlies the response to environmental stress, such as variable food quality, of a male sexual ornament, eye span.[52] Healthy individuals can afford to suppress their immune system by raising their testosterone levels, at the same time augmenting secondary sexual traits and displays.

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. ^{[

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Graph showing mathematically how a handicap would in theory work — Graph based on Johnstone's 1997 graphical representation of a Zahavian handicap. Where $C_{L}$ is cost to a low-quality signaller and $C_{H}$ is cost to a high-quality signaller. Optimal signalling levels are $S_{L}^{*}$ for a low-quality signaller, and $S_{H}^{*}$ for a high-quality signaller. ^{[

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Photo of a Rolls-Royce car — Luxury cars and other " Veblen goods " may be an example of the handicap principle in humans. ^{[

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Photo of an impala jumping high in the African bush — Impala stotting , a behavior that may serve as a pursuit deterrence signal to predators. ^{[

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Amotz Zahavihypothesis"honest" or reliable signallingsexual characteristicsbiological fitnessbehaviourmorphologyconspicuous consumptiongame theoryIsraeliSignaling gameJohn Maynard SmithAlan Grafensignalling gameMichael Spencejob market signalling modelpeacocksexually selected signalsevolutionary stabilityCheap talkthreat displaysmate choiceMonte Carlo simulationsdiscrete modelscontinuous modelsconflict modelsempirical evidenceVeblen goodssexual ornamentbird songscourtship dancesbowerbirdJared Diamondbungee jumpingpotlatchThorstein VeblenTheory of the Leisure Classgene-centered view of evolutiongroup selectionstottinggazellespredatorcheetahArabian babbleraltruisticallykin selectionnatural selectioncompetitive altruismstalk-eyed flyCyrtodiopsis dalmannigenotypesAnti-predator adaptationpursuit deterrencepredatorsmerlinsimmunocompetenceandrogenimmunosuppressivetestosteroneornamental traitsimmune systemgametesfertilityAposematismCostly signaling theory in evolutionary psychologyFisherian runawayMultiple sexual ornamentsParasite-stress theorySacrificeBibcodeZahavi, AmotzAmerican NaturalistProceedings of the Royal Society BMaynard Smith, JohnEvolutionBiological ReviewsHarper, DavidOxford University PressQuarterly Journal of EconomicsAnimal BehaviourTrends in Ecology & EvolutionNatureProceedings of the National Academy of Sciences of the United States of AmericaBergstrom, C. T.bioRxivCurrent AnthropologyThe AukCambridge University PressCaro, Tim M.Behavioral EcologyEvolutionary biologyIntroductionOutlineTimeline of evolutionHistory of lifeAbiogenesisAdaptationAdaptive radiationAltruismCheatingReciprocalBaldwin effectCladisticsCoevolutionMutualismCommon descentConvergenceDivergenceEarliest known life formsEvidence of evolutionEvolutionary arms raceEvolutionary pressureExaptationExtinctionHomologyLast universal common ancestorMacroevolutionMicroevolutionMismatchNon-adaptive radiationOrigin of lifePanspermiaParallel evolutionSignalling theorySpeciationSpeciesSpecies complexTaxonomyUnit of selectionPopulationgeneticsArtificial selectionBiodiversityEvolutionarily stable strategyFisher's principleFitnessInclusiveGene flowGenetic driftParental investmentParent–offspring conflictMutationPopulationSexual dimorphismSexual selectionFlowering plantsSocial selectionTrivers–Willard hypothesisVariationCanalisationEvolutionary developmental biologyGenetic assimilationInversionModularityPhenotypic plasticityBacteriaoriginBrachiopodsMolluscsCephalopodsInsectsbutterfliesMammalswolvesdolphins and whaleshorsesKangaroosprimateshumanslemurssea cowsPlantspollinator-mediatedReptilesSpidersTetrapodsVirusesorgansFlagellasymbiogenesisauditory ossiclenervous systemprocessesAvian flightBiological complexityCooperationColor visionin primatesEmotionEthicsEusocialityMonogamyMoralityMosaic evolutionSexual reproductionLife cycles/nuclear phasesMating typesMeiosisSnake venomTempo and modes