Editing Signalling theory (section)

{{Short description|Theory in evolutionary biology}}
{{About|signalling in evolutionary biology|the analogous theory in economics|signalling (economics)|the engineering concept|signal processing{{!}}signal theory}}
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[[File:Springbok pronk.jpg|thumb|By [[stotting]] (also called pronking), a [[springbok]] (''Antidorcas marsupialis'') signals honestly to predators that it is young, fit, and not worth chasing.]]

Within [[evolutionary biology]], '''signalling theory''' is a body of [[theory|theoretical]] work examining [[animal communication|communication between individuals]], both within species and across species. The central question is how organisms with conflicting interests, such as in [[sexual selection]], are expected to provide honest signals rather than deceive or [[Cheating (biology)|cheat]], given that the passing on of [[Pleiotropy|pleiotropic]] traits is subject to [[natural selection]], which aims to minimize associated costs without assuming any conscious intent. [[Mathematical model]]s describe how signalling can contribute to an [[evolutionarily stable strategy]].

Signals are given in contexts such as mate selection by females, which subjects the [[advertising in biology|advertising]] males' signals to selective pressure. Signals thus evolve because they modify the behaviour of the receiver to benefit the signaller. Signals may be honest, conveying information which usefully increases the fitness of the receiver, or dishonest. An individual can cheat by giving a dishonest signal, which might briefly benefit that signaller, at the risk of undermining the signalling system for the whole population.

The question of whether the selection of signals works at the level of the individual organism or gene, or at the level of the group, has been debated by biologists such as [[Richard Dawkins]], arguing that individuals evolve to signal and to receive signals better, including resisting manipulation. [[Amotz Zahavi]] suggested that cheating could be controlled by the [[handicap principle]], where the best horse in a [[Handicap (horse racing)|handicap race]] is the one carrying the largest handicap weight. According to Zahavi's theory, signallers such as male peacocks have "tails" that are genuinely handicaps, being costly to produce. The system is evolutionarily stable as the large showy tails are honest signals. Biologists have attempted to verify the handicap principle, but with inconsistent results. The mathematical biologist [[Ronald Fisher]] analysed the contribution that having two copies of each gene ([[diploid]]y) would make to honest signalling, demonstrating that a [[Fisherian runaway|runaway effect]] could occur in [[sexual selection]]. The evolutionary equilibrium depends sensitively on the balance of costs and benefits.

The same mechanisms can be expected in humans, where researchers have studied behaviours including risk-taking by young men, hunting of large game animals, and costly religious rituals, finding that these appear to qualify as costly honest signals.