Honest signaling conveys information that is a true indicator of the underlying quality of the sender and it is useful to the receiver.
In animal communication, information is transmitted from a sender (signaler) to a receiver, and the receiver acts upon the signal (McFarland 2006). Signals can be “honest” when giving reliable information or “dishonest” when the sender is sending out false information to a receiver (Laidre and Johnstone 2013).
Evolution of Honest Signaling
According to signaling theory for a signal to be preserved in the population, the interaction should be beneficial for the sender and receiver. Furthermore, the honest signal should convey information that the receiver cannot obtain in another way. Honest signaling does not need to be perfectly informative, but it needs to be useful, so that certain behavioral responses to the signal are advantageous, in comparison with the behavior that would occur in absence of the signal. Therefore, honest signals in communication are given when both the sender and receiver benefit from the result (Laidre and Johnstone 2013).
Dishonest signaling doesn’t have to suggest conscious deception, rather it has functional meanings in animal communication (Shettleworth 2010). Deceit takes place when the signaler can exploit the receiver in order to improve its fitness, and it is common in communication between species. Similarly, manipulation is when the receiver acquires information from the signaler contrary to his interests (McFarland 2006), and this may arise when sender and receiver have opposite interests (Laidre and Johnstone 2013). In evolutionary terms, dishonest signaling may persist if it doesn’t harm recipient fitness or when it has a low frequency of occurrence (Laidre and Johnstone 2013).
Although animal communication is open to cheating, the receiver can choose whether or not to respond to a signal and therefore can impose honesty. Signals must be truthful indicators of underlying quality because the value of the signaled information rests on the degree to which it enables the receiver to increase its fitness. If signals become unreliable, then the recipient will no longer respond to them (Laidre and Johnstone 2013).
Signals favored by natural selection are those that enhance an animal’s probability of reproduction. Therefore, the honesty of a signaler’s messages is guaranteed by their cost and that makes them evolutionarily stable. According to the Zahavi (1975) in mate choice and parental care, honest signaling develops because some signals are too costly for signalers to cheat, and that is termed “the handicap principle” (Laidre and Johnstone 2013) or “costly signaling” (Higham 2014). An individual without handicapping marker does not advertise its quality, so a potential mate cannot perceive it. That is to say, when the receiver answers only to costly signals, the sender’s ability to pay the cost to define the evolution of communicative signals. Zahavi (1975) considered that signals such as loud calls or rich displays that require a lot of energy are reducing the fitness of the sender and so it can show its quality by its capability to survive in spite of the costs, i.e., handicap caused by signaling.
The handicap principle is generally acknowledged (Shettleworth 2010), but is still discussed (Higham 2014). However, the handicap principle is only one of several mechanisms that give possible explanations for the honesty in animal signaling, and honesty is possible without significant costs. For example, if signalers and recipients are related to each other or when they have negligible conflicting interest, then signals may be free of charge. Moreover, even when signalers and recipients have strong conflicts of interest, honesty is guaranteed if it requires lower cost than lying (Higham 2014; Laidre and Johnstone 2013).
In conclusion, signaling strategies may vary from cost-free cues to costly handicapping signals. Where any benefit for evolutionary fitness occurs, a cue may progress into to signal with a certain amount of exaggeration. Signals become exaggerated only when they start as weak cues of individual quality, but not when they start as strong cues of quality (Biernaskie et al. 2018).
The classic example of a costly honest signal that can’t be explained by natural selection is the peacock feather tail. The tail has large feathers that require a lot of energy to grow, it is heavy, and it makes hard for peacocks to move around and to hide from predators. This signal is so costly that the signaler can hardly lie about its quality. However, this investment is effective because it improves the ability of females to choose mates of good quality (Shettleworth 2010; Zahavi 1975).
It is believed that Thompson’s gazelles “stot” is an honest signal because it demonstrates gazelle’s good body condition, stamina, and strength. Indeed, higher rate stotters appear to be better at running and escaping. This discourages the predators from attacking, and therefore the signal provides an advantage to both parties. The gazelle is less likely to be attacked, and the predator avoids a long, unproductive pursuit (Krebs and Davies 2006; Dawkins 2007).
Leal (1999) studied push-up display in lizard Anolis cristatellus, which is common in anoline social interactions. In the research, lizards were faced with a model of a natural predator, snake Alsophis portoricensis. The research confirmed that the number of push-ups that lizard performed toward the predator was positively correlated with lizard’s endurance capacity, i.e., by push-ups the lizard was communicating to the snake its alertness and that is able to escape an attack. However, endurance was not correlated with lizard’s body size, so the snake was not able to evaluate the ability of the lizard to escape based on its visual bodily qualities. Therefore, the author concluded that: “predation pressure and sexual selection may simultaneously favor the evolution of honest communication to allow both the predator and the potential mate or male rival to assess individual quality using the same signal” (Leal 1999).
Animals with conspicuous colors and specific body structures, such as some amphibians and insects, are honestly signaling that they are unpalatable. Their appearance is selected by evolution because predators learn to avoid animals with such prominent warning signals (Shettleworth 2010).
In the animal kingdom, honest signaling is shaped by evolution but is liable to change by environmental conditions. Finally, plants may also use signals that can be honest or dishonest, when communicating with animals.
- Krebs, J. R., & Davies, N. B. (2006). An introduction to behavioural ecology (3rd ed.). Malden: Blackwell Publishing.Google Scholar
- McFarland, D. (2006). Dictionary of animal behaviour. Oxford: Oxford University Press.Google Scholar
- Shettleworth, S. J. (2010). Cognition, evolution, and behavior (2nd ed.). Oxford: Oxford University Press.Google Scholar