Signalling theory
The mathematical biologist Ronald Fisher analysed the contribution that having two copies of each gene (diploidy) would make to honest signalling, demonstrating that a runaway effect could occur in sexual selection.
[7] Kinship is central to models of signalling between relatives, for instance when broods of nestling birds beg and compete for food from their parents.
Biological signals, like warning calls or resplendent tail feathers, are honest if they reliably convey useful information to the receiver.
[16] An example of dishonest signalling comes from Fiddler crabs such as Austruca mjoebergi, which have been shown to bluff (no conscious intention being implied) about their fighting ability.
[16] The game theoretical model of the war of attrition similarly suggests that threat displays ought not to convey any reliable information about intentions.
[22] Deception within species can be bluffing (during contest)[23][24] or sexual mimicry[25] where males or females mimic the patterns and behaviour of the opposite sex.
[32] In Vonnegut's futuristic dystopia, the Handicapper General uses a variety of handicapping mechanisms to reduce inequalities in performance.
A spectator at a ballet comments: "it was easy to see that she was the strongest and most graceful of all dancers, for her handicap bags were as big as those worn by two hundred pound men."
[33] Zahavi's conclusions rest on his verbal interpretation of a metaphor, and initially the handicap principle was not well received by evolutionary biologists.
[39][40] The handicap principle has proven hard to test empirically, partly because of inconsistent interpretations of Zahavi's metaphor and Grafen's marginal fitness model, and partly because of conflicting empirical results: in some studies individuals with bigger signals seem to pay higher costs, in other studies they seem to be paying lower costs.
[41] A possible explanation for the inconsistent empirical results is given in a series of papers by Getty,[42][43][6][44] who shows that Grafen's proof of the handicap principle is based on the critical simplifying assumption that signallers trade off costs for benefits in an additive fashion, the way humans invest money to increase income in the same currency.
These models are most often applied to sexually selected signalling in diploid animals, but they rarely incorporate a fact about diploid sexual reproduction noted by the mathematical biologist Ronald Fisher in the early 20th century: if there are "preference genes" correlated with choosiness in females as well as "signal genes" correlated with display traits in males, choosier females should tend to mate with showier males.
Russell Lande explored this with a quantitative genetic model,[35] showing that Fisherian diploid dynamics are sensitive to signalling and search costs.
[65] Large game hunting has been studied extensively as a signal of men's willingness to take physical risks, as well as showcase strength and coordination.
[65][66][67][68] Costly signalling theory is a useful tool for understanding food sharing among hunter gatherers because it can be applied to situations in which delayed reciprocity is not a viable explanation.
[69][70][71] Instances that are particularly inconsistent with the delayed reciprocity hypothesis are those in which a hunter shares his kill indiscriminately with all members of a large group.
[74][75] Hawkes has suggested that men target large game and publicly share meat to draw social attention or to show off.
[28][65][80] Bliege Bird et al. observed turtle hunting and spear fishing patterns in a Meriam community in the Torres Strait of Australia, publishing their findings in 2001.
[81][82] Here, only some Meriam men were able to accumulate high caloric gains for the amount of time spent turtle hunting or spear fishing (reaching a threshold measured in kcal/h).
Due to the time and energetic costs of preparation, torch fishing results in net caloric losses for fishers.
[90] Torch fishing thus provides women with reliable information on the work ethic of prospective mates, which makes it an honest costly signal.
[95][96] In these northern Kalahari groups, the killing of a large animal indicates a man who has mastered the art of hunting and can support a family.
[65][98] Research on physical risk-taking is important because information regarding why people, especially young men, take part in high risk activities can help in the development of prevention programs.
[28] When those peers are criminals or gang members, sociologists Diego Gambetta and James Densley find that risk-taking signals can help expedite acceptance into the group.
Costly religious rituals such as genital modification, food and water deprivation, and snake handling look paradoxical in evolutionary terms.
He argued that hard-to-fake religious displays enhanced trust and solidarity in a community, producing emotional and economic benefits.
[111] Wood found that religion offers a subjective feeling of well-being within a community, where costly signalling protects against free riders and helps to build self-control among committed members.
However, the reinforcement of religious rites as well as the intrinsic reward and punishment system found in religion makes it an ideal candidate for increasing intragroup cooperation.
[115] Some scholars view the emergence of language as the consequence of some kind of social transformation[116] that, by generating unprecedented levels of public trust, liberated a genetic potential for linguistic creativity that had previously lain dormant.
A very specific social structure—one capable of upholding unusually high levels of public accountability and trust—must have evolved before or concurrently with language to make reliance on "cheap signals" (words) an evolutionarily stable strategy.
