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Amotz and Avishag Zahavi - The Handicap Principle

Introduction - The Gazelle, the Wolf, and the Peacock's Tail

p. xiii: "Why does the gazelle reveal itself to a predator that might not otherwise spot it? Why does it waste time and energy jumping up and down (stotting) instead of running away as fast as it can? The gazelle is signaling to the predator that it has seen it; by 'wasting' time and by jumping high in the air rather than bounding away, it demonstrates in a reliable way that it is able to outrun the wolf. The wolf, upon learning that it has lost its chance to surprise its prey, and that this gazelle is in tip-top physical shape, may decide to move on to another area; or it may decide to look for more promising prey."

The gazelle is sending the wolf a signal. The authors write: "The encounter between the gazelle and the wolf dramatizes the basic theme of this book: in order to be effective, signals have to be reliable; in order to be reliable, signals have to be costly. [...] If a given signal requires the signaler to invest more in the signal than it would gain by conveying phony information, then faking is unprofitable and the signal is therefore credible (p. xv)."

Part I - Partners in Communication

p. 40: "We believe that natural selection encompasses two different, and often opposing, processes. One kind of selection favors straightforward efficiency, and it works in all areas except signaling. This selection makes features--other than signals--more effective and less costly; we suggest calling it 'utilitarian selection.' The other kind of selection, by which signals evolve, results in costly features and traits that look like 'waste.' It is precisely this costliness, the signaler's investment in the signals, that makes signals reliable. We suggest calling this process 'signal selection.'"

Part II - Methods of Communication

p. 59: Cost is the essence of an effective signal. "If the cost of a signal is reduced to the extent that every individual can use it equally well, then the signal can no longer reveal differences in the quality or motivation of individuals. In such a case, the signal loses its value." Eventually, such signals will disappear.

p. 91: "What Darwin termed sexual selection is a subset of the process we call signal selection."

Part III - The Handicap Principle in Social Systems

p. 134: On the emergence of altruism--long a puzzle for evolutionary biologists--the authors write: "If we assume that the function of altruism is to benefit others, then it makes no difference who the altruist is, and there is no sense in competing for the 'right' to help. [...] But if the helper benefits directly from the act of helping, and the benefits to others are incidental--a side effect--then it makes sense to compete for the opportunity to help. As we shall show, the helper--the 'altruist'--does reap a direct gain--in prestige."

p. 142: In species such as babblers, altruism often replaces physical aggression. "By showing off how much they can invest in standing guard, in feeding their comrades, in taking risks, and in other altruistic acts, babblers show off their ability to win in a fight and their desirability as groupmates. The altruist's investment in the altruistic act offers a reliable, concrete index of that individual's ability."

p. 143: "To reflect these differences in the quality of relationships within groups, we use the term prestige, which for us is different from and complementary to rank. [...] Prestige reflects the degree of a superior individual's dominance, as recognized by subordinate members of the group."

p. 157: Altruism has a dual message. The "altruistic" individual serves its own interests by expending effort to demonstrate its quality reliably. But because it does so by engaging in altruism instead of by pure showing off, it also shows its interest in continued collaboration with the group.

p. 160: "Showing off by consuming harmful chemicals like alcohol, tobacco, betel nut, opium, and the like is common among humans. [...] One who can drink quantities of alcohol without apparent ill-effect shows reliably his or her good physical condition; one in poor condition would get visibly drunk. Laborers who do hard physical work are notoriously heavy drinkers in many societies."

Part IV - Humans

p. 225: The authors argue that there is no distinction between the "moral and ethical" behavior of humans and the "material" interests of animals. On average, altruistic people gain more than they lose, although the gain or benefit may come in a form other than material payback. "Investing in another's welfare shows off the altruist's quality, improves his or her social standing, and increases his or her chance at success."

p. 226: "Many sports are dangerous--auto racing is a blatant example; so are such pursuits as mountain climbing, voyaging in space, and exploring unknown parts of the planet. But those who succeed gain fame."

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