The Costly Signals of Attraction: Peacocks' Tails and Ivy League Degrees
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Why are peahens so attracted by the peacocks with the most extravagant tails – which are very costly to maintain but otherwise seemingly useless? Why do employers care that you put yourself hundreds of thousands of dollars in debt to get an Ivy League degree in sociology with no obvious relevance to the job? In the 1970s, the zoologist Amotz Zahavi and the economist Michael Spence offered a provocative answer. They argued that the cost paid by the peacock (or the college graduate) is the whole point. Their argument (which won Spence a Nobel Prize in Economics in 2001) is a bit subtle, so it is worth carefully looking at how it works. Communication is difficult because individuals have incentives to lie. Employers are looking for certain qualities (intelligence, conscientiousness, ambition) in their employees. They could ask the people they interview if they are intelligent and conscientious, but why wouldn’t the job candidates simply lie?
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Instead, employers select their employees on the basis of signals that are difficult to fake, such as university degrees. In general, having the qualities that employers value makes it easier to get a degree. People who do not have the right mix of intelligence, conscientiousness and ambition will find college more difficult, and either drop out or spend much more time completing their studies. People who anticipate that getting a degree would be too costly for them will opt out. So, in principle, even if nothing you had learnt was relevant to the job you want, completing the degree still sends a valuable signal to potential employers: you are the kind of person for whom this high-effort achievement is easy enough. Because it sends a valuable signal, it is in your interest to get a degree, and in the employer’s interest to hire you on its basis.
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A similar argument applies in the biological domain, but with natural selection in the driver’s seat. Growing an extravagant tail is moderately costly for a healthy peacock – but a diseased bird would put its life at risk if he spent that much energy growing the ornament. Therefore, only the peacocks in good enough condition can afford to grow an elaborate tail. As such, natural selection favours peahens who prefer peacocks with a long tail, because these peahens mate with healthy males, and get healthy offspring as a result. Costly signals – signals that are honest because of the fact that they are costly – are ubiquitous.
