A Link Between a Prostitute's Age and Her Income

A seemingly salacious topic answers a broad scientific question

Posted Jul 31, 2016

A new study, published in the journal Evolution and Human Behavior, examined the link between a prostitute's age and the price she charges. At first blush, it might seem easy to dismiss such a study as appealing to narrow prurient interests. But the author, economist Kitae Sohn, used prostitutes' earnings to address a much broader scientific question, one that applies not only to paid sexual exchanges, but to everyday concerns that many of us obsess about at some point in our lives: What does the opposite sex actually find attractive in a partner? 

If we simply survey you and ask what you desire in a mate, as some researchers have done, your answers might be biased to make you look good. Even if we examine actual marriages, we can't be sure those reveal people's true preferences—most people marry someone of their own socioeconomic status, for example, but that is influenced not only by what a person wants, but by what he or she can get. Maybe everyone wants a wealthy and stunningly attractive partner, but it is easier to find and attract someone of your own SES and attractiveness level. 

When asked, most people express a preference to marry someone around their own age. Social scientists used to presume that this is simply another example of the similarity-attraction rule (the idea that I want to marry someone who matches me in as many ways as possible—political beliefs, religion, height, and so on). But when researchers looked more carefully, they found that age preferences raised some interesting exceptions to the similarity rule. Women often marry much older men, for example. Conversely, older men often marry much younger women. And survey data revealed another discrepancy: high school boys said they would be quite interested in college-age women, even though they knew they were very unlikely to attract those older women. So the teenagers' preferences were violating two supposed generalizations: that people generally desire similar others, and that men desire younger partners. 

Why age matters

The age that women and men desire in a mate is important, because it addresses interesting theoretical questions—about the relative importance of universal biological constraints on human mate choice. In particular, biological theorists expect that men's attraction to similar partners should be altered by the fact that female fertility peaks in early adulthood, drops during the ages 25 to 45, and goes to zero after age 50. Hence teenagers and their grandfathers may be similarly interested in women in their early 20s, although each may have a difficult time attracting a woman of that age, for different reasons. 

By examining what men are willing to pay for sex, Professor Sohn provides a new window onto this issue of fertility and attraction. Men do not have unrestrained choice in whom they marry or date, but they do get to choose whether or not to pay a prostitute for sex, and the amount they are willing to pay reveals something about what they most prefer. Economists call this "revealed preferences," assuming that the amount we are willing to pay for any commodity gives a good index of how much we value it. 

Sohn’s sample was very large, including 8,560 prostitutes from 15 different cities in Indonesia. As Sohn notes, Indonesia provides an ideal place to examine this issue, because prostitution is “quasi-legal,” tacitly supported by the government, which keeps official records on prostitutes’ income alongside incomes from other professions.

Normal link between age and income flips for prostitutes

When it comes to hiring the short-term services of a prostitute, men pay the most for women between the late teens and early twenties. Between the ages of 25 and 35, the price men are willing to pay for a prostitute drops precipitously. 

Original figure, based on two different graphs in article being reviewed here (Sohn, 2016)
Source: Original figure, based on two different graphs in article being reviewed here (Sohn, 2016)

Sohn also examined how a woman's age influenced her income in traditional jobs, and found more or less the opposite pattern. Although women in traditional occupations made a generally lower hourly wage than prostitutes, those women normally made more money as they got older, rather than less. The age-related increase for other occupations slowed between the ages of 25 and 35. Sohn suggests that this is perhaps because these are the years of child-bearing and child-raising. But after age 35, women in other occupations appeared to continue the upward climb. As Sohn notes: "The literature on human capital has long demonstrated that wages increase with age (up to a certain point) ... Prostitution spectacularly defies this regularity" (p. 274).

Sohn attributes the typical age-related increase in women’s income to the fact that people usually gain experience and skills with tenure on the job. Although the same may be true for women in the sexual services business, the value of experience appears to be outweighed by age-related decreases in sexual desirability.

As an economist, Sohn provided an exact monetary equation: For each increase of a year in age, a prostitute's hourly wage decreases 4.5 percent. Looked at another way, Sohn found that prostitutes between ages 35 and 40 earned 52.8 percent less per hour than women under 20.

Although this data comes only from Indonesia, Sohn argues that: “evolution influenced all humans, so we expect that future research will find similar results in other countries.” Supporting Sohn’s argument, the age preferences found in this research are quite consistent with findings using other methods in other societies around the world.

Related blogs:

When statistics are seriously sexy: Sex, lies, and big data.

The Mind as a Coloring Book: Universal mechanisms reveal surprising cultural diversity.

The Mind as a Coloring Book 2: Why cultural diversity does not mean a blank slate mind.

References:

Kenrick, D.T., Gabrielidis, C., Keefe, R.C., & Cornelius, J. (1996).  Adolescents'  age preferences for dating partners: Support for an evolutionary model of life-history strategies. Child Development, 67, 1499-1511.

Kenrick, D.T., & Keefe, R.C. (1992).  Age preferences in mates reflect sex differences in mating strategies. Behavioral & Brain Sciences, 15, 75- 91.

Kenrick, D.T., Nieuweboer, S., & Buunk, A.P. (2010). Universal mechanisms and cultural diversity: Replacing the blank slate with a coloring book. Pp. 257-271 in M. Schaller, A. Norenzayan, S. Heine, T. Yamagishi, & T. Kameda (eds.) Evolution, culture, and the human mind. New York: Psychology Press.

Sohn, K. (2016).  Men's revealed preferences regarding women's ages: Evidence from prostitution. Evolution & Human Behavior, 37, 272-280.