The surest way to boost your earnings is to get a college degree. But it is hard to tell whether university makes you smarter—and thus, more valuable—or if it simply signals to employers that you are a smart, motivated person they should hire for well-paying jobs. A recent study offers some answers, from an unlikely source. It turns out that the financial benefits of a college eduction even exist in sex work.

Economists Scott Cunningham and Todd Kendall conducted an extensive survey of female sex workers in 2009. They asked detailed demographic questions as well as gathered details about the women’s clients, work patterns, and pay. They estimate that college-educated sex workers are less likely to work than their less-educated counterparts in any given week. But when they do work, they earn about 12% to 13% more. College educated sex-workers see more clients and book longer sessions. They charge slightly less on an hourly basis, but the volume and nature of their services means they end up earning more.

College-educated sex workers tend to have more regular clients and maintain a more favorable view of them. Cultivating regulars is an important part of the business. Many sex workers now find their clients online. Before seeing a new client, escorts (especially the college-educated ones) conduct extensive, time-intensive background checks. A roster of regulars then saves future screening time and results in more regular, lower-risk income. Cunningham posits that educated sex workers build a stronger connection with their clients.

College-educated sex workers tend to have more regular clients and maintain a more favorable view of them.

Education can also explain the larger earnings. In legal brothels, longer, pricier sessions tend to involve talking, cuddling, and even going on dates, in addition to sex. This is dubbed the Girl Friend Experience (known as GFE in the industry), which commands a significant premium over purely sexual services, because it takes more time and mental energy on the part of the sex worker. Cunningham says the survey indicates GFE carries higher costs, since women report that they have to mentally prepare more in advance of the encounter and remain emotionally engaged throughout. College-educated sex workers appear to offer more GFE services, at least in illegal markets, which explains much of the premium they earn relative to those without degrees.

Educated sex workers almost certainly have better, legal employment options, Cunningham notes. The higher earnings they receive for sex work, then, could be because it takes more money and a compelling client to agree to enter the sex business in the first place. There must also be some demand for educated escorts, otherwise customers wouldn’t pay more for their services.

There is a spirited debate about whether college actually makes someone smarter. Some argue it improves earnings potential by making graduates more skilled and productive. Others argue that smarter people choose to go to college, so it merely acts as a signal about the worth of a worker. At least when if comes to sex work, signaling probably doesn’t explain the higher earnings. After all, clients don’t normally know (or care) whether a woman went to college when soliciting sex. When escorts advertise their services, they don’t normally list their educational credentials.

It could be that college really does impart skills. Educated sex workers may pick up business acumen and soft skills (empathy, professionalism) in college, which is manifest later by their ability to up-sell and maintain longer-term relationships. Or, it could be that people who go to college naturally have characteristics that are useful for high-end sex work: good social skills, patience, and intelligence.

Whatever the case, this is yet more evidence that a college degree pays off, regardless of industry.