Best. Experiment. Ever.

Studies have shown that men's testosterone levels increase after sexual stimulation. However, other research shows that merely briefly chatting to a woman also causes testosterone release, making it unclear whether sex, per se, is associated with testosterone changes.

So an intrepid band of researchers decided to find out using a unique methodology. Their paper's called Salivary Testosterone Levels in Men at a U.S. Sex Club and it's about... that.

They first set the scene:

Subjects were recruited from an internationally known "adult social club" in Las Vegas, Nevada, also referred to as a "sex club"... patrons pay a membership fee (akin to an entrance fee) to enter the 18,000 square foot, 2-story club. The first floor is open to all paying customers. The second VIP floor is available for an additional fee and includes a variety of rooms, including fetish rooms...

All are not created equal in this Garden of Eden, however:

Personal observation and communication with staff and members revealed to the investigators that there is a semi-structured hierarchy of patrons in the club. Single men (also referred to as ‘‘sharks’’) are easily identified by an orange wristband. Single women also wear an orange wrist band. Couples are identified by a green colored wristband. Single men are often considered to be a nuisance, as reported by many patrons, and are avoided in certain circumstances. Single women, moderately rare, do not share the stigma.

Anyway, the authors went there and recruited 44 men, of whom 18 ended up having sex, while 26 only looked at other patrons doing so. Saliva samples were taken before and afterwards, and levels of testosterone were measured. The results showed that testosterone increases were much larger in the do-ers than the watchers (see above).

This is an important result, the authors say, because

it runs against the grain of previous human testosterone and sexual stimuli studies in which testosterone increases in response to erotic videos and "courtship"’ behavioral interactions appeared more reliably induced than those related to active sexual behavior... We suggest that the reason for our findings, in contrast to the overarching pattern of previous work, is that lab-based paradigms may quell men’s testosterone responses... engaging in sexual behavior while wired up to machines in a sterile lab may put a damper on men’s arousal and physiological responses.

A good point.

In general, lab studies can be misleading when the behaviors under investigation are the kind of thing you can't really do in a lab. For research on fairly 'basic' memory, perception and cognitive tasks, a lab is probably as good an environment as any but for more complex behaviours it may be systematically misleading. And if a lab is bad, an MRI scanner is even less realistic.

Now, I thought the neuroscientists who threw a cocktail party on their grant money had it good, but these authors really hit a home run by using theirs to get into a sex club. It would be hard to top that but I note that surprisingly little is known about the, er, physiological correlates of lying on a beach in the Bahamas atop a pile of gold bars and bottles of Dom Pérignon. Someone needs to find out and I for one would be willing to undertake this challenge.

 Escasa, M., Casey, J., and Gray, P. (2010). Salivary Testosterone Levels in Men at a U.S. Sex Club Archives of Sexual Behavior, 40 (5), 921-926 DOI: 10.1007/s10508-010-9711-3