Economic Evidence of Human Estrus?

by Jason Stotts

Someone sent me a link to this study “Ovulatory cycle effects on tip earnings by lap dancers: economic evidence for human estrus?” in the journal Evolution and Human Behavior.  The idea of which is to map earnings of strippers compared to their menstrual cycle to see if they can find strong correlations between them.

Abstract
To see whether estrus was really “lost” during human evolution (as researchers often claim), we examined ovulatory cycle effects on tip earnings by professional lap dancers working in gentlemen’s clubs. Eighteen dancers recorded their menstrual periods, work shifts, and tip earnings for 60 days on a study web site. A mixed-model analysis of 296 work shifts (representing about 5300 lap dances) showed an interaction between cycle phase and hormonal contraception use. Normally cycling participants earned about US$335 per 5-h shift during estrus, US$260 per shift during the luteal phase, and US$185 per shift during menstruation. By contrast, participants using contraceptive pills showed no estrous earnings peak. These results constitute the first direct economic evidence for the existence and importance of estrus in contemporary human females, in a real-world work setting. These results have clear implications for human evolution, sexuality, and economics.

While the study is interesting because it does (tentatively, n=18) establish a link between the amount of money men tip the strippers and where they are on their cycle, it’s not clear that it is evidence of estrus.

Estrus is like being in “heat” for mammals, it’s the period of time during which the female is receptive, and capable of receiving, sexual advances from the male.  For example, in dogs, the bitch will not stand for a male dog (allow him to mount her) unless she is in heat.  Moreover, neither dog will have any interest in sex unless the bitch is in heat.  Now, if you compare that to humans, you might see the problem.

Humans do not have heats.  Human males can always become sexually aroused (even in the absence of females) and human females are always capable of being sexually receptive (and even receptive of non-penises).  So, there is no way for someone to “find” estrus in humans, since we clearly don’t have one.  Now, what the article does show is that there appears to be a pheromonic response by men to women at certain times in their cycle.  There is no other way to account for the difference in the difference in tips based on their cycles, since we can presume that the strippers will always be acting in ways that they think will net them the greatest economic reward.  I’d like to see more studies about pheromones in humans, as the studies are at best conflicting right now and there is no clear evidence either way.

Regardless, the study is worth taking a look at and the implications of it are interesting.