Ovulatory cycle effects on tip earnings by lap dancers: economic evidence for human estrus? Geoffrey Miller, Joshua M. Tybur, Brent D. Jordan ZOL 313 Example presentation by Lindsey Walters May 14, 2008

Introduction Estrus: phase of increased female sexual receptivity, common in mammals Common knowledge is that estrus has been “lost” in humans, but recent lab evidence suggests the women are more attractive to men at the most fertile part of their cycle (just before ovulation). “Gentlemen’s clubs” provide an “ideal setting” for investigating human estrus.

Hypothesis/predictions Hypothesis: Estrus in human women is not hidden; men can detect when a woman is fertile. Predictions: 1.Men will give lap dancers higher tips when they are fertile than when they are in non-fertile parts of their cycle. 2.Tips of women using birth control will remain consistent across their cycle.

Methods Each day, lap dancers self-reported their earnings, their menstrual phase, and whether or not they used the birth control pill.

Results

Discussion Hypothesis: Estrus in human women is not hidden; men can detect when a woman is fertile. Predictions: 1.Men will give lap dancers higher tips when they are fertile than when they are in non-fertile parts of their cycle. 2.Tips of women using birth control will remain consistent across their cycle.

Future Directions What are the proximate mechanisms behind this phenomenon? Is this effect a “signal” or a “leaky cue”? Does it benefit women to advertise their fertility or should they try to hide it?