Male income and height are were included to measure male quality, because both parameters have previously been found to affect male reproductive success. Rich men are sexy. Tall men are sexy. But does male sexiness translate into more female orgasms?
The hypothesis about female orgasms that Pollet and Nettle investigate is this one.
If female orgasm is adaptively designed for discriminating male quality, then it should be more frequent in females paired with high-quality males.And since male quality is wealth and height, their prediction is clear.
If the adaptive view of female orgasm is correct, then we predict that women will report more frequent orgasms the richer their partners are and the taller their partners are.The 1534 women in the study self-reported via computers away from the their homes, so if you think you can trust self-reporting (which is always an issue), you may agree with the authors that women have more orgasms the higher their partner's income is. But does this explain why women have orgasms at all?
They end the paper thus.
The data produced so far, while apparently consistent with an adaptive role for female orgasm, are far from definitive. Moreover, even if consistent with an adaptive role for female orgasm, these data do not allow conclusive testing between two alternative proposed functions—namely, that female orgasm differentially promotes emotional bonding with high-quality males or that it differentially promotes conception with such males under conditions of sperm competition.More research is need to elucidate the function of the female orgasm. Anyone disagree with that?
Additionally, there was a slight trend that partner height influence orgasm frequency the same way that wealth does. The probability that this was a random effect was 0.5<p<0.1, meaning that it didn't quite make below the magical P-value of 5%. We definitely need more data on that.
T POLLET, D NETTLE (2009). Partner wealth predicts self-reported orgasm frequency in a sample of Chinese women Evolution and Human Behavior DOI: 10.1016/j.evolhumbehav.2008.11.002