Men with more masculine digit ratios are partnered with more attractive women

The low 2nd to 4th digit ratio (2D:4D) is thought to reflect higher prenatal exposure to testosterone and may be associated with higher testosterone levels in adulthood and higher reproductive success in males. However, there is little evidence that higher testosterone levels are directly responsible for higher male fertility. Here, we investigate if this phenomenon may be related to mate choice, and, in particular, if males with lower 2D:4D are partnered with more attractive and potentially more fertile women. We compared waist-to-hip ratio and breast size of 50 women from two groups, depending on the 2D:4D (more masculine, more feminine) of their actual partner. Moreover, we examined the relationship between men's digit ratio and their mate's body type. Men with more masculine 2D:4D were coupled with women with significantly lower waist-to-hip ratios. They were also four times more often partnered with women who had both relatively narrow waists and large breasts. These findings suggest that levels of sex steroids during fetal development in males may have long-lasting influences on their mating value. This is the first study to show relationships between men's intrauterine environment, reflected by 2D:4D, and their actual partners' anthropometric traits, linked to perceived attractiveness and potential fertility.