The ratio of index finger length to ring finger length (2d:4d) is an index of prenatal androgen exposure. In a study with 71 female and 52 male undergraduate students, we assessed the relationship between 2d:4d and jealousy with respect to various dimensions of rival characteristics. Following the presentation of a jealousy-evoking scenario, participants rated the extent to which they would feel jealous if the rival possessed various characteristics (some which have been found to be more jealousy evoking for men, others which have been found to be more jealousy evoking for women). Men with higher, more feminine 2d:4d reacted more jealously toward more socially dominant rivals. Women with lower, more masculine 2d:4d reacted more jealously toward more physically attractive rivals. These results show that the level of prenatal testosterone affects which rival characteristics elicit the highest level of jealousy, which are different for men and women.
Park, J. H., Wieling, M. B., Buunk, A. P., & Massar, K. (2008). Sex-specific relationship between digit ratio (2D:4D) and romantic jealousy. Personality and Individual Differences, 44, 1039-1045. https://doi.org/10.1016/j.paid.2007.10.023