Bonobos have a more human-like second-to-fourth finger length ratio (2D:4D) than chimpanzees: a hypothesized indication of lower prenatal androgens.

Journal Article (Journal Article)

The ratio of the second-to-fourth finger lengths (2D:4D) has been proposed as an indicator of prenatal sex differentiation. However, 2D:4D has not been studied in the closest living human relatives, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). We report the results from 79 chimpanzees and 39 bonobos of both sexes, including infants, juveniles, and adults. We observed the expected sex difference in 2D:4D, and substantially higher, more human-like, 2D:4D in bonobos than chimpanzees. Previous research indicates that sex differences in 2D:4D result from differences in prenatal sex hormone levels. We hypothesize that the species difference in 2D:4D between bonobos and chimpanzees suggests a possible role for early exposure to sex hormones in the development of behavioral differences between the two species.

Full Text

Duke Authors

Cited Authors

  • McIntyre, MH; Herrmann, E; Wobber, V; Halbwax, M; Mohamba, C; de Sousa, N; Atencia, R; Cox, D; Hare, B

Published Date

  • April 2009

Published In

Volume / Issue

  • 56 / 4

Start / End Page

  • 361 - 365

PubMed ID

  • 19285708

Electronic International Standard Serial Number (EISSN)

  • 1095-8606

International Standard Serial Number (ISSN)

  • 0047-2484

Digital Object Identifier (DOI)

  • 10.1016/j.jhevol.2008.12.004


  • eng