Selective Breeding for a Behavioral Trait Changes Digit Ratio

  title={Selective Breeding for a Behavioral Trait Changes Digit Ratio},
  author={Reginia H. Y. Yan and Jessica L. Malisch and Robert M. Hannon and Peter L. Hurd and Theodore Garland},
  journal={PLoS ONE},
The ratio of the length of the second digit (index finger) divided by the fourth digit (ring finger) tends to be lower in men than in women. This 2D∶4D digit ratio is often used as a proxy for prenatal androgen exposure in studies of human health and behavior. For example, 2D∶4D ratio is lower (i.e. more “masculinized”) in both men and women of greater physical fitness and/or sporting ability. Lab mice have also shown variation in 2D∶4D as a function of uterine environment, and mouse digit… 

Figures from this paper

Digit Ratio (2D∶4D) Differences between 20 Strains of Inbred Mice

The inbred mice model presents an opportunity for researchers to investigate the genetic, and gene-environmental influence on the development of digit ratios, and calls into question the use of this trait as a broadly applicable indicator for prenatal androgen exposure.

Digit ratios in two lacertid lizards: sexual dimorphism and morphological and physiological correlates

Comparing digit ratios of two Podarcis lizards among sexes, colour morphs and species concludes that digit ratios in lizards deserve attention, because they exhibit sexual dimorphism and correlate with ecologically relevant morphological and performance variables.

Environmental levels of oestrogenic and antiandrogenic compounds feminize digit ratios in male rats and their unexposed male progeny

Pregnant environmental levels of endocrine-active substances permanently disrupt digit ratios in male rats, and digit ratio measurement in adults is a promising biomarker of prenatal exposure to low-dose endocrine disruptors in rodents with potential implications for future studies in humans.

Sand lizards Lacerta agilis with higher digit ratios are more likely to autotomy

The results are probably the first attempt to link digit ratio to the susceptibility of lizards to tail autotomy, and suggest that these morphological characteristics are most likely related to intraspecific differences which may determine an individual's reaction or susceptibility to be a prey and escape behaviour.

Asymmetric Behavior in Ptyodactylus guttatus: Can a Digit Ratio Reflect Brain Laterality?

This work tested whether the digit ratio in the gecko Ptyodactylus guttatus was associated with behaviors attributed to brain laterality, and found that geckos starting to move with their left leg were much more likely to bypass obstacles from the right side, and vice versa.

Sex differences in anogenital distances and digit ratios in wild David's rock squirrels Sciurotamias davidianus

2D:4D may not be fixed or influenced by the prenatal steroidal environment in David's rock squirrels, and there are no sex differences or lateral asymmetry in 2D: 4D.

igit ratio ( 2 D : 4 D ) moderates the relationship between cortisol eactivity and self-reported externalizing behavior in young dolescent males

The importance of considering the organizational influence of prenatal testosterone in order to understand the activational influence of circulating hormones during adolescence is demonstrated, as well as the importance of a multi-systems approach in which interactions between multiple hormones are taken into account.



Digit ratio (2D:4D) and behavioral differences between inbred mouse strains

Large differences in digit ratio between the strains are found and it is suggested that inbred mice are a promising system for investigating the correlation between digit ratio and behavioral traits.

Sexual dimorphism in digit‐length ratios of laboratory mice

The mouse may be a useful animal model for studying the factors that influence finger length patterns, which have recently been correlated with several specific behaviors and disease predispositions in humans.

Intrauterine Position Effects on Anogenital Distance and Digit Ratio in Male and Female Mice

The lack of correlation between 2D:4D and AGDs in this mouse strain suggests that these two measures do not reflect a common influence of androgen exposure, and the possible roles of temporal and localized effects of masculinization are discussed.

Quantitative genetics and behavioural correlates of digit ratio in the zebra finch

  • W. Forstmeier
  • Biology
    Proceedings of the Royal Society B: Biological Sciences
  • 2005
It is found that variation in digit ratio was almost entirely additive genetic, with heritability estimates ranging from 71 to 84%, and the rearing environment explained an additional 5–6% of the variation, but there was no indication of any maternal effects transmitted through the egg.

Second to fourth digit ratio and male ability in sport: implications for sexual selection in humans.

  • J. ManningR. Taylor
  • Education
    Evolution and human behavior : official journal of the Human Behavior and Evolution Society
  • 2001

Of mice and men – cross‐species digit ratio (2D:4D) research: comment on Bailey, Wahlsten and Hurd (2005)

Cross-species 2D:4D research is reviewed and other pertinent evidence is presented to offer possible explanations for these unexpected findings and to motivate future research efforts in this field.

Digit ratio varies with sex, egg order and strength of mate preference in zebra finches

  • N. BurleyV. Foster
  • Biology
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 2004
Digit ratio increased across egg order, which is consistent with a pattern of decreasing androgen allocation, and may prove to be an extremely useful tool for addressing a wide range of questions about vertebrate differentiation and behaviour.