Digit Length May Reveal Unusual Breeding Behaviour In A Seabird

The hormonal environment experienced during prenatal development may affect adult phenotype and behavior.

Digit lengths may provide an estimate of steroid levels encountered during embryonic development in humans and other vertebrates.

Finger patterns in humans, specifically 2D:4D finger ratios, have been shown to reveal sexual orientation or cooperative behavior.

Here we show evidence of linkage between digit lengths, specifically first digit length, and cooperative breeding in a monogamous seabird.

These results are a starting point for further tests of the hypothesis that first digit length is an indicator of prenatal hormone levels. Moreover these results may offer practical use in wild populations to study implications of changes in prenatal environment for adult social behavior.


Royal Society journal Biology Letters


Biology Letters publishes short, innovative and cutting-edge research articles and opinion pieces accessible to scientists from across the biological sciences. The journal is characterised by stringent peer-review, rapid publication and broad dissemination of succinct high-quality research communications.


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