Alexander V. Georgiev, Calen P. Ryan, Judith B. Borja, Christopher W. Kuzawa
Objectives: The ratio of the length of the second to the fourth digit (2D:4D) of the hand is often used as an index of prenatal androgen exposure but it might also be affected by androgens during “minipuberty,” a period of temporarily high testosterone (T) production in the first few months of life. To examine this, we tested the prediction that men with lower 2D:4D ratios had greater weight growth velocities during the first months of life—a metric recently shown to correlate with concurrent T levels. Methods: We related early growth data to 2D:4D ratios of both hands measured in 756 men (25–26 years) from Cebu, The Philippines. Results: Birth-to-fourth-month (B4M) weight gain velocity (a proxy of early postnatal androgen action) was not associated with adult 2D:4D ratios of either hand, when the latter was measured continuously. When comparing men with more male-typical digit ratios (<1.0) to those with more female-typical ratios (≥ 1.0), the group of men with more male-typical ratios had greater B4M weight velocity, but this was only the case for the left hand. Conclusions: We found modest evidence that adult digit ratios relate to an anthropometric correlate of androgen exposure during minipuberty. Definitive assessment of the role of postnatal T in shaping digit ratios will require direct measures of perinatal T related to longitudinally assessed digit ratios. © 2017 Wiley Periodicals, Inc.
Department of Anthropology, Northwestern University, 1810 Hinman Avenue, Evanston, 60208, IL, United States; School of Biological Sciences, Bangor University, Deiniol Road, Bangor, LL57 2UW, Gwynedd, United Kingdom; Office of Population Studies Foundation, Inc. and Department of Nutrition and Dietetics, University of San Carlos, Cebu City, Philippines; Institute for Policy Research, Northwestern University, 2040 Sheridan Road, Evanston, 60208, IL, United States
