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Visualizing facial shape regression upon 2nd to 4th digit ratio and testosterone
Katrin Schaefer1, Bernhard Fink, Philipp Mitteroecker
1Department of Anthropology, University of Vienna, Vienna, Austria. katrin.schaefer@univie.ac.at
Collegium Antropologicum
|January 19, 2006
Summary
Prenatal testosterone influences lower face shape, while pubertal testosterone affects overall facial elongation and eyebrows. These androgen effects on male facial structure vary by developmental timing.
Area of Science:
- Evolutionary biology
- Human anatomy
- Endocrinology
Background:
- Sex steroids significantly influence sexual dimorphism in facial features.
- Facial sexual dimorphism is organized early in development, not just at puberty.
- The precise timing and causes of sex steroid variations in facial shape are not fully understood.
Purpose of the Study:
- To investigate the differential effects of prenatal and pubertal androgens on male facial shape.
- To examine the relationship between digit ratio (2D:4D) as a proxy for prenatal testosterone and circulating testosterone levels with facial morphology.
Main Methods:
- Utilized geometric morphometric methods to analyze male facial shape.
- Regressed facial shape against 2D:4D ratio (proxy for prenatal testosterone) and salivary testosterone levels.
- Employed data from Neave and colleagues for measurements.
Main Results:
- Prenatal testosterone (indicated by 2D:4D ratio) showed potential opposite effects on upper and lower facial regions.
- Higher circulating testosterone levels were associated with a general elongation of the face.
- Increased salivary testosterone correlated with more pronounced, medially-tailed eyebrows.
Conclusions:
- Prenatal and pubertal testosterone exert distinct influences on male facial morphology.
- These findings highlight the importance of considering developmental timing of androgen exposure in facial shape studies.
- Results have implications for understanding female preferences for male facial characteristics.