Variations in count and width of the human middle phalangeal hair: A microscopic study

Abstract

The aim of the present pilot study was to analyze human middle phalangeal hair (MPH) size at a microscopic level and to study relationships between MPH and prenatal androgens through a statistical combination with a 2D:4D ratio, which have not been studied so far.

The pilot sample consisting of 28 volunteers (16 males) was subjected to hand scans, counting their MPH numbers and collecting hair samples. The MPH widths were measured at the microscopic level, and their variations related to sex, body side, finger and the 2D:4D ratio, as measured based on the hand scans, were studied by means of a linear mixed-effects model.

In the 3^rd and the 4^th fingers, we found significant sex differences with higher counts in males, and significant asymmetry in the counts in males with higher counts on the 4th right finger. Males had wider MPH shafts than females. In both sexes, significantly wider hair shafts were found on the 4^th finger compared with the 2^nd finger. No significant relationship was found between MPH shaft width and the 2D:4D ratio.

The present study found that MPH shaft width was significantly different between the sexes and between the 2^nd and 4^th fingers of both hands.