To keep himself awake as he flew east during the long night, Post tied a piece of string to one finger.
VOA: special.2009.03.18
They also estimated the students' exposure to the hormone before they were born by measuring the ratios of their index fingers to their ring fingers (a long ring finger indicates high testosterone exposure) and by measuring how accurately they could determine human emotions by observing only people's eyes, which also correlates with prenatal exposure to testosterone.