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| | Michael E. Mills reviews Digit Ratio: A Pointer to Fertility, Behavior and Health by John T. Manning |
 | | Manning reviews evidence to suggest that the ratio of the length between the ring and index finger is somewhat sexually dimorphic, that this ratio is determined during early fetal development, and that it is influenced by sex hormones, particularly testosterone. |
 | | Specifically, it is the ratio of the length of the index finger (digit 2, or "2D") and the ring finger (digit 4, or "4D") that is sexually dimorphic. |
 | | The ratio of index finger length to ring finger length is called the “2D:4D digit ratio,” or more simply, the “digit ratio.” Manning reports that, for males, the index finger is generally about 96 percent of the length of the ring finger, which gives an average digit ratio for males of.96. |
| human-nature.com /nibbs/02/manning.html (2015 words) |
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