Several articles such as this one are floating about just now, but all of them leave open a couple of obvious follow-up questions.
To summarize: researchers have found that the ratio of the lengths of one’s index finger to one’s ring finger is affected by the amount of testosterone one was exposed to while still in the womb.
For women, “normal” is for the two fingers to be about the same length - for men it’s for the ring finger to be slightly longer. But for those who were exposed to higher testosterone levels before birth, the ring finger will be somewhat longer than “normal” for their sex.
Furthermore, they’re also finding that a number of less-trivial aspects of a person at adulthood are also related to this. The current articles discuss the finding that there are higher aggression levels among people exposed to higher testosterone in the womb, but previous studies also point to links with fertility, attractiveness to the opposite sex, sexual preference, tendencies toward sex-linked diseases, etc.
The upshot is that this finger-length ratio can be a simple physical marker that relates statistically to important aspects of ourselves.
Anyway, as you can tell I’ve been through the articles in some depth, but still haven’t seen the answers to two important questions:
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What are the important ratio values? How is the measurement done, and what constitutes a “significant” variation from “normal” for your sex?
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What factors determine testosterone levels in the womb? Would, for instance, emotional stress on the part of the mother during pregnancy affect hormone levels?
Does anyone know any more details on this?