Want to know how well you or your kids will do on their SAT’s? Want to measure how aggressive you are if you’re a man? Just check the size of your fingers. Recent studies are being conducted to measure both of these qualities in kids and men. Scientists have found that different levels of testosterone and estrogen in the womb account for finger lengths, which reflect areas of the brain that are more highly developed than others. Testosterone affects spatial and mathematical skills which is exhibited in the length of the ring finger while estrogen exposure does the same for verbal ability and tends to lengthen the index finger relative to the ring finger. So, kids with longer ring fingers compared to index fingers are likely to have higher math scores while children with the reverse finger-length ratio are likely to have higher reading and writing, or verbal scores on their SAT’s.

To test the link to children’s scores on the College Board’s Scholastic Assessment Test, Brosnan and his colleagues made photocopies of children’s palms and measured the length of their index and ring fingers using calipers accurate to 0.01 millimeters. They then looked at boys’ and girls’ test performances and compared them to the ratio measurements they had taken. The results found a clear link between high prenatal testosterone exposure, indicated by the longer index finger compared to the ring finger, and higher scores on the math section of the SAT’s for boys and higher literacy scores for girls who had shorter ring fingers. The shorter the ring finger, the greater the gap between a child’s math and literacy scores.

Researchers have also found that the longer a man’s ring finger is, the more aggressive he is likely to be because of the high exposure to testosterone he had in his mother’s womb. This study does not apply to women, regardless of the length of their ring fingers. The research was based on surveys and hand measurements of 300 undergrads at the University of Alberta. Of course, environmental factors also play a large role in affecting violent behavior, but this study supports that biology plays a factor as well, emphasizing the collective teaming up of nature and nurture to create an outcome.

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