It may look like a joke, but the length of children's fingers can forecast their learning ability, as students.
Individuals with longer ring fingers than index fingers have a flair for math and exact sciences, as compared to literacy or verbal scores, while children with the reverse finger-length case are more predisposed to have higher verbal and writing scores.
"Scientists have known that different levels of the hormones testosterone and estrogen in the womb account for the different finger lengths, which are a reflection of areas of the brain that are more highly developed than others," said lead researcher Mark Brosnan, psychologist of the University of Bath.
"Exposure to testosterone in the womb is said to promote development of areas of the brain often associated with spatial and mathematical skills," he said.
But the same hormone elongates the ring finger.
Estrogen boosts the brain area linked to verbal ability and tends to elongate the index finger. To check this connection in the case of children's scores on the College Board's Scholastic Assessment Test, Brosnans' team photocopied the children's palms and assessed the length of their index and ring fingers with an accuracy of 0.01 millimeters.
Separately, the boys' and girls' test performances were compared with the finger-length ratio. There was a clear connection between high prenatal testosterone exposure (pointed by the longer ring fingers) and higher scores on the math SAT.
Girls with lower prenatal testosterone exposure (revealed by a shorter ring finger) had high literacy SAT scores. The overall results revealed that a relatively longer ring finger (a sign of higher prenatal exposure to testosterone) was correlated to higher math scores versus literacy ones.
"Finger ratio provides us with an interesting insight into our innate abilities in key cognitive areas," said Brosnan.
The team is planning to investigate if finger-length ratios are connected to other cognitive and behavioral abilities, like technophobia, career paths or dyslexia.
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