Research supports correlation between finger lengths and stress hormones

If you find yourself lacking in motivation to go for a run or hit the gym, you may want to check your fingers. According to a joint University of Alberta/ University of California- Riverside research study to be published by PLoS ONE, the online, open-access journal from the Public Library of Science, there is a direct correlation between digit length and voluntary exercise.

The study also casts some doubt on a previously released study which linked digit length and male aggression.

While both situations were first thought to have been caused by exposure to elevated levels of prenatal testosterone in the womb, research conducted using lab mice yielded no concrete evidence to support that original hypothesis.

The new study, conducted using 1,000 white mice, seems to support a stronger connection between digit length, voluntary exercise and high levels of prenatal stress hormones, which was indicated by the difference in activity level between the control mice and the selectively-bred active mice. Given the results, the findings suggest that prenatal stress rather than prenatal testosterone levels in the womb, forms a component of the inherent desire for physical activity.

"The research shows a link, or relationship, between the brain, behaviour and personality traits and the shape of the hand," said Peter Hurd, University of Alberta psychology professor and one of the lead researchers. "It opens the door to the notion that aspects of one's personality, in this case the desire to exercise, are fixed very early in life."

Citation: Yan RHY, Malisch JL, Hannon RM, Hurd PL, Garland T Jr. (2008) Selective Breeding for a Behavioral Trait Changes Digit Ratio. PLoS ONE 3(9): e3216. doi:10.1371/journal.pone.0003216 http://dx.plos.org/10.1371/journal.pone.0003216

Source: Public Library of Science

   

• WillB - Sep 17, 2008
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  Ok, I checked my finger length... Now what?
  
  
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• Minnaloushe - Sep 17, 2008
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  I'd check my finger length, but I would have to move.
  
  Be nice if they had actually stated the correlation.
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• humanist - Sep 17, 2008
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  And what about black mice? What correlates there?
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• holmstar - Sep 17, 2008
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  From the paper:
  
  The ratio of the length of the second digit (index finger) divided by the fourth digit (ring finger) tends to be lower in men than in women. This 2D:4D digit ratio is often used as a proxy for prenatal androgen exposure in studies of human health and behavior. For example, 2D:4D ratio is lower (i.e. more "masculinized") in both men and women of greater physical fitness and/or sporting ability. Lab mice have also shown variation in 2D:4D as a function of uterine environment, and mouse digit ratios seem also to correlate with behavioral traits, including daily activity levels. Selective breeding for increased rates of voluntary exercise (wheel running) in four lines of mice has caused correlated increases in aerobic exercise capacity, circulating corticosterone level, and predatory aggression. Here, we show that this selection regime has also increased 2D:4D. This apparent "feminization" in mice is opposite to the relationship seen between 2D:4D and physical fitness in human beings. The present results are difficult to reconcile with the notion that 2D:4D is an effective proxy for prenatal androgen exposure; instead, it may more accurately reflect effects of glucocorticoids, or other factors that regulate any of many genes.
  
  So to summarize... the greater the difference between the length of the ring and index finger (ring finger being the longer one), the more likely that the person was exposed to stress hormones and possess a greater athletic motivation.
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