Digit Ratio

2D:4D ratio

What is it?

  • 2D:4D ratio is a digit ratio.
  • 2D = 2nd digit aka index finger
  • 4D = 4th digit aka ring finger

Inline image 1

What is the significance?

The lengths of your fingers are affected by the your exposure to androgens while you are still growing in your mother’s womb. The 2D:4D ratio has a negative correlation with prenatal androgen exposure. i.e The lower the ratio, the greater the exposure.

Low ratios (<1) have been correlated with more masculine facial features and traits as well as being better athletes. Whereas people with high ratios tend to have more feminine facial features and better at artistic pursuits. One interesting finding is that the digit ratios seems to correlate with disease risk, physiological behaviors and body composition. Below are a few examples.

Lower ratio:
  • increased risk of prostate cancer
  • increased risk of autism, anorexia and ADD
  • increased reproductive success in males
  • more aggressive
  • better at sports
  • prone to risky behavior
Higher ratio:
  • increased risk of depression, bulimia and anxiety
  • increased risk of coronary heart disease
  • increased risk of obesity and metabolic syndrome
  • increased reproductive success in females
  • more polite

Here are a couple of interesting articles and studies on digit ratio.

Can Persistence Hunting Signal Male Quality? A Test Considering Digit Ratio in Endurance Athletes

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4390232/

2D:4D ratio negatively correlated with running performance in the half marathon.

i.e. lower ratio = faster times for both male and female.

Inline image 1

The second-to-fourth digit ratio correlates with aggressive behavior in professional soccer players

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3694562/

lower 2D:4D ratio

  • higher mean salivary testosterone concentration
  • more fouls
  • better performance
  • more aggressive based on Picture Frustration Test results

Second to fourth digit ratio confirms aggressive tendencies in patients with boxers fractures.

https://www.ncbi.nlm.nih.gov/pubmed/23972912

People who get boxer fractures tend to have lower 2D:4D ratios, which may suggest they are more prone to aggression and violence.

The 2nd–4th digit ratio (2D:4D) and neck circumference: implications for risk factors in coronary heart disease

http://www.nature.com/ijo/journal/v30/n4/full/0803154a.html

High 2D:4D ratio = risk factor for obesity and CHD

Why? High 2D:4D = increased tendency to be overweight/obese = increased risk for CHD

Second to fourth digit ratio (2D:4D) and coronary heart disease

http://www.earlyhumandevelopment.com/article/S0378-3782(15)00086-9/abstract?cc=y=

2D:4D may correlate particularly with risk of coronary heart disease in Chinese men.

Is your son at risk of heart disease? Look at his hands

http://www.telegraph.co.uk/news/uknews/1360061/Is-your-son-at-risk-of-heart-disease-Look-at-his-hands.html

Scientists at the University of Liverpool made the discovery after studying men of various ages who had suffered heart attacks.

They found that men whose ring fingers are the same length or shorter than their index fingers are at far greater risk of a premature heart attack in their thirties and forties.

The reason for the differences in the relative lengths of the fingers appears to be related to the levels of the sex hormones in the body, and may be linked to their influence on development even before the child is born.

Longer ring fingers are found on males who also have relatively high levels of the sex hormone testosterone, which is known to protect against heart disease in men. Younger heart attack victims with shorter ring fingers have been found to have depleted levels of testosterone.

Previous research has shown that the finger-length ratio is linked with fertility and breast cancer risk in women and even sexual orientation in men and women.

This is because the genes that are indirectly responsible for the production of testosterone and the female hormone oestrogen also control the development of the fingers.

However, this is the first time that evidence of a direct correlation between finger length, age and heart attacks has ever been reported.

The age range for heart attacks in men where the index finger was relatively long (a ratio greater than one) was 35 to 80 years of age, but in those with relatively long ring fingers (ratio less than 0.9) it was 58 to 80.

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