What Science Can Tell About Us from Our Hands
In the past, many cultures thought that hands had a prophetic value. Based on the structure and lines on the hand, they believed they could discover things about themselves and their future. This practice evolved into what is know today as palmistry, and like other forms of divination -- it has not been taken seriously by science.
But, what if there is some truth to palmistry?
What can science tell about us from our hands?
Over the past decade, research has found that the hand does have merit as an instrument to gauge heath, innate abilities, personality traits, and even sexuality.
One of the most fascinating things discovered about hands is the ratio between the second and fourth digit and its link to levels of testosterone and estrogen. This has become known as the "Digit Ratio" or "2D : 4D ratio", and is obtained when the length of the second (index/ 2D) finger is measured, and divided by the length of the fourth (ring/4D) finger. (see fig. 1).
This ratio has been found to be one of the only sexually dimorphic (different norms for men and women) characteristics that are fixed before puberty. Men tend to have longer fourth (ring) fingers compared to their index finger, while women have longer index fingers comparatively.
Simplified, the fourth fingers length is positively correlated to testosterone, while the second (index) finger with estrogen. In Europeans 2D:4D ranges between 1.0 and 0.96, with females tending towards the higher values and males tending towards the lower. In other populations 2D : 4D may be different.
Check out this video with Professor John Manning explaining digit ratio.
He attempts to deduce the winner of a race by studying 5 athletes hands.
From the BBC documentary "Secret of the Sexes".
Males with a lower 2D:4D ratios (greater fetal exposure to testosterone) have been correlated with being more fertile, more aggressive, and having higher music & sports aptitude.
Men with higher 2D : 4D ratios have been found to be more at risk for heart disease.
Male to female transsexuals were found to have a higher digit ratio than control males, but one that was comparable to control females.
Lower digit ratios in women have been correlated (but not statistically significant) with lesbian/bisexual tendencies, along with with aggressiveness and assertiveness.
While women with higher digit ratios are more at risk for breast cancer, and more fertile.
Schizophrenic men and women were found to have higher digit ratios and a lower 2D:4D ratio has also been found more often in those with Autism.
Color of Hands
Beyond digit ratio, there are other medical clues we can gather from our hands.
The color and appearance of our hands can often be a good indicator of our general health:
Poor circulation (a symptom for a variety of ailments) can cause hands to take on a blue-ish hue.
Red hands may indicate cirrhosis of the liver.
Diabetes is often accompanied with "Terry's nails" (half white, half pink nails).
Blue fingernails can be sign of heavy metal poisoning, (very) poor circulation, lung or heart problems.
Yellow or green finger nails can indicate a respiratory problem.
Clubbing (nails curve over the fingertips) is often caused by low oxygen levels in the blood, and could be a sign of lung, liver or bowel disease.
Spoon nails (concave shaped) may indicate an iron deficiency.
Hand Lines & Fingerprints
Even the lines on our palms can have some medical significance -- certain swirl patterns are known to be associated with genetic disorders such as down syndrome.
The presence of a single transverse palmar crease can be, but is not always, a symptom of certain medical conditions such as Fetal alcohol syndrome and genetic abnormalities including Down syndrome and Noonan syndrome.
Males are twice as likely as females to have this condition. (see fig 2 & 3)
Dermatoglyphics is the scientific study of fingerprints, and rare dermatoglyphic patterns often relate to genetic disorders. (see wikipedia article for more info)
In one study patients with Alzheimer's showed a significantly increased frequency of ulnar loops on their fingertips.
A pattern of eight or more ulnar loops was found significantly more often in patients with Alzheimer's (72%) than in the control group (26%).
Cool Hand Fact:
Hands begin to form about four weeks after conception. By the end of the fourth month the formation of linese, ridges, and creases on the fingers and palms will be complete, and this structure will remain the same for the rest of the person's life. Making hands like a fossil record of our life in the uterus.
Single transverse palmer crease on Wikipedia
Digit ratio on the BBC
Fingerprints - Audio broadcast from BBC
Bad Driving 'linked to hormone levels' (touches on the digit ratio)
Gay Fingers via CNN health
The hand can be viewed as a map of psychological development in the uterus much like the rings inside a tree mark its growth. They can be used to gauge levels of prenatal testosterone and estrogen in the uterine environment during the critical formative stages. Using this information, it is possible to measure what effect the prenatal environment had on physical development.
While it is not possible to look at hands to screen people for these particular traits, it is possible to see if they have a higher probability of them.