Our fingers can speak volumes about our personality traits, our future health - and even our sexual orientation. Roger Dobson explains

In the latest research, scientists have also discovered that intelligence is also closely related to the relative lengths of these two digits. The longer a man's index finger, it seems, the more likely it is he will get a good degree.

The link between finger length and such diverse effects as these is not as far-fetched as it may at first seem. The theory behind several hundred pieces of scientific research is not that having one finger shorter than the other causes disease or differences, but that these two digits are simply markers for hormonal exposure in the womb.

Hormones are the chemical messengers that direct development in the growing foetus, and the contents of the cocktail of hormones to which the foetus is exposed plays a huge role in its development.

The idea behind digit-ratio research is that the finger ratio is a historical record of what went on in the womb, particularly in the critical first three months.

A relatively long ring finger is a sign that these organs were exposed to higher levels of the male hormone testosterone, while a relatively long index finger is a marker of oestrogen. More testosterone pre-birth might lead to a more masculine brain, more adept at maths and navigation, more prone to aggression and heart disease, but lacking in social skills and agreeableness. High levels of oestrogen, on the other hand, may increase fertility in a woman, but also heighten the risk of developing breast cancer.

"The digit ratio is a living fossil. It is a record of what the foetus was exposed to at a critical time for the development of many other things," says Professor John Manning, an evolutionary psychologist at the University of Central Lancashire, and an expert in the area.

"It is the relative length rather than the length itself that is important. Digit ratio is the length of the index finger divided by the length of the ring finger. If they are equal in length the ratio is one. If the ring finger is longer the ratio is less than one. Men in general have a longer ring finger relative to their index finger. Low ratios indicate high testosterone before birth.''

A number of traits, including aggression, fertility, and personality types, are known to be gender-related, and were among the first to be looked at by researchers whose measurements are made on the palm side of the hand, from the midpoint of the line that runs across the base of each finger to the top.

Researchers at the University of Alberta looked to see if there was a link between digit ratio and aggression in both men and women. They found that men with lower, more masculine, finger-length ratios had high rates of physical aggression. No link was found for women. "The results are consistent with the hypothesis that testosterone has an effect on adult physical aggression in men,'' they say.

Another testing ground for the theory has been depression. Women are more prone to suffer than men, and if the digit theory is correct, men with feminine-type ratios should experience more depression than others men.

Researchers at the University of Alberta, who put the theory to the test on several hundred men, found that was indeed the case. "Given that women commonly show higher rates of depression than men, we suggest that depression should be associated with lower testosterone. We did find that men with more feminine finger ratios scored higher on a test for depression,'' they say.

Another difference between male and female brains that has been consistently reported is that men are better at spatial tasks. When that was put to the digit-ratio test by psychologists at Fordham University, it was found that women with more masculine digit ratios were better at spatial tasks, while men with less masculine ratios were more articulate. Some of the research also suggests that finger ratio many be a marker of attractiveness. Studies have shown that women are consistently more attracted to men who have more masculine finger ratios.

Just why is not clear, although research by urologists at the Naval Hospital in Athens has thrown up one clue. Finger length in general is thought to be related to hormone exposure, and in research based on men aged 19 to 40, they found that the long-held belief of a link between male sexual dimensions and digit length is on the whole accurate. More specifically, they showed that the male dimension is significantly related to the length of the index finger.

The Greek researchers only looked at the index finger length, rather than the ratio, but unpublished research is showing that the ratio is also a clue to potential male prowess. For the first time, researchers have found that the more masculine the ratio, the greater the male dimension.

Handy hints

New Italian research shows that men with more female finger ratios are more likely to get a good degree. It suggests that men with a smaller ring finger, relative to their index finger, are more likely to get first or upper-second degrees. No such effect was in women students in the research at Milan University.

"A number of studies have now looked at different types of abilities that relate to intelligence," says Professor John Manning of the University of Central Lancashire. "Overall, verbal fluency and better language-use are linked to longer index fingers and higher prenatal oestrogen.'' A second study showed that people with more masculine ratios were better at maths and spatial skills, whole those with female-type ratios had better social skills.

* Disease:

Several disease-risks have been linked to the digit ratio, including that of breast cancer, which is associated with the female-type ratio that signals high prenatal oestrogen exposure, and heart disease, linked to high levels of testosterone.

Autism and ADHD, both conditions that affect more boys than girls, have also been associated with "male" digit ratios. Schizophrenia is another condition which shows a gender bias, and researchers at the University of Florida found that such patients were more likely to have a feminine-type digit-ratio.

* Personality:

Many studies have linked various personality traits with finger ratios. Men with "masculine" ratios, for example, are less agreeable, more prone to aggression, and greater risk-takers. One study found that women with a male-like ratio were more likely to have a masculine occupation, while having a "female" ratio was associated with openness and being neurotic.

* Sexual orientation:

Controversial research, at the University of Southern California, based on more than 2,000 men and women, found that heterosexual men had significantly lower ratios than gay men, but no effect was found among women.

Researchers say the findings add to evidence that prenatal hormonal factors may be linked to men's sexual orientation.

Work out your digits

Measure the distance between the mid-point of the line where your index finger meets your palm, and the top of the finger. Then take the same measurement on your ring finger.

A relatively longer index finger indicates a so-called 'female' pattern. By contrast, a relatively longer ring finger indicates a 'male' pattern.

* WOMEN:

Traits associated with having a 'female' hand :

High fertility

Large family

Low levels of assertiveness

Right-handed

Neurotic

Vulnerable to breast cancer

Low risk-taking

Women with 'male' ratio:

Low fertility

Left-handed

High risk-taking

High assertiveness

Lower levels of breast cancer

Homosexuality

* MEN:

Traits associated with a 'male' hand:

High fertility

Fast running speed,

Good soccer ability

Large birth-size

Autism

ADHD

Low verbal fluency

Aggression

Good maths skills

Male with 'female' ratio:

Low testosterone

Reduced fertility

Good verbal skills,.

Poor soccer skills

Slow runner

Small families

Poor navigation skills

Greater intelligence

Vulnerability to depression

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