#74

ring finger
–noun
the finger next to the little finger, esp. of the left hand, on which an engagement ring or wedding band is traditionally worn.
[Origin: bef. 1000; ME, OE]
Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.



Hidden significance of a man's ring finger

Scientists at The University of Liverpool have found a link between finger length and depression in men: the longer a man's fingers are relative to his height, the more likely he is to suffer from depression. Ironically, perhaps, the strongest single indicator is the relative length of his ring finger.

Susceptibility determined before birth
[Dr John Manning]The key to this improbable link appears to be testosterone. Some kind of link has been suspected for some time: the loss of libido which accompanies many episodes of depression has led scientists to hypothesise that testosterone levels diminish during depression, and rise again upon recovery - but in fact, research results have been equivocal. The University of Liverpool study confirms suspicions regarding testosterone and depression, but suggests that the culprit is prenatal testosterone, produced from week 8 of a pregnancy, rather than day-by-day testosterone levels in adults.

Dr John Manning displaying a series of photocopied hands (illustrated)

Dr John Manning of the University's School of Biological Sciences explains: "Foetal testosterone plays a key role in the development of the male genital system. It also impacts on the development of fingers and thumbs, and the central nervous system.

"Men who experienced high concentrations of foetal testosterone have relatively long fingers - in particular, fourth digits which are longer than their second digits. Conversely, men who experienced low concentrations of foetal testosterone have shorter fourth digits than their second digits."

The Liverpool investigation
Dr Manning, his colleague Sue Martin and Professor Chris Dowrick of the University's Department of Primary Care studied 102 men and women from different socioeconomic backgrounds. Each had a variety of physical measurements taken, including wrist size, ear size, height - and the length of digits 2 to 5 (ie their fingers) from the basal crease to the tip. The Beck Depression Inventory (BDI) - widely used to detect depression in the population as a whole, as well as psychiatric patients - was then deployed to identify those who suffered from depression, and to score the severity of their depression.

The results showed that in men - but not women - a high BDI score was positively related to long digits, particularly the fourth digit (ie the ring finger). Dividing digit length by height, to take account of the fact that taller men tend to have longer limbs, fingers and feet, gave an even stronger predictor of high BDI scores in men.

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Likely explanation
Foetal testosterone concentrations are the most likely explanation, given the sex-dependent pattern of the data. Says John Manning: "Testosterone has strong influences on the development of the male nervous system - not all of them beneficial.

"It is believed that excess testosterone promotes the growth of the right hemisphere of the brain at the expense of the left hemisphere. This can lead to impaired reading ability, but also to enhanced mathematical and musical abilities. Unfortunately, there seem to be other, less welcome effects: excess testosterone has already been implicated in the origins of migraine, autism, stuttering, schizophrenia - and now depression, too.

"Interestingly, the study's results suggest that depression in women has a different and as yet undetermined origin".

Simple, objective indicator
Having relatively long ring fingers does not necessarily mean that a man will, in fact, suffer from depression - just as people with high cholesterol levels do not necessarily have a heart attack. However, since the symptoms of depression can discourage sufferers from acknowledging their condition and seeking treatment, ring finger length could offer GPs a simple, objective indicator of susceptibility in men.

Wellcome Trust
This is not the first time that John Manning's research has identified a hidden significance of finger length. Last year he established a link between the relative length of women's ring fingers and their fertility levels: women with shorter ring fingers than forefingers tend to have high fertility.

Conversely, men with relatively long ring fingers are more likely to have high fertility. His work has now attracted the interest of the Wellcome Trust, which recently awarded him an innovative research grant to support an investigation into a possible association between risk of heart attack and second to fourth digit ratio.

The results of this study were published by Martin SM, Manning JT & Dowrick CF in "Fluctuating Asymmetry, Relative Digit Length and Depression in Men", Evolution and Human Behaviour 20: 203-214 (1999)

For further information see www.liv.ac.uk/biolsci/html/population___evolutionary_biol.html


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Academics find that finger of destiny points their way
Male scientists are good at research because they have the hormone levels of women and long index fingers, a new study says.

A survey of academics at the University of Bath has found that male scientists typically have a level of the hormone estrogen as high as their testosterone level.

These hormone levels are more usual in women than men, who normally have higher levels of testosterone. The study draws on research that suggests that these unusual hormone levels in many male scientists cause the right side of their brains, which governs spatial and analytic skills, to develop strongly.

The study, which as been submitted to the British Journal of Psychology, also found that:
# these hormonal levels may make male scientists less likely to have children.
# those men with a higher level of estrogen were more likely than average to have relatives with dyslexia, which may in part be caused by hormonal levels.
# women social scientists tended to have higher levels of testosterone, making their brains closer to those of males in general.

The study drew on work in the last few years which established that the levels of estrogen and testosterone a person has can be seen in the relative length of their index (second) and ring (fourth) fingers. The ratio of the lengths is set before birth and remains the same throughout life.

The length of fingers is genetically linked to the sex hormones, and a person with an index finger shorter than the ring finger will have had more testosterone while in the womb, and a person with an index finger longer than the ring finger will have had more estrogen. The difference in the lengths can be small – as little as two or three per cent – but important.

A survey of the finger lengths of over 100 male and female academics at the University by senior Psychology lecturer Dr Mark Brosnan has found that those men teaching hard science like mathematics and physics tend to have index fingers as long as their ring fingers, a marker for unusually high estrogen levels for males.

It also found the reverse: those male academics with longer ring fingers than index fingers – the usual male pattern – tended not to be in science but in social science subjects such as psychology and education.

A further study also suggests that prenatal hormone exposure, and hence index finger length, can also influence actual achievement levels. In a survey of male and female students on a JAVA programming course at the University, the researchers found a link between finger length ratio and test score. The smaller the difference between index and ring finger - the higher the test score at the end of the year.

"The results are a fascinating insight into how testosterone and estrogen levels in the womb can affect people's choice of career and how these levels can show up in the length of fingers on our hands," said Dr Brosnan.

In the general population, men typically have higher levels of testosterone than women, but the male scientists at the University of Bath have lower testosterone levels than is usual for men – their estrogen and testosterone levels tend to match those of women generally.

This research now suggests that lower than average testosterone levels in men lead to spatial skills that can give a man the ability to succeed in science. Other research has in the past also suggested that an unusually high level of testosterone can do the same thing by encouraging the development of the right hemisphere.

This right brain development is at the expense of language abilities and people skills that men with a more usual level of testosterone develop and which can help them in social science subjects like psychology or education.

Dr. Brosnan said that men having levels of testosterone very much higher than normal for males would also create the right hemisphere dominated brain, which could help in science. The extremes of low testosterone and high testosterone for men would create the scientific brain, and the normal range in the middle would create the 'social science' brain.

The question also arises as to why more women, who have this lower level of testosterone, are not in science, which is male-dominated, with only one in 40 science professors being a woman.

The short answer is that we don't know: the high levels of estrogen in women may act differently on the brain and not give them the spatial skills that men with similar levels of the hormone have.

There may be social reasons: science has been male-dominated the past and this may be putting women off entering it, even though they are able to. Why male scientists should have fewer children is not known.

"The study of my colleagues at the University of Bath was also interesting in that it shows that women in social science tend to have a higher level of testosterone level relative to their estrogen level, making their brains closer to those of men in general, said Dr. Brosnan."