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Euclides
Saturday, September 25th, 2004, 07:43 PM
Evolutionary biologist John Manning has come up with a handy way of working out just how masculine or feminine we really are. He’s measured the fingers of thousands of men and women, and he found that the amount of testosterone and oestrogen you get in the womb determines the length of your ring finger. Testosterone effects the development of the right side of the brain, where we have our visual ability and judge speed and distance. So now he’s putting his theory to the test in selecting promising football players on the basis of finger their length alone.

Evolutionary biologist John Manning has been very busy measuring the fingers of thousands of men and women, and now he’s come up with a handy way of working out just how masculine or feminine we really are.

Dr John Manning: It turn out that the genes which control the development of the fingers are exactly the same genes which control the development of the testes and the ovaries, that is a very, very odd observation but it’s true.

Narration John found that the amount of testosterone and oestrogen you get in the womb determines the length of your ring finger.

Dr John Manning: Because the development of the ring finger is under the influence of testosterone males have longer ring fingers relative to their index fingers than women do. So what possible use does this finding have? Well for a start John thinks it could be a reliable way to choose champion football players.

Dr John Manning: Testosterone effects the development of the right side of the brain. The right side of the brain is where visual special ability is. Now this is important term in any kind of physical endeavour where you have to judge distance. Where you have to judge in playing football for example where the ball is where the foot is when your foot is going to hit the ball and where the ball is going to go any kind of interactive sport.

Narration: To test his theory he photocopied the hands of 24 English soccer players. He then measured their fingers and selected his top six players on the basis of finger length alone.

Dr John Manning: These are the six that I’ve chosen from the exceptional group. So one measures from the base of the finger, which is very well marked on this finger. You can see the basal crease to the tip of the finger. And this particular finger is about 81.65 millimetres. You measure the index finger and the index finger on this particular hand is 69.25 millimetres So a difference of 81 millimetres to 69 millimetres this is a phenomenal difference. Indicating high testosterone before birth. Low oestrogen is what this hand is saying. Well you find that kind of ratio quite commonly in football players.

Narration: John chose his six top players. Would they match the coach’s top six? It turns out four out of six were the same.

Coach: I mean to get four out of six was a big surprise to us and we’re very impressed.

Dr John Manning: Measurements of fingers could be used I think in a very important way for young boys. For 10 year olds eleven and twelve year olds and so on. Pick them out and coach them properly and bring them on.

Coach: There’s obviously something in it. I’d like to find out more so we can get a head start on our rivals



http://www.abc.net.au/catalyst/stories/s674140.htm#transcript

http://www.dse.nl/~frvc/palmistry/science.htm

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Gareth
Saturday, September 25th, 2004, 08:43 PM
The length of my ring fingers only differentiates in 7mm from my index fingers.

Is that something to look with sorrow upon?

Tore
Saturday, September 25th, 2004, 11:41 PM
The length of my ring fingers only differentiates in 7mm from my index fingers.

Is that something to look with sorrow upon?

No.

The average (Caucasian) male has a mean 2D:4D (index: ring) ratio of .95 (thus the average Caucasian male has an index finger 95% as long as his ring finger).

Moreover, is the difference more evident in respect to your right hand as opposed to your left? The right 2D:4D ratio tends to be more responsive towards the effects of pre-natal androgenization than the left hand.


Testosterone effects the development of the right side of the brain, where we have our visual ability and judge speed and distance.

This is grossly misleading, if not downright incorrect.

Firstly, visuo-spatial ability probably does not correspond to the right hemisphere function of the brain, and certainly does not exhibit a positive correlation with pre-natal testosterone. Those with Autism and Asperger's syndrome derive their condition from exposure to abnormally high levels of pre-natal androgens (testosterone), and such individuals exhibit notoriously poor visuo-spatial ability. It is likely that visuo-spatial abilty relates inversely to rate of maturation (hence the fact that males outperform females; neurotypicals outperform those with Autism and Asperger's, who mature abnormally fast), or that it expresses a curve-linear relationship with serum testosterone levels.

The only thing that can be accurately inferred is that exposure to pre-natal testosterone will have varying effects depending on other factors (i.e. testosterone sensitivity, circulating testosterone levels). For example, high levels of testosterone in the womb in combination with high serum testosterone levels will likely produce a gifted athlete, yet exposure to high levels of pre-natal testosterone combined with somewhat lower levels of serum testosterone levels may produce a gifted mathmetician or computer scientist (who likely has mild or perhaps full-blown Asperger's).

Gareth
Sunday, September 26th, 2004, 12:50 AM
No.

The average (Caucasian) male has a mean 2D:4D (index: ring) ratio of .95 (thus the average Caucasian male has an index finger 95% as long as his ring finger).

Moreover, is the difference more evident in respect to your right hand as opposed to your left? The right 2D:4D ratio tends to be more responsive towards the effects of pre-natal androgenization than the left hand. Right hand:
71mm
76mm
= index finger 93,42%

Left hand:
72mm
78mm
= index finger 92,30%


Despite of that, my arms (80cm, from shoulder to hand) and legs (90cm, gained through subtracting my sitting height from my standing height, 182cm; so that's a relative figure) are about 1cm longer on the right side.

Tore
Thursday, September 30th, 2004, 10:04 PM
Here is a collection of mean 2D:4D ratios of various groups. Although most of the studies have been conducted by Manning, the results are somewhat varied, and it is important to assess group differences within the context of each specific study.

http://www.google.ca/search?q=cache:xLgoJvRghpUJ:freud.tau.ac .il/~anova/files/Lippa%25202003.pdf+Asians+tend+to+have+l ow+digit+ratios+&hl=en

Easily the most comprehensive and detailed study I have encountered, where separate ratios are presented for sex, sexual orientation, and race (for both the right and left hands).

Whites

LH Overall Mean-.970
RH Overall Mean-.957
LH Male-.965
RH Male-.949
LH Female-.974
RH Female-.963
LH Homosexual Male-.969
RH Homosexual Male-.953
LH Heterosexual Male-.955
RH Heterosexual Male-.941

Hispanics

LH Overall Mean-.950
RH Overall Mean-.940
LH Male-.945
RH Male-.934
LH Female-.952
RH female-.944
LH Homosexual Male-.948
RH Homosexual Male-.937
LH Heterosexual Male-.941
RH Heterosexual Male-.929

East Asians

LH Overall Mean-.953
RH Overall Mean-.943
LH Male-.943
RH Male-.932
LH Female-.959
RH Female-.949
LH Homosexual Male-.940
RH Homosexual Male-.937
LH Heterosexual Male-.945
RH Heterosexual Male-.931

Tommy Vercetti
Thursday, September 30th, 2004, 10:47 PM
Having long index finger is not necessarily bad thing

Gareth
Thursday, September 30th, 2004, 11:59 PM
Measured one more time, including a digit behind the comma... I have crooked fingers ;):

Right hand:
69,5 mm
76 mm
= index finger 91,45%

Left hand:
72,5 mm
77,5 mm
= index finger 93,35%

I'm also very ectomorphic in stature, as the figures I stated before indicate. It's because the greatest percentage of my ancestors were ectomorphic too, so the breeding led into me I guess.

Tore
Friday, October 1st, 2004, 10:46 PM
Having long index finger is not necessarily bad thing

Of course, as there are positive and negative aspects of both high and low 2D:4D ratios (regardless of sex).

It appears men with low 2D:4D are more fertile, more aggressive and assertive, possess a greater proclivity towards homosexuality/bisexuality* and a higher aptitude in sports and music, and are possibly of lower socio-economic status,** whereas men with higher 2D:4D ratios tend to be at a greater risk for developing heart disease (Manning 2002).

http://human-nature.com/nibbs/02/manning.html

* I recently read a study which postulated that homosexuals only appeared to have lower 2D:4D because the factor of race was not controlled for. Presumably, Black and Latino(although not East Asian) populations produce a higher percentage of (male) homosexuals, thus altering the results (as such populations have lower mean 2D:4D ratios). The study in my last post corroborates this.

**This finding has not been confirmed, to the best of my knowledge, although it is entirely possible. My theory is that those with low 2D:4D (again, probably only applying to samples where race is controlled for in light of the fact that Whites have the highest 2D:4D ratios of any racial grouping, and also exhibit more IQ variance) have a higher IQ standard deviation as groups subject to higher levels of pre-natal androgenization also exhibit more IQ variance (males, left-handers, those suffering from allergies, asthma and other immune disorders). In support of this, it appears exposure to high levels of prenatal testosterone is a hallmark among the (intellectually) gifted (Benbow 1986).

http://bbsonline.cup.cam.ac.uk/Preprints/OldArchive/bbs.howe.html

Tommy Vercetti
Friday, October 1st, 2004, 10:54 PM
I was more like referring to this:

http://forums.skadi.net/showthread.php?p=174315#post174315

Tore
Friday, October 1st, 2004, 11:40 PM
I was more like referring to this:

All three studies are conducted by the very same "Greek Scientists," and at that, run contrary to everything already established (i.e. that index finger length is a biological correlate of prenatal estrogen, and not testosterone, exposure).

Tore
Sunday, November 21st, 2004, 09:13 AM
Firstly, visuo-spatial ability probably does not correspond to the right hemisphere function of the brain, and certainly does not exhibit a positive correlation with pre-natal testosterone.

I was somewhat premature in my conclusion, it would appear.

Visuo-spatial ability does correspond to the functioning of the right hemisphere.

However, pre-natal testosterone may not enhance right-hemisphere function.

Success in athletic activities (sprinting, skiiing, and soccer) which negatively correlate most strongly with 2D:4D ratios (thus positively correlating with prenatal testosterone) don't exactly rely heavily on visuo-spatial skills.

Prenatal testosterone masculinizes the fetus, although the effects are likely more physical than neurological. 2D:4D ratios negatively correlate to perceived dominance and aggressiveness among males, and may also correlate with criminality.

Although some studies report findings that suggest prenatal testosterone positively relates to visuo-spatial skills among males, others find no relation, or even a correlation in the opposite direction. Left-handers (who have lower 2D:4D ratios than right handers) may have superior visuo-spatial ability on average, although this could very well relate to other factors such as serum testosterone levels or rate of maturation. Some studies even report no relationship between handedness and spatial visualization ability.

The findings linking prenatal testosterone to visuo-spatial ability are either weak or in contrast to previous discoveries.

Serum testosterone levels are likely more influential in terms of visuo-spatial performance, as suggested by the greater amount of consistency present among studies.

The general consensus is that males with moderate to low levels of testosterone have superior visuo-spatial ability than males with above average or extreme levels of testosterone. With females, it appears those with higher levels perform better than those with lower levels. A minority of studies fail to replicate such results, however, and it is perhaps more suitable to link low testosterone with superior left-hemisphere function, and low estrogen with superior right-hemisphere function.



The above information was derived from a variety of studies, and if anyone wishes to have any specific links or sources provided to verify it, I'd be willing to oblidge.

Germanicus
Saturday, February 26th, 2005, 03:47 PM
No.

The average (Caucasian) male has a mean 2D:4D (index: ring) ratio of .95 (thus the average Caucasian male has an index finger 95% as long as his ring finger).

.
My 2D:4D ratio is .89 (index: 72, ring:81).

Me=manly:D