Ein kleiner Fingerzeig.

Ich wusste gar nicht, was man so alles an der Fingerlänge* ablesen kann - jedenfalls angeblich. Letzte Woche gab es einen Artikel in ScienceNOW zu einer Veröffentlichung in der Mai-Ausgabe des British Journal of Psychology [Brosnan, Digit ratio as an indicator of numeracy relative to literacy in 7-year-old British schoolchildren. British Journal of Psychology, 30. März 2007 DOI: 10.1348/000712607X197406].

Boys with the longest ring fingers relative to their index fingers tend to excel in math, according to a new study. In girls, shorter ring fingers predict better verbal skills. The link, according to the researchers, is that testosterone levels in the womb influence both finger length and brain development.

Scientists have been interested for years in the observation that ratios of finger lengths differ in men and women. In men, the ring (fourth) finger is usually longer than the index (second); their so-called 2D:4D ratio is lower than 1. In females, the two fingers are more likely to be the same length. Because of this sex difference, some scientists believe that a low ratio could be a marker for higher prenatal testosterone levels, although it's not clear how the hormone might influence finger development. The 2D:4D ratio has also been fingered in connection with brain-related characteristics--most often in males--such as depression, left-handedness, musical ability, and homosexuality.

[Quelle: ScienceNOW]

Eine Google-Suche ergab außerdem noch einen Zusammenhang zwischen Aggressivität und Fingerlängen-Verhältnis:

In the current study, Dr Peter Hurd and his student Allison Bailey measured the fingers of 300 undergraduates at their university.

Men with the shortest index fingers scored higher on measures of physical aggression than those with longer index fingers, but the study's findings did not apply to women.

[Quelle: BBC]

Ein Zusammenhang zwischen Risiko eines Herzinfarktes und Fingerlängen-Verhältnis:

Lead researcher Dr John Manning told the BBC: "Males tend to have a relatively longer ring finger compared to the index finger than females.

"This is a very early trait and it is under the influence of sex hormones.

"For a man, the ring finger tends to be about 2% longer than the index finger. The longer your ring finger, the more protected you are against heart attack, because the more testosterone you have.

"There is a relationship between the ratio between these two finger lengths and the age at heart attack of people who do have heart attacks."

[Quelle: BBC]

Ein Zusammenhang mit Fruchtbarkeit:

Manning links the proximate causes of digit ratio sexual dimorphism to the effects of sex hormones during early fetal development. He believes the evidence is persuasive, but not yet definitive, that higher levels of testosterone during this critical developmental stage facilitates the growth of the ring finger, while higher levels of estrogen facilitates the growth of the index finger. He states: “In general, it seems that 2D:4D is the most reliable of the predictors of hypermasculinization…” (p. 139). One of the consequences of hypermasculinization, as reflected by the digit ratio, may be higher levels of fertility in men and lower levels of fertility in women. He also suggests that hypermasculinization increases the likelihood of homosexuality or bisexuality, in both males and females.

[Quelle: Mills, Book Review of 'Digit Ratio: A Pointer to Fertility, Behavior and Health" by John T. Manning, NJ: Rutgers University Press. 2002. In: Human Nature Review 2002 Volume 2: 418-423]

Ich könnte wahrscheinlich noch länger so weiter machen.

Ich stimme völlig mit Omni Brain (der zwei weitere Beispiele bringt) überein: Korrelation ist nicht Ursache. Es gibt einen Zusammenhang zwischen Fingerlänge und Testosteron-Level während der Schwangerschaft? Toll. Das Testosteron-Level hat einen Einfluss auf die Gehirn-Entwicklung? Interessant. Aber darum Fingerlänge und mathematische Begabung, sexuelle Orientierung oder Aggressivität in Zusammenhang zu bringen - das hat für mich was von Handlesen und Küchenpsychologie.

MfG,
JLT


[Bild-Quelle]

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*Bestimmt werden die Länge des Zeige- (2D) und Ringfingers (3 4D) und das Verhältnis der beiden zueinander bestimmt (2D:4D):

Digit ratios were obtained from photocopies taken of each child’s hands (see Manning, Fink, Neave, & Caswell, 2005). [...] The 2nd and 4th digit of both the left and the right hands were measured using digital vernier callipers, accurate to 0.01 mm. Measurements were taken from the basal crease to the central tip of each finger.

[Quelle: Brosnan (2007)]

Für eine weitere Kritik, warum Fingerlängen-Bestimmung Handlesen ist und dazu ein paar Bilder, wie's gemacht wird: Open Reading Frame