Can a glance at the relative length of your fingers
reveal important information about you? -

information such as: a predisposition to homosex-
uality; fertility; athletic ability; spatial skills; verbal
skills; musical aptitude; susceptibility to heart dis-
ease, breast cancer . . ?

the answer is YES, according to a hypothesis for-
warded by psychologist John T. Manning in his
Digit Ratio: A Pointer to Fertility, Behavior, and Health;

and the key data is the relative size of two of the
fingers of the right hand -

the ratio of the size of the index finger (2D) to the
ring finger (4D), the 2D:4D ratio






the 2D:4D ratio is correlated with exposure to
testosterone in the womb

a low 2D:4D ratio is correlated with high testosterone
and a high 2D:4D ratio with low testosterone

a low 2D:4D ratio, is more prevalent in males than
it is in females

low 2D:4D is associated with low better visual-
spacial skills, high sperm count in men, assertive-
ness in women, and athletic ability

high 2D:4D is associated with better verbal skills

below is a list of 2D:4D correlates provided by
Wikipedia

- What follows is a non-exhaustive list of some traits which have been either demonstrated or suggested (some of these studies are questionable) to correlate with digit ratio.

- Physiology and disease

* Sperm counts (Manning et al 1998)
* Heart disease (Manning & Bundred 2001)
* Obesity & Metabolic syndrome
(Fink, Manning, Neave 2005)

- Psychological Disorders

* Autism (Manning et al 2001)
* Depression (Bailey & Hurd, 2005b)
* Schizophrenia (Arato et al 2004)

- Sporting and Physical Ability

* Skiing (Manning 2002b)
* Soccer ability (Manning & Taylor 2001)
* Sporting ability in females (Paul et al 2006)

- Cognition and personality

* Assertiveness in women (Wilson 1983)
* Spatial ability (van Anders & Hampson 2005)
* Aggression
(Benderlioglu & Nelson, 2004 , Bailey & Hurd 2005a)
* Masculinity of Handwriting
(Beech and Macintosh 2004)
* Perceived 'dominance' and masculinity of man's
face (Neave et al 2003; Burriss et al. 2006)
* Personality
(Austin et al 2002, Fink et al 2004, Luxen & Buunk 2005)
* Exam scores: a higher ratio is correlated with
higher exam scores among male university students
* Musical ability (Sluming et al 2000)

- Sexual orientation

* Bem sex role score in women
(Csatho et al 2003), erotic role preference in men (McIntyre 2003)
* Lesbians vs. straight women, butch vs. femme
lesbians (Brown et al 2002)
* Gay vs straight men and the very odd
Europe vs. North American straight man effect
(reviewed in McFadden et al 2005).
* Difference in digit ratio between identical
female twins discordant for sexual orientation
(Hall & Love 2003)
* Fraternal birth order effect on digit ratio
(Williams et al 2000).

the premise of Manning's Digit Ratio: A Pointer to
Fertility, Behavior, and Health;is summarized on the book's back cover,

It has been known for more than a century that men and women tend to differ in the relative lengths of their index (2D) and ring (4D) fingers, which upon casual observation seem fairly symmetrical. Men on average have fourth digits longer than their second digits, while women typically have the opposite. Digit ratios are unique in that they are fixed before birth, while other sexually dimorphic variables are fixed after puberty, and the same genes that control for finger length also control the development of the sex organs.

The 2D:4D ratio is the only prenatal sexually dimorphic trait that measurably explains conditions linking testosterone, estrogen, and human development; the study of the ratio broadens our view of human ability, talent, behavior, disposition, health, and fertility.

In this book, Manning presents evidence for how 2D:4D correlates with traits ranging from sperm counts, family size, musical genius, and sporting prowess, to autism, depression, homosexuality, heart attacks, and breast cancer, traits that are all linked with early exposure to sex hormones.

for more on the 2D:4D ratio, check out the video
below, an excerpt from a National Geographic
documentary,