Digit Ratio: A Pointer to Fertility, Behavior, and Health

by John T. Manning, Robert Trivers (Editor)

Could the length of your fingers indicate a predisposition to breast cancer? Or musical genius? Or homosexuality? In Digit Ratio, John T. Manning posits that relative lengths of the second and fourth digits in humans (2 ratio) does provide such a window into hormone- and sex-related traits.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 2 ratio is the only prenatal sexually dimorphic trait that measurably explains conditions linking testosterone, estrogen, and human development; the study of

208 pages, Library Binding

First published January 1, 2002

Reviews

[Steven · Rating 4 out of 5]

In some ways this is an interesting book, but the ecology people develop in is basically ignored. That presents some problems.

The depression and autism comments don't really stand up to any scrutiny once you realize that the world is being designed against men in favor of women and that the material culture of today is anti-theistic. If you live in a world designed for women, being masculinized is going to be a detriment to your well-being. If you're comparatively asocial, and less socially competent, you're going to be further atomized and prone to being abrogated by the regime towards atheism.

All scientists ignore these facts, and it's soooo annoying.

[Themba · Rating 4 out of 5]

Controversy; scientific racism; reductio ad absurdum; rejection of empiricism in humanities and liberal arts; ideology, identity politics; not inherently prenicious, short-sightedness. This is not establishing causation merely from correlation, however it's a vacuous misunderstanding of that fallacy. To have so many correlations with so many secondary traits does not guarantee but it does suggest, and surly digging into causal factors rounds it out.

Robust data; there's a considerably greater number of androgen receptors in the ring finger
Arguments against, ring finger only longer because of hand size. If that were the case, then the ratio would be substantially similar and yet it is not. It's not phrenology

Medical benefits, diagnosis...utility

The danger lies in ignorance and ideology

[Tracey · Rating 2 out of 5]

By John Manning, as seen on the bbc's secrets of the sexes here and also here. The strongest evidence was given for the negative correlation between (2nd finger to 4th finger measured base wrinkle to tip) digit ratio and (a) athletic ability and (b) visual-spacial perception (as explained and demonstrated in the video) but here Manning gives the data for numerous experiments relating the digit ratio to various other topics. It's not really suited for the casual reader (and probably not worth reading unless you're super interested), but one can get the gist from reading the preface and skimming the chapter conclusions.
Ch. 1: Males tend to have lower 2D:4D ratio (4th finger longer than 2nd) than women (caused by exposure to higher testosterone levels in utero).
Ch. 2: Lower 2D:4D in males = higher fertility; higher 2D:4D in women = higher fertility.
Ch. 5, 6: Lower 2D:4D in males = possibly higher rates of autism, heart disease.
Ch.7: Gay women tend to have lower 2D:4D relative to heterosexual women; correlations in homosexual males relative to straight males were less clear-cut.
ch.8: explores the effect on musical ability and musical appreciation.
ch.9: athletic stamina, spacial perception, and football

[David · Rating 4 out of 5]

1. It's more of a textbook than casual reading. It presents copious data and is immaculately presented and organized in easy to read fashion. It is easy to refer back to over and over again, as it should be with good reference material;

2. As such, this book will dispel any disbelief in what is considered a mildly controversial topic in mainstream news. People are still uncomfortable with the fact that something as obvious as the finger length on their hands can tell a lot about them, even to total strangers;

[PastAllReason · Rating 3 out of 5]

I'd rate this as three stars.

[Afalcon20 · Rating 1 out of 5]

As a fellow academic I can confidently state that John T. Manning is not only a fraud but a disgraceful human being who shouldn't be allowed use an academic title. His shoddy research is a definitive waste of taxpayers/students money, as of yet none of it solidly proven. We all know correlation does not imply causation, however John has managed to become the leading authority on finger measurements doing just that. No wonder his biggest and only proponents to date are sensationalist press and those trying to latch onto a dying research fad to promote their own name.

Having seen first hand how academia can be used purely for evil I suspect John T Manning inner motives. His obsession trying to link personality traits, success and failure to the length of ones bodyparts is at best distasteful but strikingly similar to that of the Nazis who almost perverted the course of science with similar claims. Ironically Hitler was fascinated with finding the stronger, faster, high IQ type male and female also, its just unfortunate that this is allowed pass as science in todays world. Buy this book if you like reading trash pseudoscience otherwise avoid at all costs.