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

by John T. Manning

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 (2D:4D 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...

• Format: Paperback
• Language: English
• ISBN: 081353030X
• ISBN13: 9780813530307
• Release Date: February 2002
• Publisher: Rutgers University Press
• Length: 192 Pages
• Weight: 0.75 lbs.
• Dimensions: 0.5" x 6.1" x 9.4"

Customer Reviews

the only work of its kind?

This book by John T. Manning, who is apparently the leading authority on digit ratio and its biological/hormonal causes. To summarize: this book posits and goes about proving how prenatal testosterone levels affect the masculinazation of the fetus, resulting in a low 2d:4d digit ratio. This ratio is the ratio of finger length of the index finger vis-a-vis the ring finger on the same hand. Masculine ratios are under 1.0, meaning that the index finger is shorter than the ring finger. Feminine ratios are generally 1:1 or the index finger is slightly longer than the ring finger. Manning also goes on to determine how this ratio may be an indicator of adult masculine traits, such as athletic ability, musical ability, and physical aggressiveness and assertiveness. What this book does right: 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; 3. Despite the copious anecdotal evidence and hard data, Manning does exercise due caution in jumping to conclusions about where this area of study may lead; 4. The prose is very succinct and to the point. Though only around 170 pages, it is packed with information; This book only gets four stars because of some minor quibbles. First, it is not a book that will entertain the casual science reader. Those who will get the most benefit are those who are actually in a field of biological study that deals specifically with areas like prenatal hormonal conditions, sex differentiation of brain patterns, etc. Second, Manning may be overly conservative in conjecturing where this field of study may lead. Granted, he is justified in doing so, given the potentially controversial and ethically questionable course it may take; however, I felt this book leaves almost too much to further study, given the fact that scientists have known about the 2d:4d ratio and its biological roots for decades. At this stage, this book could have been written as a roadmap for further study rather than being mainly a recap for what has already been done. Still, it is the only book of its kind that I know of, and it does very ample justice to a fascinating and obscure topic that literally affects all of us.