December 27, 2011
Recently professor John T. Manning revised his theory about finger length ratio development. While he had already mentioned the role of prenatal sex steroids, now the ‘balance’ between sexe hormones (testosterone & oestrogen) has become a key-element in his theory.
Manning described his revision in the PNAS-article: ‘Resolving the role of prenatal sex steroids in the development of digit ratio‘.
Manning’s working hypothesis now includes the following 7 key elements:
1 – 2D:4D Finger ratio results from the balance between prental testosterone & prenatal estrogen;
2 – High 2D:4D finger ratio result from low testosterone concentrations OR high estrogen concentrations;
3 – Low 2D:4D finger ratio result from high testosterone concentrations OR low estrogen concentrations;
4 – The ring finger (4D) has much more hormone receptors than the index finger (2D), therefore the 2D:4D finger ratio is mostly driven by changes in the length of the ring finger (due to prenatal hormone concentrations);
5 – Studies in human & animals indicate that the link between prenatal hormones and 2D:4D finger ratio is generally stronger for the right hand;
6 – 2D:4D Finger ratio varies with sexe: males generally have longer fourth digits relative to second digits than females;
7 – 2D:4D Finger ratio varies with ethnicity.
“Armed with this list of skeletogenic genes linked to 2D:4D, we can now be more focused in our examination of the links between 2D:4D and the etiology of sexdependent behaviors and diseases of the immune system, cardiovascular disorders, and a number of cancers.”
September 6, 2011
For quite a few years researchers have assumed that finger length development and the 2D:4D digit ratio is directed by sex hormones. Nevertheless, until now direct experimental evidence was lacking. However, researchers from Florida have reported an important discovery. They discovered via a study of the limb buds in mice – which are known for having a digit length ratio similar to humans – that human fingers are likely to have likewise sex hormone receptors as seen in the paws of mice.
A few comments made by researchers Martin Cohn (one of the researchers from Florida) and ‘finger professor’ John Manning:
“The discovery that growth of the developing digits is controlled directly by androgen and estrogen receptor activity confirms that finger proportions are a lifelong signature of our early hormonal milieu,” Cohn said.
“I’ve been struggling to understand this trait since 1998,”said John T. Manning, Ph.D., a professor at Swansea University in the United Kingdom, who was not involved in the current research.“”When I read this study, I thought, thank goodness, we’ve attracted the attention of a developmental biologist with all the sophisticated techniques of molecular genetics and biology.” “When Zheng and Cohn blocked testosterone receptors, they got a female digit ratio,” Manning said. “I find this completely convincing and very useful,” Manning said.“We can now be more focused in our examination of the links between digit ratio and sex-dependent behaviors, diseases of the immune system, cardiovascular disorders and a number of cancers.” “He suggested that the 2D:4D ratio would be an interesting question, and I have to admit to being skeptical,” Cohn said. “When he came back with the initial results, I was blown away. We looked at each others hands, then got busy planning the next experiment.”
The new discovery provides a genetic explanation for a raft of studies that link finger proportions with traits ranging from sperm counts, aggression, musical ability, sexual orientation and sports prowess, to health problems such as autism, depression, heart attack and breast cancer.
The report about the new study appears in this week’s Proceedings of the National Academy of Sciences.
An overview of some key-reports about finger ratios:
May 24, 2011
Various studies have shown that babies exposed to higher levels of testosterone when developing in the uterus have longer ring fingers as adults, and higher levels of oestrogen typically result in longer pointer fingers. However, testosterone & oestrogen levels also affect the rest of the body, including a person’s physical appearance. The ratio between the length of the index and ring fingers has been found to be a good indication for a variety of social and economic factors, thought to be directly or indirectly related to the effects of the prenatal testosterone. These photographs are part of a study on beauty and sexual attraction.
In 2010 a Meta-analysis studyby researchers from the University of Ontario, Penn State, and the Centre for Addiction and Mental Health found that the second to fourth finger length ratio (2D:4D) serves as an indicator of sexual orientation. The study included 1.618 heterosexual men, 1.693 heterosexual women, 1.503 gay men, and 1.014 lesbians.
In addition to identifying the normative heterosexual sex difference in 2D:4D for both hands, the researchers found that heterosexual women had higher (more feminine) left- and right-hand 2D:4D than did lesbians. However… the researchers found NO difference between heterosexual and gay men (though moderator analyses by the researchers suggested that ethnicity explained some between-studies variation in men).
MORE FINGER & DIGIT RATIO REPORTS ARE AVAILABLE AT:
Academic science has developed a new theory about how finger length is related to human biology & behavior. A significant part of theory is focussed on the so-called: ‘2D:4D digit ratio’, which concerns the full length ratio of only two fingers: index finger vs. ring finger. In women the length of both fingers is usuallly about equal, while in men the ring finger is usually slightly longer: a tiny sex difference.
NOTICE: This tiny sexe difference has been confirmed among many ethnic populations around the world, but one should also keep in mind that the finger length differences between ethnic populations are often larger than the finger length differences between males and females.
FINGER LENGTH & ATHLETIC ABILITY
Professor John T. Manning of the University of Liverpool (School of Biological Sciences, Liverpool, UK) explains the link between finger length & athletic ability as follows (see video: starting at 2m5s):
“Our fingers have information about how much testosterone and how much oestrogen we’ve been exposed to in the whomb. So, the longer one’s ring finger relative to one’s index finger, the more testosterone you’ve had. And that testosterone has an effect on the brain, and on the body. If a boy has a large amount of testosterone before birth, he is likely to be born with a very efficient heart and vascular system.”
“So the longer one’s ring finger relative to one’s index finger, the faster one can run.”
The BBC’s “Secret of The Sexes” confronted the ‘finger Professor’ with six athletes – all 5000 meter specialists, and asked him to “predict” the outcome of the race based on finger length only. Actually, the BBC provided Manning photocopies of the athletes hands, and in return Professor Manning risked his reputation by providing the results of a race that had yet to be run.
The outcome of the experiment is unvealed “LIVE” in the video (starting at 5m10s). And surprizingly… the theory appeared to be pretty accurate in practice. After Manning & the athletes are controfonted with the results Manning summarizes:
“… We’ve got four out of six right, but the two that are wrong were kind a quite close.”
The winner of the 5000 meter race responds:
“I thought… that finger thing is bullox because there are so many variables… I am very impressed”.
Manning’s theory was also confirmed by the results of various studies e.g. on endurance running & sprinting speed. And in another likewise experiment finger length correctly predicted the outcome of a 100 meters race with 5 young sprinters.
FINGER LENGTH & OTHER LIFE ISSUES
In his second book – titled ‘The Finger Book‘ – Professor Manning explains that because of the prental link with the androgens (testosterone & oestrogen), finger length studies have generally shown consequent sensible correlations with a rainbow of life issue. The tiny sex difference appears to be highly revealing, for hundreds of studies the ‘2D:4D digit ratio’ appears to correlate with a wide range of topics that are usually also known for a typical male-female difference, including: musical ability, personality, health, and even sexual preference.
The following two videos present other materials from the BBC’s “Secrets of The Sexes”: in the second video Manning explains how finger length is related to performance in spatial-visual tasks, and in the third video Manning demonstrates how finger length is related to another typical sexe-related aspect of personality: the ability to empathize!
HOW TO MEASURE DIGIT RATIO?
NOTICE: Measuring the ‘2D:4D digit ratio’ is really a matter of measuring the full length of both fingers. Two additional tips to avoid: 1 – don’t try to ‘judge’ the 2D:4D digit ratio with bare eyes only (conscientious measurment + calculation is a necessity) 2 – one can not find the ‘2D:4D digit ratio’ from the back of the hand, nor the tips of the fingers only.
Picture source: University of Cambridge.
IS THIS THE NEW ‘PALM READING’?
In 2008 Professor Chris McManus of the University College London (Psychology and Medical Education) characterized Manning’s finger research as follows:
“Chiromancy, the notorious pseudoscience that Sir Walter Scott bracketed with physiognomy, astrology and “other fantastic arts of prediction”, has for two decades been creeping back into scientific favour. And John Manning is its high priest. In The Finger Book, he [Manning] writes: “I believe that the pattern and nature of our decline in middle life and the disease which will eventually lead to our death, is dependent to a large extent on our experiences as a foetus”, a phrase that could almost have been written by Cheiro, the early 20th-century society palmist.”
Because of the obvious association with the divination aspect of palmistry (which is still very popular in various countries such as India & Pakistan), the issue of the ‘2D:4D digit ratio’ will probably continue to have a controversial status.