The link between a man's ring finger and sex!
形態不只是形狀，反而是整個機制的具體呈現。
多年下來的觀念，愈來愈強烈....
The form is not just apparent shapes ; on the contary, it is the realization of the whole mechanism.
The idea existed for years, not fading away but getting stronger...
The longer his finger, the higher his libido!
(info from rediff)
Here's advice for ladies who are really passionate about someone -- check his ring finger, as its length could be linked to his sex drive!
The longer the fourth finger compared to the second, known as the 2D:4D ratio, the more attractive he is likely to be to the opposite sex.
Over the years, the difference between the ring finger and the index finger has been linked to everything from health problems and sperm count to aggressive behaviour, sexual orientation and sports prowess.
Now, biologists at the University of Florida [ Images ] have discovered that male-female ring finger proportions are tied to sex hormones in the womb -- a finding that may offer health insights.
Their study explains for the first time why men's fourth fingers are usually longer than their index fingers, while for women it is the other way round.
Martin Cohn, PhD, and Zhengui Zheng, PhD, of the Howard Hughes Medical Institute and the department of molecular genetics and microbiology at the UF College of Medicine, found that the developing digits of male and female mouse embryos are packed with receptors for sex hormones.
Differences in how these hormones activate receptors in males and females affect the growth of specific digits.
By following the prenatal development of the limb buds of mice, which have a digit length ratio similar to humans, the scientists controlled the gene signalling effects of androgen -- also known as testosterone -- and estrogen.
The researchers found that while more androgen equated to a proportionally longer fourth digit, more estrogen resulted in a feminised appearance.
The study uncovered how these hormonal signals govern the rate at which skeletal precursor cells divide and showed that different finger bones have different levels of sensitivity to androgen and estrogen.
"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," said Cohn.
The findings appear in this week's Proceedings of the National Academy of Sciences.
Photograph: Leon Brocard on Flickr/Wikimedia Commons
Penis size, sex drive tied to men's finger length: Why?
(info from CBS NEWS)
(CBS) Women often glance at men's ring fingers to tell if they're married. But in addition to marital status, scientists say a man's ring finger can reveal his sexual orientation, libido level, penis size, and even risk for certain diseases like prostate cancer.
Penis size linked to finger measurements, say Korean scientists
And now scientists say they know why.
A new study reported sex hormone exposure in the womb determines finger length, and this finding could offer insights into the origin of other behaviors and diseases.
For the study - published in this week's issue of Proceedings of the National Academy of Sciences - researchers studied digit length in mice, which are considered to have similar digit ratios as human males and females. When researchers exposed the mouse embryo to more male hormones, the mouse had a proportionally longer fourth digit. More estrogen resulted in a more female-looking mouse, and smaller fourth digit.
"When they added testosterone they got super male ratios, and when they added estrogen, super female ratios," Dr. John T. Manning, evolutionary psychologist at Swansea University in England, who was not involved in this study, said in a written statement. "And they've provided us with a list of 19 genes that are sensitive to prenatal testosterone and prenatal estrogen."
Some of the 19 genes may help scientists discover the origin of certain behaviors and diseases, and may help doctors find new treatments for diseases like ALS and prostate cancer, which have been linked to finger length.
Said Manning, "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."
Sex ID
Testosterone
(info from BBC Science)
It's thought that testosterone plays an important role in the way we think and behave. Many of the questions in the Sex ID experiment were related to theories about testosterone.
The Sex ID test was originally an online experiment. We've stopped collecting data now and many of the questions have been removed from the test, but we've kept the fun stuff!
Read about the experiment
Take the test
The role of testosterone
Testosterone is a male sex hormone required for sperm production, the development of male reproductive organs and the emergence of secondary male sexual characteristics such as facial hair, a deeper voice and muscles.
In men testosterone is produced in the testes and adrenal glands.
Testosterone is also produced in women's ovaries and adrenal glands. Little is known about the exact role of testosterone in women, but scientists believe it helps maintain muscle and bone strength and contributes to sex drive or libido.
On average, men produce between 4 and 10mg of the hormone per day and overall they have about 20 times more testosterone than women.
Testosterone and digit ratio
In the Sex ID test we asked people about their index and ring finger measurements. Some scientists believe that the ratio of index finger length to ring finger length indicates how much testosterone we were exposed to in our mother's womb.
Higher testosterone exposure is thought to lead to a longer ring finger. This is determined as early as 14 weeks into a pregnancy.
On average, women's index and ring fingers are almost equal in length because they are exposed to less testosterone. In men, the ring finger tends to be longer because they have higher testosterone levels. In general, women exposed to more testosterone have more 'masculine hands' – ie longer ring fingers.
Testosterone and birth order
When the Sex ID test was an online psychology experiment, we asked people about their siblings in order to investigate the theory that pre-natal testosterone exposure changes systematically every time a woman gives birth to a male child. The scientists who designed the survey will compare the number of older brothers a test taker has with their finger measurements to see if there is any correlation.
Testosterone and assertiveness
In the Sex ID ultimatum task people were asked to decide how they would split £50 between themselves and a stranger. Scientists want to find out if there is a relationship between testosterone levels and assertiveness.
It is assumed that people with higher testosterone levels would drive a harder bargain and be less compromising. Research into the effects of testosterone and competitive behaviour suggests that testosterone increases competitiveness and risk taking.
Interestingly, some studies show that testosterone levels in women change according to the status of their occupations.
