Humans have a large complex head and a pair of dexterous hands, but almost everyone has a preference for use one of the hands. However, left-handedness is far less common than right-handedness. Today approximately 10% of the world population are left-handers. What is puzzling so far is that left-handed people seem to have nothing to do with genetic and environmental influences, or that science has so far failed to explain what causes some people to be left-handed.
Although as a minority, there have been a lot more left handed famous people than you would expect. Super geniuses left-handers include Albert Einstein, Charles Darwin, Benjamin Franklin and Sir Isaac Newton. Great business leaders like Henry Ford, Microsoft President Bill Gates, oil magnate John D. Rockefeller, Facebook founder Mark Zuckerberg, Alan Turing (founder of computer science), are examples of just a few. Five of the last eight American presidents were lefties: Gerald Ford, Ronald Reagan, George H.W. Bush, Bill Clinton and Barack Obama.
On the other hand, left-handed people have more health problems, including depression, schizophrenia, alcoholism, and so on (1), and they have shorter life.
Moreover, lefties have the following significant characteristics:
1. There are obviously more left-handed men than women. Most recent statistics says 1.23:1, and the data was about 2:1 decades ago. The number of left-handed women seems to be rising in modern society. The percentage of left-handers change related to age, culture, ethnicity, geography, etc. For example, the ratio of lefties is slightly higher in white people. Recent survey shows that the top three countries with more lefties are: Netherlands, 13.23%; USA, 13.1%; UK, 12.24%. China is one of the countries with lowest percentage of lefties, and three sources said that lefties in China to be 1%, 2%, and 3.5%, respectively, depending on how you define lefties.
2. Although the proportion of left-handed people in the world is about 10%, the data from different sources in history were varied greatly, ranging from 1% to 27%. Even in the same ethnic culture, the proportion of left-handed people born in war-torn areas is higher than in the peaceful area.
3. For the arm-based sports, the left-handers often have advantages, including table tennis, badminton, tennis, fencing, boxing, etc. For example, 40% of top tennis players were left-handers. On the other hand, in non-arm-based sports, there are no significant differences in handedness.
All these characteristics can only be explained according to the Yin and Yang theory. The basic knowledge of Yin/Yang is as follows:
Yang: left, upper, male, warm, motile, energetic, creative, etc.
Yin: right, lower, female, cool, peaceful, quiet, conservative, etc.
Moreover, the balance between Yin and Yang is the foundation of health.
Therefore, the cause of left-handedness can be explained as: during the fetal period, if Yang of the upper limbs of the fetus is excess over Yin, this will lead to better development of the left hand over the right hand in the fetus.
The theory provides perfect explanation to the facts about left-handedness. Because men possess slightly more Yang than women, the proportion of left-handed men is higher than women. Also because of the excess Yang in their upper limbs, left-handed are superior in upper limb sports. When there is more Yang in the environment, e.g., a turbulent environment that promotes the increase of Yang, a higher birth rate of lefties would occur. Interestingly, Dutch people are the tallest in the world, suggesting a higher level of Yang in Dutch population, and this is reflected with highest percentage of left-handed Dutch in the world. On the other hand, China, with a conservative culture, has low rate of left-handers.
(This means that the percentage of lefties in a country is a very reliable index of Yang Qi in that region.)
The theory also explains other phenomena observed in left-handedness. Since Yang is more volatile, left-handed people tend to have stronger creativity; also because of slight deviations in Yin-Yang balance, left-handed people have more health problems.
The Yin and Yang in every organism are largely balanced, including balance of upper and lower, left and right. Because humans have a huge complex brain, the Yang in the head is always in excess, so the limbs possess slightly more Yin, resulting in the right hand to be common. In addition, the left and right sides of a person tend to balance in Yin/Yang. Since the heart (more Yang) is on the left, the use of right hand will resulted in better balance. In most animals, the Yin and Yang of the whole body are more balanced. In cats, dogs, and horses, it was found that male animals tend to use the left forelimb first, while female animals use the right forelimb first (2). These observations fit the theory of Yin/Yang perfectly.
According to the theory, it is speculated that there may be three types of left-handed people as explained as follows:
1. Yang excess, that is, the individuals have too much Yang. Typical appearances of these people are: red face, high voice, preferring cool than warm. Their physical performance is exuberant and the spirit is flourishing.
2. Yin deficiency. They appear to be drier, lack of Yin liquid in the body, thin build, weak stomach, and not able to endure hot temperature. They are more susceptible to labor, more likely to have nocturnal emission, excessive anxiety, etc.
3. The upper limbs are imbalance in Yin/Yang, and have more Yang than Yin. This is only a hypothesis, and may be tested by scientific methods. If there is an instrument that can accurately measure the temperature of different parts of the body, the relative temperature of the upper limbs of such people may show slightly higher than that of the right-handed.
The handedness is likely developed in the womb (3), influenced by Yin/Yang fluctuation in that little compartment, which is determined by the mother’s environment, diet, and emotion. The balance of Yin and Yang can be changed after birth due to the environment, but strong left-handed people will be continuing using their left hand, and some weak lefties may be “corrected” to righties, especially in old times and in some more conservative societies. Therefore, the above-mentioned three types should exist in fetuses, but are likely present in a high proportion of left-handed people.
Genes are unlikely involved directly in generation of left-hander (4). However, some genes may have indirect effects as suggested by this hypothesis. For example, some DNA mutations may contribute to Yin deficiency, resulting in a large percentage of these mutation carriers to develop Yin deficiency, and among these Yin deficient people, a significant proportion would develop as lefties.
The great significance of the theory is that it guides practice. If the health status of a person is related to the left-handedness, then adjusting the Yin and Yang is an important part of improving the health of the patient. For example, most left-handed people have higher sexual desires. Both Yang excess and Yin deficiency will result in an excess of kidney Yang over kidney Yin, leading to easily erection and impulsivity. Persons with Yang excess often seek women everywhere, which can be adjusted through reducing their Yang. Congenital Yin deficiency people are lean. They must pay more attention to conserve their Yin, and absolutely cannot indulge. Also, those left-handed with health problem may have more difference in temperature in their different body parts, as they may have greater imbalance in Yin and Yang within their body. Promoting the Qi movement in their bodies to even the temperature would improve their health.
1. Goodman, Joshua (2014). "The Wages of Sinistrality: Handedness, Brain Structure, and Human Capital Accumulation". Journal of Economic Perspectives. 28 (4): 193–212.
2. Callaway, Ewen (2009). "Is your cat left or right pawed?". New Scientist. Retrieved 6 November 2016.
3. Hepper, Peter G. (2005). "Prenatal thumb sucking is related to postnatal handedness". Neuropsychologia. 43 (3): 313–315.
4. de Kovel, C., & Francks, C. (2019). “The molecular genetics of hand preference revisited”. Scientific reports, 9(1), 5986.