In people's impression, the left and right sides of the human body seem to be symmetrical. Because everyone knows that if a central axis is drawn from the nose to the middle of the legs, then a pair of feet, two legs, one pair of hands, two eyes and one pair of ears are very symmetrical. In addition, the distribution of hair and the unevenness of human surface are also symmetrical. Although the nose and tongue are single, the nose is located in the center of the face and the tongue is in the middle of the mouth, and their shapes are also symmetrical.

actually, the left and right sides of the face are not completely symmetrical. A small experiment can prove this point: take a positive photo of yourself, divide it into two halves according to the center line, and then restore it according to the left half and the right half respectively, and the result will be two different portraits.

There is no symmetry from the outside to the inside

If you carefully observe the people around you, you will find that there are many asymmetries in the human body. Most people's forehead, the left side is slightly larger than the right side, so the right cheek protrudes slightly forward. Some people's eyes, one big and one small; A double eyelid, a single eyelid. Some people have high eyebrows and low ears. The fetus is in the mother's womb and will naturally tilt to the right by the sixth month. People's spine bends to the right in the chest and often to the left in the waist, so the left shoulder is often wider and higher. Most people's right hand is longer than their left. In terms of length, weight and volume, the right leg also exceeds the left leg. No wonder walking blindfolded on the flat ground naturally will bend to the left after a while. When you walk in newly bought shoes, you often feel that the shoes on one foot are comfortable and suitable, but the shoes on the other foot are not so comfortable. It turns out that people's feet are one big and one small, and they are also asymmetrical.

people's internal organs are also asymmetrical. Two thirds of the heart is on the left side of the median plane of the body, and one third is on the right side. The left lung has only upper and lower lobes, while the right lung is divided into upper, middle and lower lobes. Most of the liver and gallbladder are on the right side of the body, while most of the pancreas and spleen are on the left side.

The functions of organs are also asymmetrical

The human body is not only asymmetrical in morphological structure, but also asymmetrical in the functions of various organs. 6% of people, the role of the right eye is greater than that of the left eye. Everyone has two nostrils, and the left and right nostrils can breathe, but their effects on the human body are different. When breathing through the right nostril, the brain is easily excited and the nerves are in a state of tension. Therefore, when you are engaged in intense study and work, you often breathe through your right nostril. The left nostril, on the other hand, breathes when it is relaxed and peaceful.