Always blush, okay?

Of course, a person's sudden blushing is not because he is refreshed, but more likely because he is nervous. If you feel uneasy about ghosts in your heart, or embarrassed, or shy when you meet someone you secretly love, or embarrassed when you are praised ... suddenly your face is hot, and you know you are blushing. This process is caused by sympathetic nerve excitation, and consciousness can't control it. The more you try to control yourself from blushing, the more it will aggravate your blushing. This is actually a stress reaction: when you feel uneasy, embarrassed, shy and embarrassed, your body will secrete a lot of adrenaline. This hormone will make you breathe harder, your heart rate will be faster, your pupils will be dilated, and you will be ready to fight or escape. It can also relax blood vessels, thus increasing blood flow and providing more oxygen. Red blood cells carrying oxygen in the blood make the skin red. This is the whole body's reaction. Why is only the skin on the face red, and the skin color of other parts has not changed? There are two reasons for this. Compared with other parts of the skin, the blood vessels of facial skin are denser, wider and closer to the surface, so its changes are more easily noticed by others. More importantly, the veins of general skin only contain α -adrenoceptors, while the veins of facial skin contain both α -adrenoceptors and β -adrenoceptors. Both receptors receive signals from adrenaline, but their properties are different. Alpha adrenoceptors are not sensitive to adrenaline, which makes blood vessels contract, while beta adrenoceptors, on the other hand, are more sensitive to adrenaline, which makes blood vessels relax and more blood flows into face and skin, telling people that you are uneasy. But what good is it for you to let others know that you are sad? Or, how did this blushing instinct evolve? This problem troubled Darwin, who devoted a whole chapter to the discussion of blushing in the book Emotion between Man and Animals. Even now, why people blush is still an evolutionary question. People are not born to blush. He began to appear in kindergarten, reached the peak in adolescence, and then gradually declined. With the growth of age, people are less and less likely to blush, or "more and more thick." Kindergarten is a period when people's self-awareness begins to appear and social awareness is cultivated through communication with others. Teenagers have strong self-awareness, paying special attention to what others think of them, while adults' self-awareness gradually weakens. The appearance and change of blushing seems to be synchronized with the evolution of people's self-consciousness. In addition, there are other social factors related to blushing. For example, women are more likely to blush than men, and Europeans are more likely to blush than Asians (this has nothing to do with skin color, and Europeans with dark skin color will also blush obviously). All these show that blushing is a social way. Although blushing is not controlled by consciousness, it involves very advanced intelligence. If a person wants to blush, he should not only have self-awareness, but also be aware of the existence of other consciousness, and put himself in other individuals' shoes, that is, he has empathy ability. Humans have the ability to empathize after they are three years old. Other animals only apes have this ability. Therefore, only humans, and perhaps apes, can use blushing to communicate subtly. This kind of communication is good for yourself and others. When you blush in front of someone you have a crush on, it is possible to turn your crush into a crush by making the other person aware of your feelings. When you blush because you did something wrong, you can let others know that you are sorry and forgive you. When you blush, people will think you are honest and trustworthy, so they are willing to cooperate with you. Of course, for human beings, language is the most important way of communication. But language is controlled by consciousness, which can deceive people, while uncontrolled blushing can expose true thoughts, and you sometimes want to use words to cover it up. The signal from blushing is sometimes even more accurate than language. Other primates can also communicate through skin color changes in bare parts, such as blushing when angry and swelling of buttocks during estrus. Primates are extremely sensitive to skin color changes, which may be related to the origin of color vision. Among mammals, only primates have trichromatic vision and can see the color world composed of three primary colors. Other mammals are color blind. This is because there are three kinds of cone cells in primate retina, which feel different wavelengths of light: the optimal absorption wavelength of S cone is about 440 nm (blue light), M cone is about 540 nm (green light) and L cone is about 560 nm (red light). Why are the optimal absorption wavelengths of M-cone and L-cone so close? It is obviously more reasonable if we can separate them a little further (the optimal absorption wavelengths of the three cones of birds are evenly distributed). Facts have proved that such a conical wavelength distribution can most sensitively feel the change of other people's skin color: when the skin of primates is full of oxygenated blood, the wavelength of their skin color is about 550 nanometers. In a sense, we have such sensitive eyes just to see you blush easily.