Why do men grow beards when they are old? ?

Men after puberty generally have beards. Beard grows faster than hair, which is the result of androgen. The more vigorous the reproductive function, the faster the beard grows. Beard has more blood vessels than hair roots, and nutrients are easy to obtain. Therefore, the beard that has just been shaved will grow back in a few days.

Recently, foreign experts found that beards have the characteristics of adsorbing harmful substances. When people breathe, they can discharge a variety of harmful chemical gases, all of which can stay on their beards; The atmosphere contains a variety of heavy metal particles, especially in busy streets, polycyclic aromatic hydrocarbons and lead emitted by automobile exhaust will also be adsorbed by beards; Smokers, carcinogens such as benzopyrene in smoke, will also stay on their beards. In addition, the epidermal oil of long beard is secreted more, so it is often difficult to wash your face with water at ordinary times. Studies have shown that oil has the property of adhering to dust and microorganisms.

Foreign experts analyzed the shaved beard with gas chromatograph and found dozens of harmful substances, such as carbon dioxide, nitrogen oxides, benzopyrene and lead. Under the microscope, you can also see a large number of microorganisms on the beard. These harmful substances may be sucked back into the respiratory tract with human breathing, which is harmful to human health. Therefore, people are advised not to grow beards.