Why do we go gray?

Legend has it that Marie AntoinetteQueen consort of France, dawned the day of his execution in the guillotine with totally white hair. The same happened to Tomás Moro, political philosopher and English writer, before his execution in the Tower of London in 1535. Obviously this is something impossible. A person's hair cannot turn gray in a single night. However, the stress accumulated over months, knowing that you will be executed, as is the case, can cause hair loss (alopecia areata or syndrome Marie Antoinette). Usually the first ones to get lost are dark hair and this can give a false feeling that the hair has suddenly turned white.
Possible causes
The root cause is the loss of the function of cells called melanocytes They produce melanin. This substance, which acts as a pigment, is responsible for giving a dark tone to our hair, iris or skin when we sunbathe. We have hundreds of thousands of hair follicles in our body, these contain keratinocytes, which produce keratin, a substance from which our hair is made and that is dyed dark with melanin.
But when does the hair turn white? Under normal conditions this phenomenon is conditioned by our genetic inheritance. In the white race usually begins over 30 years, while in the black it does it over fifty. The darker the skin, it seems that graying arises later. There are people, like the actor Richard Gere, to those that appear early, over 20 years of age. They say that he even had to dye his chestnut hair during his first roles.
There are also congenital diseases such as albinism, in which there is a reduction or absence of melanin pigment. This disorder not only occurs in humans, also in animals. Remember Snowflake, the albino gorilla of the Barcelona zoo. There is another disease that is known as Vitiligo in which the pigmentation deficit is localized and white spots (without color) occur on the skin or scalp. White hair has also been linked to smoking and other diseases such as hypothyroidism or malnutrition. And who has not heard the famous phrase: "do not tear a cane that comes out more"? This is something totally false, if you tear off a cane, the same hair will come out of the hair follicle again.
Nor is the relationship between stress and gray hair very clear. Although high levels of this can end up affecting the immune system and melanocytes. In any case it seems that it is more related to alopecia.
In recent times, the role of immunity is being investigated. It has been observed, by chance, that in some immunosuppressive treatments, used to treat cancer, hair whitening can be reversed. The role of hydrogen peroxide (hydrogen peroxide) produced in our capillaries is also analyzed, and how some antioxidant substances or foods could slow the phenomenon. You just have to see a president like José Luis Rodríguez Zapatero, Pedro Sanchez or Barack Obama to realize that some role plays stress, at least that of the legislatures.
At the moment there is nothing we can do to delay or slow down the appearance of gray hair. If you decide not to dye your hair, you can do as Christine Lagarde, president of European Central Bank, George Clooney or Brad Pitt and show off maturity and become an icon of elegance.