**Why Do Old People Grow White Hair ?
The roots of our hair contain a number of pigment cells. These pigment cells produce a chemical that gives color to our hair. When we grow older, out body stops producing their chemical so, our hair starts to become gray or white in color. The chemical that gives color to our hair is called melanin. Infact, there are two types of melanin found in the hair — dark and light. They blend together in various proportion to make up the wide eange of haor colours. That of hair colors. Thats why we see people with black , brown, red and blond hair.
If we grow white hair with age, how come some young people also have white hair ? well, it seems there are other factors that can make our hair grow white sooner. Exposure to pollution and frequent use of harsh chemicals such as hair dyes and strong shampoos can make our hair white too.
2. Why do some people have darken skin than others ?
The cells in our skin produce melanin that gives color to the skin. So, if the pigment cells in your skin more melanin , you will have a dark color. In the same way one will have fair skin color if less melanin is produced by the skin.
* what makes some skins to produce more melanin than others ?
It is because melanin has another purpose too. It absorbs the harmful ultraviolet (UV) rays of the sun. So, people living in hotter climants make more melanin to protect their skin. People living in colder climates don’t need this protection, so they make less melanin and have fair skin color. But there is make less melanin and have fair skin color. But there is another factor that decides our skin color. It is our genes !
3.What are genes ?
Have you ever wounder why people often remark that you look like your mom or dad or grandfather or even some distant uncle ?How can one person looks similar to other in the family ? well, it is because each of us carry a secret code in out bodies. These codes have a lot of information on our physical appearance and sometimes even the special skills that we are going to posses such as artistic skills etc. Your parents pass these codes on to you through genes. Each cell in our body contains thousands of genes.
So where did your parents get their genes from ? Of course , from their parents ! So when you inherit your genes , it is not only from your parents but also from ancestors. There is no wonder then if you look like your grandfather ! It is all in the genes after all !
And genes are’t just in humans. All animals and plants have genes , too.