The fact that your hair turns grey because of stress is nothing more than an old wives' tale.

The fact that your hair turns grey because of stress is nothing more than an old wives' tale. It's true that stress isn't good for you but it's not going to turn you into a silver fox just yet. In fact, the answer comes from the cells in your hair. These are what decide the color and, eventually, the fade to grey.
Most of us start to notice our first grey hairs by the time we hit our thirties. A general rule to go by is that by the age of 50,half of the population will have lost the color in 50 percent of their hair.
But why does it happen? Firstly, we need to understand how hair gets its color.
Your hair is made up of cells called melanocytes(黑色素细胞) which produce pigments(色素) as they grow into the hair fiber. There are two different types of melanins: eumelanins and pheomelanins. The former produces black and brown pigments, while the latter produces red and yellow pigments. The exact amount of these pigments decides whether a person has black, brown, blonde or red hair.
As we age, the ability of the melanocytes to produce more pigments weakens. That's because our hair grows in different periods.
The growing period lasts between three and five years, after which our follicles(毛囊) turn off for about three months to rest and get ready to grow more hairs. This goes round and round and, after a time, our bodies aren't as good at producing new hairs.
Scientists are continuing to try and find ways to prevent greying hair. A team of scientists in France is working to try and stop the melanocytes from being damaged at the end of each hair cycle. They are trying to use a special enzyme(酶) to protect the cells from damage. If successful, it could lead the way for new products that keep our hair full of color for years to come.
8. The phrase “an old wives' tale” in Paragraph 1 probably mean________？
A. a wrong belief B. useful talk
C. a scientific rule D. helpful experience
9. What do we know about red hair?
A. It doesn't turn grey as people get older.
B. It contains more pheomelanin’s than eumelanin’s.
C. The amount of pigments in it doesn't change over time.
D. People with red hair have weaker ability to produce pigments.
10. What do the French scientists aim to do?
A. To repair damaged hair follicles.
B. To protect hair cells against damage.
C. To shorten the hair cycle to protect the hair.
D To study the relationship between health and hair color.
11. What can we infer from the article?
A. Grey hair has nothing to do with stress.
B. Grey hair is a symbol of declining health.
C. It takes three months for new hair to grow.
D. The growth and color change of hair depend on cells.

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