Getting to the root of an age-old question: why gray hair?

So, why does hair turn gray?

"It's kind of a straightforward answer because there is a genetic predisposition to gray hair, when it will happen and whether it is gray, silver or white," said Dr. Thomas Garrott, an Ocean Springs dermatologist. "I explain our appearance this way: Because of our genetics, there is a picture of you when you are 100 years old and you just work your way there."

In this era of hair-color products that do minimal damage, gray hair is not such a big deal. You can wear it proudly, like an age badge, or you can return your hair to the color of your youth. Still, it's unpleasing for most people when they discover their first single gray hair. For some, that can come as early as the teens; for others, they may still have distinguishable natural color into their 70s.

Blame these discrepancies on genes. We've heard that for years, although aging mechanisms are not totally understood. For example, there's a strong theory now that premature graying is not caused by fright or trauma as much as gene mutations.

"Graying hair is linked to skin aging when there is less pigment in hair follicles," Garrott said. "With white hair you have no pigment left, with gray hair you have a little pigment. It's part of the aging process, whatever that is. Why put zillions of dollars in research of gray hair when we have so much else going on in medical science?"

In other words, medical researchers aren't going to get gray hair worrying about why we get gray hair. But if they unlock a piece of the mystery because of other research, that's a bonus.

Apparently that happened in 2004 when the Dana-Farber Cancer Institute in Boston researched the skin cancer melanoma. A summary of that research in the journal Science reported that researchers found the cellular cause of graying.

Scientists already knew that melanocytes are the pigment-manufacturing cells that help give color to hair and skin. These Dana-Farber researchers traced the loss of hair color to the gradual dying off of adult stem cells that create a continuous supply of melanocytes.

Try to follow this: Melanocytes manufacture and store pigment that combines with hair-making cells called keratinocytes. That's how we get hair color, but we apparently lose the color when the number of stem cells diminishes. The Dana-Farber report also mentions the Bcl 2 gene, essential for maintaining healthy melanocytes. When Bcl 2 dies off, apparently so does hair color.

Now the scientists must answer why this essential gene is affected by age. Stay tuned.

Simpler ways of understanding gray hair do exist. Many medical and scientific publications, such as Scientific American and the Library of Congress, have tackled the question of gray hair because so many people ask about it.

Basically, this is how the experts explain our hair's change of life. Each hair is made up of a shaft and a root, and each root is surrounded by a tube of tissue, or follicle. The follicle contains pigment cells that produce melanin, which gives us hair color.

Melanin is made by melanocyte (that word again!), a specialized pigment cell that resides in the follicle. The two types of melanin determine hair color: eumelanin for dark hair and pheomelanin for light, both of which blend to create assorted hair colors.

As we age, the pigment cells die and the hair becomes transparent. It's that transparency that makes hair look gray, or white if there are no pigment cells at all.