Why does hair turn grey or white, and why does it happen later for some?

Question

The question is pretty simple: what is happening molecularly when hair turns grey or white? I would imagine that it is due to the lack of a particular compound. I'm also interested in why some people's onset of grey hair happens much later than others.

Answer 1

It has to due with the lack of pigment cells in the hair. The lack of melanin will cause the hair to become more transparent hence why it looks white or gray. The melanin comes from a melanocyte cell and as you age, these cells die. With less of these cells, less melanin can be produced. Some people just have melanocyte cells that die earlier than others.

Answer 2

Some men, and women, are probably born with an inherited tendency to go grey before their time.

Presumably, the genes that encode for the compounds that give hair color are no longer transcribed and translated as aging progresses. For older organisms, the need to attract a mate has passed.