Grey hair growth...

[Externet]

Hi.

Hair turns gray or grows grey?

I have not seen dark hair at the older top end and grey at the newer bottom; or does it happen?

If grey hair never has a dark top section; does it mean that it grows grey from the 'new' start ?

Then, if it grows from the scalp as grey, it has to be from a follicle that previously lost its dark hair to the root, right ?

[SkepticLance]

A single hair may be darker at top and greyer at bottom. Hairs go grey as the basal cells stop producing pigment. This happens at individual follicles, meaning that the whole head of hair does not go grey all at once. It kind of sneaks up on you, a hair at a time.

[Phi for All]

A woman who used to cut my hair told me that tweezing/plucking gray hairs causes more gray hairs in that area. I've heard others espouse this belief as well, but it sounds like an old wive's tale turned urban legend to me. Any truth to it?

[SkepticLance]

If you pluck out a grey hair, the new one growing back will be grey, since the basal cells are not pumping out pigment. However, it will not affect nearby hairs. They will stop their pigment production in their own good time.

[Barry II]

A hair could go grey then go dark again. I've seen hairs on my own body that were grey at the end and dark near my skin. Someone asked about that in a letter to the New York Times science section a few years ago and the expert's answer was basically that it's not known how it works.

[amiya]

If you plucked a gray hair, there is a faint possibility that nearby ones could turn gray as well. I don't know if is true, but if it were, then the act of plucking could disperse 'autoimmune insult' onto nearby hairs. Autoimmunity, I'm not sure, could be a possible offender in the causation of graying. There isn't much written about this in medical literatures. Old wives tales, thus, may not be dismissed forthright.

 

One explanation of ol' wives tales: When you're plucking out, graying already has started. It is more likely then that more (new) gray hairs will emerge. These new gray hairs falsely make us believe that these new hairs were the result of previous plucking. Anyway, I'm not sure which one is true. Perhaps a longitudinal study may reveal the stats.