Curious factoid

[Erebus the Black]

Here is a not so interesting yet curious fact:

The human body has four types of external hair:

1. Scalp hair which grows indefinitely both if cut and if plucked (male hair stops growing after about 20 pluckings is the theory I've heard).

2. Body hair which grows to a certain length even when cut and regrows the root if plucked.

3. Eyebrow hair which grows to a certain length and grows back to that (or a similar one) length (or so I've been told) if cut, yet does not regrow if plucked.

4. An eyelash which grows to a certain length, regrows if plucked yet does not grow to it's original length if cut.

Very curious, don't you think?

[Rowen]

Originally Posted By: Galanos

3. Eyebrow hair which grows to a certain length and grows back to that (or a similar one) length (as I am told) if cut, yet does not regrow if plucked.

Anyone who has ever plucked their eyebrows would say that this fact is not right. They grow back when plucked or waxed.

[Erebus the Black]

Originally Posted By: uǝʍoɹ

Anyone who has ever plucked their eyebrows would say that this fact is not right. They grow back when plucked or waxed.

So you're saying I have some sort of genetic disease?
I had pink eye, or to be more exact I got an infected zit on my eyelid, an it was so irritated that it kept feeling as if my eyebrow hairs are tickling it, so I errantly pulled at them. This was a year ago and my eyebrow is still thin (as in dwindled or as in not as thick)

[Alorael at Large]

This really isn't right. No human hair will grow to indefinite length; while hair on the head will grow much longer than any other, it too has a maximum length of several feet. The length of hair is determined by the follicle: it will spend a certain length of time producing new hair, then go into a relatively brief dormant phase during which the old hair remains attached to the body but separated from the follicle, then return to hair generation. The new hair will push the old hair out; thus, maximum length is determined by the growth (anagen) phase.

 

There are different types of hair, but it has more to do with the consistency, location, and triggers for growth. Men have different hair pattern than women, and both have new patterns after puberty. But these aren't really determinants of length or regrowth.

 

Like most cells, the cells of hair follicles are sensitive to a number of stresses. Plucking hair is more likely to cause the follicle to stop producing hair at a normal rate, at least temporarily. This is true for any hair; it's just that for cosmetic reasons few hairs besides eyebrows are routinely plucked.

 

—Alorael, who thinks the easiest way to understand it is by thinking of humans as really not so different from any other mammal, except of course in that humans have their own unique distribution of hair. Left unshorn, humans would have a characteristic look of long hair on the head (and, for many males, on the face), some hair on the body and limbs, and none on the palms, soles of feet, or a few other small areas. Humans can cut their own hair (or their pets hair!) to change the pattern, and there are treatments for more durable alterations, but cutting and plucking normally won't do more. Disease can, though!

[Harehunter]

Where'd my hat go? The glare from my bald pate is distracting airline pilots.