How does hair know when to stop growing?

[Coppertop]

I need to know why some hair knows when to just stop growing.
Anybody able to help me out and should i already know this? :lol:

 

[Lellipop]

the reason body hair grows only to a certain length is due to the differences in the hair follicle. different hair follicles give off different amounts of nutritient to the hair. because eg. pubic hair follicles supply only limited amount of nutrients the hair does not grow unlimitedly. as opposed to your hair on your head which keeps growing due to a more steady supply of nutrient

it is also interesting to note that pubic hair is very rigid and curly due to the fact that it does not gain enough nutrients to have a healthy look.
hths

 

[Coppertop]

I really should of know this, oh the shame :lol:

Ray made me ask, honest. I told him i'd be sent away in ignominy