Why and how do some hairs “know” when to stop growing (e.g. eyebrows, arms, eyelashes) while others (e.g. scalp, beard) doesn’t seem to?

Question

Is it that they don’t know or the “threshold” is so long that we don’t get to see it very often?

In: Biology

Answer 1

Ugh wait till 50. They ALL forget to stop growing and also they decide to grow in areas that have no business having hair in the first place =…(