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

My dad’s eyebrow hairs did not stop. They got long and spindly. Kinda all over the place. Was really funny. May he rest in peace after that eyebrow fiasco he always had going. 🤣❤