[ELI5] Why do some hairs continue to grow and others don’t?

Question

For example, head hair seems to grow forever if I don’t cut it, but my arms doesn’t, there’s like a *limit* of growing

In: 0

Answer 1

With long head hair you have to coax it because the hair is dead. It relies on oil from the scalp and doesn’t need to be washed daily. I have really thick curly hair almost to my waist now but it used to be unhealthy until I started wrapping it into a bun during a lot of my showers instead of washing it. Brushing distributes the oil and that’s why hair looks the way it does after it’s brushed- shinier and in place.