system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why is it that hair on most animals are always at a constant length, while our hair will continue to grow unless we cut it?
gpt
Our hair does not continue to grow forever either. Every type of hair has a certain life expectancy if you will. For eye lashes it's a few weeks or months, for hair on your head it's a few years. After that, the you lose the hair and the animal does, too. The life expectancy and the speed at which the hair grows determines the maximum length.