→Subscribe for new videos every day! https://www.youtube.com/user/TodayIFoundOut?sub_confirmation=1 →How "Dick" came to be short for 'Richard': https://youtu.be/BH1NAwwKtcg?list=PLR0XuDegDqP2Acy6g9Ta7hzC0Rr3RDS6q Never run out of things to say at the water cooler with TodayIFoundOut! Brand new videos 7 days a week! More from TodayIFoundOut Why is it Impossible to Tickle Yourself? Why do we go Bald? https://youtu.be/3OIeGXzd5PY?list=PLR0XuDegDqP01NqW8KRpOy-_y2m6S2VEF In this video: I very briefly mentioned this in an article about two years ago that you might also be interested in (There is No Difference Between Fur and Hair), but I’ll go into more detail here. Hair length is completely controlled by the length of the anagen phase of your hair follicle. How long this period lasts is generally determined mostly by genetics, but can also be affected by hormones, and even extreme stress. More specifically, there is a chemical signal that ultimately controls the exact growth cycle. Want the text version?: http://www.todayifoundout.com/index.php/2012/05/why-does-hair-only-grow-to-a-certain-length/ Sources: http://www.todayifoundout.com/index.php/2010/02/there-is-no-difference-between-fur-and-hair/ http://www.hairfactz.com/ http://tlc.howstuffworks.com/style/question100.htm http://dermatology.about.com/od/hairanatomy/l/bldefanagen.htm http://dermatology.about.com/library/bldefcatagen.htm http://en.wikipedia.org/wiki/Hair_follicle http://en.wikipedia.org/wiki/Epidermal_growth_factor