How Hair Grows

Girl wondering about hair growth direction
Photo: Olena Zaskochenko/Shutterstock
Q: I just want to know from where the hair's growth starts, from the top or from the bottom?
A: The hair grows from the scalp outward. There are follicles in the skin of the scalp (actually in the skin all over your body) whose sole job is to produce hair. The length and texture of the hair generally depends on the area of the body in which these follicles are located.
The follicles generate hair cells in long strands and as these strands get longer and longer they are pushed out of the follicle and emerge above the surface of the skin. Because of the way the hair grows the portions of the hair that are furthest from the scalp are - of course - the oldest.
In fact, if you measure the length of the hair and divide the it by one-half inch (or 2.5 cm) the resulting number would be the approximate age of the hair at the ends of the strands in months.
This is why most damage to the hair shows up at the ends of the hair first. It is older, and has been exposed to styling stresses and environmental damage longer than the rest of the hair closer in to the scalp.
See also:
What exactly is hair made of and how does it grow?
The human hair cycles
Does a man's hair grow faster than women's hair?