The secret of straight and curly hair lies four millimeters below the human scalp, according to L'Oreal's researchers. They are also trying to find the reason for the whitening of the hair. The hair bulb is hook-shaped for curly hair and straight, for straight hair.
To get to the root of the shape of hair, researchers led by Bruno Bernard, head of hair biology at L'Oreal, grew curly African-American and straight European hair in the laboratory. The cultured follicles revealed key structural differences.
"The curl in African hair is not limited to its shaft, but exists already in its bulb. On the contrary, the bulb of a straight hair is itself straight," the researchers were quoted as saying.
"A curly follicle makes curly hair," Bernard concluded.
The finding could pave the way to revolutionary drugs that can control hair shape, according to Bernard.
"We can hope to straighten African hair more easily without damaging the fibers or, conversely, put in a curl in straight hair using gentle methods," the researchers wrote.
"Effectively, the hair shape can be modified in various conditions such as hormones or drugs. The better example is the re-growth after antimitotic drugs for cancer with thick, coarse and more pigmented hair," dermatologist and scalp surgeon Pierre Bouhanna said.
Bernard's team also discovered that the graying process in the hair depends on the gradual disappearance in the hair follicle of the melanocytes, the pigment cells that give hair its colour.