Forget what the textbooks said. A new study from L'Oréal Research & Innovation and Queen Mary University of London found that hair doesn't grow by being pushed out from the root — it's actively pulled upward by coordinated cell movements inside the follicle. The discovery could reshape how scientists approach hair loss treatments and regenerative medicine.
For decades, biology textbooks have told us that hair grows because cells at the base of the follicle divide and push the hair shaft upward — like a slow-motion conveyor belt. A new study published in Nature Communications says that picture is incomplete, and possibly wrong.
Researchers at L'Oréal Research & Innovation and Queen Mary University of London used advanced 3D live imaging to watch human hair follicles grow in real time. What they found was surprising: cells in the outer root sheath move downward in a coordinated spiral pattern, generating a pulling force that actively draws the hair shaft upward — acting like a tiny biological motor.
To confirm this, the team ran two key experiments: blocking cell division barely slowed hair growth, but disrupting actin — a protein essential for cell movement and force generation — caused growth rates to drop by over 80%.
By the Numbers
Why it matters: This reframes hair growth as a mechanical process, not just a biochemical one. It opens new doors for designing therapies that target the physical forces inside follicles — potentially transforming how we treat hair loss and approach tissue regeneration.
