A team from L’Oréal Research & Innovation and Queen Mary University of London has discovered that human hair grows because the surrounding tissue pulls it upward, not because it is pushed from the root. The study, conducted in London in 2024, used advanced 3D imaging on living hair follicles to determine what truly drives hair growth. It turns out that a coordinated movement of cells in the outer root sheath is responsible for this process, rather than cell divisions at the follicle base as textbooks have long claimed [1][2][3].
Why the Market Got It Wrong for Decades
For over 50 years, biologists repeated that hair grows as dividing cells push it upward. That’s a misconception. Dr Inês Sequeira of Queen Mary explains: “We see a fascinating choreography inside the follicle, where hair is actively pulled up by tissue acting almost like a microscopic engine.” When researchers blocked cell division, hair growth continued. Only when they disrupted actin—a protein responsible for cell movement—did growth drop by as much as 80%. Computer simulations confirmed that without this pulling force, hair does not move at the rate observed in humans [2][3][4][1].
3D Imaging Transforms Our Understanding of Hair Growth
Technology proved decisive. Dr Nicolas Tissot from L’Oréal explains that the team used “novel real-time 3D time-lapse microscopy”. This allowed them to track forces acting locally on individual cells. Dr Thomas Bornschlögl adds: “Hair growth is not solely dependent on cell division. The outer root sheath actively pulls the hair upward.” This breakthrough paves the way for new therapies for hair loss and advances in tissue engineering [1][2][3].
Understanding these mechanical forces opens up the possibility of treating hair loss not just through biochemistry, but by modifying the follicle’s physical environment. The new imaging method enables live testing of drugs, eliminating the long wait for results. Biophysics is no longer just a curiosity—it is starting to shape practical medicine. Is science changing the way we see our own hair? [2][3][1]