![Hair Grows by Being Pulled, Not Pushed](https://cdn.slatesource.com/4/6/4/4642932a-3d03-479d-af19-9794c2ddc211.webp)

# Hair Grows by Being Pulled, Not Pushed

- [Made in Slatesource](https://slatesource.com/@steph/hair-grows-by-being-pulled-not-pushed)
- By [Steph](https://slatesource.com/@steph)
- Created on Aug 5, 2026

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## PulledPulled, Not PushedPushed

For decadesdecades, everyevery biologybiology textbooktextbook explainedexplained hairhair growthgrowth the samesame wayway: cellscells at the basebase of the folliclefollicle dividedivide, stackstack up, and pushpush the hairhair shaftshaft outwardoutward likelike a slowslow conveyorconveyor beltbelt. It was neatneat, logicallogical, and almostalmost certainlycertainly wrongwrong. ResearchersResearchers from L'OrealL'Oreal ResearchResearch and InnovationInnovation and QueenQueen MaryMary UniversityUniversity of LondonLondon usedused high-resolutionhigh-resolution 3D time-lapsetime-lapse microscopymicroscopy to watchwatch livingliving humanhuman hairhair folliclesfollicles in realreal timetime, trackingtracking individualindividual cellscells as they movedmoved. What they sawsaw did not matchmatch the textbooktextbook at all. The hairhair was not being pushedpushed. It was being pulledpulled upwardupward by a ringring of cellscells in the outerouter rootroot sheathsheath, a previouslypreviously overlookedoverlooked layerlayer that surroundssurrounds the hairhair shaftshaft. Those cellscells spiralspiral downwarddownward whilewhile generatinggenerating an upwardupward mechanicalmechanical forceforce, actingacting lessless likelike a conveyorconveyor beltbelt and moremore likelike a tinytiny engineengine. The findingsfindings were publishedpublished in NatureNature CommunicationsCommunications.

Growth mechanism (old model)

cells divide at base and push hair upward

Growth mechanism (new finding)

outer root sheath pulls hair upward

Drop in growth when actin is blocked

more than 80 percent slower

Drop in growth when cell division is blocked

nearly unchanged

Technique used

3D live time-lapse microscopy on ex vivo follicles

Research partnership

L'Oreal Research and Innovation + Queen Mary University of London

The experiment that overturned the textbook. The team ran two separate tests. First they blocked cell division inside the follicle, which was supposed to be the engine of growth. Hair kept growing at almost the same rate. Then they disrupted actin, the protein that lets cells physically contract and move. Growth collapsed by more than 80 percent. The conclusion was unavoidable: mechanical force, not cell division, is the primary driver. Computer simulations confirmed that only the pulling model

What is the outer root sheath and why did we miss it. The outer root sheath is the layer of cells that wraps around the outside of the hair shaft inside the follicle. It had been studied before, but always in static images, essentially snapshots that could not show motion. Live 3D imaging revealed that its cells move in a coordinated downward spiral, and as they do, they exert an upward pull on the hair above. Lead author Dr. Thomas Bornschloegl described it as the follicle acting "almost like a

**subtitle:** hair follicles on the average human scalp

Why this matters for hair loss treatment. Current treatments for androgenetic alopecia (pattern hair loss) target hormones and blood supply. The new findings suggest a third target: the mechanical environment of the follicle itself. If the outer root sheath loses coordination or its cells stop contracting properly, the pull weakens and hair growth slows. Researchers believe this opens a new class of drug targets, ones that affect the physical rather than the biochemical behaviour of the follicle

> This reveals that hair growth is not driven only by cell division. Instead, the outer root sheath actively pulls the hair upwards.

The research team and what comes next. The paper, titled "Mapping cell dynamics in human ex vivo hair follicles suggests pulling mechanism of hair growth," was co-authored by Nicolas Tissot and colleagues at L'Oreal and Queen Mary. Dr. Ines Sequeira, Reader in Oral and Skin Biology at Queen Mary, noted that the imaging method developed during the study will allow researchers to test new compounds on living follicles in a way that was never possible before. Both institutions have signalled furthe

[Textbooks were wrong: scientists reveal how human hair really grows (ScienceDaily, June 2026)](https://www.sciencedaily.com/releases/2026/06/260620100319.htm?utm_source=slatesource)

[Scientists discover hair is pulled by a hidden cellular engine (Science News Today)](https://www.sciencenewstoday.org/scientists-discover-hair-isnt-pushed-out-its-pulled-by-a-hidden-cellular-engine?utm_source=slatesource)

[Human hair grows through pulling not push, Queen Mary University of London](https://www.qmul.ac.uk/news/latest-news/2025/medicine-and-dentistry/fmd/human-hair-grows-through-pulling-not-push--study-.html?utm_source=slatesource)