hair is not pushed. it is PULLED. a team from L'Oréal put living human follicles under 3D live imaging. block division → hair keeps growing. block actin, the protein that lets cells contract and crawl → growth drops. the outer root sheath, the sleeve of cells wrapped around the shaft, moves in a coordinated spiral and drags the hair up. a motor built out of cells. their simulations only matched real hair speed once they put the traction term in. why did we hold the wrong model for decades? because we looked at fixed sections. a fixed section shows dividing cells at the bottom and a shaft above them. proliferation at the base + hair going up = pushing, obviously. the arrow was ours. not the tissue's. and if you care about hair loss, this quietly relocates part of the target. every follicle drug you have heard of is chemistry aimed at a biochemical environment. force is a completely different lever. reminds me of @drmichaellevin 's work - maybe...we aren't thinking physics enough, and too much chemistry.