Skip to story
ELI5 Yahaaa

Dead rope, pushed out of a living hole

Why Does Cutting Hair Not Hurt?

The only living part of a hair is buried in your skin — everything you can see is already dead.

A living factory underthe skinIt pushes out deadproteinThe strand you can seehas no nervesColour is decided downat the root
Hair is made once, at the bottom, and never repaired.

  1. Step 1 of 5

    Only the root is alive.

    1 Cells divide atthe base2 They fill withprotein and die3 The dead strandis pushed out

    At the base of each follicle a ring of cells divides constantly, packs itself with a tough protein, and dies. That dead material is pushed upward as the strand.

  2. Step 2 of 5

    So the visible hair has no nerves at all.

    Cutting Dead material — nothingto feelPulling Tugs the living root —that hurts

    Cutting it is like cutting a fingernail or a piece of rope. Pulling it hurts because that tugs the living follicle, not the strand.

  3. Step 3 of 5

    Straight or curly is decided by the hole's shape.

    A round follicleRound strand — straighthairAn oval follicle Flat strand — curlyhair

    A round follicle extrudes a round strand that grows straight. An oval one produces a flattened strand that curls, and the flatter it is, the tighter the curl.

  4. Step 4 of 5

    Each follicle works to its own clock.

    Growing, for years Resting, forweeks Shed — and itbegins again

    A hair grows for years, rests for a few weeks, falls out, and the follicle starts again. Because they are all out of step, you shed steadily rather than in patches.

  5. Step 5 of 5

    Grey hair is a factory shutting down, not a colour change.

    Pigment cells stopworking New growth arriveswith no colour

    The pigment cells at the root wear out and stop. Nothing that has already grown changes colour — the strand simply comes out unpainted from then on.

    A scalp hair grows about 1 cm a month and lives for two to six years, so its full length is set by how long its own cycle runs.

The short version

Cutting hair is painless because only the root is alive — everything above your skin is dead protein pushed out from below.

Try it yourself

Look at where a hair meets your skin. Everything above that line was made months ago and has been dead ever since.

Topics

Next tiny story