Skin, hair and nails — The World, with the Evidence

Black-and-white anatomical drawing of a section of skin: stacked layers crossed by a hair set in its root, with small glands beside it. — Section of skin: the epidermis and dermis, a hair in its follicle, the small muscle that raises it and the sebaceous glands (drawing by Henry Vandyke Carter, before 1858). Henry Vandyke Carter, Public domain, source

Shaving does not make hair grow back coarser: this was measured as early as 1928.

This page examines two received ideas about hair and nails, this one and another, older one. Both start from a correct observation that was misinterpreted — and their explanation is far more interesting than the myth itself.

What really happens

After death, the tissues retract: they lose their water and dry out.¹

The skin surrounding the base of the nails and hairs draws back slightly. What was hidden beneath the epidermis then becomes visible.

A contrast effect adds to this: the soft tissues have shrunk, the nails and hair have not. The difference between the two makes the latter look longer than they were.²

The apparent lengthening is explained by a retraction of the skin, not by growth.³

Nothing has grown. What has changed is what we can see.

A forensic anthropologist quoted in the medical literature puts it in one sentence: it is a powerful, disturbing image, but it is pure moonshine. No such thing occurs.⁴

Two received ideas to take apart

“Hair and nails keep growing after death”

This claim is false — and yet the observation that produced it was correct.

As it dehydrates, the skin retracts around the nails and hair follicles, uncovering the hidden part of the hair shaft and of the nail plate.

The observation was accurate; the explanation was not. This is a common situation: one can observe a phenomenon correctly and be completely wrong about its cause.

A fundamental reason, moreover, makes this growth impossible: growing a hair or a nail requires living cells and regulation by hormones. All of this stops at death.⁵

How a false idea travels

This case is instructive because it lets us follow the routes the myth has taken.

It circulates through fiction: a great novel about the First World War describes a comrade’s fingernails growing in corkscrews after his burial.⁶

It circulates through humour. A famous American television host had made a joke of it: for three days after death hair and fingernails continue to grow, but phone calls taper off.⁷

A joke does not try to convince. That is precisely why it gets through without being examined. We laugh, we remember, we do not check.

“Shaving makes hair grow back thicker”

This, too, is a received idea.

Shaving cuts the hair at the level of the pore. It does not interfere with the root, which lies deeper and determines the thickness, the rate of growth and the pigmentation.⁸

This is no longer a matter of deduction, but of measurement. A 1928 study, since confirmed, established that shaving has no effect on either the rate of regrowth or the thickness of the hair.⁹

Three impressions, three simple explanations:

Coarser? An unshaven hair tapers towards its tip. A cleanly cut hair no longer has this fine tip: it emerges at its full thickness, which makes it feel rougher to the touch.
Stiffer? A short hair bends less than a long one. It is a question of length, not of nature.
Darker? An old hair has been bleached by the sun. A new hair has not been yet.¹⁰

Here again, the sensations are real, but their interpretation is wrong.

The common pattern

These two beliefs share the same structure:

An accurate observation is made.
A plausible but false explanation is put forward.
The false explanation is passed on and replaces the original observation.

Many false ideas do not come from people who saw nothing. They come from facts that were correctly observed but misinterpreted.

The skin: an organ in its own right

The skin is not just a protective envelope. It is a complete organ — the largest in the human body, covering about 1.5 to 2 m² of surface area in an adult.¹¹

It performs vital functions:

Protection against external aggressions and microbes.
Thermoregulation through sweating and blood flow.
Sensory perception (touch, temperature, pain).
Continuous cell renewal.

The case of fingerprints

On the surface of the skin of the fingers, the papillary ridges form unique patterns. While the uniqueness of these patterns is widely accepted, the analysis of prints by human comparison remains a method with a margin of error, which calls for strict scientific rigour in expert examinations.¹²

Diversity and representations

Skin, hair and nails vary greatly from one individual to another (colour, texture, shape).

Biological variation is a natural fact: there is no “normal” body from which the others deviate.

Note: The mechanisms of skin pigmentation and the genetic origin of its variations are covered separately in the article devoted to human diversity (see links below).

Note 1

dehydration of the body after death and drying or desiccation may lead to retraction of the skin around the hair or nails