Today: Post-Mortem Hair and Nail Growth
Everyone wonders what happens to them when they die, and while we like to ignore the more gruesome parts of putrefaction, there has long been the rumor that your hair and nails continue to grow after death. Accounts of this urban legend have been going around as far back as 1929 when writer Erich Remarque described the process:
“It strikes me that these nails will continue to grow like lean fantastic cellar-plants long after Kemmerich breathes no more. I see the picture before me. They twist themselves into corkscrews and grow and grow, and with them the hair on the decaying skull, just like grass in a good soil, just like grass, how can it be possible?”—from All Quiet on the Western Front
The Stages Of Death
Once someone dies, their body stops supplying oxygen to the cells in their body. Without oxygen, your body stops producing glucose, which is the “food” cells rely on. This is where some of the pseudo-science for this myth comes from. People know that nails and hair are made of dead tissue and that after death, there’s a surplus of the stuff.
While it is true that your hair and nails are composed of lifeless keratin, the process to make them requires activity from the germinal matrix, which produces the keratin. Without life, the matrix cannot produce any more nail. The same goes for hair, which is also made from non-living keratin and is produced by a living matrix.
That said, there is some room for technicality here. After brain activity ceases—and a person is declared dead—it can take several minutes for the rest of the cells in the body to die. Nerve cells die the quickest—in just 7 minutes—but other cellular processes do carry on. If you take the average nail and hair growth of a person in a day, about 0.1 millimeters for nails and 0.5 millimeters for hair, then adjust for old age—hair and nail growth slows with age—you could figure that the hair and nails of a deceased person grow about 3 micrometers. For reference, a single human hair is usually 100 micrometers thick.
So if we know hair and nails can’t grow without living structures to produce them, why do people think they do? While your cells die and the decomposition process begins, one of the first thing that starts to happen is dehydration. Without the ability to maintain tissue maintenance, the water evaporates from your body, drying out your skin. As your body dries, it shrinks, all except for that keratin protein that was dry already. So instead of your nails growing out, the skin on your fingers is actually pulling in, leaving more hard nail exposed. The same is true for your hair.
Morticians sometimes have to apply large amounts of moisturizing cream to human bodies to keep this from becoming obvious even just days after death. Men with beards, especially require ample moisture to keep the shrinkage at a minimum. Keeping this in mind, it’s easy to imagine early and isolated communities opening recently dug graves to see shrunken faces with long beards and nails, and think something sinister and supernatural could be afoot!