Hair resists decay due to keratin, a structural protein. The structure and chemical composition of keratin make it difficult for organisms to break it down.
What happens to our hair after we die?
Zombies, mummies, vampires… all of these undead ghouls have conspired to create several myths surrounding the post-mortem body through pop culture. However, what really happens to our mortal bodies in the long run?
You know the general process: after the decaying process is largely over, our bodies begin to shrivel up. When preserved well, the body keeps it claim only on the dry parts – bones, nails, sometimes skin, and perhaps most interestingly … the hair!
Before we jump into what happens to hair after death, let’s take a look at hair’s biology.
What is hair made of and how does it grow?
In life, hair growth is directly connected to the blood vessels at the base of every hair follicle. These blood vessels feed the hair roots to keep them growing and break through the skin. By the time the hair reaches the epidermis (i.e., the outer surface of the skin), the cells within that hair are no longer alive. That’s why it doesn’t hurt to cut your hair… it’s basically already dead!
The main component of hair is keratin. This is a protein that doesn’t contain any water, and is also completely insoluble. This insolubility is due to the amino acids—the building blocks of protein—that it’s made of and its structure—linear and tightly coiled. This makes hair one of the strongest biological substances in nature.
Does dead hair grow?
One idea that has completely enraptured our collective imaginations is that your hair continues to grow after you die! However, this is untrue.
The only reason that this myth exists is that, when studied, it genuinely seems as though the hair on a corpse is growing on its own. However, this phenomena can be attributed, quite simply, to good ol’ relativity. Considering that human bodies are composed of 70% water, it’s no surprise that they shrink considerably in size once all the moisture is lost. In comparison to its now shrunken appearance, the corpse’s hair seems to have grown longer.
Does hair decompose and how long does it take?
Hair outlasts most other soft tissue because of keratin’s insoluble and sturdy structure. Its chemical composition makes it difficult for proteolytic enzymes—enzymes that break down proteins—to degrade hair. In particular, the amino acids histidine, arginine and lysine are abundant in hair keratin, as well as the amino acid cysteine. The bonds and 3D structure these amino acids take to make keratin make it difficult to break. Very few microbes (the fungus Alternaria spp) or animals (the carpet beetle) can digest the hair.
Another protein that resists decay is collagen, which is present in bones and connective tissue. Collagen has many structural and compositional similarities to keratin, in that they are both linear and tightly coiled proteins with multiple polypeptide subunits, and their amino acid compositions lend to their strength, though keratin and collagen are made of a combination of amino acids.
This is why hair is one of the few organic relics of death.
However, nothing lasts forever and hair and bone will eventually decay. What differs is how fast the decomposition process occurs.
The burial environment affects the rate of decomposition in a major way. The soil, moisture, chemicals, and the animals found in the environment can either increase the rate of decay or preserve the corpse. Dry and arid conditions like those found in deserts are excellent preserves of hair, since microbes don’t thrive in such conditions. However, in most normal soil, after a few years, both hair and bone will eventually degrade.
Both collagen and keratin have similar chemical secrets to resisting decay. This has spawned a line of research where labs are trying to synthetically create these fibers to make stronger, yet eventually biodegradable alternatives to plastic.
Does Hair Change Color After Death?
Hair gets its color from two different types of pigments: eumelanin and pheomelanin. Eumelanin is the pigment that gives our hair its darkness, while pheomelanin gives our hair its redness. Your hair color is especially distinctive because it has its own unique combination of eumelanin and pheomelanin. Eumelanin has two subtypes: black and brown. If you have more black eumelanin in your hair, then it would naturally be a darker color. Consequently, if there is a total lack of black eumelanin and low levels of brown eumelanin, then there is a high chance of you being born with blonde hair. As you grow older, the eumelanin levels of both kinds drop, which causes the greying of your hair.
Pheomelanin, on the other hand, is responsible for adding red and orange colors to your hair. It’s rare to have a high concentration of pheomelanin, which is why there are so few natural redheads in the world.
It does, however, exist in some quantities in everyone’s hair. It is also more stable than eumelanin. Eumelanin breaks down easily through the process of oxidization, but pheomelanin does not. Pheomelanin tends to hang around within the hair even after being exposed to extreme conditions. Therefore, under wet oxidizing climates, the eumelanin in the hair is lost over extended periods of time, leaving behind the red pigment, pheomelanin.
In short, the answer is yes! There is a chance that your hair could turn red after you die! If you need a point of reference, you should look at the ancient Egyptians. Their mummies seem to sport a healthy shade of murky red locks, despite the centuries of decay. It does take longer, though, for the oxidizing process to occur in controlled dry conditions like an Egyptian tomb. Even so, nature doesn’t discriminate. Red hair, the fashion of the undead, eventually gets to us all.
It’s interesting to note how transitory we consider our hair to be, cutting it confidently, knowing that it will simply grow back. However, the last set of hair follicles you develop will probably outlast whatever civilization you call home! Not so transient after all. Who knew the hair on our head could be so dynamic—even after death!
- Proceedings Biological Sciences
- Journal of Investigative Dermatology
- Journal of Biological Chemistry
- Book chapter: Taphonomic alteration to hair and nail; University of Bradford