Aside from fire or Buffalo Bill, there’s no escaping it. So it’s best to know everything you can about it. Here are ten facts about your skin to get you started, and like every fact about skin there is—they’re gross.
10 Your Feet are Fungus Heaven
At any given time, your body is covered in fungus. And not just one or two (literal) hotspots; it’s almost every inch of you. It’s also not just one or two different kinds of fungi; it’s dozens. In one study, a group of scientists at the National Human Genome Research Institute took the time to catalog all the different species of fungi on your body at any given time, and the results are not what you want to hear. Your head and chest are the least rich. They each have only about ten different species apiece. Predictably, your hands and arms have a bit more, with each supporting about 20-30 different types. But you’re feet are a fungal Elysium. Between your toes, you tend to have about 40 different kinds; there are about 60 in your toenails. But wait, there’s whopping 80 on and around your heels. That’s around 200 different species of fungi on your feet alone. You can’t take a step without walking on fungus.
9 It’s Covered in a Layer of Acid
The entirety of your skin is covered in a fine layer of oily film known as the acid mantle. The mantle is formed by a combination of sweat and sebum, an oily secretion of glands in your skin meant to lubricate. (Excess sebum, unfortunately, is the reason you get acne.) The acid mantle maintains a pH of around 4.5-6.0, making the surface of the skin forever acidic. Luckily, this isn’t a ‘burn whatever you touch scenario’ but instead a ‘make life a bit harder for opportunistic bacteria’ scenario. Bacteria on the skin’s surface have to adapt to the acidic conditions, so any that manage to enter through wounds have an extra hard time adapting to our alkaline blood. As beneficial as the mantle can be, it is the primary reason you’re not allowed to touch the exhibits in museums.
8 It Can Become Scales
Like any organ, skin is a complicated mixture of different types of cells working in harmony to perform an important homeostatic function. That complexity makes it prone to messing up from time to time. One example of this is Ichthyosis Vulgaris, or more commonly “fish scale disease.” In those with fish scale disease, a defective gene (or less commonly another condition such as cancer or HIV) causes your skin to shed more slowly. This means that the protein keratin builds up in the upper layer of the skin instead of gradually flaking off. The result is thick, dry scales that form tile-like patterns. In both makeup and appearance, this can become almost identical to the scales found in fish, reptiles, etc. Oddly enough, one simple way to help with symptoms is to stay in warm, moist environments like our first scaled ancestors did when they ventured onto land.
7 Books are Made From It
It’s true. There are so far 18 confirmed examples of books bound with human skin. It’s a common enough practice to have earned its own scientific label—Anthropodermic bibliopegy—as well as its own dedicated research team, the Anthropodermic Book Project. The team has confirmed the existence of 18 human skin books and debunked another 13 alleged examples as mere animal skin. Strangely, there’s no one location, group, profession, or ritual that explains the majority of these dermic books. Their sources are varied and it’s clear that, somehow, many individuals came upon the same ghoulish idea. One famous example is the autobiography of career criminal James Allen, who insisted that upon his death, a copy be bound in his skin and given to one of his victims, whom Allen admired for fighting back against his robbery.
6 Furniture and Clothing, Too
You likely heard in history class about the abhorrent uses that some Nazi doctors found for their victims’ flesh during the Holocaust. In many cases, those stories are true, but the practice of using human skin for uses other than as skin actually has a long, wide-ranging history. One weird example is the skin of executed criminal Big Nose George, which was removed from his corpse by Dr. John Eugene Osborne. The doctor turned the skin into shoes- shoes that he wore to the inaugural ball when he was elected the third governor of Wyoming.
5 You’re Allergic to It
The dust in our homes that has so many seeking antihistamines and allergist appointments is mostly made up of our skin. Though different studies have produced a range of values for exactly how much of our skin makes up the dust in our home, with reports typically ranging from 40-80%, the average and accepted number is around 50%. It’s no surprise that so much dust comes from skin when you learn how much it continually sheds. Your skin completely sheds its cells and regrows replacements every four weeks or so. That requires about 30,000 cells be shed every minute. Adding all that up, it’s estimated that our skin has contributed approximately one billion tons of dust to our atmosphere.
4 Just How Much it Sweats
It’s not just dead cells. Skin is constantly at work, producing sebum and a whole lot of sweat. There are a few tens of millions of sweat glands across the average body, and on a hot day, they can release more than three gallons of sweat. Most of your sweat comes from sweat glands called eccrine glands and it’s almost entirely water. But some of that sweat comes from apocrine glands and it makes you stink. Its smell is mostly neutral upon release—even good, as it can contain attractive pheromones—but microbial activity on the skin quickly degrades its contents into gross, smelly oil.
3 You Can Grow Fingernails Instead of Hair
A woman named Shanya Isom has an illness so rare and mysterious that there is no known treatment or cure. There is not a single documented occurrence of this disease aside from her own. It has no name, but the condition causes Isom’s hair follicles to grow fingernails instead of hair. It’s awful to think about and really sad to see. The cause of Isom’s disease is unknown, perhaps due to a one-of-a-kind allergic reaction to steroid medication. It results in her hair follicles producing 12 times the normal amount of skin cells in the form of dense keratin-rich growths. Essentially, human nails. This has made her hairless and covered in nails, which grow as sharp black scabs across almost her entire body.
2 It’s Home to an Entire Ecosystem
The surface of your skin is absolutely teeming with microbes, and not just the fungus we mentioned before. Over 1,000 species of bacteria call your skin home, and at any given time, every square centimeter of your body is host to tens of millions of individual bacteria. In the darker, moister areas of your body—you know the ones—a handful of strains dominate the ecosystem, likely more specialized for those conditions. One of the more popular strains is lactobacillius. You may recognize this name as “good bacteria” found in the gut. That’s right, those probiotics you take are a little taste of what’s growing on and in you. But out in the more open, dryer areas of the skin, the bacterial diversity jumps dramatically. The most exposed parts of your skin are like the Mos Eisley Cantina, serving a whole host of different species of every shape, size, and color.
1 And A Second Ecosystem On Top of That
If we go up a few orders of magnitude in size, there’s an entire second ecosystem on your skin above the microbial one. Don’t worry, it’s still extremely small. Several mite species call your skin and hair home, the most famous of which belong to the genus Demodex—Greek for fat worm. Watch this video on YouTube The tiny arachnids spend most of their time safely hidden in your pores, where they feed on your sebum. They sleep by day and by night emerge to eat and mate. Though they pose no threat to their host, it is a bit disconcerting to realize that tiny arachnids have sex on your face while you sleep.
