In our work, skin is unavoidable. You can talk about muscles or motor nerves; trigger points or tsubos; meninges or organs; fascia, fluids, or chi — any and all of the body’s elements that fascinate us — but on your way you always go through the skin.

Familiar factoids: The skin is our largest single organ by size (the liver is heavier), covering up to about 20 square feet in a large person. Our outer skin drinks in a limited number of substances, including essential oils. Along with those other masters of surface area, the lungs and kidneys, the skin is great at elimination, excreting all manner of excessive chemistry (including last night’s garlic) via the sweat glands.

Every organism needs some type of skin to keep the outside out and the inside in. The very thought of not having skin gives us the willies. It provides the most practical division between “me” and the “not me” (the environment) — although we are learning more about interpenetrating invisible energies that communicate right through our skin as if it was not even there.

In truth, our skin is more of an antenna to the outside world than a membrane that keeps us contained. The deep investing layer of fascia — what the old hunters called the “blue skin” — is our real membrane. The skin is a specialized sense organ that uses just under one million nerve endings to take in the realities and subtleties of the outside world — touching and being touched.

A year ago, I led a dissection class to explore some of my ideas “in the flesh.” One of the three cadavers was a black woman; two were white women. We all marveled: After we had removed the few millimeters of skin, no one could tell. Race, as well as beauty, is
precisely skin deep.

Last summer, the Space Shuttle successfully re-entered the atmosphere and returned safely to terra firma after repairs made up in space to the “skin” of the shuttle — those pesky heat-resistant tiles and blankets. These surface tiles are glued to the metal surface and are very delicate, totally incapable of holding the shuttle together — that job is left to the alloy metal of the spaceship’s fuselage. Carrying that metaphor back to us, the fascia of the dermis and the unitard “blue skin” are like the metal fuselage — the sturdy part that holds us together. The skin (the epidermis) is like the heat tiles — delicate, but essential to deal with the specific conditions of the world outside, like temperature regulation and fluid balance.

But our biological “heat tiles” require constant regeneration from the inside. First, the skin has to deal with surrounding dry air, whereas cells need to be wet to live. Consequently, the surface of the skin consists of approximately 200 layers of dead “cell shells” (squamous cells) before you encounter anything living. The currently popular “exfoliants” simply encourage the sloughing off of these upper dead surface layers. So do showers and rubbing up against life — that’s why your lovely Caribbean tan, carefully cultivated during your vacation, largely disappears down the drain within a few days of being home. Exfoliation is natural, and encouraging it is all well and good if there are excessive dead layers, but you wouldn’t want to have them all exfoliated. The only time you do that is when you get a “scrape” — when enough skin gets taken off to “weep,” but not enough to bleed.

Skin cells are constantly being replaced from this underlying layer, pushed by successive growth toward the surface where conditions are drier and drier, until the cell dies and hangs on as a “scale” for a while before being sloughed off. Ultimately, you will have had literally hundreds of successive skins during your life. (These shed skin cells form the majority, along with clothing fibers, of those dust bunnies under your bed — or was that too much information?

Living in rural Maine, I come into regular contact with feathers, scales, shells, and of course the fur of our beloved cats, rabbits, and horses, but it is the infinitely variable exposed skin of the naked ape that fascinates me most. Ashley Montague reminds us that the skin is the outer surface of the brain. Both are derived from the ectodermal layer — folded apart in the early origami of embryonic development and later rejoined via the network of peripheral nerves to the many kinds of sensors — touch, temperature, pressure, vibration, and pain — that live in your skin. “Touch the surface,” Deane Juhan says, “and you stir the depths.”

Touch is the fundamental sense, and skin performs the curious role of keeping us in touch both with the outside world and with our essential selves as well. You cannot touch anything without also being touched by it. The problem is that we modern naked apes can get distracted and go “out of touch.” You don’t have to go for a spacewalk to “repair” this function of your skin; you just need to go for a good massage or bodywork session.