Saturday, February 29, 2020

Book Review: 'The Remarkable Life of the Skin: An Intimate Journey Across Our Surface' by Monty Lyman

Everyone now recognizes the skin is the largest organ of the human body, meriting far more respect than it has been given - ever. Many don't know how it is structured or how it works. Just like the universe being extraordinarily complex in its bigness, the skin is extraordinarily complex at the microscopic level. There is an astonishing amount of activity that goes into making everything quiet and unassuming, so that people don't have to even think about their skin. Monty Lyman has pulled a huge amount of data into a book appropriately called The Remarkable Life of the Skin.

Human skin is not some waterproof plastic wrap for organs. Its sealing properties are made by 14-sided structures (tetradecahedrons) than fit together tightly enough to keep out bacteria and liquids, yet allow for sweating and hair growth from the inside out. The tetradecahedrons are made of keratin, the same stuff of finger nails and rhinoceros horns.

The top layer (epidermis) is less than a millimeter thick. It is supported by two other layers that refresh and maintain it, since it alone faces the cruel outside world. It turns over every 30-40 days, constantly flaking away month-old skin. One of those other layers is lipid-rich, helping give us flexibility, stretchability and recovery from contact. It is also responsible for cellulite. That layer in women consists of fatty columns, which push their way outward as  women age and skin thins. In men, the same layer crisscrosses instead, so while most women develop some degree of cellulite, few men do.

From our twenties, we begin to lose one percent of our skin collagen every year. After 40, this accelerates. Different skin colors age slower or faster, better or worse. White Caucasian skin ages worst of all.
One of the many important aspects of the skin’s constant regeneration, is when it occurs. Lyman says it takes place during sleep when there are fewer distractions. The body actually waits for the last meal to be digested before firing up its efforts. That’s its signal to begin work. So if you eat late and/or go to sleep late, you actually deny the body its time to refresh your skin.

There is a  fascinating section on touch, and how it works. Humans can feel things as small as a micrometre (.001mm) in a microsecond from the time of contact. But that's a stat just for show. There are actually four mechanoreceptors, each contributing their specialty in touch. Merkel cells are responsible for detecting contact and relaying the fact instantly. Mesissner corpuscles detect slippage in movement of micrometres, and automatically grip the object we're holding differently, so it does not slip away. Pacini corpuscles detect pressure and vibration, making tools extensions of our fingers, applying just the right response for whatever we're doing. Not overgripping or moving too fast or too far, for example. Ruffini endings detect horizontal stretching, guiding finger movements of whatever we're holding and using. Lyman uses the example of keys, which you blindly fish for in your pocket, grab, withdraw, feel edges and the head for the needed one, insert it into a lock with the proper edge up, and twist, using all four of these mechanoreceptors without missing a beat (most of the time).

Ridges on soaked fingers (and only on fingertips and toes) allow for better gripping in water, and the lack of hairs on fingers and palms combine with thicker skin and extraordinary touch sensitivity to make hands (as well as lips and genitals) superlative touch machines. And all this says nothing about the parallel system of emotional touch, the sensations of feeling a surface or another person, and far moreso with a loved one. Their signals travel a completely different network. Finally, nociceptors detect harm and respond with pain in yet another network pathway for touch.

Lyman has experienced the extremes of skin conditions all over the world, from leprosy to imaginary insects breeding under the skin (The physical manifestations of stress, in their sheer variety and intensity, are hard to overestimate), though that can be a real condition, too. He discusses a depressingly large number of diseases and conditions, as the battlelines against health and homeostasis are everywhere. That's what skin is there for. Its defenses and repair crews are remarkable, and Lyman details their playbook in easy to understand terms.

Probably the longest section involves sun damage, the three kinds of skin cancer, each one worse than the previous, and the effects or non effects of sunscreens, supplements, various foods, and good old abstinence. So while we need sunshine on skin to produce vitamin D, sunshine is always harmful. At very least, it ages skin prematurely. At worst, it can set off processes like cancer that can be fatal. And once again, White Caucasian skin fares worst of all.

Another kind of skin abuse is tattooing. Lyman shows it goes back to man's beginnings, has been a feature or requirement of many religions, and if it didn't kill you, was a badge of honor and beauty. He describes the modern process as trapping the disease fighters of the body as they come to fight off the invasion. He calls tattoos infinite infection, as no movement can take place in the standstill between the ink and the repair crew. The ink remains despite the skin's best efforts, stymied and frozen in place.

The only useless part of the book is Lyman's examination of how skin references pop up in clich├ęs and cultural references. At least he didn't go into jokes, song lyrics and politics. The Ancient Greek derivations of words about skin have no importance in learning how it works and why. But for the most part, The Remarkable Life of the Skin is a very useful, informative and edifying read that puts myths in their place and gets real data into our ever-hardworking hands.

Editor's note: This review has been published with the permission of David Wineberg. Like what you read? Subscribe to the SFRB's free daily email notice so you can be up-to-date on our latest articles. Scroll up this page to the sign-up field on your right.