17 of 18 people found the following review helpful:
5.0 out of 5 stars
Looking Deeper, December 19, 2006
This review is from: Skin: A Natural History (Hardcover)
"It isn't good to take for granted something as important as skin," writes Nina G. Jablonski in _Skin: A Natural History_ (University of California Press). Whatever risk you have of taking skin for granted, Jablonski isn't likely to do so. She is a professor of anthropology, and her research has been done on different aspects of skin, especially skin color. She describes her new book as "not a systematic treatise or a manual, but more an idiosyncratic guidebook, replete with personal detours into topics about skin that have most engaged me in my work over the years." Engaged is a good word; she clearly loves her subject, and succeeds in communicating her enthusiasm. Skin itself is of undoubted importance. It is the largest of our organs (just because it is your outer covering and not an inner mound of tissue like your liver doesn't keep it from being a unified organ). It is, unlike the skin of most animals, basically naked, with not very much hair and no scales or feathers. Like any of our other organs, it is a product of evolution that has its current properties because it has done a good job: "Our fabric doesn't wear out, our seams don't burst, we don't spontaneously sprout leaks, and we don't expand like water balloons when we sit in the bathtub." Jablonski is right that we take skin too much for granted, and her book is a happy corrective.
In a phrase that has been made famous by pop anthropology, we are "naked apes," but the reason for our hairlessness (at least compared to our primate cousins) has been disputed. Jablonski discusses the best explanation for our not having hair is that we sweat, sweating, of course, being an important function of our skin. As we developed sweating as our cooling system, we lost fur, because sweating into fur is inefficient; the cooling of a body covered with wet fur would occur at the outermost layer of fur but not at the skin so that the body itself could get cool. Jablonski has splendid chapters on skin color, the superficial characteristic on which so much history and sadness has been based. Melanin has become the governor that mediates between the opposing goals of protection from ultraviolet radiation versus synthesis of vitamin D. Humans have by now turned the "natural" and geographic order of skin color into a relative chaos because of the speedy travel that we have been able to accomplish only in the last few centuries, but the play of skin colors originally evolved on strictly geographic lines because skin molecules were being juggled as key mediators of our ability to be out in the sun. Skin colors represent evolution at work in dermatological molecules, and do not have deeper significance. With our tendency to judge and group based on superficialities, skin colors carry a lot more meaning, but not in any biological sense.
Jablonski winds up her tour with thoughts about the future of skin. Oh, sure, we will always have skin, but perhaps robots will, too; our skin helps us in measuring tasks as delicate as lending an arm for support to another or turning a doorknob, and artificial skin for robots may do such things, and perhaps even help robots start making the me / not me distinction that is essential for consciousness. If that sounds too far fetched, then consider tattoos of the future that will be essentially permanent until the wearer wants to be rid of them, and does so by shining a light of a single wavelength upon them, breaking down the dye. And if that sounds too frivolous, consider the possibility that burn patients might have a spray put on their wounds consisting of cultures of their own cells, all the many types of cells found in the skin; such a preparation would enable new and natural skin rapidly to regenerate. The speculation is fun, but Jablonski's history of the evolution of skin and the many functions it accomplishes for us brings a complicated topic into deep and appealing focus.
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2 of 2 people found the following review helpful:
4.0 out of 5 stars
Why we need to hug and sweat, how silly to think skin color matters., March 10, 2008
This review is from: Skin: A Natural History (Hardcover)
This review just touches the surface, to flesh this book out, read it.
Skin is amazing - it's strong, resilient, sensitive. Skin protects us from microbes and chemicals, shields us from heat, water, abrasion, and punctures. As Jablonski puts it "this is a list of qualities that make the epidermis sound more like a revolutionary new type of carpeting than a natural material".
We have as many hairs on our bodies as apes, but ours are much thinner, practically invisible in most places. We can't communicate emotion by standing our hair on end like angry chimps or cats (piloerection), so we've evolved other ways to show anger, such as pursed lips.
I've always liked Morgan's aquatic ape theory, but I've had to give it up after reading so much criticism. Jablonski points out that we couldn't have lived on the water's edge in our ancestral environment because we'd have been killed by crocodiles and other predators lurking at waters edge. Since we're quite vulnerable to water parasites and show no sign of an evolved immune system to fight them, it isn't likely we spent much time in the water. Nor is skin is an advantage, due to thermoregulation issues. Walrus and hippo's are so huge that heat loss is not a problem. Otters and other water mammals have thick fur they don't get cold in the water or back on land.
Sweat
Everyone zeros in our big brains to define humanity, but what about our sweat? Sweat has played a huge role in how we evolved.
Our nakedness is a great advantage in hot weather. If we had fur, we could only produce 10 to 20% of the sweat we're capable of to cool us down. Fur is great in the heat until it gets wet, and then it's hard to dissipate and animals can die if they stay out in the sun then. Though of course, only "mad dogs and Englishmen go out in the midday sun". Furry creatures are safely in their dens or in the shade during the worst heat of the day. Which leaves a niche open for us to be out and about, hunting.
We're so good at sweating to cool down, we can sweat 12 quarts of water a day, or even up to 3.5 quarts in an hour.
Sweat keeps our enormous brains cool. If you get a temperature of 103 F, you enter delirium territory, where your thinking, reasoning, and communication skills start to go haywire. At 106 F you die.
We also keep our brain cool by walking, less surface area is exposed to the sun, and our head hair protects us from UV radiation, especially frizzy hair, where the surface can be quite hot, but lower down, the air is cooler.
Once the outdoor temperature goes over 98 F and the humidity is higher than 90%, sweat is 90% of our ability to cool down. You must keep drinking water at this point to stay alive. If you exercise, your sweat glands better be in top form. It's good to be tall and lean with thick limbs to provide more surface area for sweating.
Skin color
Sunburn interferes with sweat, so that's a good reason to have dark skin if you live where there's a lot of sun. In fact, we have a wider range of skin colors than any other species, and you can predict roughly what skin color a native population will have by how far they are from the equator. What seems to determine the optimum skin tone is vitamin D - a greater selective force than skin cancer, because women need to produce twice as much calcium when they're pregnant, which you need vitamin D to pull off.
Although dark skin gives you an SPF of 10-15 (not as much as I'd expected), dark skinned people need to spend about 5 times more than a light-skinned person to get enough vitamin D (which is why lighter skin evolved). The Innuit are not as light-skinned as you'd expect, because they get a lot of vitamin D from their diet, and their darker skin protects against UVA.
People who live in 23-40 degrees of latitude have excellent tanning ability to cope with the wide UV fluctuations. These tans offer a protective level of SPF 2.5 (very little). Tanning does not protect against UV damage and leads to premature aging of skin, visible wrinkles, and uneven pigmentation.
People with freckles are at much greater risk of developing skin cancer and need to use sunscreen or cover up outside.
Touch
Being touched is incredibly important. The young grow better if touched. Touch leads to friendship and ultimately, perhaps, sex. In orphanages where infants weren't touched, they often died, or suffered chronic disability from the stress caused by a lack of caresses.
In cultures all over the world, babies are massaged in oil, vigorously stroked, then swaddled. Mothers swear babies are calmer, sleep and grow better, and this seems born out by premature infants who do better if cuddled and held. Mothers with postpartum depression are less depressed if they massage their babies. A few hospitals are experimenting with massage in normal infants. Children with autism given deep pressure massage seem to be calmer and have better relationships.
Grooming is the social glue that holds primates together - it resolves conflicts, helps maintain alliances, and reduces stress. High ranking common baboon infants get more grooming and mature faster than lower-ranking babies.
Touch deprivation harms immune systems as was shown in macaque experiments.
We humans groom too with reassuring touches and hugs, but it's not nearly enough, and so we go off to get massages and spa treatments.
How much people touch each other varies considerably from culture to culture. High touch cultures hold and massage infants and shun any kind of device that isolates babies from people, like cradles and strollers. Non-touching cultures only hug and touch babies a small part of the day, which only grows worse as children get older.
Maybe we could get people off andi-depressants and other drugs if we hugged each other more. Jablonski points out that in non-touch cultures, like America, institutions and workplaces often have strict rules against touching. She concludes that no wonder there's so much depression, anxiety and other social pathologies.
Children who are routinely punished physically rather than nurtured, are likely to be especially disturbed, addicted to drugs, and commit physical violence themselves.
Nursing home elderly who were massaged and hugged "acted younger" and seemed more alert than those who didn't receive this contact.
Some final random facts:
Fingerprints aid in gripping.
Body lice descended from head lice about 40,000 years ago. They're more deadly since they can carry typhus.
Melanoma: detect by one or more of these qualities: non-symmetric, irregular border, mixture of colors, larger than a pencil eraser.
Tattoos aren't as visible on dark skin, so in these cultures, branding and scars are more common.
Botox: over time, this will leave your face deadpan. Great for poker, but you won't be having animated conversations, you've lost your power to "emote".
I wish Jablonski had spent more time on how how much skin protects you from chemicals. Although she mentions lead is bad, there are thousands of other chemicals found in many products we all buy. If you google "cosmetic safety database", you'll see that some hair color, skin cleansers, skin lotions, lipstick, etc., products are highly hazardous.
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