Mammals

Feeling mammalian lately? Basic zoology texts tell us that we mammals are warm-blooded vertebrates that possess hair, mammary glands, three middle-ear bones, and a characteristically developed neocortex. Humans, like many mammal species, have sweat glands, specialized teeth, placental births, and dual-fluid penises (yep, you read that right).

Page from an early 1970s children’s book on animals

When I was a kid, what I wanted to be when I grew up was an ethologist – a scientist who studies animal behavior. I devoured books on animals like the one whose page I’ve featured above. The idea of being the man depicted in the drawing–walking along naked in nature with a horse, an elephant, a lion, a tortoise, etc.–was exciting to me. (Until recently there was a Vimeo video of an unclad man and a similarly unclad elephant–could have been the ones in this picture!–playing on the beach.)  As I grew older my interest in anthropology grew, and I discovered the now classic title The Naked Ape by Desmond Morris. His study considers humans in a comparative analysis with primates and other mammals, and spawned a series of successful books and television series for the British zoologist.

In The Naked Ape, Morris starts with the tongue-in-cheek proposition of trying to identify what kind of animals humans are by comparing us to other species. What stands out is the human condition of relatively hairless nudity. In contrast, the apes and other primates, while they may have bald patches or sparse hair, are nonetheless much more thoroughly hairy than we are. Morris mentions several hypotheses for our nudity–everything from parasites to sex signaling to the “aquatic theory”–but ultimately finds the most convincing explanation to be the need to help the sweat glands do their job in the bursts of energy required to hunt prey. Fast-running wolves or cheetahs have many advantages over humans as predators, but they have no sweat glands in their skin. For sweat glands to work properly, our skin needs to be exposed to the air. Too much fur or clothing impedes evaporation of the sweat and the cooling effect it provides.

But sweat also fills a more ancient function of scent-identification. In situations of high emotion–whether aggressive or erotic–our hair stands on end, our body temperature rises, and we also sweat profusely. Our bare skin acts as the massive surface of a warmed scented candle, letting off the smell of the hormones that have soaked our systems. Smell is one of the most primitive senses, yet we still struggle to explain exactly what are the effects that these body smells unleash. Studies on pheromones prove their general effect if not exactly how they play into a range of factors that influence our choice of a mate, for example. As artificial skin coverings, clothes don’t entirely conceal body odors, of course, but they may mitigate them in different ways based on textile variety, thickness, layers, etc., often trapping smells from both inside and outside the body all day long.

As biological anthropologist Barbara King has written, one of the characteristics of humans is precisely that we do seem to be the only species given to covering ourselves up and decorating ourselves, in certain culturally prescribed ways that vary wildly in context and design from “penis sheaths for males to full-body cloth claustration for females.” In the end, we are indeed mammals, but we’re very special ones (for many reasons) whose entire textile-driven array of cultural manifestations is intimately but ironically linked to the evolution of our almost hairless hides. Those of us who are naturists don’t desire to disavow clothing completely, but rather to nurture–more proactively and more frequently–that more ancient mammalian part of our nature that needs to feel and smell the elements on our bare skin.