Despite having now posted twice on the topic, I’m not obsessed with nudity. I’m not a nudist, and I have no interest in becoming one. I don’t think I have ever met anyone who is a nudist. Nothing against them, of course, but in the context of everyday life it is certainly the exception. As adults, we are instead enamored of clothing, and we use it for so many functions. We use it to attract potential mates, to stay warm, and to indicate our affiliations with schools, brands, and institutions. A multibillion-dollar fashion industry has grown out of this intense use of garments. But this is an advanced state that we humans have achieved, and the primitive condition is much different.
If we look to the immature stages of humans we see what is clearly the ancestral state. In raising two young children it has become clear why we call it au naturale, and that the most primitive state for humans is not being clad in fancy getups, but is instead a simple birthday suit. It does crop up in private circumstances for adults too, of course, and I will direct interested parties to much of the rest of the internet for that. There are also occasional public expressions as well. Living on a college campus, I have found that there is the occasional moon here, a streaking there. 
There is even a popular song about it. Suffice it to say that although nudity crops up in certain situations in human life and serves certain functions, clothing is the rule rather than the exception.
In the rest of the animal kingdom, however, nudity reigns. Clothing use is extremely rare in animals, and the reasons for why this has only evolved in a small fraction of species are unclear. By using the term “clothing,” I am referring to instances where animals obtain external materials from their environment and apply them to their bodies. A technical term for this is “adventitious adornment,” but I’m going to just stick to calling it clothing and the lack thereof “nudity.” This is certainly anthropocentric terminology, but outside of humans clothing is almost exclusively the domain of a few invertebrates.
In insects, there are several groups that take materials from their environment and apply them to their bodies. The caterpillars of the emerald moth Synchlora frondaria take bits of the flowers on which they feed and sew them to spines on their backs with silk (see picture on this post). Other insects such as lacewing larvae disguise themselves with a cloak that can contain lichen, bark, plant fibers, and even spider webs. Come chrysomelid, or “leaf” beetles reclaim their own excrement – “frass” in entomological terms” – and attach it to the end of their abdomen to wave in the face of predators.
Other invertebrates also wear clothing, and some of the most fantastic are the mujid crabs. Their common names of “masking” or “decorator” crabs accurately describe the habit of these inverts as they actively place fragments of algae, wood, and parts of other invertebrates such as hydroids and bryozoans on their shells. Some sea urchins have a similar, if less selective, habit. Another example is the hermit crab, Eupargurus prideauxi, which takes clothing to a new level by attaching an Adamsia palliata anemone to its shell. This anemone, much like those that protect Nemo and other clownfish, have stinging nematocysts that ward of potential predators. Invertebrates certainly provide a number of interesting examples of clothing use, but given the huge number of their species, they reveal that clothing use is extremely rare.
And in vertebrates, clothing use is almost absent. Take mammals, for example. Outside of humans, I needed to do an extensive search to find another mammal that uses anything like clothing. Out on the Javan grasslands, Sunda sambars (a type of ungulate) spar in their characteristic territorial displays. Males engage in contests to attract females by roaring, and they then run through brush and pick up twigs and grass to make an impressive display on their antlers, effectively creating a type of headdress. But Sunda sambars are an obscure mammal, and why is it that one needs to work so hard to find single example of another mammal that uses clothes? Wouldn’t it make sense for at least one other primate, with an opposable thumb, to craft some primitive dress?
Outside of mammals, clothing use in other vertebrates is barren. No reptiles do it. No amphibians. No fish. No birds. Walt Whitman, naturalist and naturist, identified this pattern well before I was born (in Specimen Days in America, 1887):
Never before did I get so close to Nature; never before did she come so close to me…Nature was naked, and I was also… Sweet, sane, still Nakedness in Nature!
Animals have explored the evolutionary potential of so many aspects of morphology and behavior, and it is hard to understand why clothing hasn’t cropped up more. I am simply pointing to a pattern here because no comparative work has been done on this subject. So for now, I’m going to cue up Ray Stevens one more time, have a good laugh, and ponder the possibilities.
{ 6 comments… read them below or add one }
I’ve been reading your posts with relish! I remember your telling me about your interest in animal clothing and was waiting the whole post for the deer who puts twigs on his head. Maybe you should do a post on symbolic object use (not exactly tools) by animals. I learned from David Haig about a bird who for a long time was supposed to be monogamous, but then was discovered to have many secret mistresses, to whom he brings an offering of a flower in his beak. I wish I could remember more details.
Great post! It also seems that from your examples there is little correlation between being “clothed” and being tropical or not, and the examples seem to decrease with the organism’s size, until us. I wonder if you put primates in a room with snuggies if they would eventually wear them around continuously.
The decorating crabs are awesome! Also perhaps in a more passive self-decoration could be seahorses, who are so stationary that passing ocean debris settles on them, creating a cloak of sorts.
Maybe we wear clothing for the same reason we turn the lights off when we have sex: we know how funny we look when we don’t.
Half kidding. But few animals can recognize themselves in a mirror, and at any rate, mirrors do not occur in any natural habitat I know of. Humans are uniquely self-conscious creatures, and in addition to the unconscious social and sexual signals we send to others (like all animals do), we also engage in very deliberate “signaling” of status and other personal characteristics through a number of behaviors, “dressing up” being one of them.
I think that the deliberate modification of one’s appearance to produce a desired affect in others is unique to humans (and if not, then we are certainly unique in the degree and skill with which we do it). Not only do our mental capacities allow us to do this, but our social living makes it extremely advantageous to take advantage of the ability. When you live in a social group so large that you may not know everybody in the group, knowing what SORT of person somebody is (e.g. which tribe they are in, what social role or rank they have, etc.) becomes really important, as does being able to signal your own (honestly or dishonestly). As I see it, the most critical role clothing plays in human life is as a medium for communication and expression of identity and status.
The planning and skill that goes into producing an article of clothing might be beyond the cognitive abilities of a chimpanzee. But even if a chimp could make a dress, will she really bother to make one if she knows her friends aren’t going to be jealous? And besides, what if every high ranking male in the group is going to rape her once a month no matter what she’s wearing?
To put it another way: if clothing is ubiquitous among humans because it serves as a medium for communication, in order for it to “evolve” in a species, the species must be able to both create and interpret the form of communication. Some species might be limited by their inability to physically create clothing (for example, I don’t see how even the most cultured dolphin could make or wear anything), while other species might physically and even cognitively be capable of creating clothing, but clothing would never become fundamental to the species’ existence unless it began to take on cultural significance.
Anyway, maybe its the case that clothing follows culture (and opposable thumbs). If that’s true, then the question of why clothing use isn’t observed in animals is really a question about the evolution of culture in social animals. This might further reduce to a question about the evolution of certain cognitive abilities, such as a theory of mind? Also, I wonder if it is around the same age that children began to develop a theory of mind and also began to worry about what they are wearing. I’m not convinced that nudity is “natural” for humans. Rather, I think it is perfectly natural that at a certain age, and often with complete disregard for parental wishes, children began expressing themselves through their clothing.
Just ramblings!
Great blog! I have to add here that a lot depends on one’s definition of “clothing” – if loosely speaking it’s a use of objects to decorate or disguise oneself, there are lots of examples. The first one I think of is the aquatic young of caddisflies, and there are also mammals that use leaves, sticks, etc. for various purposes. Orangutans in the wild drape themselves with leaves for shelter, and in captivity they love to place blankets, bags, etc. over themselves. Male chimps pick up branches to charge and impress others (cf. the sambars). An intriguing topic!
Pigs, cows, horses and hippos coat themselves with mud to ward off flies. If frass is clothing can mud be far behind?
Abnormally well written article…