If, like me, you're one of those softies who likes cute animals—especially baby animals—and visits places like The Daily Squee, Zooborns, or Acting Like Animals, and if you're also a tad reflective, you may have asked yourself, "Why do I find these things so god-damned adorable?"

There are, of course, two ways to answer that question.  The proximate answer requires that you single out those features of animals that make them cute versus ugly, and perhaps amalgamate them into some general explanation.  Why are baby ducks so cute, and baby parrots so ugly?  Why are baby chimps so much more appealing than adult ones?  Why are hairless cats uglier than normal ones?  Why are human babies so irresistible compared to teenagers?  General answers to these questions might involve fur, relative size of the head or of the eyes, length of the limbs, and so on.

Then there's the ultimate answer: the evolutionary one.  Is there an evolutionary reason why I find some features attractive and others repugnant? Would such preferences have been adaptive in our ancestors?  Those questions are the bailiwick of evolutionary psychology. And although answers are elusive—and indeed, may be forever beyond our grasp—it's fun to think about these things.

Although Steve Gould was an implacable enemy of sociobiology, he sometimes indulged in evolutionary psychologizing.  In one of his more famous essays, "A biological homage to Mickey Mouse" (free online), Gould noted that over the fifty years since his creation, the image of Mickey had evolved from a rather etiolated rodential form into a squat creature with a big head, big eyes, and short limbs, which were made to seem even shorter but putting them in clothes.  Here's a figure from Gould's essay (do read it: it's blessedly free of the cant and pomposity that plagued his later efforts):

The evolution of Mickey over half a century: neoteny rules!

Gould even plotted some of these morphological changes (relative head, eye, and cranial vault size), demonstrating that Mickey was undergoing gradual change (I gleefully add that it wasn't punctuated!) towards the appearance of a juvenile mouse: bigger head, bigger eyes, and larger cranial vault, and that this juvenilization was driven by viewers ' preference for a cuter, more anthropomorphic mouse. Mickey was undergoing neoteny: the evolutionary process whereby juvenile features in an ancestor are retained into adulthood in a descendant.  (We humans are supposedly neotenic, resembling a juvenile chimp or gorilla far more than we resemble their adults.)

Gould also argued that the baby animals we love so much (he shows figures of a rabbit, bird and dog) have relatively bigger and rounder heads, and bigger eyes, than do adults—as, of course, do human babies.  He speculates, following Konrad Lorenz, that we have an innate tendency to lavish attention and affection on mammals with these juvenile features, and that this aesthetic preference is adaptive:  those of our ancestors who fixated on the big heads and eyes of babies would leave more offspring than those who weren't as turned on by the sight of their infants.  Importantly, Gould showed that if natural selection had favored this preference, it could have done so in two ways: a) evolving a hard-wired preference for juvenile morphological traits: we are born with this aesthetic sense, or b) evolving a somewhat flexible "learning module": we have genes that tell us to favor whatever features appear in our offspring.  The latter explanation is a form of imprinting: presumably if your and everyone else's baby were suddenly born with small heads and eyes, and long legs and noses, we'd instantly find those features cute.

These questions came to mind again when I read Natalie Angier's piece in yesterday's New York Times science section, "Masterpiece of nature? Yuck!" Accompanied by a slide show of butt-ugly animals, Angier briefly touches on evolutionary psychologists' explanations for why we're repulsed by some animals.  Her poster child for Animal Ugly is the star-nosed mole.  With her usual panache, she describes getting a photo of one in her email: "A head-on shot of a star-nosed mole, its 'Dawn of the Dead' digging claws in full view and its hallmark nasal boutonniere of 22 highly sensitive feelers looking like fresh bits of sirloin being extruded through a meat grinder." Now that's a great word picture of this:


Star-nosed mole (Condylura cristata); photo by Gary Meszaros/Photo Researchers

Angier gives the speculations of some evolutionary psychologists, including Denis Dutton (author of The Art Instinct), David Perrett, and Geoffrey Miller; she also cites a recent paper by Trimble and van Aarde showing that, among endangered species in southern Africa, large mammals are way overstudied compared to smaller mammals, reptiles, and amphibians.

The message of her piece is this: the reason we find animals cute or ugly is that we're using criteria that have evolved to help us evaluate members of our own species.  Baby animals are cute because natural selection has, for obvious reasons, made us go all mooshy when we see the big, round head of a human infant.  We don't like the star-nosed mole because its naked nasal protuberances might, if seen in a human, indicate bad health or bad genes.  (As Dutton says, probably correctly, "No one would find the star-nosed mole ugly if its star were iridescent blue.").  Likewise for other animal traits that, if seen in humans, would make us avoid them: "We distinguish between the signs of an acquired illness and those of an innate abnormality. Splotches, bumps and greasy verdigris skin mean 'possibly infectious illness,' while asymmetry and exaggerated stunted, or incomplete features hint of a congenital problem."

So, for example, something like the African wart hog, which surely qualifies as an ugly animal, is doubly cursed.  It has not only those wartlike growths on its face, but also patchy hair, both of which remind us of disease.  (Who wants a diseased mate?)  And it has a long, protruding snout—and tusks!  (The alopecia that comes with disease may also explain why many of us are repelled by hairless cats.)

Phacochoerus africanus

Now it's fun to ponder these issues, and some of these ideas can even be tested.  We could determine, for instance, whether there is a commonality to the features people see as ugly or repulsive in animals, and compare those with similar features in our own species.  Testing ultimate, evolutionary explanations is of course much harder—or impossible.  Nevertheless, in our ignorance it's still salutary to remember that things are not innately ugly or beautiful.  A warthog is not innately uglier than a panda.  Presumably, a female warthog finds a male warthog the epitome of hotness, and would find a panda noisome. Some of our visual preferences, like our gustatory ones, must reflect the action of natural selection, and be in that way adaptive.  We find a plate of rotten meat repulsive, but to a vulture it's the equivalent of an ice cream sundae.  As Darwin recognized, our tastes may be no less evolved than our brains or our bodies.

The other day a female friend mentioned that she could never be attracted to Hugh Hefner, despite his wealth: he was simply too old and wrinkled to be sexy.  Female actresses have trouble getting work beyond the age of 40, presumably because males don't find them attractive.  But there's no reason why the signs of age—the wrinkles, the gray hair, and so on—are innately less attractive than the dewy freshness of youth.  Could it be that our standards of beauty, or attractiveness, have evolved to fit adaptive ends?  Could we find older people less attractive simply because, being near or past the cessation of reproduction, they're not good candidates for mates, and that this preference could have been instilled in our ancestors by natural selection?

Do let us remember that beauty in nature is not innate but evolved, and truly in the eye—and brain—of the beholder. Our biology precedes our tastes, or rather, co-evolves with them.  In only one way is the situation reversed: animal breeding*.  There, in the big eyes of the Chihuahua, the short snout of the fluffy Pomeranian, in the round face and small ears of the Scottish fold cat (e.g., Maru, who won), in all the features of animals bred for appearance rather than work, we find our desires, evolved and otherwise, sculpting the beasts in our environment.

Ugly? Moi?

Photo of Sphinx cat by Patrick Matte

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*It's also true of plant breeding, of course.  It's the (undoubtedly correct) thesis of Michael Pollan's The Botany of Desire that things like domesticated potatoes, tulips, and apples are simply vegetal embodiments of human taste.