For all our inability to definitively describe it or to pin down its nuances, beauty is not hard to see. It exists everywhere in the world around us, and we are usually pretty good at spotting it. We see it in ourselves, of course, and by extension in the things we make and the places in which we live. We see it in the natural world – in the blooming of a cherry tree or in the snow blanketing a mountaintop. But we also find it in the animal kingdom – in the sultry spotted coat of the leopard, the awesome power of the horse in motion, the resplendent wings of the bird and butterfly.
That humans can see and enjoy beauty in other animals is understood, but what of animals’ ability to recognize and appreciate beauty in themselves? Do they possess an aesthetic sensibility for that which is beautiful? Might a bird-of-paradise get its feathers all ruffled at the sight of another particularly fine specimen? Does a blue striped grunt find that, of all the fish in the sea, the stripes of one shimmer just a little bluer than the rest? That is, are aesthetics the sole purview of humans, or do animals, too, have the capacity to appreciate beauty for beauty’s sake?
Sexual selection
There is a small cohort of scientists who believe that they just might. Chief among them, none other than the eminent Charles Darwin. While Darwin is noted for his theories on evolution and natural selection, he also advanced a lesser known (and far less well received) theory regarding sexual selection. As the name suggests, it describes the process whereby members of the same sex (typically males) compete for access to mates, and members of the opposite sex (usually females) assess the contenders and select a suitable mate.
The males vie for the attention and ultimate favor of the females through courtship rituals – song and dance – and the flaunting of elaborate ornaments – bright colors, exotic feathers, impressive headgear, and the like. These may even border on the outlandish, with the classic example being the altogether impractical plumage of the male peacock. It is through this process of selection that the most appealing males are chosen and whereby certain “aesthetic” characteristics are selected for, evolving over time towards the preferred standard.
These sexual traits are non-adaptive in that they may not advance the adaptive capacity, or the fitness of the animal to survive (which is the purview of natural selection). In fact, excessively flamboyant ornament may even work against adaptations that have evolved to enhance fitness. The example often given here is the male deer’s antlers, which likely originally emerged through natural selection to aid in combating rivals. But over time, the process of sexual selection favored larger racks, which are metabolically costly to grow and physically burdensome to wield through the forest undergrowth – all of which ultimately works to impede survival.
Thus while natural and sexual selection are complementary processes, they may not always be perfectly aligned, as the selection of flashy sexual traits may sometimes advance reproductive success at the expense of survival. So even while many ornamental traits may have originally developed with utility in mind – to serve some life sustaining purpose – over time through sexual selection, that function may diminish or be lost altogether. Yet the ornaments persist merely as things of beauty. It is this very lack of utility, this absence of adaptive function serving survival, that Darwin uses to justify his claim that animals have an aesthetic capacity to appreciate beauty.
Good taste
Also critical to Darwin’s theory of sexual selection – and to advancing the argument of the animal aesthetic capacity – is the idea of female choice. While it is typically the males of any given species that are so beautifully ornamented, it is through the females’ favor that the winning traits are selected for. These ornaments and other aesthetic characteristics, argues developmental biologist Christiane Nüsslein-Volhard in Animal Beauty: On the Evolution of Biological Aesthetics,
“work as communication signals, since their function depends on an observer, that is, on the subjective visual perception by another individual. These signals are recognized and stimulate an appropriate response. One may consider this aspect of sexual selection as a special case of a more general ‘aesthetic selection’ because of the cognitive function involved in social communication. Choice is determined by the subjective sensibility of an observer. A special feature of these aesthetic characteristics and of their function in the life of animals is that the receiver of signals must both recognize them and set a value on them.”
The female considers her options and chooses a male whose charms she finds the most appealing, the most beautiful. In choosing a suitor who is more lovely than the rest, she is making a kind of value judgment, an aesthetic preference. Indeed, it is often the most elaborately ornamented or the best performer who catches her eye and wins the day. It is through this process of male signalling and female selection that both animal beauty and its aesthetic appreciation evolved simultaneously. In “Animal Aesthetics,” philosopher Wolfgang Welsh demonstrates how these two sides of sexual selection evolved in tandem:
“Beauty and the sense of beauty originated together and reinforced each other — they developed through coevolution. At the beginning, minute elements of male beauty and an incipient female sense of beauty had the effect that the more beautiful males were chosen by the females; as a result both the disposition for beauty and the sense of beauty gradually acquired greater representation in the offspring; and thus finally beautiful males and tasteful females became the standard of the species. In this way, beauty and the sense of beauty have coevolved.”
As with our (human) experience of the aesthetic, animal beauty hinges on two sides of the same coin – the object of beauty and its admirer. A kind of dialogue thus unfolds between the male, who might flash artfully fanned feathers or perform an alluringly choreographed dance, and the female, who in turn perceives this display of beauty and judges its subjective value.
Proximate beauty
Of course, not everything boils down to a simple beauty contest. The process of natural selection is very much still at work in the pursuit of survival and reproduction, with a female’s calculus also factoring in adaptive advantages and fitness of the competing males. Those demonstrating higher levels of health and vigor are more likely to emerge victorious because they have a better chance of survival and are therefore likely to pass their “good genes” on to their offspring. But what if beautiful ornamentation is actually correlated with these same traits – superior fitness – and females are responding, not to fine ornament for its own sake, but to beauty as a sign of health? This would reduce beauty to a signal of fitness, a proxy for desirable genes.
It is this very point that Darwin’s peers and many contemporary scientists make in the case against animal aesthetics. This camp argues that the female does not appreciate the fanciful embellishments of a suitor for their beauty per se, and thereby does not possess an aesthetic sense. Rather, she equates the male’s beauty with good health and quality genes. She interprets a fine, sleek coat or striking plumage as a signal of high fitness that will be inherited by her progeny.
This adaptive reading of animal beauty is also given by way of explanation for human preferences for beauty – i.e. women with long, thick hair and an hourglass figure are said to be viewed as more attractive because these attributes are apparently indicative of youth and fertility. The old child-bearing hips chestnut. Individual preferences and bad clichés notwithstanding, this adaptive view of beauty seems to present us with a plausible alternative theory to Darwin’s evolutionary aesthetics.
It all seems so very arbitrary
Until recently, the adaptive theory of beauty has been the dominant school of thought among scientists, who view natural selection as the indisputable crux of evolution. But as we are gradually beginning to unravel more about the complex and interdependent ways that animal beauty evolves, there has been a return among some scientists to Darwin’s emphasis on sexual selection and his long-neglected theory of beauty. For the 2019 New York Times article, “How Beauty Is Making Scientists Rethink Evolution”, Ferris Jabr profiles the work of several such scientists who are studying the evolution of aesthetics among diverse animal populations.
One of these is evolutionary ornithologist, Richard Prum, a modern day champion of animal aesthetics. He views sexual selection as an even more powerful and creative force than natural selection, and like Darwin, argues for an understanding of aesthetic mating preferences as playing “an independent role in the evolution of an enormous diversity of secondary sexual traits, including many of the most extraordinary instances of design in nature.” Believing that “all sexual ornaments and preferences should be regarded as arbitrary until proven useful,” Prum is wholeheartedly against the notion that animal beauty is simply a proxy for underlying fitness, or that preferences for aesthetic traits need to have arisen out of any particular evolutionary need. Rather, he contends that animal beauty is too diverse and varied to not be the product of arbitrarily produced aesthetic traits and preferences.
To illustrate this point, Jabr points to Prum’s studies of the club-winged manakin, a passerine bird native to South America, which Prum himself regards as “emblematic of nature’s capacity for pushing creatures to aesthetic extremes.” The male manakin courts females by showily jumping about and making a curious mechanical violin-like hum with his wings by rapidly beating them over his back, shaking his feathers against one another at the manic rate of one hundred times a second.
This high frequency vibration is made possible by oversized solid wing bones, which also have the (far less desirable) effect of making flying a bit awkward. Contrast that with almost every other bird, whose wings are made up of light, hollow bones engineered for flight, and we can see how the manakin’s predilection for a pretty tune is rather problematic in the aeronautics department. Prum found that female manakins have also inherited similar bone structure anomalies and points out that, because the females do not court males, there can be no advantage to their “warped bones and feathers.” Rather, an extreme aesthetic preference has resulted in wings that can produce unique musical notes, but that are maladaptive for flight.
Prum believes that at some point in their evolutionary history, the club-winged manakin’s courtship dance incidentally produced a sound through the rustling of feathers that, over time, became highly attractive to the females. This in turn put pressure on males to evolve adaptations that would enable them to produce a louder and more noticeable sound, eventually culminating in their signature rapid buzzing. But when pushed to speculate why the females might have been attracted to those particular sounds in the first place, Prum demurs. Rather than there always being an explicit causal explanation as to why certain aesthetic preferences arise, he contends that more often, both beauty and preferences for it develop arbitrarily, without reference to underlying biological constraints.
But it is this very question of the origin of aesthetic taste that intrigues Molly Cummings, professor of Integrative Biology at UT Austin. While she concedes that animal beauty is not necessarily always adaptive or a signal of fitness, she is quick to add that this does not mean that it develops arbitrarily or at random. Cummings argues that there is often a reason that females develop the preferences they do, whether it’s an evolutionary vestige or due to neurobiological or environmental constraints. A leading researcher in the field of sensory ecology – the study of how an animal’s ecological niche and way of experiencing the environment through its senses sculpts its behavior and preferences – Cummings’ works demonstrates that female aesthetic preferences can be shaped by environmental factors such as water quality and changes in natural light.
In her study of surfperch living in kelp forests off the California coast, Cummings found that different populations of fish exhibited varied color preferences. Surfperch living in murky waters preferred males with shiny, silvery ornamentation, while those residing in brighter waters gravitated towards bold colors like blue. The female’s preference had not arisen arbitrarily, Cummings says, but as “a consequence of the particular wavelengths of light that traveled farthest through her underwater niche. Whichever males happened to have scales that best reflected these wavelengths were more likely to catch the eye of females.” In the case of the surfperch then, female preference for beauty is not the byproduct of a random whim, but a direct result of the fishes’ environment and anatomy.
And the crown goes to…
So which view is the right one? Do animals possess an aesthetic sense akin to that of our own, or is beauty simply a proxy for fitness? If we believe the former to be true, then from where do aesthetic preferences originate? Do male beauty and female preference evolve together according to random chance, without apparent origin or influence, or do they emerge in response to environmental and physiological constraints?
As best as we can tell, the answer is both. There is no single, linear evolutionary path, but rather a branching and intersecting network of forces and contributing factors working in tandem and at odds with one another. As Jabr puts it, more eloquently than I could hope to,
“Beauty reveals that evolution is neither an iterative chiseling of living organisms by a domineering landscape nor a frenzied collision of chance events. Rather, evolution is an intricate clockwork of physics, biology and perception in which every moving part influences another in both subtle and profound ways. Its gears are so innumerable and dynamic — so susceptible to serendipity and mishap — that even a single outcome of its ceaseless ticking can confound science for centuries.”
While we don’t know – and may never fully understand – how or why animals have evolved such elaborate and varied forms of beauty, we can at least begin to appreciate that, like so many other faculties thought to belong to the privileged realm of human exceptionalism, the aesthetic capacity – to varying degrees of sophistication – is a critical aspect of life across the animal kingdom. As we uncover more about the inner-workings of the animal mind, piecing together how they might perceive and experience the world around them, we are finding that the range of animal cognition often approaches a level of development previously believed to be exclusive to that of our own.
Of course, it might seem far-fetched to equate animals’ aesthetic mating preferences with our own capacity for aesthetic experience. And I don’t know that anyone would advocate for putting the human drive to produce and consume art and literature and symphonies and other things of beauty on quite the same level as, say, the club-winged manakin’s one-note musical inclinations or the surfperch’s preference for silver stripes. That said, we shouldn’t discount the fact that animals – with their kaleidoscopic fins and feathers, choreographed ballets, and crowns of branching bone – are the organizers, contestants, and judges of nature’s original beauty pageant.