Photo by Liu Ranyang/China News Service/VCG via Getty ImagesIn 1994, Russian-American artists Vitaly Komar and Alex Melamid set out to create America’s most beautiful painting. The result was striking: a verdant lakeside scene complete with trees, deer, picturesque hills, dawdling youngsters and, incongruously, George Washington, the first president of the United States.This odd inclusion points to the artwork’s unusual origins. Komar and Melamid had contracted a market research company to survey the American public about its views on beauty in art. The painting’s cool blues, natural setting and eminent historical figure all reflected majority preferences of the US population.This painting, “America’s Most Wanted”, was one product of The People’s Choice art project. The artists repeated the exercise in several countries, finding some variations – in Kenya, a hippopotamus and Jesus replaced deer and president – but almost all images depicting natural landscapes featured water, plants and hilly terrain. Review: Why Is the World So Beautiful? Our Minds in Search of Nature’s Rhymes – Nicholas Humphrey (MIT Press)The project also explored ugliness. A painting titled “America’s Most Unwanted” is a mess of triangles that looks like an explosion in a corn-chip factory or, as one critic observed, “the ragged old linoleum under the kitchen stove, only oranger”.The People’s Choice is a parody of popular taste, but it also suggests there is something universal about what people find beautiful. Perhaps beauty is in the eye of the beholder, but human nature has shaped that organ. That, at least, is the starting point of the field of evolutionary aesthetics. According to its “biophilia hypothesis”, which proposes that humans possess an innate desire to seek connections with nature, we find vistas that afford good prospects for human habitation beautiful. Water, greenery, animals and other people signify places where we could live comfortably off the fat of the land.The psychology of beautyNicholas Humphrey, author of Why Is the World So Beautiful, shares this evolutionary worldview, but to him our adapted psychology of beauty goes much deeper than landscape preferences. A self-described theoretical psychologist, Humphrey is a lucid writer with a wonderful nose for intriguing topics and original angles. He has written extensively on consciousness, religious faith and the origins of social intelligence. His new book brings a gentle, donnish erudition to the study of aesthetics. An extended speculative argument on why we perceive beauty and how our world is furnished with it, the book is richly illustrated with examples from visual art, poetry and the natural world. It’s a splendid collision of philosophy with biological and cognitive science.The central concept in Humphrey’s account of aesthetics was inspired by a quote from the English poet Gerard Manley Hopkins: “All beauty may by a metaphor be called rhyme”. Humphrey proposes that rhyme’s role in aesthetics is not merely figurative. Just as words can align in a pleasing way, so can images, objects and ideas.Humphrey uses the word allusively at times, but the gist of his idea is that two things rhyme when they are essentially of the same kind but differ in some contingent way. Cat rhymes with mat because the terminal -at binds them together despite their differing initial consonants. Similarly, a cat and a dog “rhyme” in that both are mammals despite their obvious differences. Just as rhyming words can give us a sense of rightness and harmony, seeing essential similarities between things gives us a sort of pleasure. Humphrey argues appreciation of this sort is not merely cognitive but also aesthetic, with a moral tinge. What seems right and harmonious also seems good.This kind of aesthetic enjoyment can be found in works of art, which have a human creator, but also in works of nature, which do not. There are plainly visible symmetries in leaves and flowers, but the entirety of nature also has a taxonomic structure whose beauty we can discern and appreciate. There are visible symmetries in leaves. Ash Amplifies/unplash, CC BY-NC-SA One of Humphrey’s more fascinating claims is that humanly created and naturally occurring beauty may not be so different, psychologically speaking. Not only are both grounded in rhyme, but people also intuit that beauty in nature has a maker, just as art has an artist. Whether or not we explicitly believe in world-making gods, we implicitly infer a creative presence behind beautiful things.Humphrey suggests we are not only sensitive to the deep structures and symmetries of nature, but also driven to find them. “People take pleasure in imposing cognitive order on the world,” he writes. This sense of pleasure in beauty rewards our intrinsic desire to develop better and more refined understandings of how the world is constructed. “The world is a poem, and we are constantly anticipating how the next line will end.”Early in the book, Humphrey poses this question: “How can we explain the remarkable convergence between what human beings find beautiful and what the world at large has on display?” His answer is that our evolved sense of beauty attunes us to that display so we can grasp it better. The laws of nature have designed the world we live in, it’s the nature of these laws to generate a world that’s full of rhyme, it’s because the world rhymes that we can make sense of it, and it’s because we can make sense of it that we can live.ChallengesHumphrey’s ideas about rhyme and beauty are provocative and both concepts pose challenges to his account.One problem the idea of rhyme faces is its own expansiveness. To Humphrey, the range of things that rhyme is vast. Visual symmetries and musical variations are straightforward extensions of the poetic prototype, but at times Humphrey treats rhyme as almost any form of pattern or resemblance. Clouds can rhyme and so do the periodic table, Monet’s paintings, repeating number patterns and love. Cats of different breeds rhyme with one another, Humphrey writes. He adds that any individual cat rhymes with itself on another day and its front half rhymes with its back. The trouble with treating more or less any similarity or affinity as rhyme is that “rhyme” becomes semantically empty. Everything is similar to everything else to some degree. Specifying that the similarities must be essential and the differences contingent doesn’t offer a reliable way out of the problem, because what counts as essential or inessential is often arbitrary and dependent on context. “The cat sat on the mat”, with its essential verbal tails and inessential heads, undoubtedly rhymes. But so does “The mutt moped on the mat” – or at least it alliterates – with the opposite pattern of essential heads and changing tails. Neither line is achingly beautiful, it must be said.Even if the concept of rhyme can be pinned down, how much does it truly underpin the perception of beauty? Does a conventional lakeside vista really rhyme any more than a splatter of corn chips? The triangular theme and variations of “America’s Most Unwanted” rhyme in more obvious ways than the less ordered elements of its more favoured sibling.Form(s) and contentThere seem to be at least two alternative factors in play here. We might accept that beauty ultimately lies in the formal properties of what we see or hear – that some configurations are more aesthetically satisfying than others – but recognise that those formal properties aren’t always reducible to rhyme. Bilateral symmetry is certainly one factor in the perceived beauty of faces and could be described as a kind of rhyme. However, it is not obvious that the most appealing configuration of eyes, nose and mouth could be understood as optimally rhyming. We might say a beautiful face looks harmonious, but that is just a way of expressing appreciation metaphorically, not an explanation of the mental process that generates that appreciation. Is a beautiful face harmonious? ziphaus/unsplash, CC BY-NC-SA And perhaps form isn’t the whole story of beauty anyway. Some aspects of content may also drive aesthetic appreciation on their own, not only in their rhyming relations with something else. Blue may be more beautiful than burnt orange for many people, regardless of how it’s arranged in space. Big eyes may be more beautiful than small ones. A butterfly may be more beautiful than a slug – except perhaps to a goth – although they are equally symmetrical.Rhyming may capture some aspects of beauty, but perhaps for some people more than others. And when we consider art, the idea that beauty is its central element seems almost quaint when many expect it to educate, protest, perplex, shock and surprise rather than ravish. Humphrey’s argument is about beauty, not art, but it’s important to remember our aesthetic sense pursues dissonance, chaos and the unexpected, not just rhyme.One beauty or many?Rhyme may be too broad a concept to anchor a theory of beauty, but beauty itself is difficult to corral, even as a cognitive phenomenon. When we say that a face is beautiful are we referring to the same experience as when we say the same thing about a song, a story or a mathematical equation?Humphrey recognises this challenge. Discussing research on “neuroaesthetics”, he reports how recent work has undermined early claims that the brain has a beauty centre. Different brain regions seem to activate when we perceive beautiful faces and beautiful music. This finding does not rule out the possibility that aesthetic experiences of different kinds have important similarities, but it does make that claim less credible. Humphrey wants “beauty” to encompass many things, and distinguishes personal, structural and environmental forms. But do these forms all manifest the same mental process, or is the word “beauty” forcing together dissimilar experiences?The “lexical fallacy” refers to our tendency to believe a word corresponds to a single coherent entity. It is not unknown in psychology. Beauty may be so hard to theorise about because in addition to being a target that moves, given changing tastes, it also takes quite disparate forms.Figuring out whether beauty is sufficiently coherent to explain in a unified way might be easier if we could agree on the nature of the supposed “aesthetic emotions” accompanying its perception. Humphrey gestures towards these emotions without being specific. Sometimes they are profound and intense, like “Stendhal syndrome”, a psychosomatic condition in which people encountering great works of art have an intense, physical response (especially if they are young, single and jet-lagged, according to research). In some contexts, the emotions involved are permeated with desire and attraction. And in others, the aesthetic experience seems to be an affect-less appreciation of good form, like an elegant theory or a well-tucked sheet.Do all of these experiences present a singular aesthetic response, or is beauty too manifold to surrender its mysteries to one theory? Humphrey wants his account to apply across the board, but just as “rhyme” may be too broad to explain beauty, “beauty” may be too broad to be explained.Humphrey’s book won’t be the last word on the psychology of beauty and whether “rhyme” is an adequate conceptual tool for the job remains to be seen. However, the book’s ambition is just what the field needs. Big, audacious ideas like Humphrey’s, expressed poetically but coming from a scientific sensibility, should inspire researchers and thinkers to reflect more deeply on this endlessly fascinating topic.Nick Haslam receives funding from the Australian Research Council. He was employed by the same university as the book's author in the 1990s.