Humans are an extremely visual species, with much of our brains devoted to visual processing. Sight is one of the most important ways we experience our external environment; consequently, it may not be surprising that certain images can invoke a visceral “gut reaction” in us. For example, compare the cuddle factor between a giant panda and a star-nosed mole; chances are the mole with twenty-two tentacles on its face would receive far fewer hugs than the panda. But why is this the case, and what does this have to do with human evolution or species conservation?

In truth, what is beauty?

There has been a wealth of studies done on what constitutes beauty in humans. Symmetry is a highly attractive quality in human faces, and studies have shown that babies spend a longer time staring at photos of symmetric faces than those of asymmetric faces [1]. In the 1990s, Dr. Stephen Marquardt, a cosmetic surgeon working on patients with severe facial deformities, undertook a mathematical examination of the proportions found in “beautiful” human faces. He found that the ratio of 1.618 to 1 was liberally found throughout those faces- for example, their mouths were 1.618 times wider than their noses and the length of the head from forehead to chin was 1.618 times the width of the head [2]. This so-called “Golden Ratio” has been studied through the ages by mathematicians to artists for its recurring role in everything from geometry to aesthetics. Criticisms of Marquardt’s work, however, include his lack of peer-reviewed publications and that these “ideal” proportions may be biased towards faces of European descent. Other studies done have described human beauty in much more general terms. In Western cultures, males tend to prefer females with more “infantile” features – small jaw, large eyes, and defined cheekbones. Female preference can change with their menstrual cycles from a slight preference for a soft-featured male during menstruation, to a preference for masculine features at other times of the month [1].

Some of those qualities that we may find attractive in potential mates also seem to influence the types of animals we deem “cute.” Studies have shown that humans consistently display a preference for animals with juvenile features, such as large eyes, a flat face, and a large head, that are retained in the adult animal (e.g. toy dogs such as Chihuahuas and Yorkshire terriers) [3]. These youthful traits are also highly prominent in one very important human context – our offspring. From an evolutionary standpoint, these physical attributes may be positively selected, as they act as a behavioral trigger, promoting feelings of affection and nurturing towards our infants [4]. This attraction drives parents to care for their infants, thus improving the child’s fitness and chances of survival. A side effect of these visual cues, however, is that even animals displaying similar juvenile physical attributes can elicit an outpouring of affection as well. One prominent example of an animal that has used such traits to capture our attention is one of the world’s most recognizable trademark symbols: Mickey Mouse. The first incarnation of Disney’s icon was more Mouse than Mickey: he had small close-set eyes, a small head, and a long narrow snout. Over the course of fifty years he gradually became more youthful in appearance, eventually transforming into the beloved version that we know today with large eyes, a larger overall head, and a wider forehead [4].

Why was the ugly duckling ugly?

In contrast to our standards for beauty, what determines “ugliness” is a more complicated question. Simply reversing the attractive juvenile features is not sufficient, as there are plenty of animals with small eyes, large noses, and small heads that are still considered cute; a piglet for instance. One theory is that the concept of an “ugly” animal is much more philosophical; the more closely an animal’s body part resembles ours, the more likely we are to be repulsed by it [5]. For example, an elephant trunk is not necessarily considered ugly, because it is so foreign from our concept of a nose. We simply view it as an elephant trunk. However, the nose of a proboscis monkey is similar enough to our own for us to judge it by human aesthetic standards, which would deem such a schnoz as ugly.

These seemingly innocuous ideas about ugly vs. cute animals have a wide-ranging impact beyond which critters are featured today on For years, conservation movements have rallied around saving a particular endangered species, such as the giant panda or the grey wolf – animals that appeal to a cute-loving public [6]. While these campaigns were largely successful for the animals they supported, they often left behind other equally endangered, but perhaps less adorable, species.

In the 1990s the World Wildlife Fund switched gears and began a series of conservation efforts focused on raising money and awareness for particular habitats and regions, rather than for specific species. This strategy still utilizes public-friendly images such as waterfalls and jaguars to inspire concern for afflicted regions, but also allows the money to be distributed more evenly among the various endangered species present in the area, including less attractive species [7]. Despite these efforts, however, a strong bias still remains in many fields, including research science, to distribute funding toward the cute and fuzzy [8].

Where does that leave us now? Thankfully there are several groups today trying to bring awareness to the less visually appealing but equally important endangered species in the world. The advent of high-speed DNA sequencing has allowed scientists to look at the genomes of hundreds of species, allowing us to prioritize endangered species not by their facial dimensions but by the genetic diversity they represent. With more public awareness, we will hopefully be able to help to all endangered species, and not just those we think are cute. Although the attractive qualities described above are clearly generalizations, they do serve to remind us of one important idea: beauty is in the eye of the beholder!

Rou-Jia Sung Molecular and Cellular Biology Dept, Harvard University


[1] Feng, Charles. (2002 December) “Looking Good: The Psychology and Biology of Beauty.” Journal of Young Investigators.

[2] Marquardt, Stephen. “Marquardt Beauty Analysis”

[3] Stokes, David L. (2006) “Things We Like: Human Preferences Among Similar Organisms and Implications for Conservation.” Human Ecology. 35: 361-369.

[4] Gould, Stephen J. (1980) “A Biological Homage to Mickey Mouse.”

[5] Angier, Natalie. (9 August 2010). “A Masterpiece of Nature? Yuck!” New York Times.

[6] Levitin, Michael. (1 March 2007). “Bye-Bye to the Aye-Aye.” Slate.

[7] World Wildlife Fund. “Ecoregions.”

[8] Trimble, Morgan J. and van Aarde, Rudi J. (2009) “Species Inequity in Scientific Study.” Conservation Biology. 24:3 (886-890).

Links of Interest:

“Endangered Ugly Things” blog, written and maintained by Nathan Yaussy, a graduate student at the Kent State University.

Conservation efforts directed at saving “Evolutionarily Distinct and Globally Endangered” (EDGE) species.

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