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Key points
- We perceive attractive faces as indicators of good health, immune system quality, and a nutrient-rich diet.
- Excessive carotenoids can provide a subtle but observable clue to gut health by turning skin a yellowish hue.
- Research on Asian, African, and Caucasian faces shows that all are more attractive with added yellowish tint.
Beauty is not just about aesthetic appeal; it is a complex interplay of biological signals that guide our social and reproductive preferences. Our perceptions of attractiveness are deeply rooted in biological markers that signal health, fertility, and genetic fitness.
Symmetry indicates developmental stability, hormonal influences highlight reproductive potential, and youthful features suggest vitality, for example. By understanding these markers, we can appreciate how deeply our judgments of beauty are intertwined with indicators of health and evolutionary fitness. A lesser-known biological marker is carotenoid pigmentation, which reveals dietary health.
Carotenoid Pigmentation in Skin
Carotenoids are naturally occurring pigments found in various fruits, vegetables, algae, and some bacteria and fungi. They are responsible for the bright red, yellow, and orange colors seen in many fruits and vegetables, such as carrots, tomatoes, pumpkins, and sweet potatoes.
Carotenoids also contribute to the colors of autumn leaves. They play a significant role in determining skin coloration, but unlike some other markers of attractiveness, carotenoids are obtained exclusively through diet. That is, we don't make any in our bodies, we find them and consume them in foods. These essential antioxidants help protect the skin and other tissues from damage.
Here's how it works. Carotenoid pigmentation is related to metabolism and gut health, but our bodies do not generate any carotenoids. Instead, we consume plants and animals that have them. If you've got a lot of carotenoids—in fact, an excess of carotenoids—you put the extras into your skin, but you must have a healthy gut to absorb them. A byproduct of having loads of carotenoids is that it gives skin a yellowish hue. Thus, yellowness in the skin can be an honest marker of gut health.
Color in Other Animals
In addition to humans, variation in color is frequently used by other animals to assess the fitness of potential mates. Wolves, for example, may signal their resistance to canine distemper virus via their coat color. In turn, coat color is a signal used by other wolves to identify partners who can provide healthier offspring.
Flamingoes’ vibrant pink color comes from carotenoid pigments found in the algae, shrimp, and other small crustaceans that they consume. These pigments are broken down in the flamingo's digestive system and then absorbed, leading to the pink or reddish hue in their feathers, skin, and beak. Without these pigments in their diet, flamingos would appear much paler or even white.
Among sea creatures, salmon, crabs, sea urchins, and koi fish all derive their color from carotenoids. When cooked, lobsters turn bright red due to the release of carotenoid pigments. Carotenoid-rich birds include cardinals and canaries that are easily recognizable by their bright reds and yellows.
A Yellowish Tint
Humans with higher levels of carotenoids in their diet tend to have a slight yellowish tint to their skin, which is often perceived as healthy and attractive. If you've got a lot of carotenoids—in fact, excess carotenoids—you put the extras in your skin. Because a healthy gut is necessary to be able to absorb carotenoids, their presence can signal that an individual has a healthy gut capable of absorbing these important nutrients. Thus, the yellowness in skin—all skin, regardless of how light or dark—can be a marker of carotenoids, which in turn could indicate good gut health.
This yellowish coloration indicates a diet rich in fruits and vegetables, which is associated with good health and a robust immune system.
Studies reveal that people with higher carotenoid levels are often rated as more attractive, likely because this pigmentation is an indicator of overall health and vitality. The presence of carotenoids in the skin, as evidenced by a yellowish tint, has nothing to do with DNA, genes, or inherited traits. The ability to absorb carotenoids efficiently also suggests that an individual has a consistently healthy diet and a well-functioning digestive system, making them attractive potential romantic partners in the preagricultural ancestral past where access to high-quality food was limited.
Conclusion
The mate preferences we hold for beauty evolved as adaptations designed to help us identify potential partners with the best chances of survival and reproduction. As research continues to uncover the intricacies of these markers, we gain a deeper understanding of why we find certain features more attractive and how these preferences shape our interactions and relationships. While variations in standards of beauty exist between cultures and individuals, certain universal markers can signal health and vitality, making them nearly universally attractive. Gut health is one.
© Kevin Bennett, Ph.D., 2024.
References
Foo Y.Z., Rhodes G., Simmons L.W. (2017). Carotenoid betacarotene enhances facial colour, attractiveness and perceived health, but not actual health, in humans. Behavioral Ecology, 28(2), 570–578. doi:10.1093/beheco/arw18
Ip, F.W., Lewis, G.J., & Lefevre, C.E. (2019). Carotenoid skin colouration enhances face and body attractiveness: A cross-cultural study. Quarterly Journal of Experimental Psychology, 72(11), 2565-2573. https://doi-org.ezaccess.libraries.psu.edu/10.1177/1747021819850970
Stephen I.D., Law Smith M.J., Stirrat M.R., Perrett DI. (2009). Facial skin coloration affects perceived health of human faces. Int J Primatol. 30:845–857.
