Human Flower Project

In Lust with Symmetry

Flowers with bilateral symmetry evolved from earlier radial blooms because they’re more attractive. Sound like anyone you know?


Leonardo da Vinci’s “Vitruvian Man”

Image: DePaul University

Whom do you find more attractive, Johnny Depp or a sea urchin?

That may be because Johnny, like an orchid, radiates a higher order of balance, called bilateral symmetry. Researchers of social psychology have pretty much agreed that the faces we find most alluring are also the most symmetrical ones. To be physically balanced, right to left, is a primal hallmark of health and, therefore, beauty.

imageDahlia, with radial symmetry

Photo: Courtesy of Greg Allikas

Now a team of ecologists and geneticists who’ve looked into the faces of flowers report that plants with Johnny’s sort of features are likewise more attractive to insects than are flowers with simple radial symmetry. “The researchers found plants bearing bilaterally symmetrical flowers were more visited by pollinators and had higher fitness, measured by both the number of seeds produced per plant and the number of seeds surviving to the juvenile stage, than among plants with radially symmetric flowers.”

Radial flowers, like daffodils, hollyhocks, and dahlias, are circular in design. If you were to cut a pie slice anywhere on the bloom, it would look just about exactly like any other slice. But flowers like snapdragons,  sweet peas, and orchids have another sort of balance and form—more human. They are designed bilaterally, with two halves that mirror one another. Our shared design may explain why people have such strong (even erotic) affinities for orchids.

imageCattleya walkeriana, var. Alba

with bilateral symmetry

Photo: Courtesy of Greg Allikas

Radial flowers like dandelions and daisies arrived on the scene first, with bilateral blooms appearing only in “Paleocene and Eocene time.” Similarly, the earliest animals—like sea urchins and jellyfish—were radial in design,  Johnny’s species coming along later.

Many researchers, both botanical and psychological, have examined the effects of symmetry; Linnaeus himself was looking into the subject several centuries ago. The recent Spanish study, published in the October issue of American Naturalist, trains its attention on bilateralism as an evolutionary advantage in plants, as it also seems to have been for humans.

Let’s not be hasty to claim victory, though. Evolutonary contests go on for extra innings. The jellyfish and daisies may be looking radiant long after we and the snapdragons are gone.



Posted by .(JavaScript must be enabled to view this email address) on 10/05 at 01:52 PM


Dear Julie,
Thanks for including this post about the added attractiveness of bilateral symmetry.  I’ve been aware of the studies in human social psychology, and so it’s also interesting to hear about insect behavior. 
The subject is of particular interest to me as I work with visual meditation, and the relative efficacy of various sacred images.  Given the distinction that’s being made, it’s interesting to compare power of the image of a human face (Virgin Mary, Buddha) with the radial symmetry of a Navaho or Tibetan Buddhist mandala. 
I do think bilateral symmetry is harder to achieve in nature, and is a more distinctively unique marker of the human experience.  We are imprinted with the bilateral pattern of our caretaking parents’s faces from early infancy.  Unavoidably, we carry a very powerful association of the bilateral pattern with nuturing and goodness.

Posted by Victoria Scarlett on 10/10 at 07:23 PM

reminds me of the davinci code! sorry to lower the tone but what a great film

Posted by October visitor on 10/12 at 04:57 PM

it’s a universal law, symmtery attracts.Art is balance, symmetry. Symmtery in not only form and shape, but in colors too. You did a funny comparison with Johnny Depp. ANd I do agree there with you.

Posted by Brenda on 10/26 at 10:53 PM
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