The Beeholder, April 2009.

When selecting a mate humans tend to go for a high degree of bilateral symmetry. Indeed it is almost the case that the greater the symmetry the greater is the perceived beauty. The same quest for symmetry is working in the parallel evolution of insects and plants. Bilateral symmetry has been considered as an indicator of phenotypic and genotypic quality supporting innate preferences for highly symmetric partners. Insect pollinators have been found to preferentially visit flowers of a particular symmetry type. This has lead to a suggestion that insects have innate preferences for symmetrical flowers or flower models. Researchers* show that flower-naïve bumblebees (Bombus terrestris), with no experience of symmetric or asymmetric patterns and whose visual experience was accurately controlled, have innate preferences for bilateral symmetry. The presence of colour cues did not influence the bees' original preference. The researcher’s results showed that bilateral symmetry is innately preferred in the context of food search, a fact that supports the selection of symmetry in flower displays. Furthermore, such innate preferences indicate that the nervous system of naïve animals may be primed to respond to relevant sensory cues in the environment.

(*=I Rodríguez, A Gumbert, N Hempel de Ibarra, J Kunze, M Giurfa Naturwissenschaften, Vol. 91, No. 8)

Tony Shaw