Symmetrical body plans are a form of efficiency given the rules of genetic coding.


Symmetry is common in nature, and often very useful; Human tool use developed through the coordination of our two mirror-image hands, for example. Symmetry enables things like movement (by alternating appendages), depth perception (by overlapping two eyes’ fields of view), and resiliency (if one hand is injured, we can still use the other). People, pelicans, pineapples––why exactly is symmetry so common in nature? Is it natural selection, which explains biological form so often? When it comes to the wide-ranging phenomenon of symmetry, surprisingly, natural selection is not the whole picture.

The Strategy

To a degree, the prevalence of symmetry in nature begins as an artifact of information dynamics.  This is because it takes less genetic information to code for a repeating structure, such as a pair of symmetrical antennae, than to code for a non-repeating (or asymmetrical) structure. Random chance, then, on average, will favor symmetry, at least initially, as fewer mutations are required to produce it. In other words, evolution initially has a greater chance of discovering symmetrical structures than non-symmetrical ones. If such structures then function competitively, these symmetrical forms may become preferentially inherited after processes of natural selection kick in.

Importantly, symmetry doesn’t have to be simply bilateral as in vertebrates, where the left side mirrors the right. It can also be radial as in starfish, where one form is repeated angularly in any number of repetitions before completing a circle.

One way researchers have confirmed this dynamic is using simulations of evolution with sets of shapes, starting with equal numbers of symmetrical and asymmetrical forms. Even when the probability of reproduction or survival (that is, “fitness”) is set to be the same between these two classes of shapes, much higher proportions of symmetrical shapes result from these simulations, just as we see in the natural world.

The Potential

Nature’s bias towards producing structures exhibiting repetition (such as symmetry) as an artifact of informational efficiency has a number of applications to human design. The design of software using repeating subroutines or loops is already considered an important feature of algorithmic efficiency. Other techniques capitalizing on repetition (for example, fractal compression) are used to reduce the time and energy requirements of transmitting graphic data.

Further emphasis on the use of repetition whenever possible will likely further increase efficiency in informational technologies. But the advantages of symmetry also extend to more three-dimensional technologies, just as it does in nature. For instance, when otherwise equally functional, designing repetitive structures over non-repeating structures may facilitate ease of manufacturing and ease of repair of human-made things. This can be especially important for sustainable manufacturing, in contexts such as rural technology, or in space exploration.

Last Updated November 9, 2023