Simple is beautiful: Why evolution repeatedly selects symmetrical structures

Nucleic acids and proteins are information-carrying molecules. They carry information not just about how to build an organism but also how it evolved to be. Many theorists have called information the currency of life.

The origin of life is the origin of an information-processing system.

Protein subunits attach to each other via interface surfaces to form complex structures. The greater the number of possible interfaces, the more complex a protein is. When the researchers looked at existing structures in the Protein Data Bank, they noticed that most proteins had few interfaces. Overall, it is much more common for nature to produce proteins with low complexity and high symmetry than proteins with high complexity and low symmetry. Computer simulations produced a similar result.

Modularity is another important feature of biological systems, and — just like Lego bricks — thrifty organisms often repurpose genetic or biochemical modules for new objectives. While there are different theories for why evolution selects for modular systems, this study shows that the simplicity of modular parts is a sufficient explanation. Recent work from other research groups also shows that complex morphologies are rare.