Even though the genetic code commands a seemingly immeasurable number of organisms, it also binds us all together as descendents of a shared ancestor—a lingua franca for life.

Yet for all of its diverse and essential properties, the genetic code is static. For some reason unknown to scientists, approximately 3 billion years ago it simply stopped growing. Instead of expanding to encode new combinations of amino acids, and potentially new life, it stagnated at its current size and function. But a new study published today in the journal Science Advances offers an explanation for the genetic code's mysterious evolutionary limit.

A team of geneticists from the Institute for Research in Biomedicine and the Centre for Genomic Regulation discovered that several billion years ago, the genetic code reached a point of self-preservation. Namely, it could continue evolving and risk mutating the building blocks of life it was responsible for creating, or it could remain limited, albeit functional.