Phys. Rev. X 9, 011056 (2019)

The prebiotic soup from which we all started somehow gave rise to the complex sequences that now define our every feature. Shoichi Toyabe and Dieter Braun have found evidence in support of a self-selection mechanism that might have spontaneously broken the symmetry required to amplify some sequence motifs above the general noise level.

Toyabe and Braun studied the replication dynamics of templated ligation, where the binding of two complementary sequences is facilitated by a third template strand. They found that a vast sequence space could have been significantly reduced by replicating strands in this way, because the likelihood of binding would have increased as the sequences became longer, thus accelerating the process with self-promoted elongation.

Their experiments showed that in a restricted set, highly concentrated similar sequences fared better than their less concentrated or uncorrelated counterparts. Whether the same mechanism holds in a more diverse pool of random sequences remains to be seen.