Description: How did life begin? What made molecules start to line up, and how did the resulting structures cooperate to form the first living cell? These processes happened billions of years ago in an unknown location, probably without leaving a detectable trace. Nevertheless, fascinating scenarios which may have initiated this unique process have been proposed, leading to ambitioned research on the general mechanisms of prebiotic chemistry and molecular evolution.
A regular Darwinian evolution process is based on identical or nearly identical reproduction of individual units. However, on a molecular level, the first “species” may not have been able to reproduce identically. At this point, an alternative process is proposed, based on a large pool of random structures which forms statistically. A selective mechanism accumulates a fraction of those structures which is capable of surviving in a given environment and which, in turn, also optimizes the given selection mechanism itself.
In a laboratory experiment, random chain molecules formed by 12 different amino acids are generated. The selection mechanism consists of an artificial membrane where some of the chain molecules can integrate and become protected against thermal decomposition. During the course of the experiment, the accumulated chains in turn stabilize the membrane and even develop simple functions which further increase the survival rate of the membrane structures.
The studies approach the question, if and to which extent such a selection process without identical reproduction could replace Darwinian evolution on a very early stage of the development towards protocells. Further, it is meant to elucidate the basic mechanisms leading from chaotic mixtures of small molecules with high entropy toward well ordered, complex structures.
Fig.: Stepwise development of structures with increasing complexity in a non-Darwinian evolution.
Speaker: Dr. Christian Mayer
Institution: Universitat Duisburg-Essen
Host: Paul Higgs