How did the first life on Earth come to exist? And how could complex biomolecules form without immediately dissociating, in spite of the fact that many biomolecules are chemically unstable? They only persist when energy is supplied or their concentration is kept artificially low. In living organisms, the cell environment does this. But in the waters of the primeval Earth, there were no cells that could be involved in the formation of the first building blocks of life. According to existing hypotheses, pores in claystone, in solidified lava from underwater volcanoes, or in phyllosilicate minerals could have provided the necessary reaction chambers.
Another possibility, according to Job Boekhoven, Technical University of Munich, Garching, Germany, and colleagues is the phenomenon of phase separation. The researchers ran a reaction between different carboxylic acid molecules and carbodiimides, which results in the formation of carboxylic acid anhydrides. The unstable anhydrides formed in the reaction decompose rapidly into carboxylic acids in aqueous solutions. Some anhydrides, however, persisted surprisingly long; namely, those anhydrides that form droplets in an aqueous environment.
The droplets ensure that the sensitive anhydrides are isolated from the surrounding water and, thus, prevent the decay of the molecules. When molecules compete for energy with each other, those that can protect themselves by forming droplets tend to “survive”. According to the researchers, this same effect could have stabilized reaction products in the primordial soup.
- Self-selection of dissipative assemblies driven by primitive chemical reaction networks,
Marta Tena-Solsona, Caren Wanzke, Benedikt Riess, Andreas R. Bausch, Job Boekhoven,
Nat. Commun. 2018.