The early origin of cooperation

Short non-coded peptides interacting with cofactors facilitated the integration of early chemical networks

Independently developed iron-sulphur/thioester- and phosphate-driven chemical reactions would have set up two distinct reaction networks prior to coupling in a proto-metabolic system supporting a minimal organisation closure. Each chemical system assisted initially by simple catalysts and then by more complex cofactors would have provided the precursors of the small metabolites and monomer units along with their respective polymers through dehydrating template-independent assemblies. For example, acylation reactions mediated by activated thioester groups produced peptides, fatty acids and polyhydroxyalkanoates, while phosphorylation reactions by phosphorylating agents allowed the synthesis of polysaccharides, polyribonucleotides and polyphosphates. Here, we address how these independent chemical systems might fit together and shaped a proto-metabolic system, focusing specifically on cofactors as molecular fossils of metabolism. As a result, the proposed overview suggests that non-coded peptides capable of binding a variety of ligands, but in particular with a redox active versatility and/or group transfer potential could have facilitated the chemical connections that led to a minimal closure with a proto-metabolism. Later developments would have made it possible to establish a cellular organisation with more complex and interdependent metabolic pathways.

On the Evolution of the Biological Framework for Insight

The details of abiogenesis, to date, remain a matter of debate and constitute a key mystery in science and philosophy. The prevailing scientific hypothesis implies an evolutionary process of increasing complexity on Earth starting from (self-) replicating polymers. Defining the cut-off point where life begins is another moot point beyond the scope of this article. We will instead walk through the known evolutionary steps that led from these first exceptional polymers to the vast network of living biomatter that spans our world today, focusing in particular on perception, from simple biological feedback mechanisms to the complexity that allows for abstract thought. We will then project from the well-known to the unknown to gain a glimpse into what the universe aims to accomplish with living matter, just to find that if the universe had ever planned to be comprehended, evolution still has a long way to go.