DOI
https://doi.org/10.3762/bjoc.13.155

Summary
Understanding how living cells emerged from the inanimate world remains one of the most fascinating and challenging research problems in biological chemistry. It is clear that cells are the product of a long evolutionary process, which justifies the complexity of the biochemical systems that characterize them.
Aspects of crucial importance on which research has long focused are some characteristic aspects such as for example the formation of membranes or the accumulation of information and catalytic systems. This approach is now being replaced by a more "systemic" approach which considers a cell as a complex system and not as a simple set of isolated functional systems.
This work summarizes some advances in the chemistry of systems highlighting that chemical systems imply a form of chemical contiguity which allows the passage from the synthesis of molecules to that of macromolecules.

Relevance for Complex Systems Knowledge
Contiguity is defined as “the condition of touching or being in physical or non-physical contact”. In a chemical context, contiguity can be seen as a connected set of conditions that allow not only the synthesis of the individual components of a system but also to establish connectivity between them obtaining what we know as a biochemical system.
Abiotic chemistry has provided the molecules necessary for the birth of cells and/or their precursors, but a reductionist approach fails to explain the transition between abiotic chemistry and biochemistry (precisely because it takes into consideration only one event at a time and not the whole system)
A change of vision is therefore necessary, moving from the interest on the single components or on the single event to the interest on the system and on what the system does. At the same time, it is necessary to explore the connectivity of processes to understand how this integrates, determining them, to the functions of the system.

Point of Strength
The diversity of living systems depends on the chemical-physical nature of the specific components that make them up and which take part in the various biochemical processes.
The way these chemicals are organized throughout the system is what determines the function that a biochemical system is able to perform.
The study of contiguity represents a paradigm shift capable of overcoming the reductionist limits that have so far slowed down the research and understanding of the evolution of biochemical processes in the field of the emergence of life.