DOI
https://doi.org/10.3390/life10010005<br />

Summary
It is generally accepted that life requires structural complexity. However, a chaotic mixture of organic compounds like the one formed by extensive reaction sequences over time may be extremely complex, but could just represent a static asphalt-like dead end situation. Likewise, it is accepted that life requires a certain degree of structural order. However, even extremely ordered structures like mineral crystals show no tendency to be alive. So neither complexity nor order alone can characterize a living organism. In order to come close to life, and in order for life to develop to higher organisms, both conditions have to be fulfilled and advanced simultaneously. Only a combination of the two requirements, complexity and structural order, can mark the difference between living and dead matter. It is essential for the development of prebiotic chemistry into life and characterizes the course and the result of Darwinian evolution. For this reason, it is worthwhile to define complexity and order as an essential pair of characteristics of life and to use them as fundamental parameters to evaluate early steps in prebiotic development. A combination of high order and high complexity also represents a universal type of biosignature which could be used to identify unknown forms of life or remnants thereof.

Relevance for Complex Systems Knowledge
This article uses a simplified definition and estimation of "complexity" and "order" attempting to identify the right combination of these parameters that can define the conditions for life. Order and complexity can exist alone, but they are associate to life only if they exist simultaneously and are functionally interconnected. These conditions are pretty evident in the Darwinian evolution.

Point of Strength
Functionally connected complexity and order are highlighted by the author as an essential pair of characteristics of life that can be applied to the understanding of the evolution. A similar approach can be also suggested to analyze the phenomena that characterized the prebiotic stage of the evolution