Autocatalytic Networks at the Basis of Life’s Origin and Organization

Abstract

Life is more than the sum of its constituent molecules. Living systems depend on a particular chemical organization, i.e., the ways in which their constituent molecules interact and cooperate with each other through catalyzed chemical reactions. Several abstract models of minimal life, based on this idea of chemical organization and also in the context of the origin of life, were developed independently in the 1960s and 1970s. These models include hypercycles, chemotons, autopoietic systems, (M,R)-systems, and autocatalytic sets. We briefly compare these various models, and then focus more specifically on the concept of autocatalytic sets and their mathematical formalization, RAF theory. We argue that autocatalytic sets are a necessary (although not sufficient) condition for life-like behavior. We then elaborate on the suggestion that simple inorganic molecules like metals and minerals may have been the earliest catalysts in the formation of prebiotic autocatalytic sets, and how RAF theory may also be applied to systems beyond chemistry, such as ecology, economics, and cognition.

Origin of Species before Origin of Life: The Role of Speciation in Chemical Evolution

“…One such example, mentioned previously, is the emergence of distinct fatty vesicle species that grow or shrink based on incorporation of a catalytic seryl-histidine dipeptide [ 74 ]. Inside a primitive compartment, a complex network of replicative autocatalytic reactions could also potentially emerge [ 149 , 150 ] and would survive by being fed by a constant input of nutrients from the outside. In some cases, some molecules or systems of molecules would be favored, i.e., thermodynamically, kinetically, by possible self-replication, etc., and be replicated with an increasing accuracy and efficiency (whether due to being in a more favorable environment within the compartment interior, or due to specific characteristics of the compartment itself which promote such reactions).…”

The Causal Closure of Physics in Real World Contexts

“…This is closely related to the idea of autonomous systems , characterized by their organizational and operational closure [ 138 ], where [ 135 ] Organizational closure refers to the self-referential (circular and recursive) network of relations that defines the system as a unity, and operational closure to the re-entrant and recurrent dynamics of such a system which is just the idea above. This discussion is related to the idea of Autopoiesis—a system capable of reproducing and maintaining itself—mentioned above, and to the idea of Autocatalytic sets [ 69 , 70 ]. However I will not develop those links here.…”

Investigating Prebiotic Protocells for a Comprehensive Understanding of the Origins of Life: A Prebiotic Systems Chemistry Perspective

“…The nature of the molecule carrying the protocell information remains elusive and many models have been proposed [51]. Among them, some scenarios emphasize the fact that life emerged from metabolic networks able to self-reproduce [71]. The most detailed one is probably the graded autocatalysis replication domain (GARD) model.…”