Combinatory Chemistry: Towards a Simple Model of Emergent Evolution
Researching the conditions for the emergence of life – not necessarily as it is, but as it could be – is one of the main goals of Artificial Life. Answering this question requires a model that can first explain the emergence of evolvable units, namely, structures that (1) preserve themselves in time (2) self-reproduce and (3) can tolerate a certain amount of variation when reproducing. To tackle this challenge, here we introduce Combinatory Chemistry, an Algorithmic Artificial Chemistry based on a simple computational paradigm named Combinatory Logic. The dynamics of this system comprise very few rules, it is initialized with an elementary tabula rasa state, and features conservation laws replicating natural resource constraints. Our experiments show that a single run of this dynamical system discovers a wide range of emergent patterns with no external intervention. All these structures rely on acquiring basic constituents from the environment and decomposing them in a process that is remarkably similar to biological metabolisms. These patterns involve autopoietic structures that maintain their organisation, recursive ones that grow in linear chains or binary-branching trees, and most notably, patterns able to reproduce themselves, duplicating their number at each generation.
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