Talk: Alife 2020 keynote Lee Cronin - A Top Down Chemically Embodied Artificial Life Computation

Life, ALife 2020

Complex molecules are bio-signatures, they are the sign of complex (evolutionary?) processes that have been going on.

Assembly theory

Exploring complexity: Lee is showing some theoretical idea about a complexity metric. Like many other metrics, he starts from the observation that neither entropy nor Kolmogorov complexity are suitable for considering the history of an object.

Instead of thinking in terms of disorder or complexity, why not ask simply about “how has this object been assembled?”. This leads to some other question “How likely is it that the object formed by chance?”

This is what he calls Object assembly, or assembly theory. The principle is not detailed in the talk but is based on identifying building blocks of an object and quantifying the number of move in the “object” space.

This is not detailed more in the talk but I feel would need more explanation. It seems this metric depends a lot on the space you choose for the “building blocks” of the object. It seems from the talk that chemistry is especially suited as a subject for this complexity metric, because the object space emerges naturally from experimental mass spectrography results.

Bottom-up ALife

Cronin’s team started working on chemical droplet systems with the possibility to vary many parameters and studied how this could lead to some form of evolution.

The first step is the cell. Probably chemistry is relatively dumb until it can create pockets that are separated from the rest.

Top-down Alife in chemistry

Recent work on open-endedness in CAs prompted Cronin to try and create such a thing in chemistry, by building a chemical computer that works like a CA. (Adams et al. 2017).


  1. . . "Formal definitions of unbounded evolution and innovation reveal universal mechanisms for open-ended evolution in dynamical systems". Scientific reports 7 (1):997. DOI. See notes

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