Identify properties that enable or inhibit the emergence of self-replicators

Characterize the distinguishing properties of programming languages and interaction environments that encourage or inhibit the spontaneous emergence of self-replicating programs, by analyzing features across Brainfuck-family variants, Forth, Z80/8080 instruction sets, and SUBLEQ-like substrates and explaining why some settings yield replicators while others do not.

Background

Across multiple substrates, the paper finds spontaneous emergence of self-replicators in BFF, Forth, and real-world instruction sets (Z80/8080), but not in SUBLEQ-like variants despite self-replicators being theoretically possible. The authors hypothesize that minimal replicator length may play a role and note differences among environments (e.g., primordial soup vs. long tape, spatial locality).

A general theory of conditions that foster or suppress replicator emergence is still lacking. The open problem asks for a principled account of language and environment features that determine whether replicators arise spontaneously.