ELIZA's family tree: 27 chatbots, 60 years, and one surprising ancestor
The Genealogy of Eliza
ELIZAGen applies phylogenetic tools to 27 ELIZA implementations from 1965–2025, scoring each on 13 binary features like keyword priority and backtracking. The resulting tree shows Weizenbaum's original, Cosell's Lisp, and Hay's C++ clustered at the root, while BASIC and Python versions form a derived clade of simplifications. A control file utility nests inside the ELIZA clade, and LadyMouth scores zero, revealing the limits of the feature set.
The paper argues that the result is best read not as a literal line of descent but as a map of a textual tradition, showing how implementations relate through preservation, adaptation, convergent reimplementation and critique.