This paper shows an application in the field of Electronic CAD of the Selfish Gene algorithm, an evolutionary algorithm based on a recent interpretation of the Darwinian theory. Testing is a key issue in the design and production of digital circuits and the adoption of Built-In Self-Test (BIST) techniques is increasingly popular. In this paper, the Selfish Gene algorithm is adopted for determining the logic for a BIST architecture based on Cellular Automata (CA). A Genetic Algorithm has already been proposed for identifying good BIST architectures based on CA. However, adopting 2-bit cells, such method introduced a significant area overhead. Thanks to the adoption of the new and more powerful search engine, we were able to identify simpler BIST structures with a lower area overhead, but still able to obtain the same fault coverage.