The paper presents evidence in bacteria for the utility of Godfrey-Smith’s environmental complexity thesis, using certain kinds of signal transduction systems as proxies for cognitive/behavioral complexity. Microbiologists already accept that the number of signal transduction proteins in a bacterial genome indicates the level of ecological complexity to which the organism is subject: the more signalling proteins, the greater the complexity. Sheer numbers are not always a reliable indicator of behavioral complexity, however. The paper proposes a new, ECT-based procedure for identifying, (...) from genomic sequence and signalling repertoire, novel bacterial candidates likely to exhibit behavioral complexity in response to a complex ecological niche. (shrink)