The Complex-First Paradox consists in a set of collectively incompatible but individually well-confirmed propositions that regard the evolution, development, and cortical realization of the meanings of concrete nouns. Although these meanings are acquired earlier than those of other word classes, they are semantically more complex and their cortical realizations more widely distributed. For a neurally implemented syntaxsemantics interface, it should thus take more effort to establish a link between a concept and its lexical expression. However, in ontogeny and phylogeny, capabilities (...) demanding more effort, ceteris paribus, develop and evolve later than those demanding less effort. The paradox points to an explanatory deficit in linguistic theory. (shrink)