The paper points to an apparent paradox in the science of language. It regards the semantics of nouns and consists of a set of together incompatible, but individually well confirmed propositions about the evolution and development of language, the semantics of word classes and the cortical realization of word meaning. Theoretical and empirical considerations support the view that the concepts expressed by concrete nouns are more complex and their neural realizations more widely distributed in cortex than those expressed by other word classes. For a cortically implemented syntax-semantics interface, the more widely distributed a concept’s neural realization is, the more effort it takes to establish a link between the concept and its expression. If one assumes the principle that in ontogeny and phylogeny capabilities demanding more effort develop, respectively, evolve later than those demanding less effort, the empirical observation seems paradoxical that the meanings of concrete nouns, in ontogeny and phylogeny, are acquired earlier than those of other word classes.