Non-adjacent or long-distance dependencies (LDDs) are routinely considered to be a distinctive trait of language, which purportedly locates it higher than other sequentially organized signal systems in terms of structural complexity. This paper argues that particular languages display specific resources (e.g. non-interpretive morphological agreement paradigms) that help the brain system responsible for dealing with LDDs to develop the capacity of acquiring and processing expressions with such a human-typical degree of computational complexity. Independently obtained naturalistic data is discussed and put to (...) the service of the idea that the above-mentioned resources exert their developmental role from the outside, but in compliance with other internal resources, ultimately compounding an integrated developmental system. Parallels with other human and nonhuman developmental phenomena are explored, which point to the conclusion that the developmental system of concern can be assimilated to cases currently been conceptualized as ‘cue-response systems’ or ‘developmental hybrids’ within the ecological-developmental paradigm in theoretical biology. Such a conclusion is used to support the idea that both current externalist and internalist concepts fall short of a correct characterization of language. (shrink)