From Phylogenetic Diversity to Structural Homogeneity: On Right-branching Constituent Order in Mesoamerica 1

In this article it is claimed that language contact has led to structural homogeneity in the languages of Mesoamerica. Mesoamerican languages are demonstrated to be structurally homogeneous insofar as they tend to be consistently right-branching. This tendency can naturally be explained in terms of Hawkins’ (1994, 2004) theory of Early Immediate Constituents (EIC), which predicts that uniform branching facilitates online processing. Adopting an evolutionary model of language change proposed by Kirby (1999), it is argued that Mesoamerican languages have become structurally homogeneous as a result of the adaptive interplay between the generation of structural variation on the one hand, and the process of selection from among existing variants on the other: Language contact acts as a source and amplifier of variation and therefore feeds the evolutionary mechanisms of change. It offers speakers a choice and allows for the selection of those structures which optimize Early Immediate Constituent recognition best.