In this article we extend the model of language evolution exemplified in Ringe et al. 2002, which recovers phylogenetic trees optimized according to a criterion of weighted maximum compatibility, to include cases in which languages remain in contact and trade linguistic material as they evolve. We describe our analysis of an Indo-European (IE) dataset (originally assembled by Ringe and Taylor) based on this new model. Our study shows that this new model fits the IE family well and suggests that the early evolution of IE involved only limited contact between distinct lineages. Furthermore, the candidate histories we obtain appear to be consistent with archaeological findings, which suggests that this method may be of practical use. The case at hand provides no opportunity to explore the problem of conflict between network optimization criteria; that problem must be left to future research.

This study investigates the development of canonical proportion (CP), an indicator of speech development, across diverse language and environmental contexts. Using the Speech Maturity Dataset (SMD) comprising 366 children, aged 0;2–6;4, across 10 different languages and cultures, we explore the influence of multilingual exposure, language syllable complexity, and community type (industrialised, non-industrialised) on CP. We find that monolingual children display higher CP measures than their multilingual peers. In addition, CP is higher for children learning languages with simple syllable complexity than those with more complex syllables. We also find no significant differences in the CP trajectory of children from industrialised versus non-industrialised communities. Integrating these findings in the broader literature, we highlight the importance of diversifying participant samples to capture the complex relationship between language exposure, social environment, and language development.

I am grateful to Juan Uriagereka (2000) for his thorough and thoughtful review of my book The Origins of Complex Language (henceforth Origins; Carstairs-McCarthy 1999). The book tackles fundamental questions about the relationship among syntax, semantics, and cognition, and Uriagereka is not persuaded by all my suggestions about the prehistory of this relationship. I will not pursue these large issues here; rather, I want to address a more circumscribed issue that is nevertheless crucial to the argument of the book, so that my failure to discuss it is an important omission, as Uriagereka points out. This issue is whether the syllable, as a unit of phonological description, is modality-neutral (so as to be equally at home, with fundamentally the same sense, in descriptions of signed and spoken languages), or whether the syllables of signed and spoken languages are really different phenomena, so that the use of the term SYLLABLE for both draws attention to resemblances that are more accidental than fundamental. I will argue that the evidence supports the latter view more strongly than the former; therefore, when discussing language evolution, it is legitimate to appeal (as I do) to aspects of spoken syllables that are undoubtedly modality-dependent, such as their physiological underpinnings in the vocal apparatus.

Before addressing this issue directly, I would like to summarize briefly why it is important in the context of my book. Second, by way of reassurance, I will explain why the conclusion that I reach does not belittle sign languages, nor imply any old-fashioned skepticism about their entitlement to be recognized as real manifestations of the human language capacity.

I argue that the account of the coordination of unlike categories, such as wealthy and a Republican in become wealthy and a Republican, ought to be unified with the account of feature neutralization under phonological identity, in which (for instance) coordinations of dative- and accusative-taking transitive verbs are possible just when the object is ambiguous (or underspecified) between dative and accusative case. I argue that this unified account ought not to be couched in terms of strings (as in Chametzky 1987) or features (as in Sag et al. 1985) but rather in terms of the logic of categories, in the tradition of Lambek Categorial Grammar. I present and defend such an account.