Scholars generally agree that, across languages, the relationship between particular sounds and the meaning of words is arbitrary. In this article the authors test this assumption, seeking patterned associations between sound and meaning in the basic vocabulary lists of a large, worldwide sample of languages.

The authors statistically test existing theories and proposals regarding the existence and nature of the creole language profile. Results indicate that consistencies and variation between creole languages, as with non-creole languages, is a result of genealogical and contact processes. However, creole languages are unique from non-creole languages in that they have more than one language in their ancestry. Findings "call into question the existence of a pidgin stage in creole development and of creole-specific innovations." Support is found for the idea that language learning and transmission are strikingly resilient processes.

Utilizing two independently-coded databases representing 3700+ languages, authors investigate whether cold ecologies or otherwise-desiccated ecologies are less amenable to complex tonality in language. Languages with complex tonality are primarily found to be located in tropical regions and generally absent in desiccated environments, regardless of latitude.

Is grammatical complexity shaped by sociodemographic and sociolinguistic factors? The previously accepted "linguistic niche hypothesis" claims that with an increased number of nonnative speakers in a social group (high exotericity), grammatic complexity decreases; on the other hand, grammatical complexity increases amongst isolated linguistic communities (low exotericity). Through the use of spatiophylogenetic modelling of 1314 languages, the authors of this study do not find adequate evidence to support the linguistic niche hypothesis. Instead, they suggest that linguistic complexity is better predicted by phylogeny and geographic contiguity.