How do subsystems of language evolve over time? It is commonly assumed that grammatical changes of language are slower than vocabulary changes. Using a Dirichlet process mixture model to analyze rates of language evolution in 81 Austronesian languages, the authors find that to the contrary, the grammatical features of language tend to change at a faster rate than basic vocabulary. Furthermore, their results show that grammatical features have higher rates of homoplasy, more frequent contact-induced change, and less deliberate differentiation than basic vocabulary.

This paper discusses a cross-cultural study comparing features of grammatical structure and features of social structure. The author hypothesizes that the language will emphasize "self" with more personal protection within a society.

This article focuses on environmental and social explainations for variations in sonority. As expected, results suggest that climate, vegetation density, and sexuality are associated with sonority.

This article explores the relationship between language structure and social environment, positing that linguistic factors such as morphological complexity are associated with demographic/socio-historical factors such as number of speakers, geographic spread, and degree of language contact. Data support such an association. The authors further propose a Linguistic Niche Hypothesis suggesting that “the level of morphological specialization is a product of languages adapting to the learning constraints and the unique communicative needs of the speaker population” (7).

This study tests predictors of consonant-vowel prevalence cross-culturally. Authors reevaluate the findings of Munroe et. al. (1996) and also test a new variable—baby-holding—for its relationship to CV score. Results suggest that baby-holding is a significant predictor of CV score.

The association between hunting and sign language is examined. It is hypothesized that sign language develops as a form of nonverbal communication to aid hunters in the coordinated stalking of game. Ethnographic evidence supports this hypothesis. A second hypothesis is also tested concerning the relationship between population size and non-verbal communication, however sampling procedures provided an inadequate test of this hypothesis.

This article examines the universal tendency for languages, regardless of their historical relationships, to develop similar words for mother and father on the basis of nursery forms. Findings suggest that Ma, Na, Pa, and Ta are significantly more common sound classes denoting the mother or father.

Population size is generally assumed to play a pivotal role in the evolution of languages and cultures, but the expected patterns and potential mechanisms of change are unsettled. Theoretical models are limited by this uncertainty because they require making prior assumptions about language evolution. Using a sample of 20 Polynesian languages, authors test the effect of population size on the gain, loss, and total change of basic vocabulary words.

In the field of bioacoustics, the Acoustic Adaptation theory suggests that variation in vocalization across different species can be accounted for by the acoustic properties of different habitats. Here, the researchers test consonant- and vowel-heaviness in human languages against various environmental variables in order to examine the theory's potential application to our own species. The authors identify a significant negative correlation between consonant heaviness and temperature, precipitation, and tree cover, and some positive correlation with rugosity and elevation as their most important findings, while acknowledging the potentially influential roles of migration and demographic factors in producing this relationship.

By testing relationships between musical, geographic, genetic, and linguistic distance among nine indigenous groups in Taiwan, the researchers aim to quantitatively evaluate a developing theory of coevolution between these traits. An especially strong correlation between musical variability and genetic distance suggests that music may possess worldwide time depth, diversity, and universality equal to or greater than that of language, and could thus serve as a complementary marker for reconstruction of long-term population shifts.