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).

How is the evolution of language shaped by speaker population size? Through comparative data analyses of 153 language pairs from the Austronesian, Indo-European, and Niger-Congo language families, the authors find that the influence of population size on language evolution is not the same in the three language families. Only in Indo-European languages did a smaller population size of language-speakers significantly predict more word loss.

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.

The "equi-complexity hypothesis" suggests that there is an equal complexity across languages, meaning that there are constant trade-offs between different domains. Using phylogenetic modelling in a sample of 244 languages, this study follows a diachronic perspective to explore if there is an inversed coevolution within the grammatical coding of nominal and verbal domains. The results show that while there appears to be a coevolutionary relationship between some features of these two domains, there is no evidence to support the idea that all languages maintain an overall equilibrium of grammatical complexity. Rather, the correlation nominal and verbal domains vary between lineages. Austronesian languages do not show a coevolution between the domains. Sino-Tibetan languages seem to have a positive correlation while Indo-European languages appear to have a negative correlation, meaning that this inverse coevolution can be lineage specific.

This dissertation is a cross-cultural study of the relationship between cultural complexity and linguistic variables. The hypothesis is supported using a sample of fifty languages. Cultural complexity is theorized to instigate change in linguistic devices that are better tailored to express new areas of discourse.

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.

In this paper, the authors utilize phylogenetic methods to reconstruct the evolution of land tenure norms among 97 Austronesian societies. They coded these norms for each society as none (N), group (G), group-kin (K), and individual (I). After formulating various models of evolution through these various stages, they used Bayesian analysis to determine support for each. They conclude with remarks about this type of evolutionary phylogenetic research as a form of "virtual archeology."

Using a sample of 80 Austronesian societies from the Ethnographic Atlas, the study applies phylogenetic comparative methods to explore the transmission of cultural traits. The authors follow the research question: "for each possible cultural trait in each society, does the geographical (GNN) or phylogenetic nearest neighbor (PNN) best predict the state of the cultural trait?". Cultural traits in the realms of social organization, kinship, marriage, and subsistence were examined. The results show that PNN predicted slightly more traits in comparison to GNN, but there was not much variation between the different economic and social traits. In addition, 43-48% of traits were not predicted by GNN or PNN.

This study found that the more language speakers there are, the more phonemes in the language. In addition, the more language speakers, the more vowels and consonants. While some language families have more phonemes than others, this did not affect the results. The goal of this paper was only to illustrate a link between the two and the authors hope this work encourages further examination into this relationship.

In order to investigate cross-cultural variation in systems of conversational turn-taking (who speaks and when), the researchers analyze the association of various contextual, verbal, and non-verbal factors with mean response time. Despite some variation in response time between languages, each of the explanatory variables is found to have significant impact on response time independent of language. A further test on subjective perception of ideal response time suggests that although similar factors act on response patterns cross-culturally (in support of a 'universal systems' theory), speakers are hypersensitive to even minor cultural variations in response time.