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.

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.

Using a sample of four language families, this paper replicates previous findings on the relationship between consonant-vowel syllable use and climate. An secondary finding on the relationship between consonant-vowel syllable use and writing system was also replicated.

This article adds nuanced findings to the previous generalization that high sonority of the vowel explains its more frequent use in warmer climates. The authors find that “speakers in warm-climate languages make more use of the so-called “sonorant” consonants, that is, consonants with some of the qualities of vowels” (123).

Munroe and Fought attempt to add new perspective to Ember and Ember's (2007) assertion that certain environmental features help to predict mean sonority levels in speech. This article discusses the other possible elements such as word length that might raise the level of communicative efficiency.

This article explores the possible relationship between the cultural evolution of language, music, and genetic variation beyond the level of language families. Due to their linguistic diversity, the authors use a sample of 14 Northeast Asian societies with matching information on their music, genetics, and linguistic patterns. The variables measuring language are lexicon, phonology, and grammar. Then, the authors compare each variable's relationship to music and genetic variation. The results only show a significant correlation between grammar and genetic variation.

This article presents a reanalysis of a previous study on language rhythm and consonant-vowel syllables by Ember and Ember (2000). Communicative efficiency, climate, baby-holding, literacy, and mean number of syllables per word were all considered as factors in consonant-vowel syllable use.

This article is a response to Munroe, Fought, and Fought's comments on a previous study of sonority and climate. Authors suggest that the three indices used by Munroe, Fought, and Fought to measure sonority are not the same contruct and present new results that indicate an association between climate, topography, and vowel index.

This paper examines the relationship of productive variation in land between ethnic groups to determine if an increased range of producible goods will increase trade, thus decreasing language diversity between neighboring groups. The author initially found that high-variation in land production lessened the diversity of language between ethnic groups in that area. To further test this correlation, the author found that high-productive variation increased trade and exogamous marriage and decreased inter-ethnic conflict. Based on these findings, the author suggests that neighboring ethnic languages co-evolved through the economic benefit of inter-ethnic trade and social interaction.

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.