Why do some Dagestanian languages have more complex consonant systems than vowel systems?

In the study of Caucasian languages, phonological systems often exhibit an inverse relationship between the complexity of their vowel and consonant inventories.

In many Dagestanian languages, such as Avar, Lak, and Dargin, the consonant systems are highly complex, while the vowel systems remain relatively simple. Conversely, languages that possess a more elaborate vowel system—such as the Nakh languages (e.g., Chechen or Ingush), which can feature up to 30 distinctive vowels including diphthongs and triphthongs—typically maintain a comparatively simpler consonant system.1

This structural trade-off is a notable feature of the region's linguistic diversity, where the phonetic burden of a language is distributed differently across its sound inventory. While some languages prioritize a wide array of vowel qualities, others, like those in the Avar-Andi-Dido group, utilize a vast range of consonant articulations, including various types of lateral sounds, pharyngealized consonants, and complex stop systems involving voiced, voiceless aspirated, and glottalized segments.1