We decided to test whether six language families show greater rates of change in consonant inventory size as compared to vowel inventory size using phylogenetic comparative methods.
we use BayesTraits V2 (Meade and Pagel, 2014), which implements a generalized least squares approach to modeling the evolution of continuously varying traits (Pagel,   Table 1 gives the mean rates of change of consonant and vowels on the branches of the listed phylogenetic tree sets 6 We also observe that ancestral state estimates of vowel and consonant inventory sizes are generally closer to the mean of the range than expert reconstructions of proto-languages.