The relationship between population and morphological complexity for the 6 largest language families in our sample.

Interestingly, a number of the languages that lie far below the regression line are lingua francas, e.g., Hausa, Bambara, and Oromo are all used as lingua francas (vehicular languages). The Padang dialect of Minangkabau (the second simplest Austronesian language by our measure) is also a lingua franca around West Sumatra, Indonesia.