Why are there so many languages?

A large number of factors –– social, geographical, political, linguistic –– have been proposed to account for the number and range of languages in the world. One thing that is agreed upon is that there are a greater number of languages in tropical climates (at lower latitudes). A group of scholars began by modeling the languages of Australia and was able to show that the number of languages correlated with rainfall and possible group size. While other factors may be relevant elsewhere (migration, political warfare, etc.), the proposed model represents a starting point in modeling language diversity:
https://www.scientificamerican.com/article/why-do-human-beings-speak-so-many-languages/?WT.mc_id=send-to-friend