How likely is it that the next random person you meet will speak your heart language (mother tongue)?
A man named Greenberg developed a Linguistic Diversity Index based on that question. It takes into account the number of languages in a country, but refines that by looking at how many people speak each one. When one applies his formula to the countries of the world and maps it, this is what you get. Darker is more diverse (more languages and few large languages).
This graphic has huge implications for all sorts of things, from education and development to religion and politics. As a Bible translator, it tells me where people are least likely to have the Bible in their language.
Click on the map and you will get an interactive version on the originating site.
For you math gurus, Greenberg’s formula is DI = 1 – Σ(Pi)2
Pi = the percent fraction of the total population which comprises the ith language group
i = 1 to n, where n is the number of languages that comprise the society
Σ = is the summation of (Pi)2 for all i