Measurements of language diversity and what I’ll call communications efficiency are a slippery goal, but useful in that it’s good to understand how well we, as an amalgamated whole, can communicate. Hari Balasubramanian reviews the fascinating issues and the work of Joseph Greenberg in connection with this problem on 3 Quarks Daily:
The most basic measure Greenberg proposed is the now widely used linguistic diversity index. The index is a value between 0 and 1. The closer the value is to 1, the greater the diversity. The index is based in a simple idea. If I randomly sample two individuals from a population, what is the probability that they do not share the same mother tongue? If the population consisted of 2000 individuals and each individual spoke a different language as their mother tongue, then the linguistic diversity index would be 1. If they all shared the same mother tongue, then the index would be 0. If 1800 of them spoke language M and 200 of them spoke N, then index would be:
1 – (1800/2000)2 – (200/2000)2 = 0.18
…
In fact, there are fifteen countries whose linguistic diversity exceeds 0.9, as the table above shows (based on Ethnologue data). The list is dominated by 11 African countries, with Cameroon at number two. India, whose linguistic diversity I experienced firsthand for twenty years, is at number 13. Two Pacific island nations – Vanuatu and Solomon Islands: small islands these, and yet so many languages! – are in the top 5. First on the list is Papua New Guineawhose 4.1 million people speak a dizzying 840 languages! The country’s index of 0.98 means that each language has about 5000 speakers on average and that no language dominates as a mother tongue.
Hari has a few more equations, but nothing terrifying; his anecdotes include the field work of himself and others, such as Jared Diamond, from whom he gains this story:
“One evening, while I was spending a week at a mountain forest campsite with 20 New Guinea Highlanders, conversation around the campfire was going in several different local languages plus two lingua francas of Tok Pisin and Motu…. Among those 20 New Guineans, the smallest number of languages that anyone spoke was 5. Several men spoke from 8 to 12 languages, and the champion was a man who spoke 15…”
I feel completely out-manned, with my single language command of verbal and written communications. Ah, to have such skills at one’s beck & call! But as Hari points out, their fluency is not measured – it is a slippery problem.
