“Where his book comes alive is in the later chapters where he has a map showing the diversity of language. What it shows is that the thickness of languages on the ground – how many languages there are per unit of area – correlates very well with the temperature. Just as there are more species per unit of area in the equator, so there are more languages more thickly spread in the equatorial areas than there are in the rest of the world. So equatorial countries – particularly in Africa and south-east Asia – have far more languages per unit area than anywhere else.” Read more...
The best books on The History and Diversity of Language