Linguistic diversity and time
The world’s 7,000 or so languages are not distributed evenly over the the world’s landmass. Hotspots of linguistic diversity include such areas as Western Africa, the Caucasus and Papua New Guinea. But what determines where linguistic diversity is at its highest?
One of the most important factors affecting linguistic diversity is… time! Western Africa is close to the birthplace of human language; according to Quentin D. Atkinson, it is the birthplace of human language.
Similarly, the Caucasus is one of the oldest inhabited parts of the world; recall that according to the Biblical story of Noah, his Ark landed on Mount Ararat, in the Armenian Highlands.
Finally, Papuans have inhabited Papua New Guinea for some 40,000 years, which allows ample time for the natural processes of language change and diversification. Consider the model proposed by William A. Foley (1986: 8-9) for the linguistic diversification of Papuan languages: if we assume the initial situation with a single community speaking a single language and a language splitting into two every 1,000 years -– both conservative assumptions, according to Foley -– “this alone would result in 1012 languages in 40,000 years”, and this is not taking into account language contact, language mixing and language extinction.
A similar pattern of time translating into linguistic diversity is observable in North America as well. Let’s consider the following two maps: a map of American English dialects and a map of Native North American languages.
A quick examination of these two maps reveals the following pattern: the most diversity among American English dialects is found along the Atlantic seaboard (a more detailed map confirms this and also highlights the many local dialects of big Atlantic seaboard cities), whereas linguistic diversity among Native North American languages is at its highest along the Pacific coast. This is consistent with the time factor: speakers of English first settled in North America along the Atlantic coast, whereas Native Americans arrived via the Bering straits (then most likely a land-bridge) and migrated south before difusing eastwards.