The World Until Yesterday

average New Guinea language, Italy would have 10,000 languages. Aficionados of the separateness of Italian dialects might credit Italy with dozens of languages, but no one would claim there to be 10,000 different languages in Italy. It really is true that New Guinea is linguistically far more diverse than is Italy.

How languages evolve

How did the world end up with 7,000 languages, instead of our all sharing the same language? Already for tens of thousands of years before language spread by the Internet and Facebook, there has been ample opportunity for language differences to disappear, because most traditional peoples have had contact with neighboring peoples, with whom they intermarry and trade, and from whom they borrow words and ideas and behaviors. Something must have caused languages, even in the past and under traditional conditions, to diverge and to remain separate, in the face of all that contact.

Here’s how it happens. Any of us over the age of 40 has observed that languages change even over the course of just a few decades, with some words dropping out of use, new words being coined, and pronunciation shifting. For instance, whenever I revisit Germany, where I lived in 1961, young Germans notice that they have to explain to me some new German words (e.g., the new word Handi for cell phones, which didn’t exist in 1961), and that I still use some old-fashioned German words that have been going out of use since 1961 (e.g., jener/jene for “that/those”). But young Germans and I can still mostly understand each other well. Similarly, you American readers under the age of 40 may not recognize some formerly popular English words like “ballyhoo,” but in compensation you daily use the verb “to Google” and the participle “Googling,” which didn’t exist in my childhood.

After a few centuries of such independent changes in two geographically separate speech communities derived from the same original speech community, the communities develop dialects that may pose difficulties for each other to understand: e.g., the modest differences between American and British English, the bigger differences between the French of Quebec and of metropolitan France, and the still bigger differences between Afrikaans and Dutch. After 2,000 years of divergence, the speech communities have diverged so much as to be no longer mutually intelligible, although to linguists they are still obviously related—such as the French and Spanish and Romanian languages derived from Latin, or the English and German and other Germanic languages derived from proto-Germanic. Finally, after about 10,000 years, the differences are so great that most linguists would assign the languages to unrelated language families without any detectable relationships.

Thus, languages evolve differences because different groups of people independently develop different words and different pronunciations over the course of time. But the question remains why those diverged languages don’t merge again when formerly separated people spread out and re-contact each other at speech boundaries. For instance, at the modern boundary between Germany and Poland, there are Polish villages near German villages, but the villagers still speak a local variety of either German or of Polish, rather than a German-Polish mish-mash. Why is that so?

Probably the main disadvantage of speaking a mish-mash involves a basic function of human language: as soon as you start to speak to someone else, your language serves as an instantly recognizable badge of your group identity. It’s much easier for wartime spies to don the enemy’s uniform than to imitate convincingly the enemy’s language and pronunciation. People who speak your language are your people: they’ll recognize you as a compatriot, and they’ll support you or at least not be immediately suspicious of you, whereas someone speaking a different language is apt to be regarded as a potentially dangerous stranger. That instant distinction between friends and strangers still operates today: just see how you (my American readers) react the next time that you’re in Uzbekistan, and you finally to your relief hear someone behind you speaking English with an American accent. The distinction between friends and strangers was even more important in the past (Chapter 1), often a matter of life and death. It’s important to speak the language of at least some community, so that there will be some group that considers you as “our own.” If you instead speak a mish-mash near a speech boundary, both groups may understand much of what you say, but neither group will consider you “one of our own,” and you can’t count on either group to welcome and protect you. That may be why the world’s speech communities have tended to remain thousands of separate languages, instead of the whole world speaking one language or forming one dialect chain.

Geography of language diversity

Languages are distributed unevenly around the world: about 10% of the world’s area contains half of its languages. For instance, at the low-end extreme of language diversity, the world’s three largest countries—Russia, Canada, and China, each with an area of millions of square miles—have only about 100, 80, and 300 native languages respectively. But at the high-end extreme of language diversity, New Guinea and Vanuatu, with areas of only 300,000 and 4,700 square miles respectively, have about 1,000 and 110 native languages. That means that one language is spoken over an average area of about 66,000, 49,000, and 12,000 square miles in Russia, Canada, and China respectively, but only over 300 and 42 square miles respectively in New Guinea and Vanuatu. Why is there such enormous geographic variation in language diversity?

Linguists recognize ecological, socio-economic, and historical factors apparently contributing to the answer. Language diversity—e.g., the number of native languages per 1,000 square miles of area—correlates with numerous potentially explanatory factors, but these factors are in turn correlated with each other. Hence one has to resort to statistical methods, such as multiple regression analysis, to tease out which factors have primary effects actually causing language diversity to be high or low, and which other factors have just apparent effects mediated by their correlations with those primary factors. For example, there is a positive correlation between Rolls-Royce car ownership and lifespan: Rolls-Royce owners live on the average longer than do people who don’t own Rolls-Royces. That’s not because Rolls-Royce ownership directly improves survival, but because Rolls-Royce owners tend to have lots of money, which enables them to pay for the best health care, which is the actual cause of their long lifespans. When it comes, though, to correlates of linguistic diversity, there isn’t yet a corresponding agreement about the actual underlying causes.

The four closest ecological correlations of language diversity are with latitude, climate variability, biological productivity, and local ecological diversity. First, language diversity decreases from the equator towards the poles: all other things being equal, tropical areas hold more languages than do equivalent areas at higher latitudes. Second, at a given latitude language diversity decreases with climate variability, whether the variability consists of regular within-year seasonal variation or of unpredictable between-year variation. For instance, language diversity is higher in tropical rainforests that are wet all year round than in adjacent more seasonal tropical savannahs. (This factor of seasonality could account at least in part, through the correlation between latitude and seasonality, for the higher language diversities in the less seasonal tropics than in strongly seasonal high latitudes.) Third, language diversity tends to be higher in more productive environments (e.g., higher in rainforests than in deserts), though again at least some of that effect could be because of a tendency for deserts and many other unproductive environments to be strongly seasonal. Finally, language diversity is high in ecologically diverse areas and tends especially to be higher in rugged mountainous areas than in flat areas.

These four ecological relationships are just correlations, not explanations. Suggested underlying explanations involve human population size, mobility, and economic strategies. First, a speech community’s viability increases with its number of people: a language spoken by only 50 people is more likely to disappear, due to its speakers all dying or abandoning their language, than is a language spoken by 5,000 people. Hence regions with a lower biological productivity (supporting fewer people) tend to support fewer languages, and to require more area for the speakers of each language. A viable population in Arctic or desert regions needs tens of thousands of square miles to support itself, while a few hundred square miles would be ample in productive landscapes. Second, the more constant is the environment between seasons and between years, the more self-sufficient and sedentary can a speech community be within a small area, without much need to move periodically or to trade for necessities with other peoples. Finally, an ecologically diverse area can support many different language communities, each with its