Free Wired for Culture: Origins of the Human Social Mind by Mark Pagel Page B

mutually unintelligible languages?
    But why do we behave this way? Could it be that our cultural survival vehicles have evolved tendencies to protect the knowledge and wisdom to which they owe their success?
    CULTURES CARVE UP THE LANDSCAPE—LINGUISTICALLY
    A WALK along the northeast coast of Papua New Guinea will bring you into contact every five to ten miles with a tribe speaking a different language: in that part of New Guinea you could encounter Korak speakers, quickly followed along the coast by Brem speakers, who in turn are followed by Wanambre speakers, and none of these more than ten miles apart. Each of these tribes is a distinct group of people, making their living alongside each other in the dense forests of that island, and speaking mutually unintelligible languages. If we were to encounter this diversity of languages inside an area of a typical medium-sized town, we might expect to find not just three or more different languages spoken, but three or more distinct groups of people, brought up speaking a different language and living separate lives, each having carved out a portion of the town to live in!
    The density of languages in Papua New Guinea strains credulity, but recall how the Papuan man asked if it could be true that the societies which spoke these different languages were this tightly packed together replied, “Oh no, they are far closer together than that.” And it is true, an astonishing figure of over 800 different languages, or about 15 percent of all languages found on Earth, are spoken in the mere 312,000 square miles of the island of New Guinea—with many having only a few thousand speakers. This is an area slightly bigger than the state of Texas. Languages are even more tightly packed in the tiny Polynesian island archipelago of Vanuatu, northwest of Australia. Vanuatu’s islands cover just 4,100 square miles, and yet over 100 distinct languages are spoken on them, each one by an average of just 2,000 speakers. Even this gives a more sedate picture than becomes apparent when one is on the ground in these regions. For instance, the Vanuatu island of Gora covers 132 square miles, and like so many of the islands in this region, it is the roughly circular remnant plug of an ancient volcano. Gora is just twelve to thirteen miles in diameter, but this speck of an island supports five languages—Lakon or Vuré, Olrat, Koro, Dorig, and Nume. This is a density of languages about tenfold higher than that of Papua New Guinea.
    Language is one of our defining traits as a species, but we are probably the only animal in which two of its individuals plucked from different places—even right next door—might not be able to communicate with one another, almost as if they were two different biological species. Sometimes, even speakers of the same language can confuse one another: a young English boy I know, travelling in America, was told by someone who overheard him speaking, “I can tell from your accent that you’re from somewhere in Europe.” By comparison to our linguistic isolation, you could take a gorilla from its troop and put it in any other troop anywhere gorillas are found, and it would know what to do. There would probably be some fighting over territory, and attempts at establishing who is dominant over whom, but for the most part life would be routine. The new gorilla would communicate as all gorillas communicate, fight as gorillas fight, make the same kinds of nest, and eat the same kinds of food. There is nothing special about gorillas. This experiment could be repeated with donkeys, or ducks, or goldfish, or frogs, and get much the same outcome.
    So, why is it that groups of people in New Guinea, or more generally just about anywhere in the tropics, all more or less living the same lifestyle, divide up their territories so exclusively as to evolve different languages, and sometimes every few miles? What makes this division even more peculiar is that, where different biological