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

species specialize at exploiting different features of the environment—what biologists describe as a species’ niche —in any given area the humans are all occupying more or less the same niche, save for one: human societies seem to have a disposition to acquire their own linguistic niche and then maintain it. The anthropologist Don Kulick describes how
    New Guinean communities have purposely fostered linguistic diversity because they have seen language as a highly salient marker of group identity… [they] have cultivated linguistic differences as a way of “exaggerating” themselves in relation to their neighbors… . One community [of Buian language speakers], for instance, switched all its masculine and feminine gender agreements, so that its language’s gender markings were the exact opposite of those of the dialects of the same language spoken in neighboring villages; other communities replaced old words with new ones in order to “be different” from their neighbors’ dialects.
    Kulick also relates an account from another linguist of a New Guinean village of Selepet speakers. One day, the community met and collectively decided to change their word for “no” from bia to bune . The reason they gave was that they wanted to be distinct from other Selepet speakers in a neighboring village, and with immediate effect. They have spoken differently ever since. We can only sympathize with the confusion someone would have felt who had gone away hunting for a few days.
    There is speculation that humans might be innately programmed to recognize and prefer people who share our language, or that if not innate, the preferences arise very early in life, even before we can speak. By five to six months, infants prefer to look at people whom they have heard speaking their native language. Katherine Kinzler and her colleagues note that
    Older infants preferentially accept toys from native-language speakers, and preschool children preferentially select native-language speakers as friends. Variations in accent are sufficient to evoke these social preferences, which are observed in infants before they produce or comprehend speech and are exhibited by children even when they comprehend the foreign-accented speech. Early-developing preferences for native-language speakers may serve as a foundation for later-developing preferences and conflicts among social groups.
    Neighboring communities also of course distinguish themselves in customs, beliefs, art, dance, weaponry, costumes, singing, music, and architecture. For instance, among the nomadic pastoralists of Northern Kenya, the Gabbra people dress simply in muted colors, while their next-door neighbors the Samburu wear vivid red robes, and the nearby Turkana favor dark colors and, among the women, copious amounts of metal jewelry and neck rings that can give them a daunting appearance.
    It is a pattern seen all over the world. In the first years of the nineteenth century, the explorers Meriwether Lewis and William Clark made their long trek from the Missouri River all the way to the west coast of America and then back. The lands they walked through were uncharted, and their diaries show they were struck by the sheer number and variety of the Native American tribes they encountered. Dayton Duncan and Ken Burns, in their account Lewis and Clark: The Journey of the Corps of Discovery , write that
    the dizzying diversity of Native American life is one of the clearest (though unspoken) images to emerge from [Lewis and Clark’s] journals. The West through which the Corps of Discovery traveled was neither an “uninhabited wilderness” nor a single “Indian world.” Indians thought of themselves as many different people, not as one monolithic group—and understandably so. They were as varied as the western landscape itself… . [Some] roamed the Plains following the buffalo herds, living in tepees that could be moved at a moment’s notice; people who were farmers… lived in