there, while sheep and cattle spread down the highlands of East Africa to launch herding in southern Africa among the Hottentots, who lacked locally domesticated animals of their own. African sorghum and cotton reached India by around 2000 BC, while bananas and yams from tropical Southeast Asia crossed the Indian Ocean to enrich agriculture in tropical Africa.
In the New World, however, the temperate zone of North America is isolated from the temperate zone of the Andes and southern South America by thousands of miles of tropics, in which temperate-zone species cannot survive. As a result, the llama, alpaca, and guinea-pig of the Andes never spread in prehistoric times to North America or even to Mexico, which consequently remained without any domestic mammals to carry packs or to produce wool or meat (except for corn-fed edible dogs). Potatoes also failed to spread from the Andes to Mexico or North America, while sunflowers never spread from North America to the Andes. Many crops that were apparently shared prehistorically between North and South America actually occurred as different varieties or even species in the two continents, suggesting that they were domesticated independently in both areas. This seems true, for instance, of cotton, beans, lima beans, chili peppers, and tobacco. Corn did spread from Mexico to both North and South America, but it evidently was not easy, perhaps because of the time it took to develop varieties suited to other latitudes. Not until around 900 AD—thousands of years after corn had emerged in Mexico—did corn become a staple food in the Mississippi Valley, thereby triggering the belated rise of the mysterious mound- building civilization of the American Midwest.
Thus, if the Old and New Worlds had each been rotated ninety degrees about their axes, the spread of crops and domestic animals would have been slower in the Old World, faster in the New World. The rates of rise of civilization would have been correspondingly different. Who knows whether that difference would have sufficed to let Montezuma or Atahuallpa invade Europe, despite their lack of horses?
I have argued, then, that continental differences in the rates of rise of civilization were not an accident caused by a few individual geniuses. They were not produced by the biological differences determining the outcome of competition among animal populations—for example, some populations being able to run faster or digest food more efficiently than others. They also were not the result of average differences among whole peoples in inventiveness; there is no evidence for such differences anyway. Instead, they were determined by biogeography's effect on cultural development. If Europe and Australia had exchanged their human populations twelve thousand years ago, it would have been the former native Australians, transplanted to Europe, who eventually mvaded America and Australia from Europe. Geography sets ground rules for the evolution, both biological and cultural, of all species, including our own. Geography's role in determining our modern political history is even more obvious than the role I have discussed in determining the rate at which we domesticate plants and animals. From this perspective, it is almost funny to read that half of all American schoolchildren do not know where Panama is, but not at all funny when politicians display comparable ignorance. Among the many notorious examples of disasters brought on by politicians ignorant of geography, two must suffice: the unnatural boundaries drawn on the map of Africa by nineteenth-century European colonial powers, thereby undermining the stability of some modern African states that inherited those borders; and the borders of Eastern Europe drawn at the Treaty of Versailles in 1919 by politicians who knew little of that region, thereby helping to fuel the Second World War. Geography used to be a required subject in US schools and colleges until a few decades ago, when it began to be dropped from many curricula. The mistaken belief arose then that geography consisted of little more than memorizing the names of capital cities. But twenty weeks of geography in the seventh grade is not enough to teach our future politicians about the effects that maps really have on us. The fax machines and satellite communications that span the globe cannot erase the differences among us bred by differences in location. In the long run, and on a broad scale, where we live has contributed heavily to making us who we are.
FIFTEEN
HORSES, HITTITES, AND HISTORY
I watched the little girl counting out five marbles, one by one. Her was familiar, but her words were strange. Almost anywhere else Europe, I would have heard words like our English
Today, most European languages and many Asian languages as far as India are very similar to each other
To us it may seem perfectly natural, and in no need of further explanation, that most European languages resemble each other, until we go to parts of the world with great linguistic diversity do realize how weird is Europe's homogeneity, and how it cries out explanation. For example, in areas of the New Guinea highlands where I work and where first contact with the outside world began only in the Twentieth Century, languages as different as Chinese is from English replace each other over short distances (Chapter Thirteen). Eurasia must also have been diverse in its pre-first-contact condition, and gradually become less so until finally some people speaking the mother tongue of the Indo-European language family steamrollered almost all other European languages out of existence.
INDO-EUROPEAN LANGUAGES
NON-INDO-EUROPEAN LANGUAGES
PIE stands for proto-Indo-European, the reconstructed mother tongue of the first Indo-Europeans. Fore is a language of the New Guinea Highlands. Note that most words are very similar among the Indo-European languages and totally different among the non-Indo-European languages.
Of all the processes by which the modern world lost its earlier linguistic diversity, the Indo-European expansion has been the most important. Its first stage, which long ago carried Indo-European languages over Europe and much of Asia, was followed by a second stage that began in 1492 and carried them to all other
