evidence whatsoever, we would still be able to deduce from the linguistic evidence alone that native West African crops were domesticated first, that Indonesian crops arrived next, and that finally the European introductions came in. The UCLA historian Christopher Ehret has applied this linguistic approach to determining the sequence in which domestic plants and animals became utilized by the people of each African language family. By a method termed glottochronology, based on calculations of how rapidly words tend to change over historical time, comparative linguistics can even yield estimated dates for domestications or crop arrivals. Putting together direct archaeological evidence of crops with the more indirect linguistic evidence, we deduce that the people who were domesticating sorghum and millet in the Sahara thousands of years ago spoke languages ancestral to modern Nilo-Saharan languages. Similarly, the people who first domesticated wet-country crops of West Africa spoke languages ancestral to the modern Niger-Congo languages. Finally, speakers of ancestral Afroasiatic languages may have been involved in domesticating the crops native to Ethiopia, and they certainly introduced Fertile Crescent crops to North Africa. Thus, the evidence derived from plant names in modern African languages permits us to glimpse the existence of three languages being spoken in Africa thousands of years ago: ancestral Nilo-Saharan, ancestral Niger-Congo, and ancestral Afroasiatic. In addition, we can glimpse the existence of ancestral Khoisan from other linguistic evidence, though not that of crop names (because ancestral Khoisan people domesticated no crops). Now surely, since Africa harbors 1,500 languages today, it is big enough to have harbored more than four ancestral languages thousands of years ago. But all those other languages must have disappeared—either because the people speaking them survived but lost their original language, like the 3 9 2 'GUNS,GERMS, AND STEEL Pygmies, or because the people themselves disappeared. The survival of modern Africa's four native language families (that is, the four other than the recently arrived Austronesian language of Madagascar) isn't due to the intrinsic superiority of those languages as vehicles for communication. Instead, it must be attributed to a historical accident: ancestral speakers of Nilo-Saharan, Niger-Congo, and Afroasiatic happened to be living at the right place and time to acquire domestic plants and animals, which let them multiply and either replace other peoples or impose their language. The few modern Khoisan speakers survived mainly because of their isolation in areas of southern Africa unsuitable for Bantu farming. defore we trace Khoisan survival beyond the Bantu tide, let's see what archaeology tells us about Africa's other great prehistoric population movement—the Austronesian colonization of Madagascar. Archaeologists exploring Madagascar have now proved that Austronesians had arrived at least by a.d. 800, possibly as early as a.d. 300. There the Austronesians encountered (and proceeded to exterminate) a strange world of living animals as distinctive as if they had come from another planet, because those animals had evolved on Madagascar during its long isolation. They included giant elephant birds, primitive primates called lemurs as big as gorillas, and pygmy hippos. Archaeological excavations of the earliest human settlements on Madagascar yield remains of iron tools, livestock, and crops, so the colonists were not just a small canoeload of fishermen blown off course; they formed a full-fledged expedition. How did that prehistoric 4,000-mile expedition come about? One hint is in an ancient book of sailors' directions, the Periplus of theErythrean Sea, written by an anonymous merchant living in Egypt around a.d. 100. The merchant describes an already thriving sea trade connecting India and Egypt with the coast of East Africa. With the spread of Islam after a.d. 800, Indian Ocean trade becomes well documented archaeologi-cally by copious quantities of Mideastern (and occasionally even Chinese!) products such as pottery, glass, and porcelain in East African coastal settlements. The traders waited for favorable winds to let them cross the Indian Ocean directly between East Africa and India. When the Portuguese navigator Vasco da Gama became the first European to sail around the southern cape of Africa and reached the Kenya coast in 1498, he encountered HOWAFRICA BECAME BLACK • 393 Swahili trading settlements and picked up a pilot who guided him on that direct route to India. But there was an equally vigorous sea trade from India eastward, between India and Indonesia. Perhaps the Austronesian colonists of Madagascar reached India from Indonesia by that eastern trade route and then fell in with the westward trade route to East Africa, where they joined with Africans and discovered Madagascar. That union of Austronesians and East Africans lives on today in Madagascar's basically Austronesian language, which contains loan words from coastal Kenyan Bantu languages. But there are no corresponding Austronesian loan words in Kenyan languages, and other traces of Austronesians are very thin on the ground in East Africa: mainly just Africa's possible legacy of Indonesian musical instruments (xylophones and zithers) and, of course, the Austronesian crops that became so important in African agriculture. Hence one wonders whether Austronesians, instead of taking the easier route to Madagascar via India and East Africa, somehow (incredibly) sailed straight across the Indian Ocean, discovered Madagascar, and only later got plugged into East African trade routes. Thus, some mystery remains about Africa's most surprising fact of human geography. What can archaeology tell us about the other great population movement in recent African prehistory—the Bantu expansion? We saw from the twin evidence of modern peoples and their languages that sub-Saharan Africa was not always a black continent, as we think of it today. Instead, this evidence suggested that Pygmies had once been widespread in the rain forest of Central Africa, while Khoisan peoples had been widespread in drier parts of subequatorial Africa. Can archaeology test those assumptions? In the case of the Pygmies, the answer is 'not yet,' merely because archaeologists have yet to discover ancient human skeletons from the Central African forests. For the Khoisan, the answer is 'yes.' In Zambia, to the north of the modern Khoisan range, archaeologists have found skulls of people possibly resembling the modern Khoisan, as well as stone tools resembling those that Khoisan peoples were still making in southern Africa at the time Europeans arrived. As for how the Bantu came to replace those northern Khoisan, archaeological and linguistic evidence suggest that the expansion of ancestral 394 ' GUNS, GERMS,and steel Bantu farmers from West Africa's inland savanna south into its wetter coastal forest may have begun as early as 3000 b.c. (Figure 19.4). Words still widespread in all Bantu languages show that, already then, the Bantu had cattle and wet-climate crops such as yams, but that they lacked metal and were still engaged in much fishing, hunting, and gathering. They even lost their cattle to disease borne by tsetse flies in the forest. As they spread into the Congo Basin's equatorial forest zone, cleared gardens, and increased in numbers, they began to engulf the Pygmy hunter-gatherers and compress them into the forest itself. By soon after 1000 b.c. the Bantu had emerged from the eastern side of the forest into the more open country of East Africa's Rift Valley and Great Lakes. Here they encountered a melting pot of Afroasiatic and Nilo-Saharan farmers and herders growing millet and sorghum and raising livestock in drier areas, along with Khoisan hunter-gatherers. Thanks to their wet-climate crops inherited from their West African homeland, the Bantu were able to farm in wet areas of East Africa unsuitable for all those previous occupants. By the last centuries b.c. the advancing Bantu had reached the East African coast. In East Africa the Bantu began to acquire millet and sorghum (along with the Nilo-Saharan names for those crops), and to reacquire cattle, from their Nilo-Saharan and Afroasiatic neighbors. They also acquired iron, which had just begun to be smelted in Africa's Sahel zone. The origins of ironworking in sub-Saharan Africa soon after 1000 b.c. are still unclear. That early date is suspiciously close to dates for the arrival of Near Eastern ironworking techniques in Carthage, on the North African coast. Hence historians often assume that knowledge of metallurgy reached sub-Saharan Africa from the north. On the other
