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The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Counterpoints in Science Images of Africa
As I write these words, I’m getting ready for my ninth trip to Africa, this time to Namibia. Meanwhile, the Academy is preparing to show a new exhibit on Africa. Like most of us, I have conflicting images of this “dark continent” that gave birth to humanity five million years ago, and that spawned our own species, Homo sapiens, about 140,000 years ago. Though our ancestors came from Africa originally, the motherland appeared so remote and mysterious to Europeans in recent centuries that it had to be “discovered” and “explored” all over again, its rivers traced to their sources, its peoples described and subdued. The writer Joseph Conrad summed up his view of Africa in his title, Heart of Darkness. Western images of Africa have tended toward two extremes: an idyllic Eden where people and animals lived in a “natural” state until civilization and its discontents intruded and spoiled everything; or a wild place of savage bloodthirstiness and ignorance, bereft of the advantages of Western law, technology, and religion. To me, the great paradox of Africa is that it seems to “have it all”—spectacular geography (glacier-topped mountains, great river valleys, rain forests, vast deserts), wonderful climate, a limitless treasure-chest of diamonds and gold, great diversity of plants and animals and most ancient history of life, a three-million-year head start in human evolution over any other continent, with ancient cities and societies. Yet today Africa has very little to show for these apparent advantages. The people are mostly impoverished, the governments mostly corrupt and undemocratic. Civil wars are commonplace. A striking physical image of Africa is manifest in pictures of the Earth taken from space. The continent is easily visible due to absence of cloud cover over the Sahara in the north, the world’s largest desert, and the Namib in the south, the world’s oldest desert. Africa lies prominently astride the equator, surrounded by the Atlantic and Indian oceans on its flanks and the Mediterranean and Red seas on its expansive crown. Geologically, Africa is the keystone continent. It occupied the central position in the supercontinent of Gondwana, from which formed the southern continents. While South America, Antarctica, Australia, and India have broken off and drifted away, Africa has remained relatively unmoved for the past 300 million years. Its most spectacular geological feature, the Great Rift Valley, extends from Jordan to Malawi, forming a chain of lakes, and a string of volcanoes (including Mounts Kilimanjaro, Kenya, and Meru, and the Virunga range). The Rift, created by movement of the great tectonic plates, exposes ancient fossil-bearing sites like Olduvai Gorge that otherwise would have been hidden deep in the Earth. The Barberton Mountain Lands in Swaziland, southern Africa, preserve microfossils of Earth’s earliest one-celled life, more than three billion years old. John Reader, in his fine book Africa: A Biography of the Continent, tells us that of the world’s 20 or so linguistic families, the four most ancient are African. Khoisan, Niger-Congo (including Bantu), Nilo-Saharan, and Afro-Asiatic are all heard today in East and South Africa, close to the sites of the oldest known human fossils. Starting about 5,000 years ago, the Bantu-speaking peoples expanded from the region that is present-day Nigeria and Cameroon and colonized virtually all of sub-Saharan Africa. They changed the human landscape dramatically, from a region thinly populated by groups of hunter-gatherers to one dominated by farmers living in villages. Five millennia ago, the Nile between Aswan and the Delta supported about 1.8 million people, a state unified under a single pharaoh, the divine personification of the sun god Ra. Egyptians discovered principles of astronomy and math, built pyramids, invented a written language, created pictures and statues, and employed the wheel and plow. They worked with copper and gold, made exquisite jewelry, and manufactured bronze. But they did not work iron and were conquered in 670 b.c. by Assyrian forces with iron weapons. Sub-Saharan Africa’s first literate civilization was founded in the first century a.d. at Aksum on the northern Ethiopian plateau and lasted over 1,000 years. Its inhabitants developed Africa’s only indigenous written script and erected massive carved monoliths (one weighed 700 tons) over the graves of their leaders. Aksum exported rhino horn, ivory, hippo hides, slaves, gold dust, frankincense, civet musk, and even live elephants. By 500 a.d. Aksum was considered one of the world’s most important kingdoms, along with Rome, Persia, and China, but present-day Axum, what’s left of Aksum, has declined into an obscure backwater. The animals, the people, the fossil sites, the geology, draw my wife, Adrienne Zihlman, and me back to Africa again and again. Previous trips have taken us to Olduvai Gorge, Lake Turkana, and Laetoli, where the Leakeys and their team have found many of the oldest hominid fossils, going back four million years; to the shores of Lake Tanganyika, joining Jane Goodall and her chimpanzees at Gombe; and to the Virunga volcanoes of Rwanda, where mountain gorillas roam. My own images of Africa are naturally shaped by these visits, which started in 1974. Nairobi was a relatively small dusty town in those days. Adrienne spent her time studying the Leakeys’ hominid fossils in a tiny room with a bare light bulb, while I wandered through Indian markets gathering multicolored beans and lentils for our upcoming safari. My favorite memory of that safari was driving our VW camper along Amboseli National Park’s dirt roads after we had already seen elephants, giraffes, lions, and rhinos. The view ahead held nothing of note at the moment, when Adrienne suddenly shouted, “Stop the car! Look! Look!” I stopped and looked around for the wonderful beast that had evoked such enthusiasm. Nothing there but thorn trees. “What is it?” I asked. “A dung beetle!” she cried triumphantly. Down at the edge of the road was a little scarab chuffing along, pushing its roll of dung. Adrienne was right to be excited. The dung beetle is as important a part of the ecology as its gigantic provisioners. Without dung beetles, Africa would be piled high with elephantine and bovine feces. The beetles not only consume this waste but spread the seeds embedded within it and so diffuse plant species far and wide. My first visit to South Africa 25 years ago gave me a shock of déjà vu with its whites only signs and segregated parks. These scenes took me back to my youth in southern Virginia, where the two unsanitary tin dippers hanging on chains from a public water pump were labeled for whites only and for coloreds only, as though microorganisms too had racial preferences. Yet, even then, I sensed that things were changing for the better in South Africa. Most of our friends and colleagues in the academic and scientific fields were strongly opposed to apartheid and were working actively against it. Just as I saw politically mandated segregation dismantled in my native Virginia, I’m happy to have watched apartheid being weakened and finally disposed of in subsequent visits to South Africa. Last summer, the first post-apartheid conference on human evolution was held near Johannesburg, and black and white African scientists were able to come from all over Africa and meet with their black and white South African colleagues. It was delightful to be able to greet African friends that we had met in Kenya and Tanzania, who had never been to South Africa before. Despite its current rapid growth in numbers, the human population density of Africa has historically been low, only a quarter that of most other continents. Only 22 percent of arable land in Africa is in production, compared with 92 percent in southeast Asia. One explanation for this phenomenon is that the climate and conditions favorable for humans and their domestic animals are also congenial to the parasites and microorganisms that prey upon them. Africans have been plagued by malaria, which kills millions, the tsetse fly that spreads sleeping sickness in cattle and people, bilharzia (liver flukes), hookworm, AIDS—now affecting 10 to 20 percent of the sub-Saharan population—and occasional outbreaks of other lethal infections such as the Ebola and Marburg viruses. African farmers have also had to compete for territory with the abundant wildlife, especially elephants. For millennia, this competition was a standoff, resulting in a checkerboard pattern of utilization, with elephants and people occupying adjacent squares. Thanks to modern medicine, high-powered rifles, and the ivory trade, the balance shifted in the 1950s against the elephants. The paradox of “success” for the human population of Africa is the disappearance of other animal species. The unremitting human population expansion and external demand for Africa’s agricultural and mineral resources will probably squeeze most of Africa’s wildlife into extinction or overseas zoos in the next millennium. The Rwanda story is another of Africa’s many cautionary tales that hasn’t had a happy ending. The most fertile and densely populated nation in Africa, Rwanda became independent in 1961. When Adrienne and I visited Rwanda in 1983, to study the mountain gorillas, we would often see young pregnant women walking along the road, one child on their backs and several more trailing behind. This rising tide of humanity is rapidly making its way up the mountainsides, cultivating their flanks—even though they’re supposedly national parks—and forcing the few hundred remaining gorillas into ever smaller habitats at the top. In cutting down the mountain woodlands, they are displacing the water table and severely damaging their own ecology and life-support system, as well as that of the gorillas. The Tutsi comprise 12 to 15 percent of the population of Rwanda, the Hutu about 85 percent. German and Belgian colonial powers favored the Tutsi almost exclusively for positions of authority and, since independence, the two groups have been involved in sporadic civil war. There happened to be a lull in the fighting when we were there, but bullet holes in our hotel’s plate glass window, which no one bothered to repair, told of the ongoing conflict. It came to a head when the Hutu launched a genocidal attack against the Tutsi, reducing their numbers from 930,000 to 130,000. As John Reader observes, the many wars that have flared up in Africa’s 50 or so nations since the colonial period ended have almost all been fought within national boundaries—boundaries largely set by ex-colonial powers—not across them: Hutu versus Tutsi; Maasai versus Kikuyu in Kenya; Zulu versus Xhosa in South Africa; Yoruba, Hausa, and Igbo against each other in Nigeria. The warring tribes, like those of medieval Europe and the Balkans today, often have common languages, values, marriage and family customs, and belief systems. Near the end of his biography of Africa, Reader quotes Nigerian Nobel Prize-winning novelist Wole Soyinka, “Rwanda is our nightmare, South Africa is our dream,” and he closes on the note of hope engendered by South Africa’s free elections in 1994 and Nelson Mandela’s remarkable accomplishments toward reconciling blacks and whites in his native land. I too am hopeful that the problems compounded in Africa by human greed and cruelty will be amenable to solutions by human ingenuity and imagination. One morning in Amboseli during that first visit to Africa 25 years ago, I woke up to the sight of white-capped Mount Kilimanjaro looming against the blue sky, a group of elephants feeding nearby, some vervet monkeys checking out the camp to see what they could benefit from, and a flight of golden weaver birds building a nest in a thorn tree. This is the magnificent Africa that nourished the human family for the past five million years and will write new chapters of its unpredictable story in the next millennium. Jerold M. Lowenstein is professor of medicine at the University of California at San Francisco and chairman of the Department of Nuclear Medicine at California Pacific Medical Center in San Francisco. |
Fall 1999
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