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Most scientific problems are far better understood by studying their history than their logic.
-Ernst Mayr, evolutionary biologist
I was told as a young student not to waste my time searching for Early Man in Africa, since "everyone knew he had started in Asia."
-Louis Leakey, 1966
It was an October morning in 2003. Meave Leakey was driving from Nairobi north along the eastern wall of the Rift Valley in central Kenya, expertly weaving around potholes in the tarmac and dodging oncoming buses that played chicken with smaller vehicles to scare them out of their way. Trucks belched black smoke that stung her eyes, cyclists hitched rides up hills holding on to the backs of buses, and jam-packed public shuttles called matatus spent almost as much time passing each other as staying on their side of the two-lane road. As Meave negotiated this nerve-racking traffic on the Uplands Road between Nairobi and Nakuru, she calmly recounted the story of how the search for human ancestors began in eastern Africa. "Until the middle of 1959, only a few people seriously believed eastern Africa was a sensible place to look for the earliest human ancestors," she said.
This history is personal for her, because it is the saga of her husband's parents, Louis and Mary Leakey. This formidable pair was among the first to stake their careers on Africa as the birthplace of mankind. For three decades, their work in eastern Africa was an almost solitary pursuit. Even those researchers who found fossils of early ape-men in South Africa during that time had trouble convincing their European colleagues that these primitive fossils were ancestors of humans. Then, in 1959, Mary found a fossil in Olduvai Gorge, Tanzania, that would finally give the Leakeys the hard evidence they had long sought that early humans did indeed evolve in eastern Africa. Louis named the cranium, or partial skull, Zinjanthropus boisei--Zinj from an Arabic word for eastern Africa, anthropus from the Greek word for man, and boisei from Charles Boise, a London businessman who was their benefactor. Translated, the name is an assertion: "Man from Eastern Africa." And once the Man from Eastern Africa made his appearance, the push was on to find more extinct men and women. Soon, teams of French and American researchers headed to eastern Africa, like forty-niners to California during the gold rush. The fossils they found in the Great Rift Valley in the 1960s and 1970s soon made it known as the cradle of humanity.
But Louis's search for the missing link in eastern Africa had started more than thirty years earlier, right in the gullies and rock shelters alongside the Uplands Road where Meave was driving nearly eighty years later, high above the Great Rift Valley. In 1926, the first year that Louis worked in the area, the Uplands Road did not exist, and the trip from Nairobi in Louis's Model T Ford took a half day over muddy tracks. The air was so clear that Louis could see miles across the Great Rift Valley from his camp, down a slope covered with acacia trees and scrub brush to Lake Elmenteita, a shallow alkaline lake rimmed with the pink froth of flamingos. Bush babies, leopards, aardvarks, and ibises lived in the acacia woodlands near the shore, and a herd of hippos wallowed in the lake. Beyond the lake, the jagged calderas of several extinct volcanoes lined up to form the silhouette of a human figure that the local Masai tribesmen called Elngiragata Olmorani, for Sleeping Warrior. A few British settlers were staking out the Masai's traditional grazing grounds for homesteads for cattle ranches, but otherwise the area was still remote and primeval.
Today, Elmenteita is only an hour's drive beyond the shanty sprawl surrounding Nairobi, and much of the land around the lake is fenced in by private owners. The hippos are gone and the bush babies and a few remaining leopards have retreated to a wildlife sanctuary. But the view of the rift valley far below is still stunning, and Meave named the volcanoes visible in the distance as she searched for a familiar turnoff. Spotting it, she jostled down a dirt road, past a quarry where workers mined a crumbly white rock called diatomite, and pulled into a grassy driveway. The sign said: Kariandusi Museum, National Museums of Kenya. It did not look like much: a guard's hut and a whitewashed, single-room museum with some casts of skulls and an exhibit on the formation of the Great Rift Valley. It was clearly off the tourists' safari circuit.
A curator eventually appeared, delighted to find someone who wanted to tour the site on a Monday in October. He was even more surprised to find out that the tall woman with straight, silver-gray hair and hazel eyes spoke Swahili and was a member of the Leakey family--a name that is well-known in Kenya. At sixty-one, Meave had been here many times before and knew the history of Kariandusi by heart. She is long-legged and fit after a lifetime of hard work scrambling over rugged terrain for fossils, and she did not need a guide to lead her into the gulch. She let the curator show her the way to a series of steplike pits anyway, partly because she was curious to learn what he knew. He took her to the first pit, which was covered with a corrugated metal roof. Meave leaned over the rail and pointed to the dirt floor encrusted with hundreds of stone tools, most made of glassy black obsidian, the rock that comes from volcanic lava. There were tear-shaped hand axes, two-sided flakes, and even triplets of round stones that look like black billiard balls. "This is where it all began," said Meave. She was referring to Louis's search for early man in eastern Africa. These shiny black tools at Kariandusi were among the first hard evidence of a sophisticated ancient Stone Age culture in eastern Africa. They were made by people who left them on the shores of the lake almost 500,000 years ago, perhaps when they came to hunt wild animals that were quenching their thirst at dawn or dusk. She climbed down wooden stairs into a deep gully where an ibis was roosting in a tree. Meave remembered a photo from National Geographic that showed Louis bending over a cliff there, pointing to stone tools embedded in the wall. This was precisely the spot where Louis and his team found their first ancient hand axes in eastern Africa in 1929.
* * *
In 1871, less than sixty years earlier, Charles Darwin had proposed in The Descent of Man and Selection in Relation to Sex, that the earliest ancestors of humans probably lived on the African continent. But that prediction was based on absolutely no evidence from fossils. In fact, at the time only one fossil of another type of human being was known, and that was of a Neandertal that had lived in the Neander valley of Germany sometime in the past 70,000 years. Darwin chose Africa because humans' closest cousins in the animal kingdom--chimpanzees and gorillas--lived in Africa; therefore, he wrote, "it is more probable that our early progenitors lived on the African continent than elsewhere." But Darwin admitted that it was "useless to speculate on this subject," since an extinct European ape nearly as large as humans could also have given rise to humans.
That didn't stop Darwin's colleagues from conjecture. His friend and champion Thomas Henry Huxley (also known as Darwin's "bulldog") agreed that humans should be put in the same family as chimpanzees and gorillas, and enthusiastically promoted that view in debates and in his 1863 book Evidence as to Man's Place in Nature. (Darwin himself avoided dealing directly with the issue until 1871, when he published The Descent of Man.) But a contemporary and admirer of Darwin's, the prominent German biologist Ernst Haeckel, believed that the Asian apes (orangutans and gibbons) were closer relatives of humans than the African apes were. Haeckel proposed this link in his sketches of the human family tree in 1868, drawing a direct line between Asian apes and a new species of fossil human that he proposed and explicitly called the missing link. In his writings and lectures, Haeckel fleshed out this missing link as a hairy, primitive creature half ape, half man, named Pithecanthropus alalus. (Literally, "ape-man without speech," from the Greek pithec, "ape," anthropus, "man," and alalus, "without speech.") It walked semierect, had protruding teeth, and was speechless. But there wasn't a bit of hard evidence to support this vision of an ape-man. Haeckel's missing link was purely theoretical.
One person who heard of Haeckel's ideas on human evolution was a young Dutch medical student, Eugène Dubois, who became the first of a long line of young men obsessed with finding this missing link--and winning honor and fortune. In 1887, when Dubois couldn't get the Dutch government to finance an expedition to the tropics to search for fossils, he quit his job as an anatomist at the University of Amsterdam and joined the Royal Dutch East Indies Army as a military doctor so he could be posted to the Dutch East Indies, now the Indonesian archipelago. Ancient fossils of mammals that had been alive during the earliest stages of the Age of Man (the Pleistocene epoch) had been found there. He thought it most likely that fossils of extinct ancestors of similar age would be preserved there as well. According to his biographer, the anthropologist Pat Shipman, he also reasoned that if apes lived in the tropics today, extinct apes and early ape-men would also have been more likely to live in the tropics.
It was an incredible long shot, but he sailed for the Dutch East Indies at the age of twenty-nine with his young wife and their baby. Dubois was the first of many fossil hunters to risk his life in search of an elusive missing link. He battled malarial fever without modern medicines; his team hemorrhaged workers, who ran away, became ill, or stole fossils to sell as "dragon" bones to traders from China; and they faced bad roads through the overgrown jungles of Java, mosquitoes, hellish heat, and torrential rains. Amazingly, Dubois and his family survived. More incredibly, he found what he was looking for. In August 1891, his crew discovered the molar of a hominid eroding out of the banks of the Solo River near the village of Trinil on the island of Java. Two months later, his crew found a skullcap that was larger than that of a chimpanzee's but smaller than that of a human's. Later, they found a thighbone. Dubois recognized the skullcap as belonging to a species that must have had a brain intermediate in size and development between humans and apes. But the thighbone belonged to a creature that walked upright--even before its brain had expanded.
He pronounced it Pithecanthropus erectus (or "erect ape-man"). It was an amazing feat. He had never searched for fossils but had nonetheless traveled halfway around the world to an island archipelago where he'd reasoned that such fossils should be found. Today, Dubois's Java man is still recognized as a major discovery--the first fossil found of an early hominid and the first specimen of Homo erectus (as it was later renamed), a key human ancestor that arose about 1.8 million years ago, probably in Africa, before migrating to Asia, where it persisted until sometime in the past 250,000 years. This species of human and its descendants may even have lived until as recently as 13,000 years ago in the form of the so-called Hobbit, the dwarf species of human whose remains were found in 2004 on the Indonesian island of Flores.
Convincing his colleagues that he had found the missing link would prove more difficult than finding the fossils themselves. When Dubois announced his discovery of Java man in 1893, he expected honor and scientific recognition. Instead, his monograph on this "man-ape" was met with skepticism and snide comments, some dismissing the fossil as a giant gibbon or an individual whose features had been distorted by disease or a wound. Word reached him in Java in 1894 that his European colleagues questioned many aspects of his monograph on the fossil--from his claim that all the fossils came from the same individual to the way his crew had mapped the fossil site.
Dubois traveled to Europe in 1895 to defend his discovery, winning a few converts as he lectured and displayed the bones themselves. Haeckel, who had inspired him, was one who embraced Java man as a human ancestor. But the theory of evolution was still new and was not universally accepted among scholars. Although Dubois was well educated and a meticulous scientist, perhaps the real problem was that an ancestor that looked so much like an ape was more than the scientific establishment of the late nineteenth century could accept. His biographer Shipman concluded, "In truth, the problem lay more in the prevailing beliefs among his colleagues than in Dubois' shortcomings."
As he battled his colleagues well into the twentieth century, Dubois's own shortcomings also became apparent--he grew secretive and territorial about his fossils, particularly after he gave a cast to a German anatomist who then toured the world with it, giving lectures and publishing a detailed description about Java man before Dubois had finished his own analysis of the skull he had found. After that, he withdrew from his colleagues and even rigged a mirror above his door at home so he could see who was there when his maid answered, turning away prominent scientists who'd traveled from as far as America to see the fossils that he stored in his basement.
History would prove Dubois right about Java man, but he died an angry man, unrecognized and estranged from his wife and friends--all alienated by his increasing irascibility. He was, perhaps, the first fossil hunter to become a victim of his own success in finding a human ancestor, as if the fossil came with a mummy's curse.
It was a bitter omen of the kind of controversy that would swirl around almost every new fossil vying to be a human ancestor. Even experienced researchers often react with more emotion to the discovery of human ancestors than they do to fossils of any other animal, including dinosaurs. New fossils almost always shatter preconceived notions of what our ancestors should look like, revealing our origins as ordinary apes rather than as exalted beings marked from the beginning with a big brain or some other sign of special destiny. Darwin recognized this reflexive denial of our savage past in The Descent of Man when he warned, "We must, however, acknowledge, as it seems to me, that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system--with all these exalted powers--Man still bears in his bodily frame the indelible stamp of his lowly origin."
From the Hardcover edition.