Inside Richard Leakey's discovery of an ancient human ancestor skull—the same his parents chased
In a 1970 National Geographic feature, paleoanthropologist Richard Leakey—son of Louis and Mary Leakey—recounted his discovery of a nearly complete Australopithecus boisei skull (now Paranthropus boisei), the same species his parents had found a decade earlier.
In fairness, I must give credit for the dramatic find to a camel—a large ungainly beast who had already won my affection with his deep brown eyes. I called him George.
We had hoped to reach Kenya's frontier with Ethiopia by dusk, Dr. Meave Epps and I, in our exploration last August of this vast, virtually trackless region east of Lake Rudolf. It was the second season of our survey to learn the nature and extent of the area's fossil deposits.
Had we been traveling in the relative comfort of a Land-Rover, no doubt we would have dismissed a small rocky outcrop some two miles east of our course as not worth investigating. But we were already three days' tiring march inland by camel from our base camp at Koobi Fora, on Lake Rudolf's eastern shore, where we had left the rest of the expedition. George was complaining noisily; he had carried me far enough that day. And frankly, I welcomed relief from his jolting gait.
"Let's have a look at that exposure and make camp," I said. "Another day to the border won't matter." Meave, a zoologist on our expedition's staff, offered no objection, nor did the other two members of our camel party, Nzube Mutwiwa and Kamoya Kimeu.
The grayish-brown ledge of sediments, sliced open by centuries of erosion, proved far more extensive than it had first appeared. As we approached it, Nzube and Kamoya circled out in one direction, Meave and I explored the other. Almost immediately we found fossils—heavy, bleached bones of ancient elephants, pigs, and other animals of the late Pliocene or early Pleistocene epochs, two to three million years old.
We hobbled the camels and made camp. In the morning, after tea, we split up to explore the rest of the exposure.
I was walking along the dry bed of a small stream that had carved open the fossil-bearing strata, when my heart suddenly leaped.
"Meave!" I shouted, so sharply that she ran a few steps in alarm.
"What is it—a snake?"
I pointed. There on the sand 20 feet ahead, in full view beside a thorny bush, lay a domed grayish-white object. Halfway to it I sat down stunned, incredulous, staring. For years I had dreamed of such a prize, and now I had found it—the nearly complete skull of an early hominid.
The bony sagittal crest atop the skull, together with enormous brow ridges, flat face, and small brain case, marked it clearly as an Australopithecus, a primitive manlike creature whose fragmented 1.75-million-year old remains had also been found at Olduvai Gorge in Tanzania by my parents.
The one I had found, intact except for teeth and lower jaw, closely resembled the Olduvai specimen of Australopithecus boisei, formerly called Zinjanthropus boisei. Mine was the first to be discovered in Kenya. And later study would indicate that it is perhaps 850,000 years older than the Olduvai skull!
(Remembering Richard Leakey, a trailblazing conservationist and fossil hunter.)
In the strata of sandstone and clay beside the fossil I found a perfect partial cast of the skull. From here, probably only in recent months, it had weathered and tumbled out.
Carefully we photographed everything, built stone cairns to mark the place, and packed the skull. The four of us hastened back to base camp in triumph.
This fossilized cranium is only one of the achievements of two seasons of hard work in this largely unexplored stony desert of Kenya's Eastern Province. Our team has also found a collection of what we believe are the oldest stone tools ever unearthed, and a fragmented, yet-incomplete skull that puzzles and excites me, for it seems much more manlike than any australopithecine's.
But perhaps most significantly, we have traced the outlines of what may be the richest and most extensive Pliocene-Pleistocene fossil region known in all Africa. Here lie more than a thousand square miles of sediments possibly as old as four million years, bearing countless bones of extinct animals—and, we now know, creatures akin to man.
Lake Rudolf, sometimes called the "Jade Sea," lies in the northern reaches of Kenya, in the Great Rift Valley system.
Its opaque green waters stretch nearly 155 miles from north to south, and 35 miles at its widest. The lake teems with fish and crocodiles, and herds of animals live here, concentrated along the almost uninhabited eastern and northern shorelines, where goats and camels have not stripped the soil of vegetation.
About 10,000 years ago, the level of Rudolf stood some 200 feet higher than today. Once it connected with the Nile, and even now its waters contain Nile perch, sometimes weighing 200 pounds and more. But then it shrank drastically, like other Rift Valley lakes, perhaps as climatic change altered the rainfall pattern.
In prehistoric times, great quantities of ash, and sometimes lava, erupted from volcanoes surrounding Lake Rudolf. The ash, together with soil and sand washed into the lake, built up thick sedimentary deposits.
As the lake level rose and fell through millenniums of torrential rains and prolonged drought, layers of silt and clay covered the remains of lakeside animals; their bones, thus protected, fossilized. The sediments along Rudolf's eastern shore are littered with such bones, some of them perhaps as old as four million years. And I was sure that where large herds of animals lived, man's ancestors also lived, hunting them for food.
And that, in essence, is why we were there.
Stone Tool Confirms Rudolf's Promise
In 1967, I had been co-leader of an international expedition to explore the Omo Valley, north of Lake Rudolf in southwestern Ethiopia. Teams from the United States and France, and my own party from Kenya, were given permission by the Ethiopian Government to investigate rich Pleistocene formations along the lower reaches of the Omo River, which drains into Lake Rudolf. My group located animal fossils older than four million years at the north end of the valley. So our season proved quite worthwhile. We also collected two magnificent skulls of Homo sapiens. They suggest that modern man's species may be as much as 100,000 years old.
Nevertheless, several tantalizing glimpses from the air had led me to suspect that even richer fossil ground lay to the south, along the ancient shores of Lake Rudolf itself. The American party, led by Professor F. Clark Howell of the University of Chicago, allowed me to lease its helicopter for a brief sortie down along the Ethiopia-Kenya frontier.
We had flown forty or so minutes over increasingly dry and broken terrain when I selected a promising-looking ridge of stratified sediments.
The helicopter's rotor had scarcely stopped when I stooped to pick up a primitive stone tool—a chopper distinctly like many found in the earliest levels at Olduvai Gorge!
With greater hopes than ever, in February of 1968 I approached the Committee for Research and Exploration of the National Geographic Society. To my delight, I was granted funds for a preliminary exploration of "East Rudolf"—actually, the area along the lake's northeastern shore.
It would be a formidable undertaking. The terrain itself was forbidding—nightmarishly broken, parched, sparsely inhabited. Worse, the district for years had been notorious for fierce bands of armed raiders who preyed on local livestock herds. The Kenya Government provided a platoon of police to escort our exploration parties.
At the end of May 1968, I left Nairobi with five vehicles and two trailers. Our party included Dr. Paul Abell, professor of organic chemistry at the University of Rhode Island; John Harris, a paleontology student from Bristol, England; and Dr. Bernard Wood, who specializes in anatomy.
After two and a half days our column reached the dusty little village of Loiyengalani, where the road ceased to exist. Here, in the great Rudolf basin, we were still 100 miles from our primary goal—an uninhabited spot on the map called Allia Bay, about halfway up Lake Rudolf's eastern shore. For two more days we inched through dry stream beds and over sand and rocky landscape. The trailer carrying our outboard-powered launch hung up time and again. We welcomed the added manpower of our police escort.
"Do you think the tents will stand it?" Paul Abell asked anxiously as we struggled to stake them down on the rocky shore at Allia Bay in the face of a keening gale. Wind was to be our frequent companion here. But somehow our tents held.
That same day we had found fossils embedded in nearby sandstone outcroppings—remains of ancient hippos, antelopes, elephants, and other animals. I soon found myself in the ironic position of having to urge my colleagues not to spend too much time collecting specimens.
"We've got to cover as much ground as possible," I reminded them regretfully.
Our main object in 1968 was to determine the nature and scope of the sedimentary out crops. We would merely sample fossils from different localities in order to draw comparisons with other African sites.
Mapping Parties Explore by Boat
Our motor vehicles, we knew, would be sorely handicapped in this terrain. And exploring any great distance on foot was impossible. We simply couldn't carry enough water to cope with desert heat that often exceeded 110° F.
For the first half of the season our motor boat was the answer. We made frequent trips up and down the coast and walked as far as 10 miles inland, making sketch maps of promising deposits and returning to Allia Bay each evening.
After six weeks we had reached the limits of our exploration by boat. We would have to shift our camp to reach exposures too distant from the shore. We viewed this move with mixed feelings.
"Crocodiles or not, I will miss a swim after a hot day," said Paul. Many of these great reptiles, some 16-footers, lounge along the lake edge, but they never molested us while we bathed.
None of us would miss the snakes, however. Our camp at Allia Bay had proved to be a favored gathering place for carpet vipers, Echis carinatus pyramidum, probably the worst-tempered venomous snake in Africa. Although small—averaging 15 inches or so in length—they are aggressive, particularly at night. In six weeks we clubbed or stoned more than fifty of them in and around our tents. Fortunately no one was bitten during the season. But on two occasions Bob Campbell, assigned by National Geographic to photograph our activities, narrowly missed putting his hand on the deadly brown reptiles near the entrance to his tent.
We set up our second camp 20 miles inland at a little oasis named Derati, a seldom visited group of 10 wells scattered through a small forest of shaggy doum palms. We pitched our tents in a glade surrounded by the swaying trees. There was a stark beauty about the place, surrounded as it was by rugged volcanic peaks that subtly changed colors as the sun moved across the sky. Here we spent six more weeks, exploring where possible by Land-Rover, and pushing beyond on foot.
By the end of the first season we had found exposed sedimentary deposits along the eastern shore of Lake Rudolf over an area of more than 1,000 square miles. In three months we had traversed it several times and had located dozens of sites at which fossils abound.
Comparing our specimens with those from other African sites that have been dated, we can say that our earliest fossil evidence—remnants of extinct pigs and elephants—is probably about four million years old. Most of the fossils appear to be older than those from the lowest levels at Olduvai Gorge.
Before closing out our 1968 season, three members of my staff—Kamoya, Nzube, and Mwongela Muoka—made separate and tantalizing discoveries: Each found jaw fragments of australopithecines. Although poorly preserved, these fragments indicated to me that near-man had lived along the eastern shore of Rudolf between two and three million years ago—in Pliocene-Pleistocene times. Further work, I felt certain, would turn up additional evidence of man's ancestry, and on this basis I reported to the Society at the end of 1968. Generously, it responded with support for another expedition to East Rudolf in 1969. A contribution from the William H. Donner Foundation, Inc., of New York City, enabled us to incorporate important aerial mapping of the Rudolf area into our plans.
We set out again for Lake Rudolf in late May, 1969, heading for a new base camp at Koobi Fora—a shallow cove sheltered by a long sandy spit some twenty miles north of Allia Bay.
The problem of getting about in this rugged country during our first field season had led me to consider another means of transportation: camels. We hired them—four riding animals and eight pack beasts—near the outpost of Marsabit among the villages of the Gabbra people.
As during the previous year, the bandits who frequent the northern frontier left us alone; we went without police escort in 1969. But often at night we had to persuade lions not to eat our precious transport animals, usually by firing a rifle into the air or by tossing out a "thunderflash"—a loud firecracker.
By the second week in June our camp had been set up on the grassy lakeside plain at Koobi Fora, and we had cleared an airstrip to link us quickly with Nairobi.
Our teams set to work promptly. The primary objective was a preliminary geological survey of East Rudolf, headed by Kay Behrensmeyer, a cheery, indefatigable graduate student in geology at Harvard University. Donald Siegel, who is studying for his master's degree in geology at Pennsylvania State University, was her assistant. Paul Abell again joined us, with his 16-year-old daughter Susan.
Meave Epps, of the National Museum in Nairobi, and I planned to continue the exploration of exposed sediments. Kamoya, my deputy expedition leader, would assist us, along with Nzube and Mwongela. These three, although lacking formal training, are among the most skilled field paleontologists I have known.
Kay's geology program was fundamental to our other work, for fossils collected from sites whose geological story is not fully documented lose much of their value as study material.
From specimens collected the previous year, I had estimated the age of most of the East Rudolf beds at more than two million years. Olduvai Gorge in Tanzania, where my parents have been working since 1931, has yielded a vast collection of artifacts dated at 1.75 to 1.85 million years. These stone implements, to my mind, show a degree of sophistication which implies that our ancestors began making tools well before that time. If so, I felt certain we would find them at East Rudolf.
"If you don't find something where you think it should be, don't assume that it's not there," my parents had taught me since childhood. "More likely you're simply not looking hard enough!" I was determined that we should look harder.
I had flown down to Nairobi for several days to attend to museum matters, and on my return to Koobi Fora, Kay rushed up with dramatic, if cryptic, news.
"You were right—they do exist, and we have them in situ," she said excitedly. "What's more, there's good tuff directly on the site!"
We leaped into the Land-Rover and bounced along the rough track to her discovery. My excitement quickly turned to elation. Even on the basis of a first quick look, I felt sure Kay had found tools—choppers and sharp-edged flakes of basalt, chipped by hand in a dim, distant past. The flakes had eroded from the face of a low, barren knoll; one still lay embedded in a deposit of gray volcanic ash—the "good tuff" over which Kay had been so exultant.
The precept of "look again if you don't find it the first time" had proved itself. We stood less than 400 yards from a hollow where, the year before, we had discovered a number of well-preserved fossil hippos!
(Prehistoric hippo potholes are the first fossil mammal swim traces.)
Tests Establish Age of Finds
The fact that the tools were embedded in tuff was of the utmost importance, for volcanic ashfalls can provide minerals suitable for dating by complex laboratory techniques. Kay and her team selected samples to be flown to the University of Cambridge for dating by Dr. J. A. Miller and his colleague Dr. F. J. Fitch of Birkbeck College in London.
While awaiting their report, we began an exploratory trench into the tuff. The site eventually yielded 60 specimens: four chopping tools, numerous flakes, and a dozen-odd animal bones, principally antelope remains, that may have been cracked open to extract the marrow.
Excitement reigned in camp when a preliminary report came back from the University of Cambridge. Our tools were a minimum of 2.4 million years old! The plane that brought this news also delivered some fresh Kenya strawberries. We broke out a bottle of wine and dined in sumptuous celebration.
The authors of the report have since visited the tool site at East Rudolf and, after exhaustive tests of additional tuff samples, have established a more accurate date of very close to 2.6 million years, plus or minus less than 260,000 years. Thus, if further study verifies that these, indeed, are tools, we will have pushed back the horizon of the earliest tool-maker some 850,000 years beyond the oldest previously known—at Olduvai.
Work progressed well through July and into August. Kay's team continued mapping strata, and fossil hunters found interesting specimens almost daily. Sue Abell one day brought in a beautiful jawbone of a Cercopithecus monkey between two and three million years old—the first of its kind found in East Africa. She was awarded a bottle of wine.
A new member joined the expedition: Libby Nesbit Evans, a zoology student from Cambridge, whose special interest is taphonomy—the study of what happens to organisms after death. Knowledge of how carcasses are scattered and buried, and how they deteriorate and fossilize, is particularly useful to paleontologists.
Libby staked out her province a few hundred yards from camp, for Koobi Fora abounds in game, including lions, hyenas, and crocodiles, and animal kills occur frequently. Her study area, with its odd crop of meticulously numbered bones, was promptly dubbed "Libby's Cabbage Patch." A handsome wild topi, a large member of the antelope family, formed a curious attachment to her, and it was a charming sight to watch the 300-pound animal follow her as she worked beside the lake.
Wilderness Drama Takes Place in Camp
Our expedition's taphonomist might well have conducted her bone count even closer to camp. One windy night I awoke to a brief commotion outside, but since no human voices were involved, I went back to sleep. Arising before dawn, I found the torn carcass of a zebra, killed by lions, less than 15 yards from my tent. Upon questioning, I found that several people had walked by during the night, totally unaware of the drama.
Lions often prowled around the thornbush boma that fenced in our camels at night. On our exploratory trips a determined lion could easily have taken his pick of our transport. Upon making camp for the night, we herded the camels together and tied up one foreleg of each, loosely tethering ankle to knee to discourage wandering. We then bedded down at strategic points around the herd. In theory, one of us could then head them off should a stalking lion launch a stampede.
The theory, I regret to say, broke down. One night I awoke suddenly to find a herd of three-legged camels bearing down on me at phenomenal speed. To avoid being trampled, I flung off my blanket and took to my heels. Fortunately the beasts quickly came to a halt—astonished, no doubt, at the spectacle of a human leading them in flight!
We traveled on these reconnaissance trips with Spartan simplicity in order to cover as much territory as possible. We rose at dawn, and a cup of tea sufficed for breakfast. At midday we stopped to roast a few potatoes and chew a couple of strips of sun-dried antelope meat.
It was late in the day on one such trek that my own mount, George, began complaining and we made the fateful decision not to push on to the Ethiopian frontier, but rather to make camp and investigate that insignificant-looking outcrop off to the east. Our reward was the magnificent Australopithecus skull that sent us racing back to Koobi Fora.
"That looks like nothing I've ever seen in this world," Paul said when he spotted four distant figures on camels loping in toward camp. "Don, maybe we'd better get the gun."
Kay told us the story later. We hadn't been expected back for another week, and I suppose there was a certain raffish look about us. The turbans we had improvised to ward off the desert sun flapped wildly about our heads, and the approach of any strangers in this area was cause for alarm.
Among the first to recognize us was my mother, who had flown up from Olduvai to examine the artifacts from our tool site.
After an excited exchange of greetings, I lifted the precious skull from its packing box and carefully removed its paper and sheep skin wrappings.
Mother gazed at it quietly. Perhaps she was thinking back to her first glimpse of two huge hominid premolars embedded in a bank at Olduvai. It had taken 19 days of delicate digging and sifting to recover more than 400 scraps of fossilized bone; she and my father had then worked patiently for 18 months assembling and reconstructing the fragments into the first Australopithecus boisei cranium ever found. And here I was, holding an almost identical skull—considerably older, almost intact, and stumbled across on open ground out of sheer luck.
"It's beautiful, Richard," my mother said. "Absolutely magnificent!" Then it occurred to me that I had made my find 10 years after hers, almost to the day.
Our party lost no time in getting back to the skull site—a 60-mile trip—with a sieve, in the hope of recovering a few fragments of the missing teeth or lower jaw from the deposits. But nothing more was found.
It was at this point on our expedition that I had our only encounter with one of the armed bands that roam this desolate region near the Ethiopian frontier. While I was leading two of our camels to a water hole about five miles from camp, a large bush ahead suddenly seemed to explode with people. Dark, wiry, and clad in loincloths, they carried knives, spears, and rifles. I counted 18 men as they ran off to a low ridge, where they stopped to watch me. They had been resting in the shade, and we had taken each other completely by surprise.
Several of them raised their rifles. I let them see my own-and ruefully fingered the two rounds of ammunition in my pocket. There was little to do but proceed with my business as though totally unconcerned.
The strangers followed me to the water hole, always at a distance, and watched as I filled the water tins. Then they followed me a few miles back toward camp before dropping off my trail. I never saw them again.
The following day was even more eventful. We spent the morning exploring the area around the skull site for animal fossils that might prove useful in dating the deposits, in case age determination by other methods should fail. Meave and I chose one direction, Nzube and Mwongela another.
Shortly, Meave called to me, pleased and excited. "Richard, come have a look!"
She had discovered the broken skull and jaw of a saber-toothed cat-one of the finest specimens ever found in East Africa. Under a broiling sun we collected the pieces and retreated to the lacework shade of a thornbush to fit them together.
We had almost finished the job when I heard Nzube and Mwongela returning, chattering and laughing. They bounced over a ridge wearing broad grins, oblivious of the vicious noon heat. I strode out to meet them.
"Another hominid skull!" I shouted to Meave, and we all began examining Mwongela's discovery, found protruding from a low bluff. It was in fragments: three major pieces and several smaller ones. The face and jaws were missing, but the rest of the cranium bore few of the characteristics of an australopithecine. I felt, with mounting excitement, that a search for additional fragments and further study might show this to be no near-man, but perhaps even a species of the genus Homo.
When Mwongela led us to the site of his fossil discovery, I was sure from the slope and the erosion course that we would be able to find additional fragments—but, unfortunately, not in 1969. It would require a major excavation, and our time had all but run out.
After performing a sieving operation at the site, we loaded our camels and trekked back to base camp. The closing days of any expedition are always hectic, and the end of August at Koobi Fora was no exception. Specimens had to be prepared for shipment, field notes completed, photographs taken.
When the others had departed, I remained behind with a few of our staff to close down the camp. These few days of relative calm gave me an opportunity, when the late afternoon sun burnished the surface of Lake Rudolf, to ponder our two seasons of work.
With Kay Behrensmeyer's well-drawn stratigraphic sections, we could tentatively correlate the strata at the tool site with the two skull sites to the north. Fossil fauna at all three sites agree with this correlation. Both skulls appeared to come from horizons below the accurately dated tool-site tuff. Thus these hominids were very likely to be a minimum of 2.6 million years old.
There were our tools, the oldest ever found. Who had made them? Not Australopithecus boisei, I felt.
While the first skull found by our expedition displays certain differences from the Olduvai specimen, these, I suspect, are minor enough for it to be classified as the same species, though it is likely to be some 850,000 years older. Teeth and jaw fragments found by the French and U. S. teams in the Omo Valley confirmed that these near-men were an established group more than 2.6 million years ago.
This lack of change over such a long period indicates very clearly, I think, that these creatures had reached an evolutionary "dead end." Such failure to evolve would not, to me, seem characteristic of an intelligent tool maker. Furthermore, Australopithecus boisei possessed a massive jaw and huge grinding teeth, implying that he had adapted to suit a predominantly vegetarian diet. He would have had little need to devise cutting tools.
If he was not our tool-maker, who, then? Was there a contemporary line evolving in the Rudolf basin at the same time, one involving a more intelligent creature, perhaps of the genus Homo?
I believe that such a situation existed at Olduvai 1.75 million years ago. Australopithecus boisei lived there then. So did Homo habilis, a more advanced creature discovered in 1960 at Olduvai. We now credit Homo habilis with tool-making ability.
Was Homo habilis making tools at East Rudolf 850,000 years before he hunted game at Olduvai? If so, we have not found him, for I feel the skull discovered by Mwongela bears little resemblance to that of Homo habilis.
Perhaps an answer may lie with still another early man—Homo erectus—whose remains have been found at Olduvai Gorge as well as near Peking and in Java. The earliest specimen is about half a million years old. But he is quite distinct from both of Olduvai's other forms of primitive man, suggesting to me that the Homo erectus lineage had been evolving for a very long time—perhaps at least as long ago as 2.6 million years, the era we are working with at East Rudolf.
Could Mwongela's puzzling find be a prototype of Homo erectus, then? It is much too early to say, but I believe this is quite possible.
We will find the answer, I am sure. For among the strata of the East Rudolf desert lies a fascinating volume of prehistory, holding untold chapters of the origins of mankind.
In two years we have scarcely turned the first page, and I am eager to get on with the reading.
