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By Juliari C. Kerbis Peterhans, Chapunikha M. Kusimba, Thmias P. Gnoske, Samuel Andanje, and Bruce D. Patterson

NATURAL HISTORY 11/98

One of the most popular displays at Chicago's Field Museum of Natural History is a diorama with two man-eating lions. These are the mounted skins of a pair of male lions that, one hundred years ago, went on a twelve-month rampage in southern Kenya, killing at least 128 people, many of them employed in building a railroad line into the interior of the country. Work on the railway was halted until the marauders were finally tracked down and shot by J. H. Patterson, a British engineer directing construction of a bridge for the railroad. Not long afterward, Patterson stumbled upon a "fearsome-looking" cave. In his 1907 memoir, The Man-Eaters of Tsavo and Other East African Adventures, he recalls this incident: "Round the entrance and inside the cavern I was thunderstruck to find a number of human bones, with here and there a copper bangle such as the natives wear. Beyond all doubt, the man-eaters' den." Patterson even took a photograph of the cave entrance, but unfortunately, the location of this notorious lions' den, somewhere in the west section of what is now Tsavo National Park, was soon forgotten.

As members of the Field Museum staff, familiar with the diorama and Patterson's memoir, some of us became intrigued by his description of the supposed lions' lair, which to a naturalist sounds much more like a hyena den. Although the man-eaters had been observed dragging off some of their human victims and, conceivably, could have returned to a home cave in order to feed, such behavior has not been documented in the modern lion species. Lions consume most of their prey near the kill site. Hyenas, however, do have dens to which they retreat with marrow-bearing bones. Perhaps the human remains Patterson saw were left by hyenas that had scavenged the man-eaters' prey.

Six years ago, we began to entertain the notion of locating the cave. We felt that if we could analyze the skeletal contents, this lion-versus-hyena question could be resolved. Analysis of the bones and artifacts could also confirm whether or not they had been amassed during the man-eaters' reign of terror; if so, we should find some remains of Indian laborers, who were among the victims.

A search for the cave could also prove useful for students of early human evolution. When paleontologists find fossil bones of our ancestors, they want to know how the remains got to be where they are. While we commonly think of our forebears as hunters, they could just as often have been prey, ending up as a few gnawed bones. A modern carnivore den with human remains - whether it belonged to lions or hyenas - would give paleontologists a good idea of what clues to look for when examining fossil bones.

As for the string of killings in 1898, other questions also interested us. For example, was this due to some aberration in the nature of these specific animals? In the wild, most lions and other large cats avoid contact with people. Wounded or old animals, however, must resort to relatively easy prey, frequently including humans and livestock. One of the man-eaters at the Field Museurn had a broken lower right canine with an exposed root; asymmetrical growth of the skull in response to this abnormality suggests the beast had suffered from this condition for a long time. Perhaps he was too disabled to hunt and consume the usual prey. We do know that after he was shot, no more humans were killed, although the second lion made several unsuccessful attacks before being shot as well, three weeks later. This suggests that the first lion may have been the main culprit.

Another possibility is that the attacks, which took place along an eighty-mile stretch of railroad located between Voi and Kima, were part of an established pattern. The railway track followed a traditional caravan route from the interior of East Africa to the Mombasa coastal region. From the sixteenth through the nineteenth centuries, countless caravan porters, many of whom were slaves, grew weak or died along this route, perhaps supplying generations of lions in the area with an easy source of food. Or perhaps there was a more immediate precedent. Between 1880 and 1890, a famine ravaged the Wataita, a Bantu-speaking agricultural people who inhabit the Taita Hills, near the railroad. An estimated three-fourths of the population died, and whole villages were abandoned. The corpses of many famine victims reportedly lay unburied and could have provided ready meals for scavengers, including lions. Thus, Patterson and his crew may have intruded in a region where lions were accustomed to human flesh.

Beginning in 1996 - the same year the story of the man-eaters was retold in the film The Ghost and the Darkness, starring Michael Douglas and Val Kilmer - four separate searches for the cave were organized by the Field Museum, in collaboration with the Kenya Wildlife Service. One was a reconnaissance by airplane that targeted streambeds lined with doum palms, which Patterson mentions in the description of the landscape. Patterson's memoir contains a very detailed account of how he came upon the cave. It also provides compass bearings, but as we learned the hard way, the published coordinates are in error, perhaps because they were incorrectly transcribed or because of some confusion in judging the orientation of the original hand-drawn maps. After fruitless efforts based on the compass bearings, the search refocused on the landmarks.

Finally, on April 30, 1997, a team located the cave, only a mile away from the railroad line. Despite the lapse of nearly a hundred years, its external appearance matched the photograph taken in 1899. But the bones Patterson described were nowhere to be seen. Perhaps they were part of a collection of East African skeletal remains that Louis Leakey had gathered in the 1920s and taken to Duckworth Laboratory at the University of Cambridge. Or they may have been flushed out by rain and deposited in the sandpit outside the cave mouth. Excavation of the cave and adjacent streambed is now under way to search for bones and to determine the nature of this site.

A possibility we are now considering is that the cave served as a burial chamber for the Wataita, who have inhabited the region for about five centuries. Traditionally, Wataita families buried their dead in a seated position, the head covered with only about one foot of soil. After a body was interred for a period of time, its skull was dug up and placed next to other ancestral skulls in a rock-shelter, cave, or niche in a rock. Patterson may have discovered just such a secondary repository, perhaps ravaged by scavengers. Retrieval of Witaita artifacts and skulls would support this hypothesis.

The rediscovery of the cave has helped launch a comprehensive study of the prehistory and ecology of Tsavo National Park. The Tsavo Research Program - a collaboration between the Field Museum and the Kenya Wildlife Service (which is celebrating its fiftieth anniversary) - will document, among other things, past climatic change, the effects of human settlement, the interrelation of local peoples with those of other regions, and the rise and fall of elephant populations as a result of the ivory trade. Elephants are considered a keystone species in the region because they profoundly affect the habitat. Today Tsavo consists primarily of dense, thorny bush, but there is evidence that in the past, when elephants were more numerous, they kept the landscape far more open (see "Br'er Elephant and the Brier Patch," Natural History, April 1984).

All these thorns may be having an impact on the local lion population. The movie The Ghost and the Darkness incorrectly depicts the two male man-eaters with full manes. In fact, the mounted specimens bear only the trace of a mane on their chests and sideburns, which is common among male lions in the Tsavo region. The explanation for this condition may be either environmental or genetic: male lions may simply be losing their mane hair as they traverse the thorny thickets, or natural selection may be eliminating a trait that has become useless, or even disadvantageous, in this thorn-ridden region.

To address conservation issues, the Tsavo Research Program plans a survey of the genetic diversity of Tsavo's lions - some of which are large and rangy and others small, some with and others without manes. Using mitochondrial and nuclear DNA sequences, we can determine the number of lineages within Tsavo and their relationship to neighboring prides elsewhere in Kenya and East Africa. This baseline information would assist in the management of lion populations, whose geographical range has eroded substantially during the twentieth century. The most secure refuge for lions may be in dryland parks such as Tsavo, which is large and has limited agricultural potential. While one hundred years ago, two man-eaters provoked human dread, today we extend our protection to their surviving relatives.

Covering nearly 21,000 square miles, Kenya's wildlife-rich Tsavo National Park, is split into western and eastern sections by the busy Mombasa-Nairobi road and railroad. Attractions of Tsavo West include Mzima Springs (where visitors can observe hippos firom underwater viewing hides) and the Chaimu volcanic crater. Tsavo East is a popular safari destination favored by photographers for its light and its views. Trail guides, lodgings, and campsites are aivailable in both sections of the park. For visitor information, contact: Kenya Wildlife Service

P.O. Box 30027 Nairobi, Kenya (254-2) 33-10-30