By Curtis Abraham

In 1898, a pair of male lions killed several dozen railway workers during a year long reign of terror near the Tsavo River in southern Kenya, where the British colonial government were building a railway bridge over the river. The man-eaters were finally killed by Lt. Col. John Henry Patterson, head of the bridge construction and author of The Man-Eaters of Tsavo and Other East African Adventures. In 1996, the story was popularized in the Hollywood film, The Ghost and the Darkness.

But why did the infamous man-eating lions of Tsavo resort to eating humans?

In 1998, the centenary year of the lion attacks, scientific investigation into answering this mystery began with the collaboration of the University of Chicago’s Field Museum, where the dead lions are on display, the Kenya Wildlife Service (KWS) and the National Museums of Kenya.

The main focus of the research has been on the teeth of the two lions. An analysis of the skull and mandible (lower jaw) of the first Tsavo lion (known as FMNH 23970 in the Chicago Field Museum catalogue) revealed that they were malformed because of a severely broken canine with an exposed root. A lion’s teeth are used primarily for firmly holding food in order to tear it apart. This malformity, according to experts, led to an impaired remodeling of the jaws which could have prevented the lion from efficiently killing its normal prey.

The second lion (FMNH 23969) also had teeth /jaw damage which might have hampered its effort to eat hard food items and/or reduced prey handling ability.

“Tooth breakage per se does not produce dietary shifts as older lions display some sort of wear or breakage to their dentition;”wrote Larisa R. G. DeSantis and Bruce D. Patterson in their 2017 paper. The pair examined the two Tsavo lions and another man-eater from Mfuwe, Zambia. “However, dental disease is another matter, and incapacitation via an abscessed or a fractured mandible may have prompted the Tsavo and Mfuwe lions to seek more easily subdued prey.”

Taste for humans

Scientists also believe the Tsavo lions might have developed a taste for humans after being ‘provisioned’ with dead ones. One lucrative source would have occurred during the slave trade. From the 16th through to the 19th centuries, a slave route ran through the Tsavo area. Slave porters who died along the route would have contributed a large number of abandoned bodies — an easy food source for several generations of lions.

The Tsavo region suffered severe drought and famine during the mid-to-late 19th centuries. This might have played a prominent role in the man-eating behavior of the two lions since such catastrophes led to large numbers of dead bodies in decimated villages. During the 1860s drought, cholera and plague brought by Swahili caravans ravaged the region. In the 1880s and 90s, famine ravaged the Bantu-speaking agricultural Wataita people who lived on the Taita Hills. In 1897, there was the Mwakisenge Drought and Famine, which lasted for three consecutive years.

 “[…] although the verdict is still out, it is very probable that the Tsavo Man-Eating lions got their appetite from eating victims of famine, warfare and caravan trade,” wrote Bruce Patterson, MacArthur Curator of Mammals at Chicago’s Natural History Museum.

Environmental factors were also a decisive factor. The quest for ivory during the 19th century had eliminated elephants from much of eastern Kenya, including most of Tsavo. Reduced elephant populations resulted in the expansion of woodlands and the reduction of grass-eating herbivores – prey for lions.

Unlike the Tsavo of today with its large tracts of open expanse, the Tsavo of the 1890s was composed of a nearly impenetrable, thorn thicket (‘nyika.’)  It was in this thicket environment that the Tsavo lions were able to stalk and ambush their human prey.

The Tsavo incident closely followed the debut of rinderpest on the continent, which decimated  cattle and buffalo, the primary prey of the Tsavo lions. The rinderpest epidemic would have left a low population of traditional food source for the Tsavo lions.

‘Man-eating’ behavior, however, was not an isolated incident at Tsavo. Humans were attacked and killed by lions in the Tsavo vicinity long before the construction of the railway.For example, there had been an attack in 1886 on a caravan crossing the Tsavo River. Such attacks have continued into modern times according to records of the Kenya Wildlife Service (KWS).

One curiosity about the man-eaters is that although the Tsavo man-eaters were male lions, they did not possess manes, characteristic of lions throughout the African continent.

In 1999, Patterson and colleague Roland W. Kays, then a post-doctoral fellow at the Chicago Field Museum, established beyond doubt that male lions in Tsavo were typically mane-less. The pair spent four months in Tsavo, systematically documenting the park’s lions and recording the conditions of the manes of males and the social groups in which they occurred.

Years later, Julian C. Kerbis Peterhans and Thomas Gnoske, collection manager in the Field Museum’s Zoology Department and a field biologist, published a landmark paper in the Journal of Zoology showing that Tsavo’s mane-less male lions, or those with delayed mane development, are the result of localized adaptations to the hot, dry climate of Tsavo.

One disputed fact of the Tsavo legend has been the exact numbers of railway workers who were killed and eaten by the two lions. In The Man-Eaters of Tsavo, Patterson says the two lions (“prowling demons,” he called them) ate 135 individuals over the course of a year. However, modern estimates indicate a figure of 35 with an outside probability of up to 75, according to anthropologist Nathaniel Dominy of the University of Chicago.

The Den

Yet another mystery is the existence of a den, where the two man-eaters lived and perhaps finished off their human prey? If so, where was/is it located?

In April 1997, Thomas Gnoske and Julian C. Kerbis Peterhans  discovered the cave that J. H. Patterson wrote about in The Man-Eaters of Tsavo. Gnoske had brought with him an enlarged copy of the original black and white photograph that Patterson took of that cave. This allowed researchers to make a positive identification since they had examined hundreds of caves during their search.

“After we found the cave, there was immediate interest by the Kenyan Government including David Western, then Director of the Kenyan Wildlife Service, journalists, documentary film makers, other biologists,” remembered Gnoske.

Patterson said the cave was filled with human remains, which he assumed were the remains of the victims of the two man-eaters. However, this claim remains inconclusive because in the year that followed, there was an attempted excavation of the cave by an American and Kenyan archeological team. However, the project failed to turn up evidence of the human remains and after a few weeks, was abandoned.

One of the greatest challenges facing Tsavo’s lion population today is human wildlife conflict.  In 2002, Roland W. Kays, Bruce Patterson and colleagues at the Tsavo Research Centre (Tsavo East National Park, Voi, and Taita Discovery Centre,) discovered that lion depredations on livestock are largely responsible for their conflicts with humans.

The researchers analyzed attacks on livestock over a four-year period on two neighbouring arid-land ranches adjoining Tsavo East National Park. They discovered that out of a total of 312 attacks, which claimed 433 heads of cattle, lions were responsible for 85.9 per cent of the attacks. In addition, they learned that such attacks are seasonal with the majority coming during the rainy season.

They concluded that large carnivores take more livestock when native prey are most difficult to find and kill. They also calculated that this predation represented 2.6 per cent of the herd’s estimated economic value, and cost the ranch $8,749 per annum. Each lion cost ranchers approximately $290 per year in depredations.

Curtis Abraham is a freelance writer from Queens, New York, currently based in Uganda. He writes on science, development, the environment, bio-medicine/health and African social and cultural history.