CHICAGO--Trying to separate science from mythology, two Field Museum researchers have put to rest several longstanding myths concerning the museum's infamous Tsavo lions. They propose alternative scenarios based on comprehensive reviews of historical literature, game department records, unpublished journals, and museum specimens.
First, the Tsavo lions were not 'aberrant'. Lions and other big cats have repeatedly turned to man-eating in the face of certain conditions, many of which are manmade. Furthermore, man-eating by lions continues today.
"For most of their history, extinct and living humans, have represented little more than a vulnerable, slow moving, bipedal source of protein for big cats," says Julian Kerbis Peterhans, associate professor of Natural Science at Roosevelt University, Field Museum adjunct curator and co-author of a study on man-eating by lions recently published in the Journal of East African Natural History (http://www.
Legend has it that in 1898, two Tsavo lions killed at least 135 workers constructing a bridge in Kenya, temporarily stopping the construction of a railroad linking Lake Victoria with the port of Mombasa. Lt. Col. John Patterson eventually killed the lions, which are now on exhibit at The Field Museum, Chicago.
Thomas Gnoske, co-author of the study, Field Museum assistant collection manager and chief preparator in Birds, points to newly found evidence that challenges the traditional telling of the infamous event. He cites inconsistencies between authentic records and popular treatments, especially regarding the numbers of people allegedly killed by the man-eaters. In fact, three different, ever-escalating, figures, ranging from 14 to 135, were documented by Patterson, himself, during the course of his career. Gnoske believes that Patterson's original published (1907) figure of 28 might represent a more accurate total.
"The distorted version, perpetuated by Hollywood and popular treatments, falls more into the category of myth rather than fact. Promoting such fiction can actually have a negative impact on serious conservation efforts focused on preserving lions in the wild," Gnoske says.
Man-eating: A Social tradition
In a few well-documented, localized incidents, man-eating appears to be a learned behavior. Once lions establish a pattern and begin to prey regularly on humans, they can pass it on to their offspring, along with sophisticated strategies and techniques, such as never returning to the same place two days in a row.
"Lions are a social species, capable of transmitting a behavioural tradition from one generation to the next," Kerbis says. "The fact that they can be born and raised to hunt and eat humans means that an outbreak of man-eating usually does not stop until all the responsible lions and their offspring are eliminated."
Further supporting this view is the fact that man-eating incidents in Tsavo did not begin with the arrival of railway crews, nor did they end with the destruction of the notorious lion coalition. The authors document killings by lions in Tsavo for several years prior to the arrival of Col. Patterson. Killings continued regularly through WWI when soldiers were picked off on patrol. All of this points to a man-eating culture among Tsavo lions, a phenomenon rarely documented.
Unwittingly, man had fed this culture by "provisioning" Tsavo lions with dead humans. A famine of epidemic proportions on the heels of a severe small pox outbreak, local burial 'practices' and hundreds of Indian laborers, dead from disease, all helped supply the Tsavo lions with humans in the 1890s and encourage their attraction to humans as prey.
Historic caravans with slaves and porters regularly passed through Tsavo in the second half of the 19th century despite proclamations banning the international slave trade. The authors document the abandonment of sickly or injured slaves and porters in Tsavo. A minimum of 80,000 humans was estimated to have been annually lost along the northern caravan routes, according to historical sources.
Man-eaters are able-bodied
The authors dispel the centuries-old yarn, championed by noted tiger slayer Jim Corbett, that man-eaters are aged or have damaged teeth, limiting them to a diet of slow-footed humans. Their review shows that problem lions, including man-eaters, are typically sub-adult or prime-ages males without documented injury. In fact the researchers have even used forensic techniques to analyze the last meals of the man-eaters. They discovered hairs from the prey of the lions, still embedded in their broken teeth 100 years later. The Tsavo lions are shown to have eaten 'normal' prey throughout their careers. Although the study is ongoing, no human hairs have been recovered amid the hundreds of hairs reviewed to date.
While broken limbs are certainly debilitating and may lead to man-eating, broken canine teeth do not appear to have the same consequences.
Factors contributing to Tsavo man-eating
Using historical accounts and Patterson's own unpublished journal, the authors reconstruct the Tsavo environment of the 1890's and point to other circumstances, also common to other notorious lion incidents, that are more likely to have contributed to this episode. Prominent among these is the depletion of their 'normal' prey. Between 1891 and 1893, rinderpest struck sub Saharan Africa with devastating results by decimating buffalo, one of the favored natural prey of lions in Tsavo. Although referring to other game, Patterson makes no reference to buffalo, eland, or local domestic cattle in his personal journal, suggesting that these bovine species had not yet recovered from the rinderpest outbreak of 5-7 years earlier.
Remarkably, other human behaviors also impacted the dietary choices available to Tsavo lions. The longstanding quest for ivory had eliminated elephants from much of eastern Kenya, including the Tsavo region. This caused a proliferation of dense thorny undergrowth, thereby decreasing the populations of large, social, grazing species such as zebra and gazelle. These thickets further provided ambushing lions with improved conditions to attack humans and to elude pursuit, something that infuriated Patterson. "Since lions are opportunistic hunters and regularly scavenge, all of these factors likely contributed to the outbreak of man-eating in Tsavo," Gnoske says. "Given the circumstances there in the 1890s, instead of asking how so many humans could have been dispatched, we wonder why there weren't more."
The two authors state "the same human-carnivore conflict drama, first depicted in France 20,000 years ago by Paleolithic artists, is currently at play in Africa. Competition for the same limited but fast diminishing resources, in tandem with human population explosions, is evident with newly emerging incidents between man and lion. By reacting predictably to changing circumstances, mostly beyond their control, lions are being systematically squeezed out of their final strongholds."