Why did two lions go on a legendary man-eating spree that saw 35 people killed and consumed over nine months? The short answer, after 120 years, three Hollywood movies and numerous scientific investigations: because the people were tender and easy to chew, and the lions had bad teeth.
The story of the people eaters began in March, 1898, when the British army set up camp on the Tsavo river in southern Kenya to build a bridge. The country was in drought and the river provided a reliable source of water.
Soon after the project began, the lions began using the camp as a supermarket – coming in at night and dragging victims from their tents.
Finally, at Christmas, Colonel John Patterson – after many failed attempts to bait and trap the killers – managed to shoot them. A fair number were white men, which predictably made the killings a marketable tale.
Patterson published a book in 1907, and put the death toll at 28. Ten years later, to jazz up a second edition, he claimed that 135 people had been eaten if one took into account the African natives.
The true toll remained unknown until 2009, when two scientists from the University of California pieced together the lions’ diet from analysing isotopes found in their hair and bone.
They found that in the final three months of their spree, humans made up about 30 per cent of their diet. By combining the size of an average person and how much a lion eats eat day, the researchers figured the lions ate about 35 people in total.
Still, a question remained. Why did the lions make people a significant portion of their diet in the first place? Lions were thought to eat people only rarely. The drought was thought to be a factor.
So too was a European-introduced virus called rinderpest that had killed many buffalo and wildebeests, the lions’ natural prey.
Studies have shown that desperate lions will transition to new foods when their environment is suffering catastrophe.
But Larisa DeSantis, a paleontologist and assistant professor at Vanderbilt University in Nashville, felt there was more to it – and decided to examine the Tsavo lions’ teeth. Their stuffed bodies are on display at The Field Museum of Natural History in Chicago which provided samples.
Dr DeSantis says she was inspired by a gory passage from Colonel Patterson’s book, The Man-Eaters of Tsavo.
“I have a very vivid recollection of one particular night when the brutes seized a man from the railway camp and brought him close to my camp to devour. I could plainly hear them crunching the bones, and the sound … rang in my ears for days afterwards,” she says.
DeSantis understood that heavy bone crunching – more associated with carcass scavenging than easting a fresh kill — wears down the teeth in predictable patterns.
She and a colleague analysed the teeth looking at wear patterns to determine whether the lions were eating flesh, bones or a combination of the two.
They compared the patterns with teeth from wild and captive lion specimens. They found that the teeth of the Tsavo lions bore a close resemblance to those of zoo animals fed on soft flesh such as horse and beef.
They also found evidence of dental disease and injury, including painful abscess that would have made regularly hunting techniques – grabbing and suffocating prey – impossible. They found similar dental problems in a man-eater from Zambia. Conclusion: the soft flesh of people was akin to serving mashed potato to toothless pensioners.
DeSantis presented her findings in a paper, Dietary behaviour of man-eating lions as revealed by dental microwear textures, published online this week in Scientific Reports.
Meanwhile, there’s evidence that lions in greater numbers have developed a taste for humans in lean times.
Since 1990, more than 600 people in Tanzania have been killed and eaten, notably in crop-growing areas where numbers of natural prey have declined.