The mystery of why the most famous “man-eating” lions in history developed their taste for human flesh may have been solved, 119 years after their rampage. In the process, we may have discovered the cause of other lions' transition to two-legged prey.
Despite their fearsome capabilities, lions seldom kill humans unprovoked. Yet a small number of Panthera leo eat multiple people, earning the title “man-eaters” even though they're at least as likely to feed on women. When two lions started preying on workers building a railway in Tsavo, Kenya, they not only attracted a mention in the British Parliament, but had three films made about them, most prominently The Ghost and the Darkness.
When the lions were finally shot, their bodies were preserved at The Field Museum, Chicago, where curator Dr Bruce Patterson examined them. One of the pair had an infection at the root of a canine tooth. Besides the bad mood brought on by constant pain, Patterson suspects the injury made it hard for the lion to hunt. “Lions normally use their jaws to grab prey like zebras and wildebeests and suffocate them,” Patterson said in a statement. “This lion would have been challenged to subdue and kill large, struggling prey, and humans are so much easier to catch.”
The skull of the first Tsavo lion reveals an abscess at the base of one tooth that would have caused pain and interfered with hunting. Bruce Patterson and JP Brown/Field Museum
Although the second killer lion also had a broken tooth, this probably didn't impede its hunting, and may have picked up the taste for humans from its pride-mate. Isotopic analysis of the two lions' hair and collagen indicate that while humans made up around 30 percent of the first lion's diet in its later years, we were just 13 percent of the second lion's food.
Patterson, who is unrelated to the Lt. Colonel John Patterson who shot the lions, published the study in Scientific Reports, accompanied by evidence that a Zambian lion that ate six people in 1991 also had severe dental damage, suggesting this may be a frequent reason for lions preying on humans.
Previously, it had been thought that the lions may have turned to humans in desperation as a result of a severe drought affecting wild prey. However, Patterson and first author Dr Larisa DeSantis of Vanderbilt University found that neither of the Tsavo lions' teeth had the wear associated with crunching on bones, as usually occurs when food supplies are slim.
Patterson told IFLScience that healthy lions seldom eat humans because “lions are smart and humans are dangerous.” Zebras may have a lethal kick, but if a lion catches one, the rest of the herd won't stomp it to death for revenge. Humans, on the other hand, usually retaliate. When lions do hunt humans, it's usually on moonless nights, even though unarmed humans would be easy prey in daylight.
Male Tsavo lions have little or no mane, but that doesn't make them any safer. Bruce Patterson/Field Museum