Looking for good motivation to brush and floss? Mammal experts say the infamous lions that killed dozens of rail workers in Kenya in 1898 may have been driven by dental disease. They published a report on the unfortunate beasts in the journal Scientific Reports.

There were only two of them, but the damage they did was both extensive and terrifying. “I could plainly hear them crunching the bones,” Lieutenant Colonel John Patterson wrote in his diary, “and the sound of their dreadful purring filled the air and rang in my ears afterwards.”

Patterson with one of the Tsavo lions. Image Credit: The Field Museum

Patterson eventually killed the lions, and their remains were preserved for scientific study. Today, the two skulls are kept in the collection of Chicago’s Field Museum so scientists can study them.

The Field Museum

Historians have long believed that the lions turned to human prey out of desperation when a famine eliminated their usual sources of food. If this was the case, the lions would have relished every last bite of every animal they killed, including the bones.

But when Field Museum researchers examined the Tsavo skulls, they began to suspect that the lieutenant’s “very vivid recollection” may have been at least slightly exaggerated, as the lions had clearly not been crunching anything. The microscopic signs of wear and tear that accompany regular hard use were nowhere to be found in the lions’ jaws.

They did, however, find evidence of dental problems. One lion had broken a canine tooth several years earlier, was missing three incisors, and had a periapical abscess, or pus pooled around the root of a tooth. The other had a fractured upper left carnassial (the equivalent of a molar) and exposed pulp (tissue at the center of a tooth).

Bruce Patterson (no relation) is the museum’s curator of mammals. He and his colleagues think the Kenyan lions’ suspiciously smooth teeth and dental injuries could have played a role in their attacks on humans. These types of injuries aren't uncommon, and they can be painful.

“Lions normally use their jaws to grab prey like zebras and wildebeests and suffocate them,” he said in a statement. If you’ve got a mouthful of hurt, you’re not going to leap face-first at a kicking wildebeest. “Humans are so much easier to catch,” Patterson said.

“We humans like to think we’re at the top of the food chain, but the moment we step off our paved streets, these other animals are really on top.”