Did Dental Disease Turn Tsavo Lions into Man-Eaters?

Warning: Today’s post has some rather gruesome parts to it, as we bring you the story of two of our wild cousins who were famous for all the wrong reasons. You’ve been warned.

The Tsavo man-eaters

 Every once in while, you hear of a “man-eating” lion, but why do some lions choose to hunt humans instead of the four-legged hoofed animals that are their usual prey? A new study recently published in Scientific Reports looked at “dental microwear” to see what they could learn about lions' eating behaviors from evidence left behind on their teeth. The work suggests that at least in some cases, the answer to "Why?" could be dental injury and disease.

The "Tsavo man-eaters" today, in a diorama at the Field Museum
in Chicago. The skins were sold to the museum for $5,000 some 25 years
after the lions' death.
By Superx308 Jeffrey Jung, CC BY-SA 3.0, via Wikimedia Commons.

Two of the lions whose teeth were examined were the famous Tsavo man-eaters of 1898. These were maneless male lions that, according to the most spectacular estimate, killed up to 135 people. The actual number has been shown to be much lower, about 35 people, but that is still a lot. The victims were Indian members of a construction crew building a railroad bridge over the Tsavo River in Kenya. The terror at the railroad workers’ camp began in March 1898 when, shortly after their arrival, men started to go missing. Searches turned up mutilated bodies. Efforts to protect the camp with thorny barricades failed, as the lions found a way through the barriers. One worker wrote that the lions’

“very jaws were steeped in blood. Bones, flesh, skin and blood, they devoured all, and left not a trace behind them.”

Lieutenant Colonel J. H. Patterson, an engineer and leader of the expedition, wrote of hearing the cats crunching the bones of one of their victims, purring as they did so.

The first of the two Tsavo man-eating lions (FMNH 23970)
shot by Lieutenant Colonel Patterson, 1898.
 By Field Museum [Public domain], via Wikimedia Commons

Patterson would eventually kill both of the lions, the first on December 9, 1898. That lion was over nine feet long from his nose to the tip of his tail, and it took eight men to carry him to the camp. The second lion, killed three weeks later, was of similar size. Both lions had injuries to their skin from the thorns that were used to try to protect the workers’ camp. Patterson kept the skins as trophy rugs for some 25 years, before selling them to the Field Museum in Chicago for $5,000. They were stuffed and placed on display, and they can still be seen there.

(The 1996 movie The Ghost and the Darkness, starring Michael Douglas and Val Kilmer, dramatized the events in the construction camp.)

What the teeth say

Although Patterson wrote of hearing the lions crunching their victims’ bones, the evidence left behind on the cats’ teeth tells a different story. The authors of the paper in Scientific Reports used something called dental microwear texture analysis to determine what the lions were eating. The results suggest that, in the period just before their death, the Tsavo man-eaters were not consuming the bones of their prey and were instead consuming only the softer tissues.

The second Tsavo lion shot by Lieutenant Colonel Patterson.
This lion is now known as FMNH 23969.
Public domain, via Wikimedia Commons.

The teeth also showed a possible reason the lions became man-eaters. One of the cats had a serious dental injury, a broken lower tooth, and the pain from that may have made it impossible for him to kill normal prey in the usual lion way, through suffocation. That could have prompted him to pass up his usual prey in favor of something softer, slower, and easier to catch, like people. The other lion also had dental injuries, but his were less severe. Interestingly, for the second lion, humans made up a smaller part of his diet than for the first lion—13% versus 30%. And those numbers, by the way, also show that humans still made up a relatively small part of both lions’ diets.

We think it’s worth noting that it seems that, even for the “man-eaters,” humans were not at the top of the menu. The lion with the severely injured tooth may have turned to the workers’ camp for prey because he was in too much pain to routinely catch and kill other prey. The second lion may have been a true copycat, learning from his companion how to take easy prey from the camp.

If you have about nine minutes, this video is well worth a look. It's from before the most recent paper was published, but you can see researcher Larisa DeSantis demonstrating how molds of the lions’ teeth were made. Interesting!

Sources

Larisa R. G. DeSantis and Bruce D. Patterson, “Dietary Behaviour of Man-Eating Lions as Revealed by Dental Microwear Textures,” Scientific Reports 7, April 19, 2017, doi:10.1038/s41598-017-00948-5, https://www.nature.com/articles/s41598-017-00948-5

J.H. Patterson, The Man-Eating Lions of Tsavo and Other East Africa Adventures, 1907.

Paul Raffaele, “Man-Eaters of Tsavo,” Smithsonian, January 2010, http://www.smithsonianmag.com/science-nature/man-eaters-of-tsavo-11614317/