Disturbing diets of "man-eating" lions from the 19th century discovered

In 1898, an encampment of bridge builders on the Tsavo River in Kenya felt tremors of terror. The cause? Two massive and maneless male lions had decided to make the camp their nightly haunt.

This is not about a couple of wandering cats. This is about two fearless, hefty creatures that took the darkness as a shroud to raid tents and drag off victims.

The infamous man-eating lions of Tsavo were said to have killed at least 28 people before Lt. Colonel John Henry Patterson, the civil engineer of the project, put an end to their reign of terror.

These lions weren’t forgotten, however. In 1925, Patterson sold their remains to the Field Museum of Natural History in Chicago. Fast forward to the present day, these remains have become the subjects of an intriguing study.

Tsavo man-eating lions

Recently, researchers from the Field Museum collaborated with scientists at the University of Illinois Urbana-Champaign to shed light on some previously unexplored aspects of these lions.

The experts used microscopy and genomics to identify some of the species the Tsavo man-eaters consumed.

The findings, now published in the journal Current Biology, uncover compelling new details about these maneless predators.

Human hairs in lions’ teeth

The original discovery of the hairs began in the early 1990s by Thomas Gnoske – a collections manager at the Field Museum. While examining the lions’ skulls for signs of their dietary habits, Gnoske made several intriguing discoveries.

He was the first to conclude that despite being maneless, these lions were fully grown older adult males. In addition, he uncovered that thousands of broken and compacted hairs had accumulated in their damaged teeth throughout their lifetimes.

In 2001, Gnoske, along with Julian Kerbis Peterhans, a professor at Roosevelt University and Field Museum adjunct curator, first reported on the damaged condition of the lions’ teeth and the presence of hairs embedded in the exposed cavities.

Initial analysis suggested the hairs were from eland, impala, oryx, porcupine, warthog, and zebra.

Fast forward to the present day, and the recent study has enabled a more in-depth examination of the hairs. The microscopic analysis was conducted by Ogeto Mwebi, a senior research scientist at the National Museums of Kenya; and Nduhiu Gitahi, a researcher at the University of Nairobi.

DNA investigation of lions in Tsavo

Alida de Flamingh and Ripan S. Malhi from the University of Illinois Urbana-Champaign led a genomic investigation of the hairs. They focused on four individual hairs and three clumps extracted from the lions‘ teeth.

The investigation revealed familiar signs of age-related degradation in the nuclear DNA remnants in the lions’ teeth. Once authenticated, de Flamingh geared her focus towards mitochondrial DNA (mtDNA).

This type of DNA is inherited from the mother side and can be used to trace lineage through time. So, why focus on mtDNA? For one, it’s more abundant than nuclear DNA in cells and easier to reconstruct in potential prey species.

DNA of Tsavo’s man-eating lions

The researchers built a database of mtDNA profiles of potential prey species and compared them with the mtDNA profiles obtained from the hairs.

“We were even able to get DNA from fragments that were shorter than the nail on your pinky finger,” noted de Flamingh.

“Traditionally, when people want to get DNA from hairs, they’ll focus on the follicle, which is going to have a lot of nuclear DNA in it,” Malhi said. “But these were fragments of hair shafts that were more than 100 years old.”

Lions’ dietary preferences revealed

Analysis of the hair DNA identified giraffe, human, oryx, waterbuck, wildebeest, and zebra as prey. Interestingly, there were also hairs that originated from other lions.

The findings suggested that the lions were siblings and had consumed at least two giraffes, besides a zebra likely from the Tsavo region.

Surprisingly, there was even wildebeest mtDNA present. This was unexpected, as the nearest wildebeest population during the late 1890s was about 50 miles away.

In contrast, the absence of buffalo DNA and the presence of only a single buffalo hair was also unexpected. Today, buffalo is the preferred prey for lions in Tsavo.

Linking history and science

Perhaps the most moving part of this story is the connection to the past. Julian Kerbis Peterhans mentioned a historic facet to this investigation – a handwritten field journal kept by Colonel Patterson during his time in Tsavo.

Patterson’s accounts didn’t mention buffalo or indigenous cattle, most likely because these populations were devastated by a viral disease called rinderpest brought to Africa from India in the early 1880s.

Significance of the study

Beyond the fascinating insights about the Tsavo man-eaters, this research is a leap forward in scientific exploration.

We now know that we can reconstruct complete mitochondrial genomes from single hair fragments that are over a century old! And, as there are thousands of hairs compacted in the lions‘ teeth over time, further analyses might help reconstruct their diet over time and perhaps pinpoint when they began preying on humans.

The study, supported by the National Science Foundation and the U.S. Department of Agriculture, is also a testament to the advancements in biotechnology.

Unexpected sources of knowledge

“As biotechnologies advance, there are unexpected sources of knowledge, in this case genomics, that can be used to inform about the past,” said Ripan Malhi.

“Our results inform on the ecology and diet of lions in the past as well as on the impacts of colonization on life and land in this region of Africa.”

With the methodology created in this study, the possibility of getting DNA from hairs in the broken teeth of more ancient carnivores, dating back hundreds to thousands of years ago, is now a reality.

The study is published in the journal Current Biology.

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