Human DNA found in dandelions confirms a tragic legend of history: ScienceAlert

Given half a chance, lions are not above chewing occasionally Homo sapien that could stray into their territory unguarded. Fortunately, few African big cats have ever developed the habit of actively seeking out humans to feed on.

Of course there are exceptions. One of the most infamous incidents occurred in the Tsavo region of Kenya in 1898, when two male lions terrorized workers building a railway bridge over the Tsavo River for months.

The centuries-old teeth of these lions – long mythologized as “man-eaters” – are now revealing new mysteries, including not only whether they ate humans, but also clues as to why.

Using recent advances in techniques for sequencing and analyzing ancient and degraded DNA, researchers from the United States and Kenya examined animal hair stuck in lions’ teeth.

They report their findings in a new study, including specific animals the lions ate.

Findings like these could not only help us verify the facts about the episode, but also better understand what might cause wild predators to behave so unusually.

The first reports of lion attacks occurred in March 1898, shortly after the arrival of Lieutenant Colonel John Henry Patterson, a British army officer and engineer who oversaw the project to connect the interior of Kenya and Uganda by railway.

The British hired thousands of workers to build the bridge, mostly from India, and housed them in camps that stretched for several miles, Patterson wrote.

Patterson initially doubted reports of two workers kidnapped by lions, but was convinced weeks later when Ungan Singh, an Indian military officer accompanying him, suffered the same fate.

Patterson spent the night in a tree and promised to shoot the lion if it returned. He heard “ominous roars,” he wrote, then a long silence, followed by “a great commotion and wild shouts coming from another camp about half a mile away.”

The next morning he learned that a lion had attacked another part of the camp.

So began a lengthy campaign by Patterson and others to kill the culprits: two large, maneless male lions. Maneless males are more common in some regions, including Tsavo, possibly due to local climate or vegetation.

At one point, the attacks stopped abruptly for a few months, Patterson notes, although “we heard from time to time about their looting in other areas.”

When the lions finally returned, they appeared even braver: instead of attacking individually, as before, they often entered camps together.

Patterson ultimately killed both lions in December.

The final lion death toll remains unclear; Some estimates put the number as high as 135, although a 2001 study found the number was probably closer to 30 – a number that, while far smaller, is by no means insignificant.

Patterson kept the lions’ remains and eventually sold them to the Field Museum of Natural History in Chicago in 1925.

Decades later, when ecologist Thomas Gnoske, the museum’s collection manager, found the stored lion skulls, he noticed fragments of hair stuck in exposed tooth sockets.

Some scientists believe that the lions hunted humans precisely because of their damaged teeth, which may have made it difficult to take down larger prey.

In any case, the damage appears to have received clues about the lions’ diet. Gnoske and colleagues have now examined the hair in detail, including microscopic and genomic analyses.

First, they had to confirm the age of the hair, explains co-author Alida de Flamingh, a conservation biologist at the University of Illinois Urbana-Champaign.

“We want to find out whether the DNA has these patterns that are typically found in ancient DNA,” says de Flamingh.

Once the samples were verified, the authors focused on mitochondrial DNA (mtDNA). It is more abundant in cells than nuclear DNA, and hair can also preserve mtDNA and limit contamination, which is helpful with older samples.

​​“And because the mitochondrial genome is much smaller than the nuclear genome, it is easier to reconstruct in potential prey species,” adds de Flamingh.

The hair wasn’t in the best condition, but still provided usable mtDNA. Some of the hair came from the lions themselves.

Most of the rest came from an unsurprising mix of native ungulates – with one notable exception. The teeth of these infamous man-eaters actually contained human hair.

“The analysis of the hair DNA identified giraffes, humans, oryxes, waterbucks, wildebeests and zebras as prey and also identified hairs that came from lions,” write de Flamingh, Gnoske and their team.

The mtDNA of the lions suggests that they were brothers, as suspected. According to the analysis, they had eaten at least two giraffes and a native zebra.

The team also created a database of mtDNA profiles for potential prey species that inhabited the lions’ habitat in 1898.

They note that it was strange to find wildebeest mtDNA since the closest wildebeest lived about 50 miles away at the time. But when Patterson reported a prolonged lull in attacks, perhaps the lions were hunting wildebeest.

It is also notable that only one buffalo hair was found, the authors add, and no buffalo mtDNA. “We know from the diet of lions in Tsavo today that buffalo are their preferred prey,” says de Flamingh.

This could be a clue as to why these lions hunted humans.

“Patterson kept a handwritten field journal during his time in Tsavo,” says paleoanthropologist Julian Kerbis Peterhans of Roosevelt University and the Field Museum. “But he never recorded in his diary that he saw buffalo or local cattle.”

Rinderpest, a viral disease of ungulates, had been introduced to Africa from India years earlier. In the 1890s, buffalo and cattle were wiped out across the region, possibly forcing some lions to seek new prey.

For this study, the researchers refrained from further analyzing human hair to identify potential victims.

“There may still be descendants in the region today, and to practice responsible and ethical science, we use community-based methods to expand the human aspects of the larger project,” they write.

The study was published in Current Biology.