Scientists have studied hairs taken from the broken teeth of two notorious ‘man-eater’ lions from the 19th century. Their findings uncovered DNA from various prey species, including giraffes, humans, oryx, waterbucks, wildebeests, and zebras, as well as hairs that belonged to the lions themselves.
In 1898, two male lions caused havoc among a group of bridge builders near the Tsavo River in Kenya. These lions, notably large and lacking manes, would stealthily approach the camp during the night, raiding tents and dragging away their victims. The now-infamous Tsavo “man-eaters” were responsible for at least 28 deaths before they were killed by Lt. Col. John Henry Patterson, the civil engineer overseeing the project. Patterson later sold the remains of the lions to the Field Museum of Natural History in Chicago in 1925.
A recent study by researchers from the Field Museum, in collaboration with scientists from the University of Illinois Urbana-Champaign, involved a detailed examination of hairs meticulously extracted from the lions’ damaged teeth. The study employed microscopy and genomics techniques to identify various species that the lions had preyed upon. The results of this research are published in the journal Current Biology.
The hairs were first discovered in the early 1990s when Thomas Gnoske, a collections manager at the Field Museum, located the lions’ skulls in storage and analyzed them for traces of their diet. He was the first to identify them as fully grown adult males, despite their lack of manes, and also noticed that a significant quantity of broken and compacted hairs had accumulated in the cavities of their damaged teeth over the years.
In 2001, Gnoske and Julian Kerbis Peterhans, a professor at Roosevelt University and an adjunct curator at the Field Museum, reported on the poor condition of the lions’ teeth. They suggested that this condition might have influenced the lions’ tendency to attack humans and noted the presence of hairs lodged in broken and partially healed teeth. Their early analysis indicated that the hairs likely came from species such as eland, impala, oryx, porcupine, warthog, and zebra.
In the new study, Gnoske and Peterhans coordinated a fresh examination of some of the hairs. Co-authors Ogeto Mwebi, a senior research scientist from the National Museums of Kenya, and Nduhiu Gitahi, a researcher at the University of Nairobi, conducted the microscopic analysis. Postdoctoral researcher Alida de Flamingh from U. of I. led the genomic analysis of the hairs alongside anthropology professor Ripan S. Malhi. They focused on a distinct set of four individual hairs and three clusters of hairs found within the lions’ teeth.
Malhi, de Flamingh, and their team work on innovative techniques to uncover historical insights by sequencing and analyzing ancient DNA found in biological artifacts. Their collaboration with Indigenous communities has provided significant findings related to human migration and the historical context of the Americas, contributing to the development of tools for identifying both contemporary and ancient elephant tusks from Africa. They have also made progress in isolating and sequencing DNA from museum specimens and have investigated the migration patterns and genetic history of dogs in the Americas.
During their current study, de Flamingh first examined the remaining nuclear DNA in the lions’ tooth hairs and found indicators of age-related degradation. “To confirm the authenticity of the sample we’re analyzing, we look for patterns typically seen in ancient DNA,” she explained.
After verifying the samples, de Flamingh switched her focus to mitochondrial DNA. Since mitochondrial DNA is inherited maternally, it serves as a tool for tracing familial lines across generations.
Focusing on mtDNA in hair offers several benefits, the researchers noted. Previous studies have shown that the structure of hair preserves mtDNA well, safeguarding it from contamination. Additionally, mtDNA is usually found in greater quantities than nuclear DNA within cells.
“Moreover, because the mitochondrial genome is considerably smaller than the nuclear genome, it is easier to reconstruct in the potential prey species,” stated de Flamingh.
The team created a database of mitochondrial DNA profiles for various potential prey species to compare with those obtained from the collected hairs. They considered the species suggested by prior analyses and those known to exist in Tsavo during the lions’ time.
The researchers also devised methods to extract and analyze the mtDNA from the hair samples.
“We managed to obtain DNA even from hair fragments shorter than the nail on your pinky finger,” de Flamingh remarked.
“Typically, when trying to obtain DNA from hair, scientists focus on the follicle, which contains a lot of nuclear DNA,” Malhi pointed out. “However, these were hair shaft fragments over 100 years old.”
This research provided a wealth of information.
“The DNA analysis of the hair revealed that the lions hunted giraffe, human, oryx, waterbuck, wildebeest, and zebra, in addition to hairs from the lions themselves,” the researchers noted.
The findings indicated that the lions shared a maternal lineage from the mitochondrial DNA, aligning with earlier speculations that they were siblings. Their mitochondrial DNA also suggested origins in Kenya or Tanzania.
The team determined that the lions preyed on at least two giraffes and a zebra likely from the Tsavo area.
Surprisingly, they discovered mitochondrial DNA from wildebeest, given that the nearest wildebeest population in the late 1890s was approximately 50 miles away. However, historical accounts indicated that the lions had left the Tsavo region for about six months before returning to attack the bridge-builders’ camp.
Additionally, it was unexpected that no buffalo DNA was found, with only a single buffalo hair identified through microscopy. “Today, we know that buffalo is a preferred prey for lions in Tsavo,” de Flamingh mentioned.
“Colonel Patterson maintained a handwritten journal during his time in Tsavo, yet he never noted seeing buffalo or local cattle,” Kerbis Peterhans recalled.
During that period, cattle and buffalo populations in the region faced decimation due to rinderpest, a contagious viral disease introduced to Africa from India in the early 1880s, as noted by Kerbis Peterhans.
“It nearly eradicated cattle and their wild counterparts, including cape buffalo,” he added.
The mitochondrial genome from the human hair possessed a widespread geographic distribution, but the scientists chose not to further describe or analyze it in this study.
“There may be descendants still present in the area today, and to ensure ethical scientific practice, we are employing community-based methodologies to enhance the human dimensions of this larger project,” they stated.
The new discoveries significantly broaden the range of data that can be extracted from historical skulls and hair samples, according to the researchers.
“We now understand that we can reconstruct complete mitochondrial genomes from individual hair fragments over a century old,” de Flamingh concluded.
The researchers noted that thousands of hairs were lodged in the lions’ teeth, compacted over several years. Future analyses are expected to partially reconstruct the lions’ diets over time, potentially identifying when their human predation behavior began.
Malhi is also affiliated with the Carl R. Woese Institute for Genomic Biology at U. of I.
This research received support from the National Science Foundation and the U.S. Department of Agriculture.
