In 1898, two maneless lions known as the Tsavo “man-eaters” terrorized an encampment of bridge builders on the Tsavo River in Kenya, killing at least 28 people before they were shot dead by Lt. Col. John Henry Patterson. The lions’ remains were sold to the Field Museum of Natural History in Chicago in 1925, leading to a recent study in collaboration with scientists at the University of Illinois Urbana-Champaign. Hairs extracted from the lions’ broken teeth were analyzed using microscopy and genomics to identify the species they consumed, with the findings reported in the journal Current Biology.
The discovery of hairs in the lions’ teeth was made in the early 1990s by Thomas Gnoske, a collections manager at the Field Museum, who examined the skulls for signs of their diet. In 2001, Gnoske and Julian Kerbis Peterhans first reported on the damaged teeth, hypothesizing that this may have contributed to the lions’ predation of humans, with a preliminary analysis suggesting they consumed eland, impala, oryx, porcupine, warthog, and zebra. A new study facilitated a microscopic analysis of the hairs by researchers from the National Museums of Kenya and the University of Nairobi, alongside a genomic investigation led by U. of I. scholars to determine the prey species and origins of the lions.
The analysis of the hair DNA revealed that the lions had consumed giraffe, human, oryx, waterbuck, wildebeest, and zebra prey, as well as confirming the presence of lion hairs. The lions were found to be siblings sharing the same maternal mitochondrial genome, consistent with an origin in Kenya or Tanzania. The absence of buffalo DNA was surprising, considering buffalo as a preferred lion prey in the region, but historical reports indicated the lions had left the Tsavo area temporarily, potentially explaining the lack of buffalo remains. The study also highlighted the devastation of cattle populations in Africa due to rinderpest.
The researchers highlighted the significance of being able to reconstruct complete mitochondrial genomes from single hair fragments from over 100 years ago, suggesting the potential to further analyze the lions’ diet evolution over time and pinpoint when they began preying on humans. The findings are considered an important expansion of the data that can be retrieved from past specimens, demonstrating the ability to extract valuable genetic details from ancient artifacts. The study was supported by the National Science Foundation and U.S. Department of Agriculture, underscoring the scientific advancements made possible through collaborative research efforts and innovative genomic techniques.
The researchers emphasized the responsible and ethical considerations in handling human remains, opting not to further analyze the human mitochondrial genome discovered in the lion hairs to respect potential descendants in the region today. By using community-based methods to address the human aspects of the study, the researchers aim to ensure a respectful approach to studying the genetic history preserved in the lions’ teeth. The study represents a pioneering application of genomics to explore historical biological artifacts, shedding light on the dietary habits of the notorious Tsavo “man-eaters” and offering new insights into the behavior and evolutionary history of lions in the East African region.