By isolating and sequencing DNA from the compacted hairs recovered from the teeth of two specimens in the 1890s Tsavo lion museum collection, researchers discovered that Kenya’s historic lions ate a variety of species, including humans, giraffes and wildebeest. The results were published in the Cell Press Current Biology journal.
“As biotechnology advances, unexpected sources of knowledge emerge, in this case genomics, which can be used to provide information about the past,” says Ripan Malhi (@MalhiRipan) of the University of Illinois Urbana-Champaign. “Our results inform about the ecology and diet of lions in the past, as well as about the impacts of colonization on life and land in this region of Africa,” he adds.
“A key part of this study was the development of a method to extract and analyze DNA from the single hairs of prey species found in the teeth of historical museum specimens,” says Alida de Flamingh (@adeflamingh), also from the University of Illinois Urbana-Champaign.
“Our analysis showed that the historical Tsavo lions ate giraffes, humans, oryx, waterfowl, wildebeest and zebras, and we also identified hairs originating from lions. This method can be used in many ways, and we hope that other researchers apply it to study the DNA of prey from skulls and teeth of other animals,” she explains.
The study’s co-author, Tom Gnoske, of the Field Museum of Natural History in Chicago, was the first to consider the possibility of reconstructing the diet of these historical lions using prey hairs from their skulls, the researchers say. With collaborators in Kenya, he began identifying the hairs through microscopy.
While conducting research on ancient DNA from other animals at the Field Museum, the Illinois team conceived of adding genomics as a complementary approach to studying those compacted hairs.
The Tsavo lions in the new study showed dental lesions, including partially fractured canines that exposed cavities where the hairs of their prey had accumulated over time.
From these dental cavities, the researchers extracted DNA from individual hair shafts and from small clusters of hair fragments.
Six prey species
Although the DNA from these samples was degraded in typical ways for historical or ancient DNA, the researchers managed to reconstruct it in some samples to identify the species from which the hairs originated. They ended up identifying six prey species, including the giraffe, the human, the oryx, the waterfowl, the wildebeest and the zebra.
The DNA data narrowed the giraffe sample to a Masai giraffe subspecies from southeastern Kenya. The researchers also found that the Tsavo lion DNA most closely resembled that of other lions from East Africa in Kenya and Tanzania. They said they were surprised to find wildebeest hairs, noting that this raises questions about their distribution in the past.
“It suggests that the Tsavo lions may have traveled farther than previously thought, or that wildebeest were present in the Tsavo region during that period,” says Flamingh. “The nearest grazing area for wildebeest was more than 80 kilometres from the site where the lions were killed in 1898, at the Tsavo-Athi confluence.”
The researchers say they are eager to explore the findings in even greater detail. For example, they suggest that layered hairs may allow them to rewind time to reconstruct the lions’ diet at different ages.
This analysis could help understand the conflicts between humans and lions that continue to affect communities in Africa, where lions may attack wild, domestic, and human animals. The method also holds promise for studies of even older specimens.
“This methodology could potentially be used on hairs from broken teeth of older carnivores, hundreds to thousands of years ago,” says Malhi. “The method opens a new avenue of investigation into the past,” he concludes.
