In the early 1990s, zoologist Thomas Gnoske identified the skulls of the two lions in the archives of the Field Museum of Natural History in Chicago. These are the remains of the couple of adult men who, in 1898, killed around 30 people in Kenya, most of them Indian workers helping to build a railway bridge over the Tsavo River. The felines, whose story was very popular in the newspapers of the time and which was later told in the film The demons of the nightbecame a fascinating subject of scientific research starting in 2001, when the first analyzes of the remains revealed new aspects that helped explain this strange behavior.
Among the details Gnoske observed in these early analyzes were the thousands of fragmented and compacted hairs from their prey that had accumulated in the cavities of the lions’ broken teeth. “While examining them, I noticed that there were some small hairs stuck among other remains on the surface,” the researcher tells elDiario.es. “That gave me the idea that there might be more material below the surface and that this probably represented what this lion had eaten earlier.”
Two and a half decades later, using sophisticated ancient DNA analysis techniques, their suspicions were confirmed and a team in which Gnoske himself participated was able to collect sufficient numbers of microhairs to identify the species at hand. which they belonged to. In a work published this Friday in the magazine Current biologyThe team determined that Tsavo’s “man-eating” lions preyed on at least six species: giraffes, oryx, waterbucks, wildebeest, zebras and, of course, humans.
A unique diet
The authors examined a separate sample of four individual hairs and three bundles of hair taken from lion’s teeth and focused on mitochondrial DNA (mtDNA). In humans and other animals, the mitochondrial genome is inherited from the mother and can be used to trace matrilineages over time. “And because it is much smaller than the nuclear genome, it is easier to reconstruct in potential prey,” says Alida de Flamingh, a researcher at the University of Illinois at Urbana-Champaign and first author of the study. article.
Our analysis showed that Tsavo lions hunted giraffes, humans, oryx, waterbuck, wildebeest and zebra.
Alida de Flamingh
— Researcher at the University of Illinois at Urbana-Champaign and first author of the paper
Among the most valuable data, scientists were able to confirm that the lions shared the same maternally inherited mitochondrial genome, supporting early reports suggesting they were siblings, and that their mtDNA was also consistent with a in Kenya or Tanzania. The team certified that the lions had consumed meat from at least two giraffes, as well as a zebra likely native to the Tsavo region.
Researchers were also surprised to discover genetic material from wildebeest, because the closest wildebeest population in the late 1890s was about 50 miles away. “This suggests that Tsavo lions may have traveled further than previously thought, or that wildebeest were present in the Tsavo region at this time,” says De Flamingh.
On the other hand, the absence of buffalo DNA and the presence of a single hair of this animal, identified under a microscope, is a detail of great value for scientists, since one of the main hypotheses to explain its attacks on humans is that livestock and buffalo populations in this part of Africa have been devastated by rinderpest, forcing them to look for alternatives.
Although the aim of this study is not to determine the causes that led lions to eat humans, after so many years of study, Gnoske dares to share some impressions. “The rinderpest epidemic certainly affected lions in the Tsavo region in the 1890s, because it wiped out the African buffalo, the main prey of lions in this region,” he explains. “The broken teeth theory doesn’t really hold up as we once theorized. Injuries like those seen during the first man eater They didn’t really affect or limit their diet or their ability to hunt. “In fact, the species found in its teeth exceed, in diversity, anything we currently know for an individual lion.”
Responsible science and ethics
Regarding the human DNA found in the samples, the authors identified hair from one individual, but declined to describe or analyze it further for the present study for ethical reasons. “First, the data analysis only traces one of many ancestral lines (direct maternal lineage) of that person,” notes the lead author. “Second, there may still be descendants in the area today, and to practice responsible science, we are using community-based methods to expand the human aspects of the project.” Anthropological methods require discussions with local institutions and groups about the project, as well as reporting on the detailed human colonial history of that geographic region, which is beyond the scope of this current study, he insists.
This methodology could potentially be used on hairs from broken teeth of older carnivores dating back hundreds or thousands of years ago. The method opens a new avenue of research into the past
Ripan Malhi
— Co-author of the study and head of the research group
Overall, the authors are excited to extend this methodology to analyze the different layers of compacted hair in dental cavities in more detail and apply it in future studies. “You can think of layers in the same way that geologists think of soil layers, where the deeper layers represent historical periods and the surface layers come from current soil deposits,” says De Flamingh. “Similarly, the lower layers of the lower parts of the tooth cavity represent prey eaten in the past and the layers at the top of the cavity are from recently eaten prey.”
In the researchers’ opinion, this type of analysis can provide insight into the human-lion conflict that still affects many communities in the region and Africa in general. “Our results provide information on the ecology and diet of lions in the past, as well as the impacts of colonization on the lives and lands of this region,” he summarizes. Ripan Malhiwho leads the research group. He and his team are convinced that the layered hairs could allow us to go back in time to reconstruct the diets of lions at different ages. “This methodology could potentially be used on hairs from broken teeth of older carnivores dating back hundreds or thousands of years ago,” he concludes. “The method opens a new avenue of research into the past.”
“A technical feat”
Geneticist Carles Lalueza-Fox, specialist in ancient DNA and director of the Natural Sciences Museum of Barcelona, considers this work to be an extremely original application of a subject that seems fictional but actually happened. “The work is part of a new scientific field that I called Museomics“, he explains to elDiario.es. “This field consists of the recovery of genetic material from museum specimens, which allows us to obtain historical information about species in the natural world but also, as in this case, about their prey,” he summarizes. . “To me it looks like a technical feat; The hairs are small and intricate samples, even though they are just over 100 years old.
This seems to me to be a technical feat; The hairs are small and complex specimens, although they are just over 100 years old.
Carles Lalueza-Fox
— Ancient DNA specialist and director of the Natural Sciences Museum of Barcelona
Regarding the ethical concerns of the team responsible for analyzing human DNA, Lalueza-Fox recognizes that it is necessary to be increasingly careful with possible ethical implications in this area, but considers that, if they don’t do individual identification, maybe their position is exaggerated “They could have looked at the population they belonged to and I don’t think they could have reached a level of localization lower than that of Africa from the East to locate their origin,” he said. “And that would have been general enough information.”
