A pile of ancient puma poo contains the “oldest record in the world” of parasite DNA, providing an opportunity to better understand the paleobiological history of prehistoric ecosystems on Earth.
An interdisciplinary team of archaeologists and biologists found the coprolites – a fancy word for fossilized feces – in Peñas de las Trampas, an archaeological rock shelter in the southern Andean Puna of Argentina. The area was once home to some of the earliest humans and now-extinct megafauna that pumas would have preyed upon, like giant ground sloths and other herbivores such as American horses and South American camelids.
Publishing their work in Parasitology, the researchers extracted DNA from the poop and eggs for molecular identification, confirming both that the poo was that of a Puma concolor and that the eggs were those of Toxascaris leonina, a roundworm that infects the gastrointestinal tract. Radiocarbon dating suggests that the roundworms are up to 17,000 years old.
Altogether, it is the oldest molecular parasite ever recorded and supports the presence of the parasite in America since the Pleistocene.
“While we have found evidence of parasites in coprolites before, those remains were much more recent, dating back only a few thousand years," said study author Romina Petrigh in a statement. "The latest find shows that these roundworms were infecting the fauna of South America before the arrival of the first humans in the area around 11,000 years ago.”
The area surrounding the shelter was likely wetter than it is today, providing great habitat for megafauna at the time. Serendipitously, dry, cold, and salty conditions in the years following the Holocene prevented the DNA from breaking down.
"I was very happy when I discovered how old this DNA was. It's difficult to recover DNA of such an old age as it usually suffers damage over time,” said Petrigh. “Our working conditions had to be extremely controlled to avoid contamination with modern DNA, so we used special decontaminated reagents and disposable supplies. Several experiments were performed to authenticate the DNA sequences obtained and the efforts of the team of researchers who participated was essential."
T. leonina is still found in the digestive tracts of modern cats, dogs, and foxes and its presence in ancient puma poop changes what we once knew about transmission methods. It was once believed that the parasite transferred to wild carnivores from domestic dogs and cats, however, that is no longer the case.
The puma poo confirms the presence of the carnivores in the region during the Pleistocene, adding depth to our understanding of the area towards the end of the last ice age. Furthermore, the high number of eggs also suggests that the parasite would have threatened the health of both carnivores and humans alive at the time.