You know how cats and dogs can get parasites like roundworms? Well, their larger kin can, too. And just recently a team of Argentinian scientists from the National Council of Scientific and Technical Research discovered that roundworms go back at least as far as big cats themselves.
While studying a rock shelter in Argentina’s Catamarca Province, where the remains of now-extinct megafauna have been recovered before, the researchers located a coprolite—petrified feces—from a large wildcat and brought it back to their lab. When they examined the coprolite, they were able to see roundworm eggs in the cat’s feces.
The researchers then had radiocarbon dating done on the coprolite to see how old it was, and it turned out that the poop and the parasite eggs dated back to between 16,570 and 17,000 years ago, towards the end of the last Ice Age. Mitochondrial DNA analysis was used to confirm that the coprolite came from a puma (Puma concolor) and that the eggs belonged to Toxascaris leonina, a species of roundworm still commonly found in the digestive systems of dogs, cats, and foxes.
“While we have found evidence of parasites in coprolites before, those remains were much more recent, dating back only a few thousand years,” said lead researcher Dr. Romina Petrigh. “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 climate at the time the puma decided to relieve itself in that Argentinian rock shelter, located at Peñas de las Trampas in the southern Andean Puna, is thought to have been wetter than today’s, making it a great habitat for megafauna like giant ground sloths and smaller herbivores like American horses and South American camelids, which the pumas may have preyed on.
It’s very unusual for mitochondrial DNA to survive reasonably intact for 17,000 years, but the researchers explain that the arid, cold, and salty conditions that took hold at the Peñas de las Trampas site since the onset of the Holocene would have helped to reduce the breakdown of the DNA.
“It’s difficult to recover DNA of such an old age as it usually suffers damage over time,” Petrigh said. “Several experiments were performed to authenticate the DNA sequences obtained and the efforts of the team of researchers who participated was essential.”
The discovery of prehistoric parasites marks a number of firsts: it’s the oldest record of an ancient DNA sequence for a gastrointestinal nematode parasite of wild mammals, the oldest molecular parasite record worldwide, and a new maximum age for the recovery of old DNA of this origin.
This finding has implications for parasites in modern times as well. “The common interpretation is that the presence of T. leonina in American wild carnivores today is a consequence of their contact with domestic dogs or cats, but that should no longer be assumed as the only possible explanation,” Petrigh said.