A team of Argentinian scientists from the National Council of Scientific and Technical Research (CONICET) discovered the oldest parasite DNA when they studied the coprolite taken from a rock-shelter in Catamarca Province in northwest Argentina, a place where the remains of an extinct megafauna have been recovered in stratigraphic excavations.
Radiocarbon dating revealed that the coprolite and thus the parasitic roundworm eggs preserved inside dated back to between 16,570 and 17,000 years ago, towards the end of the last Ice Age.
Ancient mitochondrial DNA analysis was used to confirm 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 modern day cats, dogs and foxes.
The discovery marks a number of firsts: it represents the oldest record of an ancient DNA sequence for a gastrointestinal nematode parasite of wild mammals, the oldest molecular parasite record worldwide, and also a new maximum age for the recovery of old DNA of this origin.
For Dr Petrigh, the findings also cast light on both the past and the present. She said: "This work confirms the presence of T. leonina in prehistoric times, presumably even before that of humans in the region, and it represents the oldest record in the world. 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.
More details of this discovery on Science Daily.
(Image Credit: Bas Lammers/ Wikimedia Commons)