Let’s talk about poop—ancient poop—ancient human poop and the parasites therein. A field of
anthropology focuses on this very topic. No kidding. Why would anyone want to study this? The answer
is simple. Scientists are interested in understanding how parasitic infections affected our human
ancestors. Seriously!
Humans have played host to more than 300 species of parasitic worms and 70 protozoa (single-celled
organisms) during the past 150,000 years. These infections were cited in some of the earliest written
documents, dating from 3000 to 400 BC. Through paleoparasitology (the study of parasites in ancient
material), scientists examine how human migration spread the inherited parasites around the globe.
Scientists gather their samples from ancient poop, called coprolites. Parasites have been recovered
from dinosaur coprolites that date to the Cretaceous (that is more than 66 million years ago).
So where does one find a sample of ancient poop? In a recent study, scientists did not actually sample
the poop. They sampled the sediment where the poop would have been. Anthropologists collected
sediment from a burial site in Rio de Janeiro, Brazil, which was the gateway to the South American
continent during the colonial period. The scientists collected two sediment samples from every intact
set of remains at the burial site. One sample was collected from the sacrum, the triangular end of the
backbone. A second sample was collected from the interior of the skull. Bum—likely source of poop.
Brain—unlikely source of poop (a negative control).
The scientists rehydrated and treated the sediment samples with a series of chemical applications
before running the samples through modern molecular methods to obtain DNA. They reconstructed
these DNA bits to identify the parasites that infected the body. The scientists used modern fecal samples
to set up positive controls. In particular they examined the samples for the presence of four parasites—
nematode worms (Ascaris sp.), whipworms (Trichiuris trichiura), pinworms (E. vermicularis), and
roundworms (Strongyloides stercoralis). All of the samples tested positive for each of the parasitic
worms, except the roundworm.
The burial site was the mass grave used to bury the victims of the epidemics that plagued (no pun
intended) the area during this time. The parasites examined in this study are typically transmitted
through soil contaminated by human feces through the fecal-oral route. These results reflect a
population living under poor sanitary conditions. Let this be a lesson to you, my fair reader, to always
wash your hands after visiting the loo.
Photo: Coprolite from the Miocene Era, Credit: The Poozeum