They say big things come in small packages. This is
certainly the case with archaeology. We can take the smallest bit of evidence –
a fragment of bone, a shard of pottery – and extract a wealth of information
from the pieces of human history buried within the archaeological record. And
one of these small parcels of the past offers an array of cultural, biological and
environmental information. I’m referring to ancient poo.
Since we’ve already explored the myriad ways humans emit
odor (last week’s Why We Stink!), I
felt it only natural to highlight one of our smellier byproducts, feces. And
from the standpoint of a bioarchaeologist, who relies on ancient skeletons to
piece together history’s complex puzzle, I’ve developed a respect and admiration
for the excrement of yore. So let’s take a look at these piles from the past,
otherwise known as “paleofeces.”
Everything we consume traverses the long and winding road of
our GI tract, providing nutrients and energy along the way before being deposited
as waste. Just as people poo today, they were pooing in the past, and occasionally,
a lucky archaeologist will stumble upon a pile. Lo and behold, a window to the
past is thrown open.
But we’re going to home in on the human version of these exotic treasure troves and explore the variety of information gleaned from ancient
turds.
I bet you’re wondering how a pile of poo can be preserved
for thousands, or even millions, of years. Well, like any bit of archaeological
data, the conditions must be ripe for preservation. In the case of paleofeces,
they manage to survive when they become desiccated (dried out) or fossilized (turned
to stone). As the poo dries and hardens, its contents become fixed. The
poo must then be reconstituted, or restored to its original consistency, which
is done using special solutions that help preserve what’s tucked inside. Interestingly, as the poo is reconstituted, not only does it offer up its contents,
it also emits its original odor!
Once the poo is soft and pliable, the investigation can
begin.
For anyone who has ever eaten whole-kernel corn, you know that the kernels magically reappear in your excrement (my fellow firefighters referred to
them as “tracers”). The study of paleofeces works on this same principle, for ancient
poo reveals a lot about the foods that were consumed, especially plants. Pollen
helps us identify the plant species, as do the phytoliths, the portion of the
plant composed of silica, which resists decay (and digestion). And why are
plants important? Plant consumption not only tells us about diet (what people
were eating), and environment (what conditions they experienced), it also helps
us reconstruct when domestication took place in different parts of the world.
By identifying the plants and then dating the poo, we can obtain the “when” and
“where” of agriculture.
But plants aren’t the only things recovered from paleofeces.
In many cases, critters are lurking from within, mainly in the form of
parasites.
Parasites are organisms that take up residence on or within
a host, drawing nutrients (at the host’s 
expense) in order to stay
alive and reproduce. Since many parasites occupy the gastrointestinal tract,
they are passed out of the body during defecation where they can then be spread
to new hosts (which is why hand washing is so vital). When parasites are discovered
in paleofeces, they provide information about health and nutrition among
ancient populations (it’s hard to be healthy with a belly full of worms). The
study of ancient parasites has become so popular it has now evolved into its
own specialty: paleoparasitology.
expense) in order to stay
alive and reproduce. Since many parasites occupy the gastrointestinal tract,
they are passed out of the body during defecation where they can then be spread
to new hosts (which is why hand washing is so vital). When parasites are discovered
in paleofeces, they provide information about health and nutrition among
ancient populations (it’s hard to be healthy with a belly full of worms). The
study of ancient parasites has become so popular it has now evolved into its
own specialty: paleoparasitology. 
So where do we find these valuable little nuggets? They show
up in the ground, in ancient latrines, in mummified corpses, and even in the
bog bodies of northern Europe. And they’re providing a vast array of
information about our past.
Evidence for people in North America was pushed back a few
thousand years when a fourteen-thousand-year-old pile of poo was discovered in Oregon. And the
earliest evidence for the domestication of dogs came from human coprolites in
Texas, dating to over nine thousand years old. Unfortunately, the dog ended up on the
menu, but it’s still a cool discovery. And in a bit of poetic justice for
critters, the oldest known human hair was recently discovered in of all things,
a crusty little hyena turd recovered from a cave in South Africa.
All that from simple dung.
But you don’t have to be an archaeologist to appreciate the
value (and beauty) of ancient poo. Thanks to some inventive jewelry designers, you can now adorn yourself or your loved one
with dino droppings. So the next time that birthday or anniversary rolls
around, say “I love you” with a bit of biological bling.
Who says you can’t polish a turd?...
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