(Credit: By Donald Trung Quoc Don (Ch? Hán: ???) – Wikimedia Commons.(Want to use this image?) – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=75874833)

I always enjoy writing about cats and dogs, but I had an especially good time covering this story on ancient dog poop for Science last week.

Here’s the gist: A team of molecular archaeologists (cool job!) had spent six years collecting ancient human feces (recovered from archaeological sites) around the world, in hopes of figuring out how the diet of our species has changed over time. (Such changes are reflected in our microbiome–the vast populations of bacteria that inhabit our guts–and they show up in our poop.). But when they began analyzing their specimens, the data didn’t seem human.

So they created an artificial intelligence program to help them sort human poop from other types of poop. The upshot: A remarkable number of their samples weren’t from people–they were from dogs. In one especially surprising case, feces recovered from a 17th-century chamber pot had been made by a canine. How it got in there, no one knows.

So why is so much dog poop showing up in places where we would expect to find human poop? One obvious answer is that dogs have lived in close quarters with us for thousands of years, even if we haven’t shared our beds with them until recently. Another explanation: Dogs, unlike humans, are more likely to poop out in the open, where a quick dry from the sun might help preserve it.  So a lot more dog poop may be being preserved than human poop.

Whatever the reason, an analysis of these ancient canine feces could reveal important shifts in the human-dog relationship over time. The wolf ancestor of dogs subsisted on a purely carnivorous diet. And early dogs would have too. But as we settled down and began cultivating different types of food (and feeding these scraps to our dogs), our canine companions would have begun to become more omnivorous. First their diet would have changed. Then their microbiome would have changed. And finally, their genes would have changed to adapt to this diet. (We already know that dogs have evolved multiple copies of the gene for amylase, a protein that breaks down starch.)

All of these changes should be reflected in ancient dog feces, allowing us to trace some of the most important timepoints in dog history–all thanks to a bunch of ancient poop.

As we all deal with the new coronavirus, SARS-CoV-2, I’ve been reminded of another plague: The Black Death, the most devastating pandemic the world has ever seen. By some estimates, as much as half of Europe’s population perished, and more than 100 million people died across the globe.

As I write in my book, Citizen Canine, some scholars believe that cats could have prevented the plague. That is, if Medieval Europeans hadn’t nearly wiped them out.

The hysteria appears to have begun in 1233 AD when Pope Gregory IX vowed to stamp out what he viewed as the growing threat of paganism in Europe.  As I write in my book:

In his Vox in Rama of 1233, the Pope warns German bishops about an evil in their midst. He describes the initiation ceremony of a cult that meets in caverns beneath homes. The followers light candles and chant. Eventually, he claims, “a black cat… with an upright tail descends backwards down a statue, which is usually at the meeting. The postulant first kisses the cat’s rear, then [so does] the master of the sect, and then the other individuals who are worthy of honor and perfect… Then they face the cat in turn… and say, ‘We know the master… and we obey to you.’” … Finally, a strange creature appears. “His upper body shines with rays brighter than the sun, the lower part is hairy like a cat.”

Gregory IX authorized the use of any and all force to rid Europe of these witches. “No vengeance against them is too harsh,” he wrote. The fate of the cat was sealed. Now seen as an incarnation of Satan, Europeans slaughtered them by the thousands. People stoned them, drowned them, and burned them at the stake.

In Classical Cats, historian Donald Engels estimates that by 1700 tens of millions of the animals had been massacred throughout Europe. In some villages it was impossible to find a cat, and black ones were virtually unheard of. Felines are master hunters, and without enough cats around, Europe’s rodent population exploded. Plague-carrying black rats swarmed the continent and grew to unprecedented size.

So could cats have stopped black rats, and the spread of what came to be known as “The Black Death”? We may never know. But I’m still grateful to have my two little demons at home.

Image by Somraya from Pixabay

Much of dog domestication is still shrouded in mystery. We don’t know where dogs first evolved, for example, or even when this happened.

So we’ve filled these blank pages with a lot of speculation. Early dogs must have been working animals, because why else would nomadic humans–living from hunt to hunt–have brought them into their fold? And we must have first been attracted to dogs because their faces–with their big eyes and rounded foreheads–reminded us of our own infants. Now, a couple of new studies are lending credence to these ideas.

In the first, researchers debunk a popular hypothesis about ancient dog spines. Archaeologists have discovered numerous ancient dogs with spondylosis deformans, a condition in which extra bone grows on the spine. Because cattle and sled dogs also sport this disease, scientists have long assumed that it buttresses the idea that ancient dogs worked for us, pulling sleds and other heavy loads as we traveled across vast plains. But the new study finds that most older dogs–even those that have never carried a pack in their life–have the condition, and that it’s present in wolves as well. Instead, spondylosis deformans seems to be a marker that early dogs reached old age. And this in turn suggests that they had someone taking care of them, namely humans.

The second study also concerns the early days of dogs, as well as something familiar to most dog owners: puppy dog eyes. These big, sad eyes seem to remind us of the expressive faces of babies, cajoling us into giving our canine pals a hug–or their favorite treat. The study finds that the facial muscles that make this expression possible are mostly absent from wolves, suggesting they’re something dogs evolved over the course of their time with us. And since our ancestors probably had the same emotional response to this expression that we do, the researchers say humans likely had a heavy hand in helping this trait evolve.

There’s still much we don’t know about the early days of dogs. And there may be some things we may never know, like how exactly the wolf became the dog. But with every new study, the picture becomes just a little bit clearer.