AVMA 2017: Insights for One Health from Millennia Past

When it comes to the issues facing veterinary medicine, physical borders don’t really exist. As human populations spread ever wider, they are more likely to come in contact with domestic and wild animals. That proximity increases the risk for exposure for humans and animals to new viruses, bacteria, and other disease-causing agents.

Food security, antibiotic resistance, and the spread of disease are among the challenges facing veterinarians, physicians, and the public in a more crowded world. That’s why the keynote speaker at the American Veterinary Medical Association Convention in Indianapolis, Indiana, was a person whose global explorations are shedding light on the connections between people, animals and the environment, said AVMA President Tom Meyer, DVM, in his introduction of Paul Sereno, PhD.

What does a paleontologist who digs in the Sahara and Gobi Deserts in search of ancient bones have to do with One Health? Sereno, a professor of paleontology at the University of Chicago and National Geographic Society explorer in residence (think real-life Indiana Jones, minus the bullwhip), brought to life those old bones as they relate to the connections between people, animals, and the environment and the human and animal health crises of today.

Sereno, who went into paleontology after a start as an artist, drew listeners back in time, not decades or centuries or millennia, but geologic time: millions of years. He began with the startling discovery, some 30 years ago, that birds are direct descendants of dinosaurs. Feathers notwithstanding, birds are, in a very real sense, reptiles, the descendants of early reptiles, he says, a fact that can be traced through their genes and every part of their anatomy.

With the story of how the ability to lay eggs allowed animals to spread across the land, free of the water, leading to the development of reptiles (and ultimately the crowning, most diversified group of all, the birds, 10,000 species strong) and mammals (which still have one or two branches that lay eggs instead of giving live birth), Sereno perhaps inadvertently answered that age-old question: Which came first, the chicken or the egg?

“I began to realize that dinosaurs are our closest evolutionary companions,” he said.

That’s because both dinosaurs and the ancestors of humans made a literal evolutionary leap: they went up on two legs. It was the big invention that started the dinosaur revolution and, eventually, the human revolution.

The eventual takeaway, after an engaging exposition that ranged from how reptiles and mammals solved the problem of flight to how humans learned to walk—a task that took millions of years to perfect—is that from a One Health perspective, we’re all in this together. Human culture truly began when we started to come together in large groups and to domesticate animals. And, of course, that was also the origin of crowd diseases and diseases that could be spread between humans and animals.

Most crowd diseases have an Old World origin dating to Neolithic times, Sereno said. Examples include influenza, measles, mumps, and smallpox, which originated with domestic animals; hepatitis B, from apes; and plague and typhus, from rodents. Four are of unknown origin.

Like everything living, diseases have mutated and evolved. We know now from studying the graves of people who died in the 1300s that the plague variant seen today, which is making a comeback in some places such as the Southwest, is not the same as the bubonic plague—better known as the Black Death—that wiped out some 30% to 60% of the humans in Europe during a 14th-century decade of death that rewrote the story of Western culture. And that variant was likely not the same as the one that may have contributed to the downfall of the Roman Empire in the 6th century.

“It’s revolutionizing what we’re learning about the plague, about leishmaniasis, which is shared with our companion animals, about tuberculosis,” Sereno said. “It’s revolutionizing the evolutionary history for One Health.”

Kim Campbell Thornton has been writing about dogs and cats for 32 years. She is the award-winning author of more than 2 dozen books and hundreds of articles on pet care, health and behavior.