The Microscopic vs. the Macroscopic at the Library

by Bill Peak

I read Barbara Tuchman's National Book Award-winning A Distant Mirror: The Calamitous Fourteenth Century when it first came out in 1978. I'd met my wife, a professional historian, two years earlier, and I was probably trying to impress her. It was, after all, a pretty thick book.

But it was also a page-turner. I had always been fascinated by deep history—the Neolithic, the Roman Empire, the Middle Ages—times that were so long ago, and so different from our own, as to appear almost fanciful, alien, more a product of science fiction than history. Yet these were times that did in fact exist, times when someone who thought his life as normal as we think our own might have found himself, on an errand, walking past the coliseum, heard the cheers coming from within, smelled the dust and the animals, wondered, absently, about the action taking place on the other side of that wall.

This was the sort of history Tuchman delivered, a story at once both familiar and bizarre. And part of what made her tale of the fourteenth century seem so exotic was the arrival in that God-bound world of an invisible, inscrutable force that killed people without regard for the way they had lived their lives—the devout and the debauched fell prey in equal numbers. I still remember a sentence Tuchman wrote about the Black Death: “One-third of the world died.” If that doesn't chill your bones, I don't know what will.

But it also fascinated me. After Tuchman, I read everything I could get my hands on about the Bubonic plague, and, eventually, wrote a novel about one of its earlier visitations—Justinian's Plague, which decimated the so-called “Dark Ages.”

After The Oblate's Confession was published, I thought my interest in plagues would wane. But then, in an obscure meat market in China, a virus particle so small it wouldn't be visible under a light microscope leapt to a human from an animal carcass … and then continued leaping from person to person, continent to continent. Covid. The world drew in on itself. Millions died. It all became too real.

And so it was that when I saw Jonathan Kennedy's Pathogenesis: A History of the World in Eight Plagues on the library's New Books shelf, I jumped at the chance to read it—my interest now decidedly less abstract, more sober, than before.

Which was fitting, as it is a sober picture of the effect infectious diseases have had on human history that Kennedy delivers. And it upsets a lot of apple carts. A perfect example is the explanation he gives for the way our species managed to steal front and center on the world's stage.

For years we have been taught that Homo sapiens replaced Neanderthals so quickly because we were smarter. We painted Lascaux; they couldn't even paint themselves. They were Neanderthals—the word itself a synonym for dimwitted. The poor things couldn't compete. We thrived; they died.

But recent research has shown that Neanderthals did paint cave walls; they buried their dead, adorned themselves with ochre pigments, and collected materials from their environment for what appears to have been purely aesthetic reasons—all evidence of the sort of symbolic thought that was supposed to have given our Homo sapiens ancestors the mental edge. According to Kennedy, the real difference between the two hominin lines lay in their immune systems.

When Homo sapiens left Africa for Europe some 50,000 years ago, they carried with them immunities their ancestors had acquired over millions of years living on a continent that teemed with animals—animals whose viruses and bacteria, like those in that meat market in China, regularly made the leap to humans. Neanderthals, on the other hand, had lived for hundreds of thousands of years on a continent with far fewer animals and, therefore, far fewer opportunities to acquire zoonotic diseases. Furthermore, the Last Glacial Period had thinned Neanderthal populations to the point that they had become dangerously inbred.

All of which meant that, when they finally did meet, Homo sapiens with their genetic diversity (estimated to have been four times that of Neanderthals) would have developed resistance to Neanderthal viruses and bacteria long before Neanderthals could develop a similar resistance to all the exotic illnesses Homo sapiens were then introducing into Europe.

And so it is that we may well have infectious diseases to thank for the fact that Sophia Loren looked like Sophia Loren and not some beetle-browed Neanderthal. If you'd like to learn more about the ways in which epidemics and pandemics have shaped our species and its cultures, I cannot recommend Jonathan Kennedy's Pathogenesis too highly. Like Jared Diamond's paradigm-breaking Guns, Germs, and Steel, it will change forever the way you look at the world.