A Dangerous Game of Chicken

Could an H5N1 pandemic from poultry lead to human extinction?

IF FUTURE HUMANS WERE TO GUESS which animal we most revered, depended upon, and loved, it would not be our cat and canine companions, noble horses, or overworked cows. It would be chickens.

Chickens outnumber all other wild birds on the planet. Last year, humans raised more than 85 billion of them for food, just under 10 billion of them in the United States. Never before in human history has such a species been so numerous. And never before has the fate of one species been so closely tied to our own. What might it mean for us, then, that this most essential animal has begun dying from a virus by the tens of millions—dropping dead so quickly that many never have a chance to develop symptoms? And what does it mean that the disease they’re dying from is the same one that experts have long worried might kill us?

Long revered in cultures ranging from ancient Greece and Rome to modern East Africa, China, Japan, and the Middle East, roosters and hens have symbolized courage, fertility, and resurrection. For centuries, chickens were considered oracular and were kept as sources for auguries—divining omens both good and ill. Today, we engineer them in labs, and produce and slaughter them annually by the tens of billions in factories. At processing plants, their flesh is turned into a pink slurry and pumped out of stainless steel tubes to be molded into nuggets. In the United States, we eat more than 100 pounds of them per person each year. At drive-throughs across the country, lines of cars snake through parking lots as customers reach through windows to claim greasy bags of chicken strips, tips, wraps, soups, sandwiches, and salads. On street corners and in grocery stores, the smell of roasted chicken wafts from restaurant kitchens and rotisserie spits. Their feathers fill our pillows and winter coats. We stew them for comfort, and keep them as diapered house companions. We literally eat, sleep, and breathe chicken. These birds are so common now, so abundant, we are leaving a literal strata of chicken bones in the archaeological record. They are also diseased, dying, and dangerous.

H5N1, the highly pathogenic influenza virus some chickens carry, has spread across five continents. The pandemic has killed a wide range of species from birds to mammals, infecting ferrets, mink, otters, badgers, skunks, opossums, critically endangered Amur leopards and tigers, mountain lions, marten and fisher, European polecats, lynx, bobcats, domestic cats, dogs, red foxes, coyotes, raccoons, raccoon dogs, bears of all kinds, seals of all kinds, domestic pigs, sea lions, various porpoises, bottlenose dolphins, short-beaked common dolphins, white-sided dolphins, Chilean dolphins, and others. To date, H5N1 has taken more than 145 million lives—a handful of them human, but most of them, chicken.

We can only lose such a tremendous number of chickens in so short a time because we produce so many chickens at a time—an industrial-scale process that itself drives zoonotic disease risk and spread of infectious disease. To keep up with our insatiable demand, a single chicken-producing facility may keep up to 6 million birds, together in crowded metal barns six hundred feet long, where each is allotted a floor space the size of an iPad. Once inside these facilities, a virus like H5N1 can spread with supernatural efficiency—cycling through hundreds of thousands of birds, or rather hundreds of thousands of nearly identical copies of the same bird, giving it endless opportunities to mutate and acquire the features necessary to infect humans and other species. Through these facilities, we have unintentionally engineered a tremendous threat. We have created the perfect infrastructure to generate and spread dangerous viruses to ourselves, wholesale. And no, this is not a problem we can vaccinate our way out of.

We are leaving a literal strata of chicken bones in the archaeological record. They are diseased, dying, and dangerous.

The USDA’s Agricultural Research Service has warned: “The U.S. currently has the largest, most genetically homogeneous and, thus potentially, the most disease-susceptible population of food animals in the history of mankind,” and that “the emergence of a new disease or a slight shift in the epidemiology of an existing disease could lead to immediate and disastrous results. . . .” That was more than a decade ago, and since then, the problem has only grown, by 200 million chickens a year. We have reshaped and reproduced this animal to fit our every need, distorting it to grotesque proportions like an over-photoshopped image.

In light of our modern habits, researchers at Stanford’s Existential Risks Initiative asked a simple question: Could an H5N1 pandemic from poultry lead to human extinction? Comfortingly, their research indicates probably not, but the models they built do suggest a human death toll on a scale not yet seen—one that could stretch into the billions. (COVID-19 has caused an estimated 7 million deaths, so imagine a virus 143 times as deadly.) Now factor in that, unlike COVID-19, many of the 50 million people who died in the last influenza pandemic were young healthy adults between twenty and forty years old. These projections are not exactly encouraging.

Humans are the most numerous species of large mammal, and chickens, the most numerous species of bird. We made it this way. We chose them. So what happens next? Populations of warm-blooded animals don’t usually make it to this point in nature. They are cut back down to size through predation, starvation, or disease. We are in uncharted waters, and no one knows how this grand human-chicken experiment will end.

We are often reminded: Don’t count your chickens! But, in truth, we couldn’t even if we wanted to. It would take 8,100 years without sleep to count every chicken produced in 2023. If we’d started counting in 6000 bc, when civilization was first developing in the Fertile Crescent and humans were first domesticating chickens, we’d finish counting around 2100. At such a time, our great-grandchildren will be able to report much of what unfolded in the first half of the century: how we survived, what gave our lives meaning, how we treated each other, what we ate.

Ann Linder is an associate director of Policy & Research with the Brooks McCormick Jr. Animal Law & Policy Program at Harvard Law School, where much of her work focuses on the intersections of animal commerce and zoonotic disease.

Bonnie Nadzam is a writer, Zen Buddhist priest and Research Fellow with the Brooks McCormick Jr. Animal Law & Policy Program at Harvard Law School.