All hail Gallus gallus domesticus—we are living in the age of the chicken

One in 23 billion.
One in 23 billion.
Image: AP Photo/Hau Dinh
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Culinarily, chicken has somehow become all things to all people. Boneless, skinless chicken breasts, and the recipes built around them, are stand-ins for bland, unadventurous palates, while a perfect roast chicken recipe has become mark of foodie pride. It’s also a potent symbol of the modern age, and likely to be one of our most easily observable legacies as humans.

Worldwide, we’re eating an awful lot of chickens—about 66 billion birds a year. The sheer volume of those chickens, and the way they’ve been bred for human consumption, is going to leave a distinct imprint on the historical, anthropological, and archeological record. That’s according to a scientific paper published this week in the journal Royal Society Open Science.

The paper concludes:

Modern broiler chickens are morphologically, genetically and isotopically distinct from domestic chickens prior to the mid-twentieth century. The global range of modern broilers and biomass dominance over all other bird species is a product of human intervention. As such, broiler chickens vividly symbolize the transformation of the biosphere to fit evolving human consumption patterns, and show clear potential to be a biostratigraphic marker species of the Anthropocene.

The Anthropocene, which most climate scientists call the current era in the Earth’s history, started when humans became the dominant force shaping Earth’s environment and climate. The chickens we eat now, particularly in the US, are nearly as much an industrial product as plastic and concrete, two of the other defining materials of the time that will be left behind in our garbage piles and scattered throughout the environment.

Humans started to breed broilers, as chickens eaten for meat are called in agricultural circles, to be heavier and to grow faster around 1950, the year that scientists have proposed should mark the beginning of the Anthropocene. As a result, the chickens became cheaper to buy and eat, consumption increased, and the global chicken population skyrocketed. “There are about 23 billion chickens on Earth at any given time, at least ten times more than any other bird, forty times the number of sparrows,” James Gorman writes in The New York Times.

Even though there are so many more chickens now than just a few decades ago, many people in the US actually see fewer bones today. Back in the 1950s, when the era of the modern chicken began, most consumers bought whole chickens. Today, in the US, the National Chicken Council estimates that about 70% of the chicken that leaves processing plants is already boneless, as boneless breasts, thighs, and tenders. Most of the bones that are left behind are pulverized or rendered for use in fertilizer and animal feed, right at the plant, Tom Super, a spokesperson for the council, told Quartz in an email.

Even with that significant dent in the number of chicken bones that are headed into the waste stream, our appetite for chicken leaves a lot of bones behind. They make up a small but weird portion of urban flotsam, as the Instagram account @randomchickenbonesofatl documents.

“Bird bones don’t fossilize well,” Gorman writes. “But many chicken bones go to landfills, where they become mummified as much as fossilized. And there are so, so, so many bones.”

It seems inevitable that future humans (or aliens) will look back through the fossil record and find unimaginable numbers chicken bones. So many, perhaps, that they’ll wonder whether the chickens were the ones breeding us.