A new study suggests that chickens may have been domesticated thousands of years later than previously believed, and may have originally been regarded as exotic animals or culturally revered animals — not food. The study also suggests that rice may have played a key role in this process.
Chicken may be extremely common nowadays (in farms and other growing facilities), but they are a junglefowl species originating in Southeastern Asia. For over 2,000 years, they’ve played an important role in human society as one of the main species grown for food, but when and how this domestication started is still unclear.
Some genomic studies have suggested that chickens were domesticated some 7,000 or 8,000 (or even up to 10,000) years ago in China, Southeast Asia, or India, reaching Europe some 7,000 years ago. But many researchers weren’t convinced.
If chickens were indeed domesticated for so long, why weren’t they showing up in more archaeological sites or cultural representations? The earliest artistic mentions of chickens in Europe are found on Corinthian pottery of the 7th century BC, so “only” 3,700 years ago. In fact, much of the evidence in favor of this early domestication theory comes from a landmark study from 2020 that analyzed 863 chickens from sites all around the world. The 2020 study results suggest that all domestic chickens today originate from a single domestication event, with these original domesticated chickens interbreeding with other local species of junglefowl to form genetically distinct groups.
But two studies published recently in the journals Antiquity and The Proceedings of the National Academy of Sciences paint a different image. Using radiocarbon dating, researchers found that 23 chicken bones from 16 sites in Eurasia and Africa were more recent than previously thought — in some cases, by a few thousand years. These bones had apparently sunk into deeper sediment layers and reached layers containing items made by earlier human cultures. The oldest bones that researchers could definitely attribute to domestic chicken were found at Neolithic Ban Non Wat in central Thailand, and date to between 1,650 and 1,250 BC — far later than previously proposed.
“This is the first time that radiocarbon dating has been used on this scale to determine the significance of chickens in early societies. Our results demonstrate the need to directly date proposed early specimens, as this allows us the clearest picture yet of our early interactions with chickens,” Dr. Julia Best, from Cardiff University one of the study authors, explained.
While one study focused on this dating, the other organized a comprehensive reevaluation of chicken bones found in archaeological sites. The researchers found that dry rice farming was a “magnet” that drew the then-wild chicken, laying the foundation for a closer relationship between humans and the junglefowl that would eventually become chickens. As rice cultivation dispersed, so too did domesticated chickens.
“This comprehensive re-evaluation of chickens firstly demonstrates how wrong our understanding of the time and place of chicken domestication was. And even more excitingly, we show how the arrival of dry rice agriculture acted as a catalyst for both the chicken domestication process and its global dispersal,” says Professor Greger Larson, from the University of Oxford, one of the study authors.
Based on historic and archaeological information, the chicken trail (quite literally a trail of bones) correlates excellently with the spread of rice, millet, and other grains. In light of this new evidence, chickens appear to have emerged some 3,000 years ago as domestic animals, in northern China and India. They then spread to the Middle East and Northeastern Africa some 2,800 years ago, and reached Europe in the following centuries. They only reached Britain and Scandinavia 1,800 years ago.
Dr. Ophélie Lebrasseur, from the CNRS/Université Toulouse Paul Sabatier and the Instituto Nacional de Antropología y Pensamiento Latinoamericano, who also worked on this research added:
“The fact that chickens are so ubiquitous and popular today, and yet were domesticated relatively recently is startling. Our research highlights the importance of robust osteological comparisons, secure stratigraphic dating and placing early finds within their broader cultural and environmental context.”
However, based on archaeological evidence, chickens were first grown for cultural or spiritual purposes — not for food. For centuries or millennia, people grew them as exotic pets and valued them for their aspect and loud crows at first light. When they were found in graves, they appeared to have been prized possessions. In addition, early chickens were smaller and would have likely not been a good source of meat.
“Eating chickens is so common that people think we have never not eaten them. Our evidence shows that our past relationship with chickens was far more complex, and that for centuries chickens were celebrated and venerated,” Professor Naomi Sykes, from the University of Exeter, said.
However, some 500 years after chickens were brought to a new place, they would lose their status and become an ordinary food.
This process has dramatically accelerated in the past century. In order to shorten production cycles and cut costs, breeders have selected the chickens that grow fastest and can produce the most meat. In the past 50 years alone, farm chickens have become 4-5 times larger.
Nowadays, chickens are the most common bird species on the Earth, but it doesn’t do them much good — quite the opposite. In 2020, there were some 33 billion chickens in the world, up from 14.3 billion in 2000.
The vast majority of these will never live to a year: over 50 billion chickens are slaughtered for food every year, and that doesn’t even include male chicks, which are slaughtered in the egg-laying industry as they are unnecessary. According to some estimates, 7 billion male chicks are also slaughtered — a big downfall for a species that was once cherished and appreciated culturally.
Andrei's background is in geophysics, and he's been fascinated by it ever since he was a child. Feeling that there is a gap between scientists and the general audience, he started ZME Science -- and the results are what you see today.