From divine creatures to dinner. The shocking 4‑fold increase in chicken size over 70 years

More than a hundred years ago, chickens were primarily seen as egg producers. Their meat was viewed as a secondary product and was not particularly sought after. This perspective changed following World War II, when feeding the rapidly growing human population became a significant challenge. As a result, our society began to consume more poultry and gradually developed a preference for it. Sensing a business opportunity, breeders started selectively breeding chickens for size and weight.

Food industry specialists sought ways to engineer chickens with more meat that would be less expensive to maintain. This led to the creation of the "chicken of the future", a new breed notably characterized by larger chests and heavily muscled legs. These chickens, known as broilers -- a term derived from the English word "broil," meaning to roast -- displayed remarkable growth rates and body mass. In the context of widespread hunger, ethical considerations about animal rearing were overlooked.

By the early 60s, the heaviest chickens weighed in at 5.5 lbs, achieved in six weeks. This was 170% larger than the standard at that time. Such results pleased industry executives, leading to the creation of the "meat bird" breed. In the ensuing years, continuous cross-breeding of chicken genes resulted in a heightening incidence of diseases, largely due to overactive growth.

To comprehend how chickens have evolved over time, a group of scientists compared chicks of three breeds from 1957, 1978, and 2005, respectively. The first two breeds were free from selective breeding and reproduced naturally, making them ideal reference points for the study. All the birds were given identical feed and lived in comparable environments. The findings revealed that in recent times, chickens had increased their breast mass by 80%, have a lifespan that is, on average, 30% shorter than the original species, and possess four times the body mass. According to the researchers, the change isn't attributable to hormones and steroids but largely to rapid growth and cross-breeding.

In conclusion, while modern practices regard hens as egg and meat producers, this was not always the case. Historical iconography and paintings illustrate that chickens held a more important role in people's lives. Once seen as divine creatures, they were revered and respected worldwide.