Too many broiler chickens to count

The story of the chicken is a story of the growth of the modern broiler chicken and the industrial processes that enabled the increase in size. It also offers fascinating insights into how “changing patterns of human resource use and food consumption have profoundly impacted the Earth’s biosphere”. 

Modern broiler skeletons are significantly larger than both the wild predecessors and archaeological domestic chickens dating between the Roman era and the end of the nineteenth century. A study published in the Royal Society has revealed that the spectacular growth in both size and numbers to chickens happened in the second half of the twentieth century, ie, during the putative Anthropocene Epoch that witnessed carbon dioxide emissions and sea level rise, the global mass extinction of species, and the transformation of land by deforestation. 

Broiler chickens are now completely dependent on the humans for their existence and have a combined mass exceeding that of all other birds on Earth. In simple terms, the broiler chicken is more ubiquitous than the red-billed quelea, house sparrow, farmed turkeys and geese. In Europe alone, the population of domesticated chickens in 2009 (1.9 billion) was greater than the combined population of the 144 most numerous wild bird species, the study reveals. The rise in the number of domesticated chickens over recent decades mirrors the decline in the population numbers of wild bird species, particularly those that are common. So, the animals that humans domesticated flourished at the cost of biodiversity. 

With great numbers came the great responsibility of feeding the ever growing human population. The domestic chicken originated from the red jungle fowl. Due to their amazing abilities to adapt to a wide climatic range, they soon found homes in the Americas, Australia, Europe and Africa when the human population scattered. While the archaeological record for chickens indicates that domestication led to alterations in bone morphology, the tempo of the speed and scale of changes picked up considerably in the second half of the twentieth century. Along with domestication came a change in diet of the chickens to produce high meat-yields. 

The study underscores how human interference has shaped the trajectory of this bird. Modern broiler chickens are morphologically and genetically distinct from domestic chickens prior to the mid-twentieth century. The study has documented that the broilers from a 1957 breed are between one-fourth and one-fifth of the body weight of broilers from a twenty-first century. If left to live to maturity, broilers won’t survive. On the other hand, increasing their slaughter age from five weeks to nine weeks resulted in a sevenfold increase in mortality rate.

The chicken’s impact on earth’s biosphere can be linked to global human trends towards increased animal protein consumption. The study of broiler chickens is also a study of the vivid transformation of the biosphere to fit evolving human consumption patterns. Make no mistake: The chicken will outweigh the production of beef and pork as red meat is saddled with health implications.