In the old days, people kept chickens for their eggs. When a hen's egg-laying days were up, she was made into chicken soup. Male chicks were called "spring chickens" and cooked for their tender meat, a treat compared to the lean, scrawny hens that ran around the barnyard.
The 1950s brought flocks of Jews from Europe into New York. As Jews, they could not indulge in Sunday ham dinners; thus a demand for chicken meat soared with this immigrant wave. Vegetable farmers in the area began to raise chickens, and a new kind of animal farming was born.
It was found that chickens grew plump and tasty if antibiotics were added to their feed. And there were dozens of ways to make chicken into food: nuggets and sticks among them. Chickens became a huge contract-farming business.
Today, quoting from a recent Mercola newsletter: The farmers who raise chickens don't actually own the chickens. They own their land, usually, although they're probably paying a mortgage on it. They pay to build those houses. They own their debt. They own the manure that comes out of those houses. The company they grow for, the company to which they're contracted (they're called contract farmers), buys parent birds from a genetics company, hatches the chicks, takes the chicks to the farmers, brings the feed to the farmers, picks the birds up six weeks later, takes them to a company-owned slaughtering plant, slaughters them, packages them, distributes them and negotiates the wholesale contract.
Breeding ever fatter chickens, even chickens without beaks and feet, is the goal. Making butterballs. Think of what is happening to humans these days as well ... the soaring of global obesity: