Picture two chicks raised in the same barn on the same feed for eight weeks. The 1957 breed weighs 2 pounds. The modern breed weighs more than 9 pounds. The gap is sixty years of selective breeding, and that explains most of the 73 billion number. In 2014, scientists at the University of Alberta tested this directly. They raised three breeds of meat chicken side by side: one from 1957, one from 1978, and one from 2005. At 8 weeks old, the 1957 bird weighed about 2 pounds. The 1978 bird weighed 4 pounds. The 2005 bird weighed just over 9 pounds, more than four times as much as the 1957 bird. Same barn, same feed, different DNA. About 90% of the weight gap traces back to breeding alone. Cheaper birds followed cheaper feed. A 1950s farmer needed 3 pounds of feed to grow 1 pound of chicken. A modern farmer needs 1.6 pounds, sometimes as little as 1.4. Feed is roughly 70% of what it costs to raise a chicken, so when feed costs dropped, retail prices dropped too. In 1960, Americans ate 34 pounds of chicken a year. Chicken passed beef in 2010. By 2024, the average American was eating 101 pounds of chicken. The bird's shape changed alongside its size. The same Alberta study found that breast muscle grew by about 80% between 1957 and 2005. Almost all of that extra meat landed in the part you buy as boneless skinless fillets, the cut that drives the modern chicken business. The business that grew around this is enormous. Global chicken meat is a $338 billion market. Tyson Foods alone sells $16.8 billion of chicken a year. The US slaughters 9.4 billion meat chickens a year, producing 62 billion pounds of meat. Almost every one comes from three breeding lines (Cobb, Ross, and Hubbard), descended from programs that started in the 1940s. 200 million birds a day is the result of design choices made decades ago. Per-person chicken consumption in the US tripled since 1960, while the chicken itself nearly doubled in size. The bird in the photo is about six weeks old. Nearly a fifth of its body weight is breast tissue. Its ancestors come from a 1948 contest called "Chicken of Tomorrow," sponsored by the A&P grocery chain and the USDA, which set out to design a faster, fatter, cheaper chicken. They succeeded. 73 billion chickens a year is what their program produces today.