One of my friends has been studying the history of the domestication of chickens. If the breed is raised for meat, it descended originally for cock fighting. Egg laying chickens came from bamboo forests, where egg laying in large amounts is part of the ecology.
And yes, it's cruel and wrong and blah blah blah, but ever see how chickens are raised for food nowadays? These guys are treated like princes while they grow up and when they go into the ring, and then in theory, they have an equal chance of winning with a chance of going on to being a breeding chicken. If given a choice of being a game cock or a production line chicken, it's a no-brainer. Less than a dollar is spent on bringing a meat chicken to production weight in the US. A game cock is a serious investment and is often raised by professional trainers on a special diet.
Condemn all you want if you are a vegan, but if you eat production chicken or eggs, have a nice steaming cup of STFU and a side of chicken nuggets.