Why We Love Dogs, Eat Pigs, and Wear Cows

"Why We Love Dogs, Eat Pigs, and Wear Cows", usually I had think a similar question like this years ago, when I heard about eating rare or even protected animals and cannibals. Why do we eat very different than our ancestors? Different than other species? I heard answers like we are born in these ways, the developments/changes of our gene change our behaviors, or we choice to live in these ways. I think this starts with curiosity. Our ancestors or even us now, can't directly eat raw meat, therefore we cook the meat to make it eatable. We are curious about what other food taste like, so we developed the technique of cooking. Laster, we learn to captive animals. But we still treat animals as food only. Gradually, our views of animals had change. We see they also have feelings and become friends with some of them. We aren't eat our friends. But why we are Carnism and not vegetarian?  Some say this is because the need of nutrients. However, I belief there is a bias. A bias with no an actual scale.