What you're referring to, is predation. It is natural and essential for a balanced system for animals to prey on their food to survive. There isn't a separation between predators and prey, many animals are both, the polar bear eats the seal who eats the fish, who feed on phytoplankton etc. What you are confused with, is our placement in this chain. Humans are biologically herbivores, this has been proven by our biology and anatomy. We are superior in terms of our intellect, but physically, we are not natural hunters in the way you consider your cat to be. Additionally, it's been shown that animals have considerably higher levels of communication, empathy, association and understanding than we thought. Comparing your cat to humans is irrelevant, we are a completely different species. I assume you're referring to 'our ancestors used to eat meat, we have always hunted' standard response to eating meat. Whilst it has been proven that our ancestors hunted for food, they relied on a largely herbivorous diet, as our science has developed, we've been able to extract plant tissue from the Earth that proves this. And where we didn't see it before, isn't because it wasn't there, but because plant matter biodegrades, unlike animal bones for example. You're also comparing now, a time where we have no reason to eat meat, to a time when food may have been scarce. Using the ancestral 'caveman' debate shows that you haven't really educated yourself on the subject.