Almost all predator animals have a territory and they will fight for that territory to keep others out. Chimpanzees and other great apes have clan wars over territory. And they have social hierarchies where some get more food than others.
There is a 100% chance early humans were fighting each other long before the invention of agriculture.
But only if they are artificially bred. If hunted wild, it has an incredibly positive impact. They are a invasive species and are harmful to any ecosystem they were introduced to.