Because aside from ants, humans are the only other species to actively domesticate and purposely breed animals for our use.
We are not of nature anymore, not since we were hunter gatherers. We've gone above and beyond destroying it for our own needs, regardless of the fact that we need nature to survive.
Animals are a part of a chain. They succumb to nature's whims, chance etc.
Humans work to never having to succumb to chance. We do things to nature that would never occur without us. We work to get away from the "cruelty" of nature.