Humans aren't separate from nature, we are nature. So, even the cities, technology, cars, pollution; anything man-made is nature. Why wouldn't we be, we're literally made of the same stuff that nature is made up of. We came from nature, from the earth itself and from supernovae...so we're not separate from nature. We all are nature.
This would mean the following are not separate from nature, too.
Every single thing
Anything that we humans do isn't unnatural, it is Mother Nature's doing.