rosborne979 wrote:If we didn't raise cows for food, they probably wouldn't exist at all (would have become extinct long ago).
Your question sort of depends on scope (how long a time, and how diverse an environment).
All animals are parasites on plants. Even animals which eat other animals are ultimately supported by plants which derive energy from the sun. The manure of some animals however may allow new species of plants to exist due to richer nutrient sources. Thus a particuar species of plant may owe it's existence to animals (Venus Flytrap) even though the Kingdom of plants overall is parasitized by animals.
I would call our relationship with cows and chickens symbiotic, even though we ultimately consume some of them.
Cattle were bred from aurochs that died out by the early 17th century probably from a human cause. If we consider the herd, rather than an individual auroch, then we can say that we parasitized the herd. The auroch could and did live without humans, and, you might say, we made them dependent on us and parasitised them. A similar case can be made for lichens, which have been thought of as mutualism between an alga and a fungus. But mant botantists consider it to be a controlled parasitism by the fungus, which feeds on the algal colony, thouth the alga could live by itself.
I always thought that animals predated plants, but usually the plant survives, especially woody plants, so it probably is parasitism.
Cultivated food plants were all derived from wild counterparts, and left alone they probably would survive in the wild and revert back to more original forms. I can see where it could be said that we parasitize plants in that sense.