Unlike other natural systems (e.g., a coral reef or tropical rain forest), the agro-ecosystem always contains a particular “keystone” species. That keystone species is Homo sapiens. It is a species that engineers its own environment far more than any other species in history, a fact that would make ignoring its ecology naïve; nevertheless, its “ecology” involves a structure that no other species has ever had. It has the ability (or is it a need?) to communicate ideas from individual to individual, perpetuated to heights that are magnitudes larger than any other organism in the history of life. That is, our species has language with which it creates structures of culture and society, of economics and politics. As the keystone species in the ecosystem, our special nature becomes part of that ecosystem. The agroecosystem is thus endowed with not only traditional subjects of ecology, but also with the immensely complicating aspects of this particular feature of the keystone species.
— John. H. Vandermeer (Preface, The Ecology of Agroecosystems )