I have been interacting with Dr. Ashish Shah, Environmental Education Expert at Centre for Science and Environment in their Facebook page recently. The discussions turned out to be a wonderful learning experience as he patiently answered my questions in a detailed manner. I thought of sharing those discussions here so that everyone can learn. You can join their Facebook page here, if you wish to take part in the discussion.
Dr. Ashish Shah: My dear friend, it is just the way we look at it. Every living being on this planet is a parasite for the environment it lives on. We are also parasites of a more deadly nature. We alter the eco-systems we live on beyond repair. The beings we call parasites have been living in their respective eco-system niches for millions of years without altering the overall balance. Take for example the micro organisms in our guts. They help metabolize food in our intestines and help in extraction of important stuff for our body. Think, how we urban denizens contribute to the distant eco-systems we feed on? In fact we don't, as our consumption patterns are linear and the end result of urban process is destruction of an eco-system the way we have known it. On the other hand natural processes are cyclic. The millions of species in our eco-system help maintain this cyclic nature.