Been wanting to re-read this. Gotta get it back from a libertarian friend who will probably hate it though.
Quinn has made the point that the way we control our food supply, propagating only the species we like, genetically modifying them, and by extension the ecosystems around the planet, is detrimental not only to our environment but our long term survival.
I think that's true, but more to the point of this book is simply that on his theory the more you increase food supply the more you encourage population growth. When population growth outgrows food supply in one section you encourage food supply. When increased food supply becomes the answer, he argues, population continues to increase without much consequence, and ultimately causes a starvation/overpopulation problem.
Also, your avatar is great.