I've been reading McLeod's new book called Freedom of Expression
. A PDF copy of the entire book is also available for download from that page. I strongly recommend reading pages 46-55 where he talks about how corporations are patenting genetically modified crops. This sounds ok before I read more. The wind can easily carry pollens of the genetically modified crops into regular organic farms. In such cases, farmers with organic fruits have been forced to pay licensing fees to the corporations that developed the modified crop (my initial guess was that the organic farmer could sue since the pollens destroyed their business)! Such contaminations have also traveled to Mexico through the air without the farmers there ever opt-ing in to use genetically modified crops.
In another area, drug companies use the help of indigenous people in other countries to find natural medicines from plants, often called Green Gold. Many of these have been local remedies for centuries. However, the corporations patent such discoveries and give no credit to the local people. And in extreme cases, they have asked for royalties from distributors who have been importing such natural medicines for years! How could one patent something that people have been using for hundreds of years?
Finally, a fact that just blew me away: 97% of vegetable varieties sold in the US at the beginning of the century are now extinct. This leads to a more uniform genetic makeup of crops and thus making them less resilient to various biological conditions. A diverse gene pool is a great way to hedge against changes in the ecosystem. Read the book for more facts and analysis.