Carl Zimmer, author of several evolution-themed books and an interesting blog, published an article on weed evolution in Tuesday's New York Times. He used one of my favorite examples of rapid evolution of complex traits (flooding tolerance and crop mimicry in Echinochloa barnyardgrass/watergrass in <1000 years) to make the point that evolution of herbicide resistance (a much-simpler trait) in only a few years shouldn't have been a surprise. For example, glyphosate-resistant weeds are becoming increasingly common, just before the expiration of Monsanto's patent on Roundup-Ready soybeans.
What does the US Constitution say about patents?
"The Congress shall have Power To...promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries...."If the original intent was to give inventors short-term monopolies, in exchange for long-term benefits to society, should the duration of patent protection be shorter for inventions whose useful life is likely to be limited by evolution? For example, 17 years with a really good resistance-management plan, 5 years with no resistance-management plan.... Of course, the Patent Office might need to hire an evolutionary biologist or two.
I agree with the statement from David Mortensen, in the New York Times article that adding another resistance gene to glyphosate-resistant crops, and spraying with both herbicides, will be only "a short-lived solution," although it might last long enough to be worth patenting. If they had put two different herbicide-resistant genes into soybean from the start, and if evolution of resistance requires two or more independent mutations -- this isn't always true -- and if farmers growing that herbicide-resistant crop were somehow required to use both herbicides, evolution of resistance might have taken much longer.
Zimnmer quoted me and mentioned my book on Darwinian Agriculture, depleting Amazon's stock, though they still have a few copies left. You could try your favorite independent bookstore or library.
Under selection pressure imposed by farmers with hoes, Echinochloa watergrass evolved to resemble rice more than it resembles its own recent ancestor, barnyardgrass (Barrett, 1983).