DR. DICKSON DESPOMMIER
spent thirty-eight years as a professor of microbiology
and public health in environmental health sciences at Columbia, where he won the
Best Teacher award six times. In 2003, he was awarded the American Medical Student
Association Golden Apple Award for teaching. He has addressed audiences at leading
universities including Harvard and MIT, and he has also been invited to speak at
the United Nations. In addition, he has been asked by governments of China, India,
Mexico, Jordan, Brazil, Canada, and Korea to work on environmental problems. Despommier
lives in Fort Lee, New Jersey.
Natural selection is an amazing thing. The environment changes and turns the rest of nature on its head trying to adjust to a rise in air temperature, or drier summers, or taller mountains, or rising sea levels, or another ice age. Whatever. But lo and behold, life just shrugs its shoulders and persists on in its goal of survival and reproduction. How does that work? It is all about genetics and the random production of mutant plants and animals that are pre-adapted to changes that have yet to occur. Sounds mysterious, but that is the way of the world as we know it. Somewhere in any given population of you name the species, there are individuals capable of surviving better given a new climate regime. Regardless of the actual nature of the change, when that change does occur, pre-adapted organisms that are better fit to survive in that new condition are able to increase their numbers faster than non-adapted individuals. In the end, after tens or more years down the road (depending on the reproduction rate of that species), the small number of pre-adapted organisms win the day and become the dominant population. They may even go on to become a new species. That is until the next set of environmental changes comes along. Then the whole process is repeated over and over again. Eons of history of climate change have taught us that no matter what the situation, life goes on producing new species from old ones.
Take the example of the use of herbicides; atrazine and glyphosate (Roundup) in specific. These are two powerful chemicals and commonly used throughout the Midwest to keep native plant species (they are called weeds by the agronomists) from invading the wheat, corn and soybean fields, and from eating up all that yummy fertilizer that the farmer sprayed on his/her fields at spring planting time. It should also be mentioned that atrazine is banned in Europe due to its strong association with teratogenic effects in cold-blooded vertebrates, especially frogs. So, as time goes on, perhaps 10-20 years of use of herbicides, the weeds eventually fight back by random selection, producing a few individuals with a higher tolerance for that herbicide than their weaker cousins. The next thing the farmer knows, they have a weed problem again, big time, and yields go down. So, the agro-chemical manufacturers produce genetically modified crops (so-called GM/GMO varieties) in the lab that are significantly more tolerant of glyphosate than last years crops. Did I mention that this industry also produces both of these plant killers? The following year the farmer, now armed with more resistant crop strains, applies a bigger dose of herbicide and with good results. But, by now I think you can see where all this is going. You guessed it! The weeds refuse to go away and up rises another mutant with an even higher tolerance for Roundup. (See here for an interctive graphis detailing the Roundup-resistant areas in the US). Hm, sounds like our current problem with the pharmaceutical industries and antibiotic resistance. Oh, well, history does in fact repeat itself, at least when it comes to natural selection. The farmer says, ‘Looks like I‘ve got myself a real problem here’. So goes the Herbicides vrs. Weeds war. In the end, who will win? Right again. The weeds, that’s who. Oh, and one more thing. When it rains, (I mean real rains and floods), down the drain go the agrochemicals, eventually ending up in our estuaries and loading them with nutrients from unused portions of fertilizers. What’s more, the nitrogen component of fertilizers scavenges all the dissolved oxygen in those brackish coastal waters so the larval fish and mollusks suffocate. Not good. So what can we do about all this? Forget herbicides and fertilizers and switch to an indoor, herbicide and pesticide free farming strategy. If we do not, then some day we might have to learn how to prepare our evening meals using weeds as the basis for all our vegetarian dishes. I would like to pass on the daisies and crabgrass salad.