For centuries, people have harvested corn by hacking it off, six to fifteen inches above the ground. A caterpillar called the corn borer appears to have adapted its behavior to the corn harvest by travelling back down the stalk to a safe height, before spinning its cocoon. This week, the Science Times reported on a study that suggests that, by descending to the bottom of the stalks, the bugs avoid being chopped off when the corn is harvested. Researchers at McGill University think that “over generations, those caterpillars that did not descend, or did not go down far enough, did not survive.” In the article, Dr. Calcagno suggests that the likeliest explanation for this behavior is the selection pressure of harvesting over generations. In other words, only the caterpillars that crawled down survived to reproduce and make baby bugs, until only caterpillars with the family trait of crawling down remained in the population.
Similar forces are at work on bacteria that live in animals and humans, only instead adapting to harvest, they’re adapting to constant exposure to antibiotics. As a result, many harmful bacteria are finding ways to “outsmart” antibiotics. This is, in part, due to the mind-boggling volume of these drugs fed to animals produced for food. I can’t give you a number, because according to the Center for Disease Control’s website, the amount of antibiotics fed to farm animals is not available to the public or to government agencies.
Feeding animals antibiotics helps them grow. No one knows exactly why. Unfortunately, using these drugs as growth enhancers, or even to protect them from disease, often creates antibiotic-resistant strains of bacteria that have the potential to end up in our food supply. These drug-resistant pathogens are especially dangerous to people who live and work on farms ( just ask Russ Kremer, who was gored by one of his hogs and nearly died from an antibiotic-resistant infection.) In reponse to the global threat presented by antibiotic resistance, the World Health Organization recommended that antibiotics used in humans should not be used to promote growth in food animals.
Healthy animals occasionally need to be treated for infections, but feeding animals antibiotics for growth benefits is a risk no one should be taking. A huge amount of money is spent each year on these drugs so producers can get top dollar for their animals. My worry is that the additional costs to public health are not being considered, especially if our pharmaceutical arsenal is rendered useless by this practice.
Congratulations to Michael Moss, of the New York Times, for winning a 2010 Pulitzer Prize for his expose “The Burger That Shattered Her Life.” According to the New York Times, his reporting on the ground beef industry “led the Agriculture Department to review it’s safety procedures and a major slaughterhouse and food retailer to agree for the first time to test raw ingredients that would go into ground beef.”
I remember reading his work and being shocked to learn that many ground beef producers wouldn’t sell to retailers who wanted to retest their meat for E. Coli contamination. The system still isn’t perfect (see my post on ground beef additives,) but at least someone is listening.