New York (CNN) -- Like most people, I'd given some thought to what meat actually is, but until I became a father and faced the prospect of having to make food choices on someone else's behalf, there was no urgency to get to the bottom of things.



I'm a novelist and never had it in mind to write nonfiction. Frankly, I doubt I'll ever do it again. But the subject of animal agriculture, at this moment, is something no one should ignore. As a writer, putting words on the page is how I pay attention.



If the way we raise animals for food isn't the most important problem in the world right now, it's arguably the No. 1 cause of global warming: The United Nations reports the livestock business generates more greenhouse gas emissions than all forms of transportation combined.



It's the No. 1 cause of animal suffering, a decisive factor in the creation of zoonotic diseases like bird and swine flu, and the list goes on. It is the problem with the most deafening silence surrounding it.



Even the most political people, the most thoughtful and engaged, tend not to "go there." And for good reason. Going there can be extremely uncomfortable. Food is not just what we put in our mouths to fill up; it is culture and identity. Reason plays some role in our decisions about food, but it's rarely driving the car.



We need a better way to talk about eating animals, a way that doesn't ignore or even just shruggingly accept things like habits, cravings, family and history but rather incorporates them into the conversation. The more they are allowed in, the more able we will be to follow our best instincts. And although there are many respectable ways to think about meat, there is not a person on Earth whose best instincts would lead him or her to factory farming.



My book, "Eating Animals," addresses factory farming from numerous perspectives: animal welfare, the environment, the price paid by rural communities, the economic costs. In two essays, I will share some of what I've learned about how the way we raise animals for food affects human health.



What we eat and what we are



Why aren't more people aware of, and angry about, the rates of avoidable food-borne illness? Perhaps it doesn't seem obvious that something is amiss simply because anything that happens all the time -- like meat, especially poultry, becoming infected by pathogens -- tends to fade into the background.



Whatever the case, if you know what to look for, the pathogen problem comes into terrifying focus. For example, the next time a friend has a sudden "flu" -- what folks sometimes misdescribe as "the stomach flu" -- ask a few questions. Was your friend's illness one of those "24-hour flus" that come and go quickly: retch or crap, then relief? The diagnosis isn't quite so simple, but if the answer to this question is yes, your friend probably didn't have the flu at all.



He or she was probably suffering from one of the 76 million cases of food-borne illness the Centers for Disease Control and Prevention has estimated happen in America each year. Your friend didn't "catch a bug" so much as eat a bug. And in all likelihood, that bug was created by factory farming.



Beyond the sheer number of illnesses linked to factory farming, we know that factory farms are contributing to the growth of antimicrobial-resistant pathogens simply because these farms consume so many antimicrobials.



We have to go to a doctor to obtain antibiotics and other antimicrobials as a public-health measure to limit the number of such drugs being taken by humans. We accept this inconvenience because of its medical importance. Microbes eventually adapt to antimicrobials, and we want to make sure it is the truly sick who benefit from the finite number of uses any antimicrobial will have before the microbes learn how to survive it.



On a typical factory farm, drugs are fed to animals with every meal. In
What factors are controlling the system? what is tied to global warming What is factory farming tied to?
the way we raise animals for food the way we raise animals for food animal welfare, the environment, the price paid by rural communities, the economic costs.
question: What factors are controlling the system?, answer: the way we raise animals for food | question: what is tied to global warming, answer: the way we raise animals for food | question: What is factory farming tied to?, answer: animal welfare, the environment, the price paid by rural communities, the economic costs.