Where Do Humans Fit on the Global Food Chain?

A few months ago, my ladyfriend and I drove out to Lassen Volcanic National Park and went on our first real backpacking camping trip. The distinction between previous toe-dipping forays into the wilderness and this outing was that instead of simply taking a day pack from the car and strolling for twenty minutes before setting up camp, this one entailed hiking out over five miles of backcountry into the middle of nowhere. As you can imagine, sleeping in that element is, alternately, exhilarating, amazing, and scary as all hell. The latter one, especially, when the bear wandered into our camp site.

During the close encounter with the furry and clawed kind -- which I won't go into detail here, other than to say that it probably got within ten feet of our tent and, predictably, we didn't sleep all that much -- one thought kept racing through my brain that comforted me through the night: Humans are on top of the food chain. It's the natural order of things. We dominate the planet.

But man, was I wrong.

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Which isn't to say that all of a sudden you need to start showering in bear repellant as they're on their way to take what's theirs. Rather, I was mistaken in regards to subtle quirks of definition. Human don't have any natural predators, so we do reign over our own food chain. But as far as the planet's food chain, we're technically not at the top of it. Actually, we're not even close.

As the insanely-interesting new study by the -- deep breath -- Proceedings of the National Academy of Sciences of the United States of America points out, to be at the scientific "top of the food chain," a species must ingest only the meats of animals below them. Seeing as we're omnivores (eating a whole bunch of plants on a regular basis), we can't have that distinction.

But where do we fall on the global scale? To find that out, scientists look at "trophic levels," a fancy way of saying the level that the plant or animal falls on the food pyramid:

On a scale of 1 to 5, with 1 being the score of a primary producer (a plant) and 5 being a pure apex predator (a animal that only eats meat and has few or no predators of its own, like a tiger, crocodile or boa constrictor), they found that based on diet, humans score a 2.21--roughly equal to an anchovy or pig.

Yet another reason to maybe think twice before eating a whole plate of bacon: Pigs are more like us than most of the animal species out there.

But that's not to say our own consumption of meat is too low. In fact, the study also points out how meat consumption by humans has dramatically increased over the past 50 years, up three percent over the time frame. (To be fair, most of that increase has been the result of two countries -- India and China -- changing their diets based, partially, on the fact that they've economically developed during that time period.) And while that number doesn't seem like a lot, the global effects of such a massive increase in meat consumption can be dangerous:

Calorie for calorie, the environmental impact of producing meat -- in terms of everything from carbon emissions to water use -- is typically many times larger than that of producing vegetable foods. Furthermore, a 2006 FAO study found that the livestock industry is directly or indirectly responsible for 18% of global greenhouse-gas emissions -- a larger share than all modes of transport combined. "If we all increase our trophic level, we'll start to have a bigger impact on ecosystems," says Bonhommeau.

Another way the study looks at what effect human meat consumption has had on the planet is by looking at the trophic levels of fish:

The trophic levels of the fish people eat has fallen, from 2.88 in 1961 to 2.69 in 2009. That's because fisheries around the world have been catching fewer big predator fish, in part because of overfishing.

All of which is to say, maybe during the upcoming holiday feasts and Christmas celebrations, when you go back for seconds, maybe it'd be best for everyone if you stack up more plants than meat on your plate.

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About the Author

Rick Paulas has written plenty of things, some of them serious, many of them not, scattered over the vast expanses of the Internet. He lives in Los Angeles and is a White Sox fan.
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