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Humans Are Not at the Top of the Food Chain

For the first time, scientists calculated out the trophic level of humans.
Carnivores dining on a carcass. Image via Wikipedia.

We humans love to believe that we are top-of-the-food chain predators. We chow down on our steaks and meat-laden sandwiches with the sort of aplomb only found in those who feel secure in their status as rulers of the trophic cascade. But a study presented in yesterday’s Proceedings of the National Academy of Sciences challenges that notion by calculating humanity’s place in the global food web.

Based on data provided by the United Nations Food and Agricultural Organization (FAO), a group of scientists calculated out the human trophic level (HTL). Trophic levels represent the place an organism falls within the food chain. The numerical span of trophic levels goes from one (primary producers that make their own food, like plants) all the way up to 5.5 (apex predators, like orcas, who have few or no predators of their own). Prior to this study, that number hadn't been reliably calculated for humans.

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Factoring in population size and using statistics from the years 1961 to 2009, the scientists deduced that the global HTL was 2.21 for 2009. This may shock a few people: that number places us on the same trophic tier as some of the animals we love to eat, namely pigs and anchovies. Additionally, the valuation firmly classifies us as closer to herbivores than carnivores.

To be sure, just because we are middle-of-the-line omnivores in terms of trophic levels does not mean that we are likely to be devoured by a hungry carnivore. As Smithsonian.com points out, “in modern society, at least, that isn’t a common concern.”

What it does signify is that at least from the scientific perspective, to dominate the food chain and all the animals within, “you have to strictly consume the meat of animals that are predators themselves.” Obviously, we do not do that.

As helpful as it is for understanding humanity’s diet as an amorphous whole, the 2.21 number does not adequately touch upon unique regional realities, the report argues. Some countries, like Iceland, have high HTLs that are dropping, while others, like that of China and India, see their HTLs rising in tandem with their improving economic development—which means more consumption of meat.

Beyond the actual content of the paper itself, there is the whiff of something else going on, only touched upon briefly by other outlets: this challenges our very important self-perception as creatures ruling the food chain. Any vegetarian can tell you that one of the top ten responses to describing one’s own aversion to meat includes some variation of the statement, “Well, humans are at the top of the food chain so I’ll eat what I want” or “We didn’t get to the top of the food chain by eating salad!”

But this paper suggests that humans are not at the top of the food chain. Though this shouldn’t require explaining, we are not carnivores. We are omnivores, eaters of things both green and red. In fact, based on the newly calculated HTL, we actually eat slightly less meat than we do plants.

This belief, that we are meat-eating animals on par with tigers and the like, is a faulty symptom of a larger sense of anthropocentrism. I won’t argue with you that humans are incredibly influential. As the scientists themselves put it, “there are no remaining ecosystems outside of human processes.” But even if we were higher on the trophic level, I’d argue that’s not a license to indiscriminately gorge on meat, especially given modern day production methods and the environmental consequences of increasing meat consumption.

But enough of my ranting. The bottom line is this new calculation of human trophic levels offers a “composite metric,” as the researchers describe it, that helps us better understand our relation to the things we eat and the things that might eat us, if we didn’t have all our handy technology.

@heyiamlex