My anchovy of Lannister
December 5, 2013 2:09 AM Subscribe
Though humans often liken themselves to top predators such as lions, a new study (paywalled) used FAO data to calculate the human trophic level (HTL), i.e. the position of Homo sapiens in the food chain, and found that humans are actually on a par with anchovies and pigs with an average trophic level of 2.21 (vs 1 for plants to 5.5 for bears and orcas). Values vary by country, from 2.04 in the 97% plant-eating Burundi to 2.57 in the 50% fish-loving Iceland. As meat consumption is growing in countries like India and China, mankind is globally becoming more carnivorous and has been improving its trophic level by 3% since 1961.
According to the study, there are only five different groups of HTLs. In the period 1961–2009, sub-Saharan countries and most of Southeast Asia have a pattern of low and stable HTLs, due to their primarily plant-based diets. Low and increasing HTLs are found throughout Asia, Africa, and South America, including China and India. Central America, Brazil, Chile, Southern Europe, several African countries, and Japan, have higher initial HTLs than the previous group and show an increasing trend due to higher consumption of animals. North America, Northern and Eastern Europe, Australia, and New Zealand, had high and stable HTLs until 1990, when they begin to decrease. Countries with the highest HTLs and decreasing trends include Iceland, Scandinavia, Mongolia, and Mauritania, where traditional diets are based on meat, fish, and dairy products with low vegetable consumption. The raw data used for the paper and the R scripts are available here.
According to the study, there are only five different groups of HTLs. In the period 1961–2009, sub-Saharan countries and most of Southeast Asia have a pattern of low and stable HTLs, due to their primarily plant-based diets. Low and increasing HTLs are found throughout Asia, Africa, and South America, including China and India. Central America, Brazil, Chile, Southern Europe, several African countries, and Japan, have higher initial HTLs than the previous group and show an increasing trend due to higher consumption of animals. North America, Northern and Eastern Europe, Australia, and New Zealand, had high and stable HTLs until 1990, when they begin to decrease. Countries with the highest HTLs and decreasing trends include Iceland, Scandinavia, Mongolia, and Mauritania, where traditional diets are based on meat, fish, and dairy products with low vegetable consumption. The raw data used for the paper and the R scripts are available here.
Enormous numbers of things eat anchovies regularly. What are some of the enormous number of things that eat us regularly? I sense an important difference here that trophic level doesn't reflect.
posted by jfuller at 3:07 AM on December 5, 2013 [4 favorites]
posted by jfuller at 3:07 AM on December 5, 2013 [4 favorites]
Please, if you're going to categorize us as food, at least group us with long pig.
posted by ardgedee at 3:42 AM on December 5, 2013 [1 favorite]
posted by ardgedee at 3:42 AM on December 5, 2013 [1 favorite]
Humans don't eat a lot of carnivores (except for lots of fish and marine species), but of the carnivores that eat us, what eats them? Surely we're only one level from the top at best/worst?
posted by wilful at 3:57 AM on December 5, 2013
posted by wilful at 3:57 AM on December 5, 2013
We can take some solace in the fact that we're the only species that knows what the fuck a trophic level is, let alone get huffy about it.
posted by a snickering nuthatch at 4:08 AM on December 5, 2013 [11 favorites]
posted by a snickering nuthatch at 4:08 AM on December 5, 2013 [11 favorites]
So another argument for the new artisanal hipster carnivorism could be "I'm just raising my trophic level, bro"?
posted by acb at 4:27 AM on December 5, 2013 [1 favorite]
posted by acb at 4:27 AM on December 5, 2013 [1 favorite]
This seems weird, considering we can kill any animal we want with ease. Lions may have been further up the food chain when we were, you know, living naturally, but it seems to me "industrial humans" and "natural humans" might have different positions in the hierarchy—at least until we're separated from our tools.
posted by sonic meat machine at 5:07 AM on December 5, 2013
posted by sonic meat machine at 5:07 AM on December 5, 2013
Hmm. So I have a trophic level of 2. If I let myself really go and managed to develop a sort of overall fungal symbiosis, I wonder if I could get to level 1?
posted by pracowity at 5:11 AM on December 5, 2013 [1 favorite]
posted by pracowity at 5:11 AM on December 5, 2013 [1 favorite]
Interestingly, anchovies and pigs are also tied for "best pizza topping."
posted by escabeche at 5:45 AM on December 5, 2013 [6 favorites]
posted by escabeche at 5:45 AM on December 5, 2013 [6 favorites]
Predators are basically glorified parasites that prey and depend on other life forms, so it seems kind of weird to me to view them as being at the top of the hierarchy.
posted by saulgoodman at 5:53 AM on December 5, 2013 [1 favorite]
posted by saulgoodman at 5:53 AM on December 5, 2013 [1 favorite]
The worms who will eat us are laughing at this.
posted by Flunkie at 6:05 AM on December 5, 2013 [5 favorites]
posted by Flunkie at 6:05 AM on December 5, 2013 [5 favorites]
This is good, yes? The lower the tropic level, the greater population that a biome can support, right?
posted by leotrotsky at 6:21 AM on December 5, 2013 [3 favorites]
posted by leotrotsky at 6:21 AM on December 5, 2013 [3 favorites]
The HTL is calculated as the mean of the trophic level of food items in the (human) diet, weighted by quantity: it's a simple metric that does not take into account our own contribution to plant and animal nutrition. It's more a metric of how predatory we are vs other species. A metric that would include our value as prey/food would certainly be more difficult to define, since all living creatures including us end up as food for bacteria and invertebrates.
posted by elgilito at 6:37 AM on December 5, 2013 [1 favorite]
posted by elgilito at 6:37 AM on December 5, 2013 [1 favorite]
The worms who eat us will have to get through the plastic packaging and be able to tolerate a lot of formaldehyde.
posted by sneebler at 6:51 AM on December 5, 2013
posted by sneebler at 6:51 AM on December 5, 2013
"Improving" its trophic level? I kinda feel like as a species that's straining hard against the carrying capacity of its habitat (the entire Earth, essentially, transformed to produce darn near as much food for us as it possibly can given our current considerable expertise) raising our trophic level actually something of a step backward. Each step up the trophic pyramid comes at a rough 90% loss of energetic efficiency compared to the level before. True improvement would involve going in the other direction -- from a purely ecological perspective, it's pretty maladaptive for a species that's already bumping up against K to be actively pursuing less efficient means of getting its calories.
posted by Scientist at 7:07 AM on December 5, 2013 [18 favorites]
posted by Scientist at 7:07 AM on December 5, 2013 [18 favorites]
Also, I'm seeing some confusion here between the simplistic "food chain" concept that's taught in middle and high school and the more nuanced and realistic "trophic network" concept used by actual ecologists.
posted by Scientist at 7:10 AM on December 5, 2013 [3 favorites]
posted by Scientist at 7:10 AM on December 5, 2013 [3 favorites]
Enormous numbers of things eat anchovies regularly. What are some of the enormous number of things that eat us regularly? I sense an important difference here that trophic level doesn't reflect.
Louis agrees.
posted by flabdablet at 7:46 AM on December 5, 2013
Louis agrees.
posted by flabdablet at 7:46 AM on December 5, 2013
Now that I have a little more time I feel I should flesh out that last comment a little because it was perhaps a little glib. The food chain concept, which anybody who's been to public school in the US (or any other developed country, I assume) is presumably familiar with, is the idea that plants make food from the sun, and then herbivores eat the plants, and then predators eat the herbivores, and then secondary predators eat the primary predators, etc. It's an easy idea to explain to young students and helps to illustrate some fundamental ecological concepts, but it's not very naturalistic – that is to say, it does a poor job of describing what actually goes on out in the biosphere.
The trophic network concept, which is the model that in one form or another most ecologists actually subscribe to, is more complex and does a better job of representing reality. Trophic networks are models that attempt to map out the movement of energy through an ecosystem. They are usually simplified working models, as true trophic networks are incredibly complex and difficult to elucidate. Here's an example of a very simple trophic network model. Here's a slightly more complex one. Here's how ecologists feel after looking at too many trophic network diagrams.
As you can see, they bear a lot more resemblance to the "food web" concept that a lot of folks are probably familiar with than they do to the "food chain" concept. Critically though, the energy in the system moves in lots of different directions. Energy doesn't just pool at the top of the pyramid; even species that are pure carnivores and have no predators will have parasites, and will be consumed when they die. Many predator-prey relationships can go either way, with the roles being reversed depending on who gets the drop on whom. (None of the images I linked do a good job of illustrating this by the way, but they're the best I could come up with on short notice.) Some energy transfers are more important than others (often represented as arrows of different widths) with for instance a predator feeding on many species but having a strong preference for one or two. It's complex, there are many participants, and trophic relationships can shift depending on environmental factors, population changes, introduction of new members to the ecosystem, etc. Like I said, we rarely try to model an entire trophic network as it really exists; normally it is much more useful to limit ourselves to mapping out the most important interactions that directly relate to whatever question we are trying to answer.
One thing that remains though is that at the end of the day you can still, if you have a model that's good enough for your purposes, figure out how far away a species is from the ultimate producers of energy, the photosynthesizers (plants and algae). You can work out how much of an organism's energy is coming from each of various sources, and how much of their energy comes from each of various sources, and trace it back in a weighted-average fashion until it all comes back to the photosynthetic producers. Then you take those weighted averages and the number of steps that is involved in each one, and come up with a mean. That's your overall trophic level for a species. Because of the complexity of the process and the limited way in which trophic network models represent actual reality, these results are not perfectly precise – but if you do your job well you can account for the vast bulk of the significant factors, and come up with a useful estimate. That's the sort of thing that this article attempted to do, for humans. I don't know if they did a particularly good job or not, though I'd venture that their broadest conclusions are probably true at least. Humans are omnivores and generalists, so our trophic level is not as high as something like a bear or a tiger that feeds almost exclusively on large mammals. And we have indeed been eating a lot more meat over the years, so our trophic level is probably rising.
Anyway though, if you want to have a realistic picture of what's actually happening out there in the biosphere, the trophic network model is a much better heuristic than the food chain model. The food chain is more of a teaching tool, it's not really a useful way of actually representing the world.
posted by Scientist at 8:00 AM on December 5, 2013 [12 favorites]
The trophic network concept, which is the model that in one form or another most ecologists actually subscribe to, is more complex and does a better job of representing reality. Trophic networks are models that attempt to map out the movement of energy through an ecosystem. They are usually simplified working models, as true trophic networks are incredibly complex and difficult to elucidate. Here's an example of a very simple trophic network model. Here's a slightly more complex one. Here's how ecologists feel after looking at too many trophic network diagrams.
As you can see, they bear a lot more resemblance to the "food web" concept that a lot of folks are probably familiar with than they do to the "food chain" concept. Critically though, the energy in the system moves in lots of different directions. Energy doesn't just pool at the top of the pyramid; even species that are pure carnivores and have no predators will have parasites, and will be consumed when they die. Many predator-prey relationships can go either way, with the roles being reversed depending on who gets the drop on whom. (None of the images I linked do a good job of illustrating this by the way, but they're the best I could come up with on short notice.) Some energy transfers are more important than others (often represented as arrows of different widths) with for instance a predator feeding on many species but having a strong preference for one or two. It's complex, there are many participants, and trophic relationships can shift depending on environmental factors, population changes, introduction of new members to the ecosystem, etc. Like I said, we rarely try to model an entire trophic network as it really exists; normally it is much more useful to limit ourselves to mapping out the most important interactions that directly relate to whatever question we are trying to answer.
One thing that remains though is that at the end of the day you can still, if you have a model that's good enough for your purposes, figure out how far away a species is from the ultimate producers of energy, the photosynthesizers (plants and algae). You can work out how much of an organism's energy is coming from each of various sources, and how much of their energy comes from each of various sources, and trace it back in a weighted-average fashion until it all comes back to the photosynthetic producers. Then you take those weighted averages and the number of steps that is involved in each one, and come up with a mean. That's your overall trophic level for a species. Because of the complexity of the process and the limited way in which trophic network models represent actual reality, these results are not perfectly precise – but if you do your job well you can account for the vast bulk of the significant factors, and come up with a useful estimate. That's the sort of thing that this article attempted to do, for humans. I don't know if they did a particularly good job or not, though I'd venture that their broadest conclusions are probably true at least. Humans are omnivores and generalists, so our trophic level is not as high as something like a bear or a tiger that feeds almost exclusively on large mammals. And we have indeed been eating a lot more meat over the years, so our trophic level is probably rising.
Anyway though, if you want to have a realistic picture of what's actually happening out there in the biosphere, the trophic network model is a much better heuristic than the food chain model. The food chain is more of a teaching tool, it's not really a useful way of actually representing the world.
posted by Scientist at 8:00 AM on December 5, 2013 [12 favorites]
Viruses and bacteria eat us. The run the food chain game from top to bottom. Period, Motherfucker. The royal Motherfucker :D
posted by lordaych at 9:53 AM on December 5, 2013 [1 favorite]
posted by lordaych at 9:53 AM on December 5, 2013 [1 favorite]
The food chain model also kind of sucks because of parasitism and symbiosis. The predators themselves can be seen as both as someone hinted at. Sure the individual weak gazelle doesn't want to be miserably eviscerated but it benefits both species. And Lions are probably less dependent of leveraging intestinal bacteria to survive, frinstance, though that's unverified ass talkin'
posted by lordaych at 10:03 AM on December 5, 2013
posted by lordaych at 10:03 AM on December 5, 2013
the Inuit Paradox
There are other factors like a vigorous outdoor life, and traditionally they often fasted, they would consume whatever food is available in unbelievable quantities eating non-stop for 12 hours in some cases. Then go days or longer without food until the next windfall came as they moved around. Of course that nomadic lifestyle has changed and now they are more settled. See the classic book Kabloona (1940) which describes it well. There is evidence that fasting is healthier.
posted by stbalbach at 12:16 PM on December 5, 2013 [1 favorite]
There are other factors like a vigorous outdoor life, and traditionally they often fasted, they would consume whatever food is available in unbelievable quantities eating non-stop for 12 hours in some cases. Then go days or longer without food until the next windfall came as they moved around. Of course that nomadic lifestyle has changed and now they are more settled. See the classic book Kabloona (1940) which describes it well. There is evidence that fasting is healthier.
posted by stbalbach at 12:16 PM on December 5, 2013 [1 favorite]
lordaych: "Viruses and bacteria eat us. The run the food chain game from top to bottom. Period, Motherfucker. The royal Motherfucker :D"
We live in the Age of Bacteria. We're just highly-dependent colonies of them (with some bacteria cohabitating single cells).
posted by IAmBroom at 12:24 PM on December 5, 2013
We live in the Age of Bacteria. We're just highly-dependent colonies of them (with some bacteria cohabitating single cells).
posted by IAmBroom at 12:24 PM on December 5, 2013
Really, is there anything both scientific and useful about this article? It can't keep straight the ideas of "top predator", "distance in lifecycles from plant life", and "complex"; it's not clear to me if elgilito or the study authors came up with the laughable idea that higher "trophic" rates are "improved"; and there just doesn't seem to be much value in their index, anyway.
Now, if "trophic rating" could be used to deduce heavy metal accumulation or somesuch, it could have value... but I'm not convinced a priori that such a correlation will occur.
posted by IAmBroom at 12:32 PM on December 5, 2013
Now, if "trophic rating" could be used to deduce heavy metal accumulation or somesuch, it could have value... but I'm not convinced a priori that such a correlation will occur.
posted by IAmBroom at 12:32 PM on December 5, 2013
"Improving" its trophic level? ...it's pretty maladaptive for a species that's already bumping up against K to be actively pursuing less efficient means of getting its calories.
posted by Scientist at 7:07 AM on December 5
I was about to say the same thing.
posted by Jacob Knitig at 12:35 PM on December 5, 2013
posted by Scientist at 7:07 AM on December 5
I was about to say the same thing.
posted by Jacob Knitig at 12:35 PM on December 5, 2013
Really, is there anything both scientific and useful about this article?
The idea of humans-as-the-ultimate-apex-predator has been a cliché of popular science for a long time. This paper just puts things in perspective. From the paper:
There is a variety of other ecological indicators based on trophic ecology theory or diets, e.g., the omnivory index, that may also prove useful in assessing the impact of humans in the functioning of ecosystems. However, a first estimate of an HTL gives us a basic tool that places humans as components of the ecosystem and assists in further comprehending energy pathways, the impact of human resource use, and the structure and functioning of ecosystems.
About the "improved" thing, that was just a poor attempt at irony, since the linked Nature article (and the authors of the paper) made clear that a higher HTL was "a bad omen for the environment".
posted by elgilito at 1:23 PM on December 5, 2013 [1 favorite]
The idea of humans-as-the-ultimate-apex-predator has been a cliché of popular science for a long time. This paper just puts things in perspective. From the paper:
There is a variety of other ecological indicators based on trophic ecology theory or diets, e.g., the omnivory index, that may also prove useful in assessing the impact of humans in the functioning of ecosystems. However, a first estimate of an HTL gives us a basic tool that places humans as components of the ecosystem and assists in further comprehending energy pathways, the impact of human resource use, and the structure and functioning of ecosystems.
About the "improved" thing, that was just a poor attempt at irony, since the linked Nature article (and the authors of the paper) made clear that a higher HTL was "a bad omen for the environment".
posted by elgilito at 1:23 PM on December 5, 2013 [1 favorite]
It's not for everyone, I guess.
Still sounds more appealing than greasy neon yellow Cheetos.
Spitbull, it's not the thought of raw meat or that much grease/fat/oil that bothers me, it's the idea of parasites.
posted by BlueHorse at 7:04 PM on December 5, 2013
Still sounds more appealing than greasy neon yellow Cheetos.
Spitbull, it's not the thought of raw meat or that much grease/fat/oil that bothers me, it's the idea of parasites.
posted by BlueHorse at 7:04 PM on December 5, 2013
We live in the Age of Bacteria.
As cited here?
posted by TedW at 8:55 AM on December 6, 2013 [1 favorite]
As cited here?
posted by TedW at 8:55 AM on December 6, 2013 [1 favorite]
« Older Bill Murray on Gilda Radner | Mannequins and the peculiar morgue between Paris... Newer »
This thread has been archived and is closed to new comments
posted by pracowity at 2:54 AM on December 5, 2013 [1 favorite]