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How many lobsters would you trade off for a human?

Neil Dullaghan writes:

I have a strange set of correlations and am wondering if they are due to some oddity of statistics rather than real associations, but I am quite lost as to an answer.

The study in brief: 3 independent surveys asking respondents how many [insert animal] would they trade for 1 human. e.g 120 chickens for 1 human. All surveys find that the tradeoff is consistently and strongly correlated (nearing r=1) with p<0.05, power ~ .8) with a range of proxy measures for animal intelligence, despite respondents not having knowledge of these measures. Outcome Variable: The tradeoff above Explanatory variables: A range of potential indicators of animal intelligence e.g. Total Cortical Neurons I have no reasons to think respondents actually know the brain size or neuron count of the animals in the survey (Cows, chickens, elephants, lobsters, chimpanzees, pigs) and so the strong correlations seem odd. Using a Spearman's correlation on the full range of tradeoff values (rather than the median value in the graph below) still suggests significant correlations. The tradeoff values have a large range (see distribution below) so I wonder if it is the much wider distributions of animals that happen to have lower values for animal intelligence which is creating an artificial correlation in some way. The correlation is weaker if one takes the mean tradeoff value.

My reply:

My inclination is to not take this correlation too seriously as it’s just based on a few types of animals. Add more animals and you could get a much different story. Also, I think that adding more extreme cases will increase the correlation. For example, imagine you include the Rocks category to the first graph above. Rocks have zero neurons, and I assume the tradeoff would be infinity, thus the data point for Rocks would be at (-infinity, infinity) on the log scale, and including that with the other points would pull the correlation all the way to -1.

Also, I have no idea how I would answer this survey question myself, as I don’t understand what is meant by this tradeoff. What does it mean to trade off 120 chickens for 1 human? Does that mean that if I serve chicken 120 times in a two-year period, I should kill a person to compensate? I feel like I’m missing something here?

P.S. I was told that the the survey specifically asked, “What number of chickens do you think is equal in moral value to one adult human?” etc. I’m not sure how to think about “moral value.”


  1. Steve says:

    The answer is five, five lobsters per person.

  2. Pierre Dragicevic says:

    This seems to imply that people should stop worrying about the fate of humanity, and turn their attention to fish, worms and insects.

    • jim says:

      Would be interesting to see the distribution of neurons on earth circa 12,000 BCE. How many mammal neurons before / after the American and European megafauna extinctions? What would have been the number of fish neurons prior to the decimation of the Atlantic cod fishery? What about insects?

      ha, even cooler, neuron evolution over geological time!

      • Presumably the number of neurons in one brain is more important than the total number of neurons in K animals. Connections between neurons are important for the sophistication of the brain. There are naively O(N^2) possible connections in an animal with N neurons… but there are no connections between neurons in different animals…

  3. jd says:

    Elephants and chimps may be considered endangered and more valuable. Looks like you need multiple animals per intelligence level. In addition, things like familiarity and cuteness could come into play. Chimps and elephants aren’t typically considered ‘food animals’, whereas lobsters, chickens, cows, and pigs are. I think these factors would come into play more than perceived brain size.

    In any case, what the heck is the point of this exercise?

    • jim says:

      “In any case, what the heck is the point of this exercise?”

      Well, ultimately we could come up with an empirical formula for human value of an animal. Then when the tough decisions in wildlife management come along, we can avoid the uncertainties of popular sentiment and use our formula to decide what to do, right?

      So today, out here on the Olympic Peninsula in WA state, there’s a good chance that a USFWS officer is poking around with a rifle in hopes of shooting a Barred Owl. Barred Owl is intruding on the habitat of Spotted Owl, which USFWS has already spent a huge pile of cash to save.

      But maybe saving the loser isn’t the right way to go. maybe we could use our empirical formula to find out which owl humanity likes best!

      • Steve says:

        An “empirical formula for the human value of an animal” is quite impossible. It is as impossible as establishing a voting procedure that does depend voting procedure or a general welfare function that does not depend on irrelevant alternatives. One survey will get one answer and another will reach a different conclusion. It is all a waste of time.

        • jim says:

          Steve! You know the old saying man! Too much data ruins a perfectly good hypothesis! A bird in hand, my friend. One survey is good’nuf for policy. We just stand in the mall and keep asking people until we get p < 0.05. Calc on the fly!

    • Martha (Smith) says:

      jd said,
      “In any case, what the heck is the point of this exercise?”

      Maybe it’s to announce the Second Coming of George Orwell?

  4. Karsten says:

    I think you are making a sign error. If you sacrifice a human aren’t you making things worse?

    To me it’s just the trolley problem. On one track, a pig, on the other 10 chickens. Who dies? (The chickens, obv) It’s a well defined problem that inevitably leads to a lobster/human value ratio.

  5. zbicyclist says:

    If we move from the realm of surveys to the realm of actual behavior, we can see that the average person eats 7,000 animals in their lifetime, and so is directly responsible for their deaths.
    the but average person is not responsible for the untimely death of even one human.

    Without doing any further math, we can see that the survey numbers don’t relate to these at all. This is just silliness.

  6. jd2 says:

    Adding humans seems to make this really messy. I am not an expert in whatever field designed this but why not just use a baseline animal like a hippo or a hedgehog?

  7. Ethan Bolker says:

    If you study tradeoffs between species you can create a very large directed graph with weights on the edges and ask lots of questions. Is the ratio of chickens per lobster the reciprocal of lobsters/chicken? Do weights multiply along paths?

  8. Lobstrosity King says:

    Dad-a-chum? Dum-a-chum? Ded-a-chek? Did-a-chick?

  9. Dieter Menne says:

    I wonder who finances these research questions. Trump effect of total loss of ethics?

    If this research were made in China, I am sure the shit storm would be a tsunami.

  10. Michael Nelson says:

    I’d argue that the 3rd variable in the correlation is cultural, not biological: something like perceived cuteness/friendliness/popularity, not necessarily of the actual animals but of anthropomorphized versions in TV, films, books, etc. Consider cartoons: Dumbo > Wilbur > Elsie > Yosemite Sam > um, the Red Lobster logo? I can’t think of a cartoon chimp, but apes are clearly more human-looking than the rest. Try throwing in some animals that don’t have cartoon icons–emus, snakes, aardvarks, starlings, octopuses, squid–and I suspect they will have disproportionately low ratings vs neurons.

    I also agree with jd that another factor could be perceived rarity or exoticness may be rated more highly. (Hence octopuses might be rated higher than aardvarks.) See if you can find data on these perceptions (ranking animals by cuteness or friendliness or rarity) from other surveys and run a factor analysis.

  11. Cute cacodemon says:

    I would sacrifice a bunch of people if I’d to choose between them and my girlfriend. So I think it follows that one girlfriend is morally equivalent to a bunch of people, maybe log(bunch) to make it sound a bit more sciency. But do I know how many cortical neurons does my girlfriend have; or those people that are in the bunch? I’ve heard stegosaurus had brain the size of a walnut. So I’d say at least a walnutful. About uh… 10 scoopfuls, but those are the kind of scoops I would use when taking ice cream for myself, it’d be more scoopfuls if I’d be giving ice cream to someone else. So let’s see… a bunch times 10 (or more if it’s for someone else) scoopfuls… was this supposed to be on log scale? I’ve lost track of what I’m trying to do. Science is hard!

  12. Kassim says:

    The question would make more sense in a Buddhist land where all life is precious and must be protected. 

  13. David P says:

    Re: “What number of chickens do you think is equal in moral value to one adult human?” etc. I’m not sure how to think about “moral value.”

    How many chickens does a state need to add one more member to the House of Representatives? I sense a concerted effort by the Chicken Power in the offing here.

  14. Dale Lehman says:

    More seriously, I think this research illustrates a deeper problem. From looking at the source organization, I suspect that the intentions are good and that the effort is focused on trying to gather evidence to support saving species. However, in order to do that, the bargain (Faustian, in my view) that has been struck is that saving species requires adopting traditional economic logic. Since species do not have an explicit price tag, this can be inferred by surveys such as this one. The result may (or may not) support species preservation, but a moral argument has been replaced by an economic one. They may point in the same direction (but won’t always), but I don’t think that is a good reason to adopt this approach. Similarly, the trolley problem has never seemed a worthwhile exercise to me. It bothers me when moral choices need to be expressed as economic tradeoffs – we seem to have lost the ability to think about morality in any other terms.

    • zbicyclist says:

      You can also argue that “saving species” is entirely wrongheaded. We should be saving ecosystems.

      There’s a huge bias in “saving species” toward mammals, toward the cute, and so on. But our understanding of the complex interplay of the environment is very limited. So far as I can tell, not much attention is devoted to saving insects, or fungi, or bacteria, for example, yet it is entirely possible that some of these species are, in the long run, more valuable than tigers.

      • Dale Lehman says:

        Absolutely. But even if we focus on saving ecosystems, I question whether it is worthwhile to determine how many ecosystems would be required/offered in exchange for something else.

      • jim says:

        You could also argue that saving species or ecosystems beyond their direct benefit to humans is neither sensible or desirable.

        Not much effort is devoted to saving insects for three reasons:

        1) probably the best and strongest one is that trying to use the preservation of an insect to block a valuable development would probably be the nail in the coffin of the endangered species act, which already under a lot of pressure.

        2) Assessing the exact range and habitat and ecosystem role of every insect to determine whether or not it’s endangered would be a ridiculous cost.

        3) insect species probably come and go so fast that they’re not worth bothering with anyway

        For bacteria, the direct exchange of genes is so frequent that Darwinian evolution is almost irrelevant, eliminating the rational for species preservation. Many laypeople believe that superbugs evolved resistance to antibacterials via Darwinian evolution. This is false. Superbugs derive their antibacterial resistance by simply acquiring the relevant genes from the environment, where the refuse of other dead bacteria is abundant.


    • jim says:

      You could also argue that traditional economic logic has not just saved, but driven a massive population and diversity explosion for chickens, cows, pigs and a bevy of other animals and plants. My goodness, how many varieties of apples do we have today.

  15. Ethan says:

    Did they also ask whether the participants were vegetarians on the survey? Looking at the histogram, a lot of the participants reported values that don’t appear to be compatible with meat eating.

  16. Terry says:

    Some comments are drifting into existentialism.

    To exist is to act is to choose.

    You may not understand the question or how to think about the question or what the words in the question mean, but you must choose, and even if you choose to not choose, you are choosing.

  17. Martha (Smith) says:

    I’m not sure how you intended this, but it sure gave me a good laughing spell.

    • Terry says:

      Not sure you are responding to my post on existentialism, but if you are, it is actually a serious post.

      In a nutshell, that is what existentialism is … if you exist, you have to act … even if you have no idea what is going on.

      Pad that insight out to a novella, and you have Camus. Pad that out to a lifetime of pretentiousness, and you have Sartre. Say it pithily in a paragraph, and you have Nietzsche.

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