Cassavas: cyanide poisoners and enemies of rationality
June 22, 2022 10:05 AM   Subscribe

Cultural psychologist Joe Henrich points to the cassava as evidence that blindly following tradition is sometimes better than individual rational choice. (book, summary article)

How are cassavas related to potatoes? They aren't. The tubers (such as potatoes, cassavas, sweet potatos and yams are all quite unrelated to each other, brothers from different mothers. Yams are thinking of getting a new haircut to stop people from mistaking them for sweet potatoes. They are not the same.

The potato's real family is the solanaceae (nightshades). You could make a sitcom about the nightshades; these genetically similar relatives couldn't be more different from a human perspective. Tomatoes! Peppers! Eggplant! But some members of the family (e.g. belladonna, mandrake) are literally toxic, not to mention the family's real serial killer, tobacco. The potato does have skeletons in its closet, but we can't blame it for what cassava does.

Cassavas kill people by cyanide poisoning when not properly prepared (horrible recent examples of mass poisonings: 2005, 2017). They are safe when properly prepared, and are the third most important food crop in the tropics. They are also used to make tapioca, I'm not saying they're all bad.

Joe Henrich bases his argument about rationality on the importance of Tucano traditional practices. The Tucano are an indigenous society whose traditional territory is in Columbia and Brazil. Cassava is a staple crop. Heinrich points out that "since the multistep task of processing manioc is long, arduous, and boring, sticking with it is certainly non-intuitive. Tukanoan women spend about a quarter of their day detoxifying manioc (cassava), so this is a costly technique in the short term."

The problem is that cassava can also cause chronic cyanide poisoning, with symptoms that don't arise for years or decades, by which time it is too late. Henrich again: "Consider what might result if a self-reliant Tukanoan mother decided to drop any seemingly unnecessary steps from the processing of her bitter manioc. She might critically examine the procedure handed down to her from earlier generations and conclude that the goal of the procedure is to remove the bitter taste. She might then experiment with alternative procedures by dropping some of the more labor-intensive or time-consuming steps. She’d find that with a shorter and much less labor-intensive process, she could remove the bitter taste. Adopting this easier protocol, she would have more time for other activities... Of course, years or decades later her family would begin to develop the symptoms of chronic cyanide poisoning. Thus, the unwillingness of this mother to take on faith the practices handed down to her from earlier generations would result in sickness and early death for members of her family. Individual learning does not pay here, and intuitions are misleading. The problem is that the steps in this procedure are causally opaque—an individual cannot readily infer their functions, interrelationships, or importance."

In short, only intergenerational observation and indigenous knowledge can keep the cassava under control. The humble potato asks only to be boiled, mashed or stuck in a stew.
posted by justsomebodythatyouusedtoknow (22 comments total) 26 users marked this as a favorite
 
The summary article is interesting. I agree with the idea that this sort of inherited knowledge is often the result of generations of refinement and confirmation and therefore often smarter than we give it credit for. I love when I hear about pharmacists finding out a substance they've isolated is actually the same one produced through some traditional process.

I wonder about examples of the opposite, however — the kinds of things we end up calling superstitions, or harmful traditions only done for religious reasons. Going from bird augury (secretly smart) to propitiating the bird lord (no effect). Such things seem to survive the transition into more complex social systems as they tend to create and enforce classes and such.

The practice of accepting inherited knowledge uncritically is surely not the point... but neither is blindly ignoring inherited knowledge as superstition. An interesting tension.
posted by BlackLeotardFront at 10:31 AM on June 22 [8 favorites]


The tension, (as the article points out as well), is that these practices evolved culturally over many generations, whereas radical changes in the human environment and the competencies to navigate that environment (safely, healthfully, for both the individual and the species) happens over at most, years, these days.

Indigenous knowledge, no matter how hard won is not guaranteed AT ALL to help us in these matters.
posted by lalochezia at 10:35 AM on June 22 [7 favorites]


The cyanide source in Cassava is found in many other foodstuffs too: cyanide is released from Cyanogenic Glycosides, which are used for defense mechanisms across many plant species.

For those of you who studied organic chemistry in college you should be able to work out how HCN is formed from these substances....

Also: some quality potato-adjacent work here justsomebodythatyouusedtoknow
posted by lalochezia at 10:41 AM on June 22 [1 favorite]


Really interesting article, and the linked article from James Scott ("Seeing Like a State") was interesting too even if it was published in the Cato Institute's online journal originally.

The common thread, whether it's cassavas, old-growth forrests or city planning seems to be that simplifying and "rationalizing" a complex tradition pays off big in the short term, but the problems become more and more apparent over time.

Redesigning the forest as a “one-commodity machine,” however, had, in the long run, catastrophic consequences for forest health and production. The mono-cropped, same-age forest was far more vulnerable to disease, blight, and storm damage. Its simplicity and formal order, together with the elimination of underbrush, deadfalls and litter dramatically reduced the diversity of the flora, insect, mammal, and bird populations so essential to soil building processes. Once the soil capital deposited by the old-growth forest had been depleted, the new forest entered a period of steep decline in growth and production. The term “Waldsterben” entered the vocabulary of modern forestry science and led, in turn, to huge outlays for fertilizers, rodenticides, fungicides and insecticides as well as efforts to artificially reintroduce birds, insects and mammals that had disappeared. By redesigning the complex and poorly understood ecology of the old-growth forest as a veritable wood-fiber farm and bracketing everything else, scientific forestry had destroyed a vernacular forest and a host of ecological processes that came back to haunt it.

That's from the James C. Scott essay linked in the summary article.
posted by subdee at 11:25 AM on June 22 [8 favorites]


I saw something like this with Hurricane Irma. The last really big hurricane here was Luis in 1996, so a lot of time had passed when people were building beautiful villas with big glass windows and stuff, presumably using modern engineering and architecture. Local builders I know, who had learned from their parents, often had rules of thumb about window size or how much a roof should overhang to shade a veranda. The people using these rules of thumb weren't blindly following them, they had experience with previous hurricanes. But they were also traditional rules rather than ones that were calculated based on physics or whatever.

One thing that is a tradition here is to use odd numbers of leaves for preparing certain bush teas. I'm not sure what that tradition might accomplish exactly, but having to count the leaves does mean you are not throwing in a whole handful, so maybe it does essentially limit the dosage to about 5 leaves.
posted by snofoam at 11:31 AM on June 22 [7 favorites]


I read The Secret of Our Success a few years ago. It's a great book. Henrich's work is interesting and important. Strongly recommended.

However … I think we should be cautious because these ideas can be used by those who seek to block improvements in social organization. You'll probably remember that a few years ago, when everyone was debating same-sex marriage, opponents of reform often argued that the prevailing system of rules around marriage was the product of many centuries of cultural evolution, and that we shouldn't risk making changes to it. In effect, they were saying that these marriage rules were like the rules for cooking cassavas.

We need to think very hard about when cultural evolution produces good norms … and when it doesn't. My suspicion is that, because cultural evolution is very slow, it is less to be trusted in a society that is rapidly changing.
posted by HoraceH at 11:41 AM on June 22 [8 favorites]


"Consider what might result if a self-reliant Tukanoan mother decided to drop any seemingly unnecessary steps from the processing of her bitter manioc. She might critically examine the procedure handed down to her from earlier generations...

Thus, the unwillingness of this mother to take on faith the practices handed down to her from earlier generations would result in sickness and early death for members of her family. Individual learning does not pay here, and intuitions are misleading. The problem is that the steps in this procedure are causally opaque—an individual cannot readily infer their functions, interrelationships, or importance."

This is where TFA goes wrong. There is not a case, I bet, where a "self-reliant Tukanoan mother" is off processing manioc by herself. I mean, I just now learned that there is a Tukanoan society, but I can see what TFA is doing here is retconning modern human behavior onto people who live in a much different way. This time- and labor-intensive, vital work is almost certainly not something that Tukanoans do in isolation from one another. The hypothetical "self-reliant Tukanoan mother" in this scenario is revolting not against tradition only but against everything in society around her, and her relationship with that society is not like that of a modern person for whom autonomy is expected to be a big goal.

Also, curiously (because the subject of TFA apparently identifies as an evo-psych person, or at least adjacent), of course what we see in surviving manioc-consuming societies are the ones who did keep absolute faith in the process after it all got figured out: the kind of society that would tolerate a "self-reliant mother" going off and changing that shit, those societies went extinct.
posted by Aardvark Cheeselog at 11:57 AM on June 22 [16 favorites]


The Yanamamo women don't eat curare-killed game during pregnancy, but eat certain fish they hunt by other means. It is easy to see why governments try to deform the processes of indigenous groups, to extract capital, and monetize everything. Slowly the knot of capitalism chokes the productivity of hunter gatherer, gardeners, and they have to skip steps, or do without traditional amounts of water, or use chemical fertilizers to make up for loss of crop rotation land. I love the story that came out of the Phuket tsunami, in which islanders with a long history survived, because an elder remembered what to do when all the streams flow out, and the water leaves the beach, that was, go to the highest ground, taking necessities that could be gathered in a hurry.
posted by Oyéah at 11:58 AM on June 22 [6 favorites]


I don't agree with the conservative subtext of the author's thesis but the cassava argument is interesting because it isn't just the hypothetical, if you read the article the substantial argument is that cassava was transferred to West Africa and the author says just look at the observed health effects of cassava consumption there. And that it fits his simple theory of "evolved unknown knowledge".

I can buy small cassava tubers at my supermarket, now I'm wondering if I needed to do more than just boil them until tender.
posted by polymodus at 12:15 PM on June 22 [1 favorite]


There's a similar example (less extreme, but similar) with corn, pellagra, and Vitamin B3.

When corn was imported from the New World to the Old Word they imported the crop only. Among the ways corn was prepared was to cook it with something alkaline to convert the niacin into Vitamin B3, along with some other benefits. This cooking process also allows corn to be made into masa flour for tortillas and other food products.

Corn is (mostly) fine without processing (except for Vitamin B, naturally) but if, for example, you were living in the American South with corn as a staple of your diet then pellagra might come a-knocking.
posted by caphector at 12:29 PM on June 22 [10 favorites]


I can buy small cassava tubers at my supermarket, now I'm wondering if I needed to do more than just boil them until tender.

Almost certainly that is sweet cassava and therefore fine to eat after you peel and cook it. This Eater article gives a detailed breakdown of preparation options
posted by Dip Flash at 2:00 PM on June 22 [4 favorites]


I seem to have missed the spud-centric memo, but once you get into yams you find all sorts of yam-adjacent things that aren't nightshades, such as eddoes and taro (genus: Colocasia), plus malanga (genus: Araceae). To cause maximal confusion, taro and malanga are both sometimes known as cocoyams, even if neither are yams (genus: Dioscorea).

Eddoes are very cute, and look as if they would make nice pets.
posted by scruss at 2:06 PM on June 22 [4 favorites]


The 2005 mass poisoning referenced looks like it was the result of pesticide poisoning, not cyanide.

Pesticide Eyed in Bohol Poisonings
posted by La Gata at 2:16 PM on June 22 [3 favorites]


I read the summary here and thought of a Chesterton quote about fences--then laughed when I saw the article opens with it.

I like the observation and think about it at work all the time--if something is "easy" why didn't we do it before? If it's counterproductive why did we start doing it at all? (This is useful because often we can answer the question, and it turns out that yes those reasons are irrelevant now and we should change.)

The article was interesting and in many ways addresses my comments--but towards the end and and not in the excerpts here.

The early framing has some "straw we" going on--oh, everyone thinks humans are successful for reason A, but actually reason B! Well, I'm not sure I ever thought only Reason A or have read serious people who did, so now I'm just a little huffy you asserted I did, rather than stunned by your insight.

It of course picked examples of successful traditional practices. (Although perhaps in some cases "just so stories". The randomization stuff is very interesting but has every example been studied carefully and found to be in fact empirically good?) There are obviously lots of bad ones--sexist and patriarchal ones, but also beliefs like "fans can suffocate you" and "you will choke if you try to drink standing up." And of course with today's level of science, the casava issue would not need generations of observations lasting generations to understand and solve.

What's most interesting to me is the part that focuses on how amazingly good this is when it extracts real rules. The signal/noise connecting chronic cyanide poisoning to cassava preparation practices has got to be infinitesimal. How do people sort that out? This is the part I loved, along with the wealth of examples.

However, I thought the argument that Darwinian selection is the right way explain these traditions was extremely contested among anthropologists. Anyone more up on the current schools of thought want to enlighten me on that?

In the end we do get back to the fence problem. There's a strong case for prudence and small-c conservatism. But the flip side is one of those fences Chesterton would worry about tearing down was the one separating good, honest Englishmen from Jews. How do you know which kind of fence you're protecting? If anything Greer ends up more skeptical than I am--"rationalism is the only tool we have left" isn't really where I expected him to go after the opening.
posted by mark k at 2:20 PM on June 22 [9 favorites]


I can buy small cassava tubers at my supermarket, now I'm wondering if I needed to do more than just boil them until tender.

Almost certainly that is sweet cassava and therefore fine to eat after you peel and cook it.

I would advise boiling it until it’s very tender all the way through, with no white chalkiness left around the fibrous core. I’ve given myself terrible indigestion by undercooking cassava. I don’t know if that has anything to do with the cyanide content, but in any case, don’t let that discourage you, a bit of care needed in preparation is more than worth how satisfying it is.
posted by mubba at 3:34 PM on June 22 [1 favorite]


To place tradition on one end of a dilemma and "individual rational choice" on another seems incorrect. Rationality is itself a tradition that isn't particularly individual, but leans on group experiences and consensus through time. For an example, see science.
posted by elwoodwiles at 5:02 PM on June 22 [10 favorites]


Rationality is itself a tradition that isn't particularly individual, but leans on group experiences and consensus through time. For an example, see science.

That's a good point. One of the mistakes made by antivaxers who shout at you to "do your own research" is that no one does their own research. Everyone engaged in science is participating in a practice with a centuries-long accretion of standards, conventions and habits. That practice includes peer-review. Science is inherently an interpersonal and intergenerational system.
posted by justsomebodythatyouusedtoknow at 6:02 PM on June 22 [5 favorites]


From my perspective, I'm really relating about the part about losing cultural traditions due to modernisation and positive prejudice for western over ours and how my people here is blindly trying to recapture them but through any number of equally or even more dumb heuristics. Like, Muslim antivaxxers here would insist reciting certain verbs and eating certain foods are enough because it's sunnah rather than be captured by colonialist practices.

Sometimes it's clear why (the climate and the basic building principles - why these concrete blocks that're low on the ground with no internal air wells in a hot, humid, flood-prone area), and other times it's completely only documented by social science-type people and storytellers with no popular (hard) science energy to investigate why so people like me are forced to find analogical explanations. Like, because of my reading about the various types of south american potatoes, I mentioned once to my mother that there's a type that needs to be eaten with clay to prevent poisoning and she said, she remembered as a child there were types of tuber (maybe cassava-related) that she recalled needing to be cleaned with clay or eaten with mud, but she won't remember what they are. The Iban in Sarawak have a long involved process about dyeing their threads before weaving but the cultural anthropologists I've seen talking about them (ethnographically) exhibit no interest nor desire to try to explain the process in a scientific way or even history of trade way - my best guess based on my own understanding as a textile hobbyist it had a lot to do with salt being the only available mordant to the community for centuries, with one other local plant acting as a pH change agent. I know no other local populist/popular references where I can even begin to understand like TFA.
posted by cendawanita at 7:46 PM on June 22 [5 favorites]


The group Kassav' from Guadeloupe and Martinique took its name from the cassava and its preparation. The studio mix had to be just right for the songs to coalesce into some of the best music on the planet.
posted by DJZouke at 5:22 AM on June 23 [1 favorite]


It is unfair, perhaps, to the women who make cassava, but it's really hard to accept this article in good faith. The mention of Chesterton's fence is what really cements it. I feel like it's a stalking horse for what we now call "conservative," which is to say, living the unexamined life -- accepting sexist, racist, homophobic, and authoritarian beliefs because they feel right.
posted by Countess Elena at 7:09 AM on June 23 [1 favorite]


I'm not sure. I I thought about that too, but if it is meant to be a stalking horse, then the last four paragraphs are really odd, as they more or less explicitly say "Chesterton's Fence doesn't apply anymore, society is changing too quickly."
posted by mark k at 5:25 PM on June 23


And also the review digs gently at the book by pointing out that if you’re using an analogy with genetic natural selection that hard, you should expect to find quite a lot of stuff that isn’t needed or even particularly useful, it just hasn’t been selected out yet, and you might not be able to tell it from actively selected traits.

Possibly this is intellectually honest conservatism.
posted by clew at 6:10 PM on June 23 [2 favorites]


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