Boiling makes the manioc taste right. The pointless-looking two-day wait is what removes the cyanide.
Rationalists keep running into the same puzzle: you can prove with facts and logic that a practice is pointless, and people go on doing it anyway.
Consider how Tukanoan women in the Amazon prepare bitter manioc. They scrape and grate the roots, wash them, separate the fiber from the starch and the liquid, boil the liquid into a beverage, leave the solids to sit for two days, and only then bake them. It takes a large share of the day, and much of it looks like ritual. A rational observer would simplify: boil the roots and eat them. Boiling removes the bitter taste, so the shortcut seems to work.
It doesn’t. Boiling removes the bitterness but not the cyanide; the elaborate process removes both. The observer who trusted his own reasoning develops chronic cyanide poisoning, and the woman following a procedure she may not be able to justify stays healthy. Joseph Henrich, in The Secret of Our Success, hints at the uncomfortable lesson: for basically all of history, using reason would get you killed.
Why reason can’t find the answer
The observer is not stupid. The trouble is that chronic cyanide poisoning develops slowly and does not cause immediate symptoms. Skip the two-day wait and nothing happens this week, or this year. Without visible cause and effect, no amount of individual cleverness can work out which steps matter, because the shortcut works locally: the food tastes fine and the cost arrives invisibly over decades.
History ran the experiment. The Portuguese introduced manioc to West Africa in the 1600s but did not bring the processing methods. Many African groups failed to rediscover proper detoxification, and chronic cyanide poisoning persists today. Centuries of intelligent people working on the problem have not solved what cultural transmission would have handled at once.
So the manioc procedure is knowledge, but not knowledge that lives in anyone’s head. It was assembled over many generations, each keeping or adding steps for reasons nobody recorded, by people who mostly never learned why it worked. The knowledge lives in the culture, not in any individual brain.
The rationalist’s trap
The will to think treats intelligence as a moral virtue: the refusal to accept an answer you do not understand. Henrich exposes its limit. Understanding is not always available on the timescale of a human life. The manioc processor does not know why the two-day wait matters, and if she insists on understanding before complying, she gets cyanide.
That does not make tradition right by default. The honest position is that tradition is a lossy compression of ancestral experience, and the compression is lossy in both directions: it preserves knowledge that cannot be articulated, and it also preserves practices that have outlived their usefulness. Reason works in domains where cause and effect are visible and fast, which is why aviation and surgery could evolve their safety habits in decades rather than generations. Tradition works where they are invisible and slow, which, historically, has been most of life. The difficulty is that from the inside, the two-day wait and a useless taboo look the same: both are steps nobody can explain.
Human success, on this account, comes less from being the smartest animal than from being the animal that can pass on complex knowledge without each generation rediscovering it. The modern habit of prizing individual intelligence over transmission risks the boiled-manioc mistake. Yet the pressure now also runs the other way. The Bitter Lesson suggests that where encoded knowledge decays within half a generation, what gets transmitted may have to shift from specific rules to the capacity to learn and search. Which of your inherited two-day waits still remove cyanide, and which guard against a poison that no longer exists, is a question neither reason nor tradition can settle alone.
References:
- Joseph Henrich, The Secret of Our Success: How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter
- Scott Alexander, Book Review: The Secret of Our Success, Slate Star Codex