Cassava, knowledge & society

Over the last ten years I have found myself drawn to explore the social nature of knowledge in more and more detail. I have done this by asking naive questions such as “how did people work out which mushrooms to eat and which to leave?” and “how did people discover magnetic compasses?”

Some of these questions have definite answers. The answer to the question “what came first: frozen food or household fridges?”, for example, has a definite answer: frozen food. (You can start investigating this by googling Clarence Birdseye.)

This week I found an article on the BBC website that approaches this from an interesting starting point. The article asks “How do people learn to cook a poisonous plant safely?” It then focuses on the cassava, a plant that needs a lot of preparation and proves deadly if the preparation goes wrong, since it contains dangerous levels of hydrogen cyanide.

According to the article,

Toxic plants are everywhere. Sometimes simple cooking processes are enough to make them edible. But how does anyone learn the elaborate preparation needed for cassava or nardoo?

No single person does, according to Joseph Henrich, an evolutionary biologist.

He argues this knowledge is cultural. Our cultures evolve though a process of trial and error analogous to evolution in biological species. Like biological evolution, cultural evolution can – given enough time – produce impressively sophisticated results.

Somebody stumbles on one step that seems to make cassava less risky; that spreads and another step is discovered. Over time, complex rituals can evolve, each slightly more effective than the last.

In South America, where humans have eaten cassava for thousands of years, tribes have learned the many steps needed to detoxify it completely: scrape, grate, wash, boil the liquid, leave the solid to stand for two days, then bake.

Ask why they do this, and they will not mention hydrogen cyanide. They will simply say “this is our culture”.

I will continue seeking other examples, anecdotal or not.