Crop That Conquered the World II: Cassava

Mention the great agricultural gifts that the New World gave to the Old and most people think corn (those who aren’t chocoholics of course). Yet there’s another that’s at least as important, especially in the tropical and subtropical regions of the world: cassava, also known as yuca or manioc.

If you’ve never seen one of these, you’re in for something of a surprise, as they’re some of the least inviting looking tubers ever. Big, heavy, brown and pointy with a woody/waxy bark on the outside, you pick one up and immediately wonder what sort of industrial-strength tools and processing are needed to turn such an object into food.

An indeed processing really is the key to these roots, for not only are they almost impossible to consume raw (being so very hard and dense) they contains some, shall we say, inconvenient chemical compounds that can actually make them dangerous.

But let me back up a little. Cassava as I just mentioned is a root. It’s very big, it’s full of water and packed with energy stored in the form of starch. As such it’s a potential gold mine of nutrition for any animal that might come across it. Which is why, a long, long time ago, the cassava evolved a defense mechanism to keep buddinski insects and rodents from crashing the buffet.

That defense is a little compound called linamarin. It’s a chemical that’s similar to sugar, but that has one important difference: when it’s digested it breaks down into, among other things, hydrogen cyanide. So animals tend to avoid it, since they have flora in their digestive tracts that contain the linamarase enzyme responsible for reducing the linamarin molecule down. For those creatures that may not possess a digestive system quite so sophisticated, the cassava root helpfully provides the very same linamarase enzyme in its own flesh, tucked away inside separate structures. Break them (by biting into the root), the enzyme is released and — presto! — poison.

A pretty neat and foolproof defense mechanism. But then the cassava plant never counted on the evolution of the human frontal lobe, which was to eventually prove its undoing. For eventually human beings would, with time, learn how to use cassava’s own linamarase enzymes against it. Oh, the irony.

The process is fairly simple. As mentioned, when you break up the cellular structure of a cassava root, by oh say mashing it, the linamarin and linamarse enzymes mix to make cyanide, which isn’t so good. But then the thing about hydrogen cyanide is, it’s volatile, which means it evaporates quite readily. Give the mash a little air and stir it around and most of the cyanide evaporates, making the cassava flesh safe to eat.

Native peoples in South America hit upon this technique about 10,000 years ago, and ever since cassava has been a staple crop there. The Portuguese were so impressed with it that they spread it around in the 1600’s, particularly among their colonies in West and East Africa where it thrived, delivering up ton upon ton of high-density carbs (and water) despite terrible soil and minimal rainfall. No wonder the cassava root became known in the Ewe language as agbeli, a word which means “there is life.”

Today sub-Saharan Africa produces something like 150 million tons of cassava each year with Asia, the Caribbean and Latin America making up the rest of the world’s quarter billion ton annual harvest. Quite popular stuff indeed.