Posted by: Rob Viens | April 20, 2012

Chirping Sand and Cyanide Pudding

Today, April 20th, the trip back to Rio began in earnest, retracing the steps of the trip on April 11th. Although he does not write in much detail about this leg, I imagine that Darwin was much more observant this time (it was on this leg that he was so sick last week). His full entry today notes:

“Returned by the old route to Campos Novos; the ride was very tiresome, passing over a heavy & scorching sand. Whilst swimming our horses over the St Joâo, we had some danger & difficulty. —the animals became exhausted & we had two drunken Mulattos in the boat.” (Apr 20)

Macaé excursion – April 20, 1832:

Map of Darwin's Expedition – April 20, 1832

In the margin of the diary he mentions the “chirping sands” (see more at The Singing Sands of Bahia). In Voyage, Darwin describes the sand a little further writing:

“Leaving Socêgo, during the two first days, we retraced our steps. It was very wearisome work, as the road generally ran across a glaring hot sandy plain, not far from the coast. I noticed that each time the horse put its foot on the fine siliceous sand, a gentle chirping noise was produced.” (Voyage of the Beagle)

Aside from the sands, Darwin crossed a lot of cultivated land. Last week I discussed the Brazilian coffee crop.  Today a few words on cassava.

Darwin first describes this crop while staying at Socêgo:

“Mandeika (or Cassada) is likewise cultivated in great quantity: every part is useful. — the leaves & stalks are eat by the horses; the roots, ground into pulp, pressed dry, & then baken makes the Farinha; by far the most import[ant] article of subsistence in the Brazils. From this is prepared the Tapioka of commerce.” (Apr 13)

Cassava (Manihot esculenta) belongs to the family Euphorbiaceae, which also includes the Caster oil plant and Poinsettia. The family is typically  found in the tropics around the world, and cassava itself is native to South America. Cassava it makes for a relatively stable food crop because it can be grown on poor soils and is also very drought tolerant.

Cassava leaves (from Franz Eugen Köhler, Köhlers Medizinal-Pflanzen, 1887):

Cassava plant

In the United State, most people are only familiar with cassava in the form of tapioca (a dried extract of the cassava root). But in other parts of the world, particularly in the tropics, it is a major source of carbohydrates. In fact, according to the United Nations, “Cassava is the third most important source of calories in the tropics, after rice and maize”. The root is very versatile and can be used like potatoes in stews, dried and made into pudding, turned into a beverage, or even distilled into a form of alcohol. In addition, the leaves can be prepared and eaten, too.

Cassava root (from and cassava chips:

Cassava root

You might ask, why the heck hasn’t cassava become more common in the US or European market? One reason is that is has a pretty short shelf life, which doesn’t go over particularly well in today’s supermarket economy where vegetables can take weeks to get to your table. But worse yet, cassava has a dark side – if you don’t prepare it correctly you could poison yourself. Darwin writes:

“It may be mentioned as a curious though well known fact that the expressed juice is a most deadly poison; a few years ago at this Fazenda a Cow died from drinking some of it.” (Apr 13)

Basically, if the root is not properly cooked it can retain enough of a concentration of cyanide to have adverse health effects – including death. Yes – cyanide – can you imagine trying to explain that to a supermarket chain risk assessment manager. Or how many tubers do you think would move off the shelf at a Wal-Mart if there was a sign saying, “Caution, contains cyanide”. (RJV)


  1. Restraining self from google search on how to cook cassava….. must know what has to be done to mitigate cyanide poisoning risk….

    • From what I recall it requires soaking (for a couple of days) and cooking/boiling. It’s probably not a good idea to save the water for soup stock 🙂

      I also recall that there is a lot of variation in the initial cyanide content of the cassava – depending on the variety and the conditions under which it was grown.

      I must say that I am intrigued, though not sure if I want to do the pre-processing myself.

      Thanks for great comments, Leslie!

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