Cyanide in food plants, naturally!

Your taste buds are a nice simple chemical testing kit. You can measure pH, how acid (sour) to how basic (bitter) something tastes; you can detect salts, soluble carbohydrates (sugars), and to some extent, metallic tastes too. In particular humans have a strong aversion to very bitter tastes, and this is an excellent instinct for avoiding two very common classes of toxic compounds, alkaloids and glycosides. One of the more famous glycosides (a molecule plus a glucose sugar) produces cyanide by combining with water and dissociating after the sugar is removed, and many plants use this compound as a chemical defense mechanism against herbivores. If you have ever read any murder mysteries, a good detective always notices the odor of "bitter almonds", and then declares, "cyanide." Actually it always smells more like rank almonds to me, but it's so hard to describe smells. We eat "sweet" almonds, seed of a close relative of the apricot, peach, and plum, and they are not actually sweet, but here sweet is used as meaning "not bitter", so they don't have any appreciable amount of the cyanogenic glycoside. The seeds of these other species tucked safely away inside the inner stony fruit wall (pit) are quite bitter and inedible, as are apple and pear seeds. Don't worry if you happen to consume an apple seed or two. First, you seldom chew them, and when unchewed their impervious seed coat allows the seed to transit your GI tract intact (a typical small seed gambit). Second, very small doses of cyanide are not particularly harmful. Whew! Larger pitted fruits operate on the eat the flesh and discard the pit model, something we primates are quite good at. Here's a recent news article about a colleague who studies cyanide producing plants, and while this subject is covered in my economic botany class, even the Phactor was surprised to learn that Lima (lee-ma, as in Peru, their native home) beans were cyanogenic. The good news is that cyanogenic compounds are both water soluble and heat volatile, so people have developed methods of food processing that reduce the bitter taste, thus reducing their toxicity. However, when we jigger with the genes and turn off the glycoside production, the crop suddenly becomes very tasty to herbivores. So you can't win even when you rig the game.
HT to the BSA.