Monday, March 29, 2010

Brussels Sprouts

As spring gears up I’ve been thinking a lot about gardening. We’re going to try growing more food this year and I’ve been researching vegetables that are easy to grow in New England. In parallel I’ve also been thinking about and researching the natural history of gardening and garden vegetables. Time and time again this project continues to illuminate our own natural history more than the natural history of the vegetables I plan to grow. This makes a lot of sense. Gardening is an incredibly human behavior and its advent marks a major turn not only in our species’ history but also in the entire natural history of life on earth.

Some of you know this but a really great fact is that the simple act of putting one’s hands in soil releases endorphins in the brain. I haven’t been able to track down a primary source for this fact so if you know of one please leave me a comment. I’m quite confident it is true, though, from secondary sources and, more importantly, personal experience. Working in the garden just makes me feel good. And that’s directly related to the fact that this is a behavior that we should engage in, from a natural history perspective. We should garden and we should engage with the natural world because these things are part of who we are as a species. We are not primates designed to hunch over a keyboard as I am presently doing but primates who evolved in a natural world and used our intelligence to remove some of the uncertainty from procuring proper nutrition.

But I digress. One variety of vegetables we are going to try to grow this year is Brussels sprouts (and I just learned that it is Brussels sprouts and not Brussel sprouts). They are actually a variety of Savoy cabbage that have an ancient connection with the Celts. Brussels sprouts are one of those bad rap veggies that people either strongly dislike as children or even throughout life. The reason is that they contain a molecule, in common with broccoli and other cabbages, called phenylthiocarbamide or PTC which is perceived as bitter in some but not all humans. About 25% of Americans cannot detect the molecule and this discrepancy accounts for the fact that some people find these vegetables disgusting while others do not. I am wagering that I cannot detect PTC because I love Brussels sprouts, cabbage and broccoli. These are three of my favorite vegetables, actually.

PTC played a major role in the development of our understanding of the biochemistry and genetics of bitter taste detection. Ability in all animals to taste bitterness has evolved as a way to avoid toxic compounds. It is the only one of the five tastes (yes, five) that is activated by more than one family of molecules. It was little understood just how this worked until the 1930s when a scientist was experimenting on PTC and accidentally blew some of the substance into the air. His colleague began to complain of a bitter taste in his throat that the lead researcher could not detect. This lead to a line of research that now accounts for the genetic difference between humans who can and cannot taste this bitter molecule.

It is still somewhat unclear why some can and some cannot taste PTC. It is often found in toxic plants and PTC itself is toxic in very high quantities. We should, at least in theory, have all developed an aversion to the molecule as it is a sign of toxicity. Perhaps the molecule’s presence in vegetables we’ve been eating since antiquity accounts for some of our inability to taste PTC (or as I like to think of it, an ability not to taste PTC). What plants (either edible or not) are you looking forward to seeing in your garden this year?

Discovery News:

Parington, Charles Frederick (1835) British cyclopaedia of natural history. Accessed via Google Books 3/29/2010. URL:

Texas A&M:


  1. This would of course be a much more official and intriguing comment if I could remember any of the specific details. Whenever visiting Boston's Museum of Science, I spend much of my time in the room devoted to evolutionary biology. I have even asked someone who works there for the PTC-covered paper; as it turns out, it tastes like paper to me. I guess that's why I can handle broccoli and Brussels sprouts.

    However, once when there a woman informed me that they have been able to track PTC tasters through race, and peoples who more recently in history would have to use their tastebuds for survival passed on the genetic qualities for tasting PTC longer than other people of other races or ethnicities. So now, apparently something like 97% of people of American Indian descent can taste PTC, versus some minuscule percentage for other backgrounds.

    Like I said, the numbers would make a much more compelling argument. Still, it was very interesting.

    This may be unrelated and considering I have asked you many questions, do not feel pressured to answer anytime soon; however, I cannot taste the bitter PTC, yet I have always been a somewhat finicky eater. Much of the dislikes I had as a child I have grown out of, but there are some tastes that other people perceive as mild that I absolutely cannot stand, for example, cucumbers. If I can't blame my pickiness on PTC, what else could it be?

  2. I haven't had a chance to really look into this yet but here's my educated guess: There are two things I can think of that really influence our perceptions of foods besides taste, the smell and the texture. Most of taste is, in fact, smell so there could be something there. However with a food like cucumber which (at least to me) doesn't have much of a taste or smell it could have something purely to do with texture. Do you dislike other foods with similar textures?

  3. i just realized that my comment to this post was placed in the comment section of the "chris jordon exhibit". *whoopsies!*

    anywoo, its there~ lot's of gardening thangs :)