Changing Taxonomies

I am amused—as it is so easy to be—by the number of basic facts I learned in elementary, nay, pre-school that have changed since I entered higher education (middle school).

Most obviously, the planet Pluto is dead. Long live dwarf planet Pluto! I guess there was always the possibility we'd discover another planet, and our solar system wouldn't stay at 9 forever. Yeah, that would have been cool to discover another planet. Maybe two other planets. We discovered there were probably about 200. So the IAU voted, and decided that it wasn't enough for a planet to orbit the sun and be sufficiently massive that it is nearly round, but it also has to clear its own orbit. Eight planets stayed in. Pluto was out. We never really learned that astronomers didn't have a good definition of a planet. Who knew this was even a possibility? That would have been an awesome lesson in ambiguity and human imperfection. Or it would have been an awesome excuse for some wise guy four-year-old not to memorize his planets. Maybe it's a good thing we just learned them.

We all learned how to eat according to the food pyramid. It looked like this. Apparently, to live healthfully, you should carbo-load like there's a worldwide grain shortage (er...) and run like hell from fats and oils. Today we know the true evil of the carbohydrate and the vast healing power of the omega-3. Or something. The food pyramid now looks like this. Apparently the pyramid was either too good a shape to lose or too good a url to change. It doesn't really matter that the pyramid no longer has a base and really looks more like a 2-D prism than a proper pyramid. The important thing is it's a pyramid. I just tried to play with the MyPyramid menu planner, but apparently a coke with a steak for dinner already puts me over my recommended "extras" maximum. We need to set realistic goals, people. I'm not becoming a raw foodie anytime soon. Anyway, the food pyramid is gone, the food prism has arrived, and Michael Pollan's approach of "Eat food. Not too much. Mostly plants." is probably the wisest option yet.*

The good Lord made four apocalyptic horsemen, four Gospels, and four sons with varying question-asking abilities. He also made four tastes: Sweet, salty, sour, and bitter. Or so we were told. Long before my birth, those c-razy Asians knew the power of MSG to make food taste delicious. But only recently did Western taste taxonomists catch on and dub "umami" a fifth fundamental taste. I guess I understand why we were confused...it's a little hard to distinguish "savory" from "salty;" but the distinction is there, and the four elements of taste aren't the complete set of orthogonal bases I was raised to believe they were.

So, now that I've finished mocking my elementary education and our general confidence with current knowledge, here's what I think the punchline is to all this: These were all good mistakes. Well, maybe the food pyramid was never based on anything especially solid, but certainly we had decent cause to believe that we had 9 planets and the tongue tastes four flavors. We didn't wildly misinterpret our evidence. We didn't miss an obvious interpretation of data because we were sticking to dogma. We just needed to wait until the right evidence became available for us to change our taxonomies. And it's also important to note that these are taxonomies, not theories. These aren't rules of science with great explanatory power from which we could make lots of predictions. It can be upsetting when we get those wrong. These are just discrete categories. If new evidence shows up, it's very easy to add and amend. And so we have done just that. I guess this just shows us that the things that lend themselves to elementary school memorization—which happen to be the things that stick in our heads for our entire lives—aren't usually the things that have the most meaning or pack the most punch. But hey, at least those multiplication tables will never go out of style.

*_{Yes, I realize that steak is not a plant and coke is not food. Shut up.}