What do you call leftovers and byproducts?

We are all familiar with leftovers from the fridge. In the fields of evolutionary biology and design there are also leftovers, which are signified by two wonderful words: spandrel and skeuomorph (pronounced “skew-o-morf”).

Spandrel first occurred in the 15th century as an architectural term. It’s easier to draw spandrels than to describe them. Imagine an arch set in a rectangular frame – the spaces between the arch and frame are spandrels. In a sense, the spandrel is leftover space, a byproduct of building with arches. If you want a beautiful, soaring arch in your cathedral, you get some spandrels too. Medieval churches often put them to attractive use by decorating them with paintings, stonework, and inscriptions.  

In 1979, biologists Stephen Jay Gould and Richard Lewontin published a famous paper, “The Spandrels of San Marco and the Panglossian Paradigm,” which is still fiercely debated today. They argued that, contrary to what “adaptationists” hold, not every trait possessed by an organism is “optimal,” that is, having been selected for by evolution over generations. Some traits, instead, are byproducts of those that have been selected for, just like spandrels.  

Whatever the strength of their scientific argument, Drs. Gould and Lewontin used the wrong architectural term in their title. They were actually talking about pendentives, the spaces left over when a dome is placed atop a square, as with Venice’s St. Mark’s Basilica.  

Skeuomorphs can be controversial too. They are leftover design features, kept in or on an object even when they are no longer necessary to its function, as a reminder of its history. Have you ever tried to pick up a bottle of maple syrup by its tiny handle and wondered, “What’s the point of that?” It’s a skeuomorph, left over from the days when syrup was stored in earthenware jugs. For advocates of “form follows function,” skeuomorphs are ridiculous. But they can help people with transitions, especially when new technology is involved.

Apple co-founder Steve Jobs was perhaps the most famous proponent of skeuomorphism, relying on it to make computers easy to use, even for people who had little technological background. When you see a trash can icon on your screen, for example, you almost intuitively understand that you can throw things away by dragging files into it. The simplicity of this beats the series of computer commands that used to be necessary to delete a file in DOS 3.3: “ERASE [d:] [path]filename[.ext]” – pretty much the opposite of intuitive. 

To sum up, evolutionary leftovers are spandrels, design leftovers are skeuomorphs, and food leftovers are delicious.