One of my paid jobs now is to check Very Short Introductions online. Very Short Introductions, or VSIs for short, are books which do just what it says on the tin: they provide a very short introduction to a subject. Oxford University Press has been publishing these books since when I worked there. In fact, I was a colleague of the very clever editor who first came up with the idea and I remember it well. There are hundreds of these books now, over a decade later, providing very short introductions to subjects ranging from the Avant Garde to Number Theory (and many things between the two).

This afternoon I was checking the forthcoming Very Short Introduction to Philosophy of Biology online (due to publish this autumn). Anything with the word ‘philosophy’ in the title is going to fascinate me and it wasn’t long before I became distracted by the content of this book rather than checking that it looks good online. As I was scrolling through the text I came across an image which caught my eye. It was very similar to the one below.

The grey bits are spandrels

The caption read: ‘A spandrel is the triangular space between a curved arch and a rectangular frame or dome.’ This occurred to me as an odd image to find in a biology book. Surely, I reasoned, this concept, of the spandrel, related to art, architecture and perhaps even mathematics.

I decided to ask more of my friend google. I found out that a spandrel is, originally at least, an architectural term to describe the curved triangular shape between an arch and the outer surface, as indicated in the image in the Philosophy of Biology book. How had I never heard this term before? I asked myself. I delved deeper.

I was right to delve deeper, there is more. A spandrel isn’t just this shape, which is amazing in itself. A spandrel has been adapted to mean something more abstract and more interesting. Those biological philosophers discussed in this book I was checking today also use the term. In their eyes, a spandrel refers to a phenotypic (relating to the observable characteristics of an individual resulting from the interaction of its genotype with the environment) characteristic that is a byproduct of the evolution of some other characteristic, rather than a direct product of adaptive selection. This, as dear reader you can tell, has nothing to do with architecture.

Rather, that is a little sciency. So, basically, in more layman’s terms perhaps, a spandrel is something that has evolved biologically which isn’t directly related to survival, but which ends up being useful for survival. It’s a bit like an afterthought that becomes useful. Just as the triangular shape above an arch is almost the ‘cut out’ from the shape, so the afterthought, as is a biological spandrel an afterthought or ‘cut out’.

An example can be seen with the human brain. Many secondary processes and actions have evolved over time, which come in addition to the main functions of the human brain. These secondary processes and thoughts can eventually turn into an adaptation of some sort, or even provide a fitness advantage to humans. Just because something is a secondary trait or byproduct of an adaptation does not mean it has no use. So we are full of such spandrels! A good example is music. We have learnt to make music. It has no obvious use at first, but it can be used to our advantage: as a language, as a skill and as a form of entertainment or distraction. A better example might be human culture.  We created it to counter-act the anxiety we feel about death. If we feel that we are individuals of importance then we don’t worry so much about death. We have caused ourselves to feel that life has a meaning so therefore preventing ourselves from existing in a constant state of existential crisis (or, perhaps not all of us feel this way).

Again, I feel energised and excited about something I have just learnt at this age I am. How on earth have I managed to avoid spandrels thus far? They are brilliant!

I need to find other examples, perhaps this geeky passion of mine which leads me to investigate something for hours on end is a spandrel. It isn’t obviously necessary for my survival in the big wide world but it is certainly acting as a distraction to life’s anxieties.

I will end here with perhaps my favourite spandrel: a man’s nipples. Why are men’s nipples spandrels? I will leave that to you to work out.

A random man’s hairy nipple – a spandrel