There is a
science behind that old book smell, and it is
bacteriology. Well,
zoology, really, and perhaps
microbiology to be most concise, since there are more
microbial interlopers beyond the humble bacterium, but bacteriology figures most prominently therein. When we recall that most every exposed surface on Earth is coated with bacteria, our bodies, our belongings, every thing we see and contact in our daily lives, then it ought to come as no surprise that many of the smells we encounter actually signify to some degree the bacteria associated with the scent detected. Think of the smell of the
ocean -- now there's a soup thick with life, there being hundreds of millions of cells living in every single drop, from the surface to the depths. And it turns out that
even that distinctive ocean smell is bacteriological, the result of a large proportion of the wee creatures exuding a gas in the course of putting their
metabolism through its paces.
And why would
books be any different? They are manufactures of man, exposed by the transference from fingers, from particles of dust, from free-floating specks of life itself carried on the
breeze, or hovering slowly, endlessly, in the still air. Perhaps some of those organisms have been clinging to what is now paper all the way from when it was within a
tree.
Mold and
mildew play their role as well. These living particles occupy books as readily as they do any surface, and especially any source of organic matter, which might be broken down into components suitable to fuel further reproduction. And so the molecular machines which we call fundamental life do, bit by bit, break down the molecules which make ink and pages, and leave behind various waste products, and their own dead bodies, which are in turn quickly consumed by their fellows and their progeny. And all of this adds up to a steady stream of curious molecules exhibited in the air around the pages of an old book, which our olfactory receptors have been attuned to recognize and perhaps associate with memories of the youthful reading of the tomes of our ancestors.