1278 THE STRUCTURE OF EVOLUTIONARY THEORY
how to jimmy a door latch with a credit card.) American dimes are therefore
adaptations as money, and exaptations as screwdrivers.
This potential for supplementary use as a screwdriver represents an inherent
capacity of the dime's size and shape, not a separate and unused entity arising as a
side consequence of some other change. The inherent potentials of any object (for
uses other than their intended purpose of manufacture) establish a large and important
category of attributes in the exaptive pool of any biological individual. I propose that
we refer to these inherent (but currently, or at least usually, unexploited) potential
functions as "franklins" to honor the most famous exaptation of the American dime.
(Indeed, if our currency inflates much further, dimes may become virtually useless as
money, and their exaptive role as screwdrivers may achieve a primary status in
immediate function. When Russia's currency hyper inflated after the collapse of the
Soviet Union, I witnessed a remarkable example of this phenomenon. Five-kopeck
coins had become truly worthless as currency, but only objects of their size, shape
and weight could operate public telephones. Sharp entrepreneurs therefore stood at
telephone booths, offering to sell old five kopeck coins for 100 rubles each— 2000
times their official monetary value, but when ya gotta call, ya gotta call.)
Franklins are not actual but unemployed "things out there." Franklins are
alternative potential functions of objects now being used in another way. In the words
of my subtitle, franklins are inherent potentials, not available things. This distinction
may seem trivial, inordinately fine as an exercise in logic chopping, or even parodic
to hard-nosed scientists committed to the professional ethos of "just give me the facts,
and leave linguistic and theoretical niceties to effete humanists who lack the luxury of
an objectively empirical subject matter." But I will attempt to show, in the next two
sections, that the distinction between inherent potentials and available things, as the
two fundamental categories of the exaptive pool, provides the conceptual key to
understanding the importance of spandrels, and for recognizing the strong weight that
must be applied to structuralist, and particularly to nonadaptationist, elements in the
exaptive pool—thus defining the revisionary power of this concept in evolutionary
theory, and exposing the depth of different explanations required to understand
evolvability vs. ordinary adaptation by natural selection.
I will just mention, for now, that franklins constitute the theoretically
untroubling category embodied in the Darwinian notion of quirky functional shift (as
discussed on pp. 1218-1229 of this chapter). Franklins capture the important concept
so poorly expressed in the old term "preadaptation"— that is, suitability for another
function not presently exploited because the feature has been adapted by natural
selection for a different utility. When feathers function for enhanced
thermoregulation on the arm of a small running dinosaur, their potential aerodynamic
benefits are franklins, or inherent but unused potentials. When Michelin's rubber
works as an automobile tire, its suitability for manufacturing cheap and durable
sandals for poor children in developing countries is a franklin. In short, franklins
represent future potentials