Punctuated Equilibrium and the Validation of Macroevolutionary Theory 963
technological change, the Lamarckian nature of inheritance for these processes
permits more directional accumulation within periods of overall stasis in basic
design than analogous chronologies of biological evolution can probably exhibit.
Thus, while the codex (that is, the familiar "bound book") enjoyed its millennium
and a half of domination in fundamentally unchanged form, several innovations
both in design (the introduction of pagination and indexes) and in human practice
and collateral discovery (the invention of eyeglasses at the end of the 13th century,
and the spread of the "newfangled" practice of silent reading in the 15th century)
greatly expanded the utility of a product that remained stable in form. (While
books remained scarce, people read aloud and, apparently, did not even imagine a
possibility that seems obvious to us—namely, that one might read without
speaking the words. By reading aloud, one copy could be shared with many, but
silent reading demands a copy for each participant.)
But the four great designs (or at least the three we know, for the fourth has not
yet stabilized) have experienced histories strikingly akin, in more than vaguely
metaphorical ways, to the origin and persistence of biological species treated as
discrete individuals. In the first of three major similarities, each principal form
persisted in effectively unchanged design for long periods of time by standards of
human technological innovation. Moreover, each transition introduced a great
improvement by solving an inherent structural problem in the previous design.
Therefore, the extended persistence of each flawed