Punctuated Equilibrium and the Validation of Macroevolutionary Theory 765
Regan, chose to say nothing, for she knew that "my love's more ponderous than my
tongue." But Lear mistook her silence for hatred or indifference, and cut her off
entirely (with tragic consequences later manifested in his own madness, blindness,
and death), in proclaiming that "nothing will come of nothing."
Cordelia's dilemma arises in science when an important (and often
predominant) signal from nature isn't seen or reported at all because scientists read
the pattern as "no data," literally as nothing at all. This odd status of "hidden in
plain sight" had been the fate of stasis in fossil morphospecies until punctuated
equilibrium gave this primary signal some theoretical space for existence.
Apparent silence—the overt nothing that actually records the strongest
something—can embody the deepest and most vital meaning of all. What, in
western history, has been more eloquent than the silence of Jesus before Pilate, or
Saint Thomas More's date with the headsman because he acknowledged that fealty
forbade criticism of Henry VIII's marriage to Anne Boleyn, but maintained,
literally to the death, his right to remain silent, and not to approve?
In summary, the potentially reformative role of punctuated equilibrium
resides in an unusual property among scientific innovations. Most new theories in
science arise from fresh information that cannot be accommodated under an old
explanatory rubric. But punctuated equilibrium merely honored the firmest and
oldest of all paleontological observations—the documentable stasis of most fossil
morphospecies—by promoting this pattern to central recognition as an expected
result of evolution's proper expression at the scale of geological time. This
reformulation cast a bright light upon stasis, a preeminent fact that had formerly
been mired in Cordelia's dilemma as a grand disappointment, and therefore as "no
data" at all, a pattern fit only for silence in a profession that accepted Darwin's
argument for gradualism as the canonical expression of evolution in the fossil
record.
The Primary Claims of Punctuated Equilibrium
Data and Definitions
First of all, the theory of punctuated equilibrium treats a particular level of
structural analysis tied to a particular temporal frame. G. K. Chesterton (1874-
1936), the famous English author and essayist, wrote that all art is limitation, for
the essence of any painting lies in its frame. The same principle operates in
science, where claiming too much, or too broad a scope of application, often
condemns a good idea to mushy indefiniteness and consequent vacuity.
Punctuated equilibrium is not a theory about all forms of rapidity, at any scale
or level, in biology. Punctuated equilibrium addresses the origin and deployment of
species in geological time. Punctuational styles of change characterize other
phenomena at other scales as well (see Section V of this chapter)—catastrophic
mass extinction triggered by bolide impacts, for example—