Punctuated Equilibrium and the Validation of Macroevolutionary Theory 955
throughout this time. Of course, cultural achievements can accumulate
progressively while Darwinian biology remains unaltered. And, of course again,
we assume that the first person who ever took ochre to wall could not render a
mammoth with all the subtlety developed by later artists; some substantial learning
and development must have occurred. But then, the earliest known cave paintings
do not record these initial steps, for our oldest data probably represent a tradition
already in full flower—so that we observe, in the total range now available to us,
something analogous to the history of Western art from Phidias to Picasso (with
much change in style, but not directional progress), not the full sweep from the
first hominid who ever pierced a hole in a bear tooth and then strung the object
around his neck, to the Desmoiselles of Avignon. Why then should we ever have
anticipated a linear sequence of change in the known history of Paleolithic parietal
art?
Indeed, and to shorten a longer story, the discovery and dating of Chauvet
cave in 1994, abetted by improvements in radiocarbon methods that provide
accurate results from tiny samples, have now disproven the controlling gradualist
and progressivist assumption in an entire tradition of research. The paintings at
Chauvet, dated as the oldest of all known sites (30,000 to 34,000 years BP),
include all features previously regarded as identifying the highest, and latest, stage
of achievement in a sequence of increased artistry (as found in the much younger
caves of Lascaux and Altamira). In other words, the full range of styles extended
throughout the entire interval of dated caves, with the most sophisticated forms
fully present at the oldest site now known.
Bahn and Vertut (1988) invoked punctuated equilibrium in their prescient
anticipation of the disproof that would soon follow. They also made an astute
argument—based on punctuated equilibrium's concept of species as discrete
individuals with considerable capacity for spatial variation at any one time vs. the
tendency of anagenetic thinking to regard the phenotype of any moment as a
uniform stage in a temporal continuum—that geographic variation, in itself, should
have precluded any expectation of a simple chronological sequence, even if a
general trend did pervade the entire series. After all, why should areas as distant as
southern Spain, northeastern France and southeastern Italy go through a series of
progressive stages in lockstep over 20 thousand years? Regional and individual
variation can swamp general trends, even today in our globally connected world of
airplanes and televisions. Why did we ever think that evolution should imply a
pervasive signal of uniform advance? Bahn and Vertut (1988) write:
The development of Paleolithic art was probably akin to evolution itself:
not a straight line or ladder, but a much more circuitous path—a complex
growth like a bush, with parallel shoots and a mass of offshoots; not a slow,
gradual change, but a "punctuated equilibrium," with occasional flashes of
brilliance... Each period of the Upper Paleolithic almost certainly saw the
coexistence and fluctuating importance of a number of styles and
techniques, ... as well as a wide range of talent and