912 THE STRUCTURE OF EVOLUTIONARY THEORY
over more than half the globe? Three groups, each moving in the same direction,
and all still able to interbreed and constitute a single species after more than a
million years of change? (I know that multiregionalists posit limited gene flow to
circumvent this problem, but can such a claim represent more than necessary
special pleading in the face of a disabling theoretical difficulty?) Do we advocate
such a scenario for the evolution of any other global species? Do we ever suspect
that rats evolved on several continents, with each subgroup moving in the same
manner towards greater ratitude? Do pigeons trend globally towards increased
pigeonosity? When we restate the thesis in terms of non-human species, the
absurdity becomes apparent. Why, then, did our media not grasp the singular
oddity of multiregionalism and recognize out-of-Africa—especially given the
cascade of supporting evidence in its favor—as the most ordinary of evolutionary
propositions?
I can only conclude that popular views of evolution conceptualize the process,
in general to be sure but particularly as applied to humans, as a linear and gradual
transformation of single entities. Most consumers would be willing to entertain the
speciational alternative for lineages (like rats and pigeons) that impose no
emotional weight upon our psyches. But when we ask the great Biblical question—
"what is man that thou art mindful of him?" (Psalm 8)—we particularly yearn for
explanations based on anticipated global progress, rather than contingent origins of
small and isolated populations in limited local regions. We want to regard our
origin as the necessary, or at least predictable, crest of a planetary flux, not as the
chancy outcome of a single event unfolding in a unique time and place.
This example, I believe, best illustrates the deep-seated nature of prejudices
that must be overcome if we wish to grasp the truly Darwinian character of
macroevolution as change wrought by differential success of favored individuals
(species) within variable populations (clades)—thus finally breaking the Platonic
chain of defining evolution as improvement of an archetypal form. Eldredge
(1979) has advocated this transition by contrasting "taxic" approaches to evolution
with the older "transformational" view. In the particular context of human
evolution (Gould, 1998b), I have labelled multiregionalism as a "tendency theory,"
and out-of-Africa as an "entity theory." However much we may yearn to regard
ourselves as the apotheosis of an inherent tendency in the unfolding of evolution,
we must someday come to terms with our actual status as a discrete and singular
item in the contingent and unpredictable flow of history. If we could bring
ourselves to view this prospect as exhilarating rather than frightening, we might
attain the psychological prerequisite for intellectual reform.
- The unsurprising stability of Homo sapiens over tens of thousands of years.
In a second example of a subject generally reported by the press with factual
accuracy accompanied by ludicrously backwards explanation, the supposedly
astonishing stability of human bodily form from Cro-Magnon cave painters to now
has provided notable fodder for science journalists during the past decade.
Consider, for example, the lead article in the prestigious "Science Times" section
of the New York Times for March 14,1995, entitled: