584 THE STRUCTURE OF EVOLUTIONARY THEORY
of plants and animals and under a variety of situations, and they have used
this opportunity to test the assumptions of population genetics that form the
foundations of modern evolutionary theory. The question that should be
asked before we proceed to new ideas is whether more extensive
evolutionary change, macroevolution, can be explained as an outcome of
these microevolutionary shifts. Did birds really arise from reptiles by an
accumulation of gene substitutions of the kind illustrated by the raspberry
eye-color gene?
The answer is that it is entirely plausible, and no one has come up with a
better explanation consistent with the known biological facts. One must
keep in mind the enormous difference in time scale between the observed
cases of microevolution and macroevolution. Under natural conditions the
nearly complete substitution of the melanic gene of the peppered moth took
50 years. Evolution of the magnitude of the origin of the birds usually,
perhaps invariably, takes many millions of years. As paleontologists
explore the fossil record with increasing care, transitions are being
documented between increasing numbers of species, genera, and higher
taxonomic groups. The reading from these fossil archives suggests that
macroevolution is indeed gradual, paced at a rate that leads to the
conclusion that it is based upon hundreds or thousands of gene substitutions
no different in kind from the ones examined in our case histories (1973, p.
792).But, pace Ms. Barrymore, there is so much more—as research in the vibrant
field of macroevolution, filling the pages of numerous journals (all founded after
these dismissive comments), attests; as the development of a tight and powerful
theory of hierarchical selection embodies (see Chapters 8 and 9); as the union of
developmental with evolutionary biology displays (see Chapters 10 and 11); as our
advancing understanding of genomic complexity asserts. Can we not feel the
frustration of E. C. Olson as he queried the titans of the Modern Synthesis in
Chicago? Can we not understand why a few iconoclasts never made their peace
with such a comfortable and limiting orthodoxy? Can we not gain a visceral (and
not only an intellectual) sense of C. H. Waddington's isolation and irritation when
he made his famous comment on the limitations of population genetics
(Waddington, 1967), and won admiration for his panache but no consideration for
his content: "The whole real guts of evolution—which is, how do you come to
have horses and tigers, and things—is outside the mathematical theory."