The Modern Synthesis as a Limited Consensus 583
this trivialization and marginalization of macroevolution, each from the most
important source in its respective genre. As mentioned above, BSCS textbooks
(written by a semiofficial consortium of private and governmental sources, The
Biological Sciences Curriculum Study) virtually cornered high-school markets
during post-Sputnik years of the 1960's and 1970's. The 1968 version of Biological
Science: An Inquiry Into Life includes a heading on "The Origin of Genera and
Larger Groups." But the text contains only two paragraphs, fully reproduced
below:
The final question which we must ask about the forces of evolution is this:
can mutation, recombination, selection, and barriers to cross-breeding
explain the major trends of evolution, such as the divergence of catlike
from doglike animals and the evolution of the horse from its small primitive
ancestors?
The mechanisms that govern these major trends of evolution cannot be
studied directly: they took place many thousands or millions of years ago.
Nevertheless, a study of populations today, and of fossils, provides strong
evidence that the same evolutionary forces in operation today have guided
evolution in the past. One species evolves into two (or more). All the new
species continue to evolve, becoming more different from one another until
eventually we would classify them as different genera (1968, p. 203).Life on Earth (1973) surely ranks as the most distinguished textbook of
introductory college biology published during the 1970's. Written by a team of
eight authors, and headed by two of the world's leading evolutionists (E. O. Wilson
and T. Eisner), this book staked an explicit claim for groundbreaking novelty by
linking appropriate expertise at the highest level with accessibility in style, and
excellence in design and illustration. Chapter 28 on "The Process of Evolution"
ends with the heading "Macroevolution." The quotation below may seem limited in
content, particularly for a college text, but I do not cite an excerpt. I have
reproduced the book's entire section on macroevolution!
In this passage, the history of life becomes a simple extension of the story of
the raspberry eye-color gene. (For the second edition, the authors switched to the
standard case of industrial melanism, but did not alter the general argument at all.)
Paleontologists may be burdened with an incomplete record, the authors assert, but
as they look more carefully, the gap between the raspberry gene and the Cambrian
explosion closes continually. I can only express my astonishment at such a limited,
but definitive, assertion by applying Ethel Barrymore's famous closing line to this
dismissal of macroevolution as a subject: "That's all there is, there isn't any more."
Each of the examples of microevolution examined, involving shifts in the
frequencies of small numbers of genes, could be multiplied a hundredfold
from reports in the scientific literature. Biologists have been privileged to
witness the beginnings of evolutionary change in many kinds