* In retrospect, I suppose that I made an adaptive choice, at least by the usual standard of subsequent discussion and brouhaha in the scientific literature — a legacy that has surely helped to clarify this important issue, and to focus attention upon alternatives to adaptationist explanation in evolutionary biology. But I must also confess that Lewontin and I never anticipated so many exaptive spinoffs from this introductory image — including an entire book by linguistic scholars on our (mostly unconscious) literary tactics (Selzer, 1993); a wise commentary by a noted scholar of medieval buildings (Mark, 1996), and, wonder of wonders in our faintly philistine (and avowedly secular) professional community, a burgeoning interest in at least two humanistic subjects generally shunned by scientists for reasons of passive ignorance, or even active distaste: church architecture (Dennett, 1995; Houston, 1997) and literary parody of the puerile, “ain't-I-clever,” sort embodied in two titles, “The Scandals of San Marco” and “The Spaniels of St. Marx.” Ouch! (Borgia, 1994; Queller, 1995).
* Because exaptations are coopted utilities, and because the attributes in this pool of potential remain as yet uncoopted, some people might object to my designation of this ground of evolvability as “the exaptive pool.” Shouldn't this fund be called the “preadaptive pool” (not that ugly and misleading word again!), or the “potaptive pool” (but why invent a neologism if a current term will suffice)? However, in a purely linguistic and etymological sense, “exaptive pool” represents proper usage, and does not convey any confusing implication of names applied before actions that justify the names. The suffix “ive” refers to “something that performs or tends towards or serves to accomplish an action” (per Webster's) — a fine description of attributes that bring organisms towards evolvability and serve to help them accomplish this happy state. Directives are meant to be followed, but perhaps not just yet. Active sockets will work when you plug in an appliance. Sedative pills will calm you down after you ingest them. Exaptive pools will supply their bearers with a leg up in the longterm sweepstakes of evolution.
* In some way, and through a very dark glass, I had some inkling of this problem as an undergraduate. In an initial embarrassing episode of juvenilia, my first undergraduate term paper in an evolutionary course, I treated this very subject, but could proceed no further than suggesting the more appropriate description of “ultraspecialization,” having at least recognized that the process commits no active “wrong.” In some psychological sense that I feel strongly but cannot clearly define, I view the genesis of this entire book as personal expiation for the puerility of this initial effort!
* I'm usually quite unshockable, and nothing from the fourth estate (even so high a denizen thereof as the New York Times) ever surprises me. But I was amazed that America's most distinguished newspaper would editorialize against a theory so clearly subject to empirical test and so eminently interesting as well. I ended up by sounding off in a popular commentary for Discover Magazine (October, 1985) with a title parody on the Times's venerable motto: “All the News That's Fit to Print and Some Opinions that Aren't.” I commented (Gould, 1985b) that the absurdity of their overreach might best be grasped by comparison with a hypothetical editorial that might have appeared in the Osservatore Romano (the official Vatican newspaper) for June 22, 1633: “Now that Signor Galileo, albeit under slight inducement, has renounced his heretical belief in the earth's motion, perhaps students of physics will return to the practical problems of armaments and navigation, and leave the solution of cosmological problems to those learned in the infallible sacred texts.” I also suggested that, as a quid pro quo of ultimate fairness, the Times might award to the Paleontological Society the right to determine the date and amount of their next price increase.
* Since I have far more often been wrong than right in my intuitions about iconoclastic ideas, perhaps I may be excused for taking some pride, in retrospect, in calling this affair, even for the right reasons. I can take no credit whatsoever for the theory's success, since I work in other areas of paleontology and never (unlike Raup and others) did any primary research on the subject. At most, I did write many private letters to participants, and several popular essays, trying to explain both to my colleagues and to general readers, why they should take impact seriously, and why the Alvarez hypothesis differed so dramatically from previous speculations. In a climate of such negativity, these efforts may have done some good — and Glen (1994, p. 49) was kind enough to write: “By contrast, the paleontologist Stephen Jay Gould, perhaps earth's science's most widely read spokesman, was intellectually predisposed to welcome the impact hypothesis straightaway, in part because his unorthodox theory of punctuated equilibrium . . . articulated well with impact theory. Gould thus provided welcome and vital encouragement through sustained communication with the Alvarez group early on, when only the iridium evidence was at hand and paleontologic backlash against the theory was strong.” Moreover, I cannot assert any general claim for anything inellectually admirable in myself or the very few initial paleontological supporters of impact — as we all had purely personal reasons for favorable predispositions (me for the punctuational themes that Glen notes above, Raup for his work on random processes, vertebrate paleontologist Dale Russell for his prior, if speculative, writing on a potential role for impacts). Always look to reasons of personal interest, rather than general wisdom, in such cases — and remember the wise words of W. S. Gilbert's most honorable, if unlikable, man: King Gama of Princess Ida: “A charitable action I can skillfully dissect; And interested motives I'm delighted to detect.”
* May I, for one last time, repeat the rationale, from the internal logic of this book, that leads me to the otherwise odd strategy of treating the refutation of the third, or extrapolationist, leg of central Darwinian logic at reduced length (in Chapter 6 in the historical half and the present Chapter 12 in the modern half) relative to the other two legs of hierarchy and levels of selection (Chapter 3 in the first half, and 8-9 in the second half) and structuralist thinking and constraint vs. strict selectionism (Chapters 4–5 in the first half and 10–11 in the second half). My reasons rest upon four arguments, the first three intertwined and intellectual, the fourth separate and personal. First, this book treats the biological structure of evolutionary, particularly Darwinian, theory. Of the three central components designated as legs on a tripod of conceptual definition for Darwinism — (1) levels of selection (Darwinian organismal vs. modern notions of a full hierarchy); (2) functional vs. structural approaches (externalist selection as virtually the sole creative force in evolutionary change vs. the importance of internal constraint from several sources, not all selectionist); and (3) uniformitarian extrapolation of microevolutionary styles of natural selection to explain the full panoply of life's changes through geological time — the biological aspects of the critique for the third theme of extrapolationism lie mainly within expansions and revisions of Darwinism on the first two legs. Second, I therefore decided to confine my explicit discussion of the third leg (since the biological critiques had already been treated under the first two legs) to the surrogate theme of geological requirements to potentiate the biological mechanism (the kind of stage needed to display the proposed play). The surrogate theme of a different profession does not require such detailed treatment as the central biological critiques. Third, and almost as a historical footnote (but a truly intriguing point missed in most discussions of Darwinism and the 19th century debates about evolution), Darwin himself became uncomfortable with his need to call upon such surrogate themes from other disciplines, and he tried (in later years) to avoid such ancillaries, and to devise a theory that would render his conclusions about life's history entirely by biological principles. Most importantly, he abandoned his early satisfaction with allopatric modes of speciation (that called upon geographic surrogacy to ensure a world with sufficient opportunity for isolation of populations), and moved towards the sympatric theory embodied in his “principle of divergence” (see
Chapter 4 of the Origin, including the book's sole figure), and considered by him (in the famous “eureka” statement of his carriage ride in 1854, see p. 224) as second in importance only to his formulation of natural selection itself in devising his full theory. Because this sympatric theory, relying upon the generality of selective benefits for extreme forms in any environment, proved ultimately quite unsatisfactory, and even illogical, we can grasp, with even greater clarity, the importance of this issue in Darwin's mind — as he so rarely allowed himself to place such weight upon a patently dubious argument (and I do mean patent, for he fretted overtly about the inherent problems, see pp. 236-248), unless its conclusion played a central role in his full system, and he could devise no other path toward a desired outcome. Hence, and in any case, in thus de-emphasizing the themes of geological surrogacy, I am only paying homage to Darwin's own preferences in the structuring of his theory. Fourth, disconnectedly, finally, and entirely personally, I have done no technical paleontological research on these geological themes (beyond some early, and largely philosophical, analysis of the concept of uniformitarianism, including my first published paper of Gould, 1965), whereas I have devoted my career to paleontological studies of the first two biological legs of hierarchy and constraint. Thus, I lack the competence and the “feel” of personal expertise (or the folly of personal engulfment) to treat this theme at comparable length, for which all readers should rejoice (as even this footnote has hypertrophied quite enough already)!
Index
ABC Model, 82, 1063-1064, 1093-1094
Abel, 1086
abrupt appearance of species. See also punctuated equilibrium theory; punctuations
gradualist view of, 749-755, 758-759, 840
inference of cladogenesis and, 840-850
migrational incursion and, 748, 840, 841, 852
acceleration, principle of, 367-368, 371
Adams, R. McC., 573-574, 956
adaptation. See also adaptationism; nonadaptive origin as evolutionary term, 117n, 263n, 662, 671, 1051, 1229-1231
Nietzsche and, 1217-1218
“adaptation at the edge of chaos,” 1213-1214, 1273-1274
adaptationism. See also Darwinism; Modern Synthesis, hardening of; structuralist-functionalist dichotomy
adaptation as term and, 117n, 263n, 662, 671, 1051, 1229-1231
Bateson and, 406-107, 412-415
co-adaptation and, 218
Darwinian efficacy and, 61, 155-159
de Vries and, 450-451
English tradition and, 252-253
Geoffroy and, 300-301
Goethe and, 288-289
Gould’s personal odyssey and, 42-44, 397n
Lamarck and, 176-179, 181-186, 479
Owen and, 324-326
Paley and, 117, 118-121, 268-271
primacy of, for Darwin, 254-260
problem of too much, 213
textbooks and, 577-579
Weismann and, 201-203, 217-219
adaptive radiations, test of, 815-816
AEPPS. See Principles of Animal Ecology
African lake mollusks, 769-771, 796, 845, 853, 867
Agassiz, Louis, 51, 271, 382, 383, 687, 1021-1022
Essay on Classification, 271-278
agency, as Darwinian principle, 14. See also hierarchy theory; levels of selection; organismal selection; punctuated equilibrium theory; species selection
coral model and, 20, 21
Darwin’s theoretical argument and, 59, 60
hardening of Modern Synthesis and, 71, 544-556, 585
historical alternatives to Darwinism and, 586-587, 588
meaning of individuality and, 597-613
modern critiques and, 589, 590
proposed revisions and, 21, 49
punctuated equilibrium and, 26, 39, 49
as theme in Origin, 125-137
age of the earth, 492-502. See also geological time
Ager, D. V., 753-754, 773, 845
Akam, M., 1144, 1145-1146, 1163, 1165, 1166
AL. See Artificial Life Albanesi, G. L., 852
Alberch, P., 1037
Alexander, G., 579
Allen, J. C., 883
Allmacht of selection, 358-359, 505, 567. See also Weismann, August
theory of germinal selection and, 63, 197-201, 215, 219, 223-224, 596
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allometry, 42
channeled directionality by constraint and, 80-81, 1037-1051
properties of levels of selection and, 683-714
scaling in nature and, 677, 680, 704
allopatric analysis, 706, 707-709
Almada, V.C., 1240
alternatives to natural selection. See also Lamarckism; mutation theory; orthogenesis; saltationism
cultural biases and, 588
Kellogg’s classification and, 353-354, 383, 439, 506, 507, 589
logical failure and, 588-590
persistence of critiques and, 586-587
Alvarez, L. W., 482, 948, 1303, 1306-1308
Amalda species, 786, 787
Ambystoma species, 360
American Civil War, 1338, 1341-1342
ammonites, 1315
Amphioxus, 1170
Amphipholis squamata, 1162
anagenesis, 190, 357n
cladogenesis and, 436, 813-822
macroevolutionary analogy and, 723-724
punctuated, 795, 840-841
trends and, 78, 777
analogy, as term, 282n, 1077
Anasazi people, 956
ancestral survival criterion, 76, 794-796, 840-850
antelope studies, 78, 866
Antennapedia mutant, 1100
anti-Darwinian theory. See creationism; natural theology; orthogenesis; saltationism
antinomies in Lamarckism, 189-192
Antonovics, J., 1035
Appel, T. A., 291-293
“aptation,” as term, 1051, 1233, 1234
aptive triangle
functional vertex, 81, 1052, 1053 (see also natural selection)
historical vertex, 81, 1052-1053, 1055-1057 (see also deep homology; historical constraint)
model of, 1051-1053
premises of traditional Darwinism and, 1173-1174
structural vertex, 81, 1053-1055 (see also spandrels)
Arabidopsis, 82, 1063-1064, 1092-1095
Archegozetes mite, 1163
archetypal theories. See also historical constraint
Darwin and, 337-339
dismissal of, 1091-1092
evo-devo results and, 82-83, 1092-1095, 1106-1122
Geoffroy’s dorso-ventral inversion and, 83, 1117-1122
Geoffroy’s vertebral archetype and, 82-83, 299-306, 320, 321, 1091, 1092, 1101, 1106-1117
Goethe’s leaf archetype and, 284-286, 1064, 1091, 1092-1095
Owen’s vertebral archetype and, 316-326, 1091
architectural metaphor, 2-6. See also Pharaonic bricks vs. Corinthian columns analogy; spandrels
Arendt, 1151-1152
“area effects,” 542
Aristotle, 85, 234n, 626, 1186-1187, 1207-1208
Arkansas equal time law, 989-990
Arnold, 901
Arnold, A. J., 611n, 656, 661, 663, 672, 733
Arnold, E. N., 1234-1238, 1240, 1244
art history, 978, 1342
arthropod and vertebrate developmental homologies. See also bilaterian history; Hox genes
arthropod hox gene expression and, 1148-1149, 1163-1170
channeling in bilaterian history and, 1161-1173
common ancestor and, 1148-1155, 1170-1171
deep segmental homologies and, 1106-1117
dorso-ventral inversion and, 83, 1117
early discoveries of, 1101-1106
Geoffroy’s vertebral archetype and, 1101, 1106-1117
“Hoxology” and, 82-83, 1095-1117
Pharaonic bricks vs. Corinthian columns analogy and, 1138-1142
setting
of historical constraint and, 1155-1161
throughout developing somites, 1109-1112
vertebrate Hox gene expression and, 1170-1173
vertebrate rhombomeres and, 1107-1109, 1112
Arthur, W., 1174-1175
Artificial Life (AL), 924-925
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asexual forms, gradualism in, 807-810. See also Foraminifera
Asimov, I., 974
atavisms, 1164-1165
Ausich, W. I., 891
Australopithecus, 834, 909
available things. See insinuations; manumissions; miltons; spandrels
avatars, 705, 706, 708-709
Averof, M., 1133-1134, 1165, 1166, 1168
Avers, C. J., 997
Avise, J. C., 812
Awake! (journal), 988
Axelrod, D. I., 558-559
Ayala, F. J., 167, 1023, 1155, 1156
Babyrussa skull, 264-265
Bacon, Francis, 887-888, 969, 1187-1188
bacteria
cause of, 898-900
episodic change and, 931-936
The Structure of Evolutionary Theory Page 229