"Objectivity cannot be equated with mental blankness; rather,
objectivity resides in recognizing your preferences and then subjecting them to
especially harsh scrutinyand also in a willingness to revise or abandon
your theories when the tests fail (as they usually do)."
the Center," Natural History 107 (December 1998):
We talk about the ‘march from monad to man’ (old-style
language again) as though evolution followed continuous pathways of progress along
unbroken lineages. Nothing could be further from reality. I do not deny that, through
time, the most ‘advanced’ organism has tended to increase in complexity. But the
sequence from protozoan to jellyfish to trilobite to nautiloid to armored fish to dinosaur
to monkey to human is no lineage at all, but a chronological set of termini on unrelated
darwiniana trunks. Moreover life shows no trend to complexity in the usual
senseonly an asymmetrical expansion of diversity around a starting point
constrained to be simple.
"Tires to Sandals," Eight
Little Piggies, New York: W. W. Norton, 1993, p.
I was lucky to wander into evolutionary theory, one of the
most exciting and important of all scientific fields. I had never heard of it when
I started at a rather tender age; I was simply awed by dinosaurs. I thought
paleontologists spent their lives digging up bones and putting them together, never
venturing beyond the momentous issue of what connects to what. Then I discovered
evolutionary theory. Ever since then, the duality of natural historyrichness in
particularities and potential union in underlying explanationhas propelled me.
I think that the fascination so many people feel for
evolutionary theory resides in three of its properties. First, it is, in its current
state of development, sufficiently firm to provide satisfaction and confidence, yet
fruitfully undeveloped enough to provide a treasure trove of mysteries. Second, it
stands in the middle in a continuum stretching from sciences that deal in timeless,
quantitative generality to those that work directly with the singularities of history.
Thus, it provides a home for all styles and propensities, from those who seek the
purity of abstraction (the laws of population growth and the structure of DNA) to
those who revel in the messiness of irreducible particularity (what, if anything,
did Tyrannosaurus do with its puny front legs anyway?). Third, it touches all
our lives; for how can we be indifferent to the great questions of genealogy: where
did we come from and what does it all mean? and then, of course, there are all those
organisms: more than a million described species, from bacterium to blue whale, with
one hell of a lot of beetles in betweeneach with its own beauty, and each
with a story to tell.
Prologue. The Panda's Thumb.
New York: W. W. Norton, 1980, pp. 11-12.
Sigmund Freud often remarked that great revolutions in the history
of science have but one common, and ironic, feature: they knock human arrogance off one
pedestal after another of our previous conviction about our own self-importance. In Freud's
three examples, Copernicus moved our home from center to periphery, Darwin then relegated
us to ‘descent from an animal world’; and, finally (in one of the least modest statements
of intellectual history), Freud himself discovered the unconscious and exploded the myth of
a fully rational mind. In this wise and crucial sense, the Darwinian revolution remains
woefully incomplete because, even though thinking humanity accepts the fact of evolution,
most of us are still unwilling to abandon the comforting view that evolution means (or at
least embodies a central principle of) progress defined to render the appearance of
something like human consciousness either virtually inevitable or at least predictable.
The pedestal is not smashed until we abandon progress or complexification as a central
principle and come to entertain the strong possibility that H. sapiens is but a
tiny, late-arising twig on life's enormously arborescent busha small bud that
would almost surely not appear a second time if we could replant the bush from seed and
let it grow again.
of Life On Earth," Scientific American 271 (October 1994): 91.
The modern theory of evolution does not require gradual change.
It in fact, the operation of Darwinian processes should yield exactly what we see in the
fossil record. It is gradualism that we must reject, not Darwinism. [
and I believe that speciation is responsible for almost all evolutionary change. Moreover,
the way in which it occurs virtually guarantees that sudden appearance and stasis shall
dominate the fossil record. All major theories of speciation maintain that splitting
takes place rapidly in very small populations. The theory of geographic, or allopatric,
speciation is preferred by most evolutionists for most situations (allopatric means ‘in
another place’). A new species can arise when a small segment of the ancestral population
is isolated at the periphery of the ancestral range. Large, stable central populations
exert a strong homogenizing influence. New and favorable mutations are diluted by the
sheer bulk of the population through which they must spread. They may build slowly in
frequency, but changing environments usually cancel their selective value long before
they reach fixation. Thus, phyletic transformation in large populations should be very
rareas the fossil record proclaims. But small, peripherally isolated groups are
cut off from their parental stock. They live as tiny populations in geographic corners
of the ancestral range. Selective pressures are usually intense because peripheries
mark the edge of ecological tolerance for ancestral forms. Favorable variations spread
quickly. Small peripheral isolates are a laboratory of evolutionary change.
What should the fossil record include if most evolution occurs
by speciation in peripheral isolates? Species should be static through their range
because our fossils are the remains of large central populations. In any local area
inhabited by ancestors, a descendant species should appear suddenly by migration from
the peripheral region in which it evolved. In the peripheral region itself, we might
find direct evidence of speciation, but such good fortune would be rare indeed because
the event occurs so rapidly in such a small population. Thus, the fossil record is a
faithful rendering of what evolutionary theory predicts, not a pitiful vestige of a
once bountiful tale.
"The Episodic Nature of Evolutionary Change,"
The Panda's Thumb, New York: W. W. Norton, 1980, pp.
I want to argue that the ‘sudden’ appearance of species in the
fossil record and our failure to note subsequent evolutionary change within them is the
proper prediction of evolutionary theory as we understand it. Evolution usually proceeds
by ‘speciation’the splitting of one lineage from a parental stocknot by the
slow and steady transformation of these large parental stocks. Repeated episodes of
speciation produce a bush. How does speciation occur? This is a perennial hot topic in
evolutionary theory, but most biologist would subscribe to the ‘allopatric theory’ (the
debate centers on the admissibility of other modes; nearly everyone agrees that allopatric
speciation is the most common mode). Allopatric means ‘in another place.’ In the
allopatric theory, popularized by Ernst Mayr,
new species arise in very small populations that become isolated from their parental
group at the periphery of the ancestral range. Speciation in these small isolates is
very rapid by evolutionary standardshundreds or thousands of years (a
Pressures of natural selection tend to be intense in geographically
marginal areas where the species barely maintains a foothold. Favorable genetic variation
can quickly spread through these reduced populations. In large central populations, on the
other hand, favorable variations spread very slowly, and most change is steadfastly resisted
by the well-adapted population. Small changes occur to meet the requirements of slowly
altering climates, but major genetic reorganizations almost always take place in the
small, peripherially isolated populations that form new species.
If evolution almost always occurs by rapid speciation in small,
peripheral isolates, then what should the fossil record look like? We are not likely to
detect the event of speciation itself. It happens too fast, in too small a group, isolated
too far from the ancestral range. Only after its successful origin will we first meet the
new species as a fossilwhen it reinvades the ancestral range and becomes a large
central population in its own right. During its recorded history in the fossil record, we
should expect no major change. We know it only as a successful central population. It
will participate in the process of organic change only when some of its peripheral isolates
species to become new branches on the evolutionary bush. But it, itself, will appear
‘suddenly’ in the fossil record and become extinct later with equal speed and little
perceptible change in form.
"Ladders, Bushes, and Human Evolution"
Natural History 85
(April 1976): 30-31.
In other words, morphological change correlates so strongly with
speciation not because cladogenesis accelerates evolutionary rates, but rather because
such changes, which can occur at any time in the life of a local population, cannot be
retained (and sufficiently stabilized to participate in selection) without the
protection provided by individuationand speciation, via reproductive isolation,
represents nature's preeminent mechanism for generating macroevolutionary individuals.
Speciation does not necessarily promote evolutionary change; rather, speciation
'gathers in' and guards evolutionary change by locking and stabilization for sufficient
geological time within a Darwinian individual of the appropriate scale. If a change in
a local population does not gain such protection, it becomesto borrow Dawkins's
metaphor at a macroevolutionary scalea transient duststorm in the desert of time,
a passing cloud without borders, integrity, or even the capacity to act as a unit of
selection, in the panorama of life's phylogeny.
Structure of Evolutionary Theory, Cambridge MA: Harvard University
Press, 2002, p. 801.
Traditional explanations for stasis and abrupt appearance had
paid an awful price in sacrificing the possibility of empirics for the satisfaction of
harmony. Eventually we (primarily Niles) recognized that the standard theory of
speciationErnst Mayr's allopatric or peripatric schemewould not, in fact,
yield insensibly graded fossil sequences when extrapolated into geological time, but
would produce just what we see: geologically unresolvable appearance followed by stasis.
For if species almost always arise in small populations isolated at the periphery of
parental ranges, and in a period of time slow by the scale of our lives but effectively
instantaneous in the geological world of millions, then the workings of speciation
should be recorded in the fossil record as stasis and abrupt appearance. The literal
record was not a hopelessly and imperfect fraction of truly insensible gradation
within large populations but an accurate reflection of the actual process identified
by evolutionists as the chief motor of biological change. The theory of punctuated
equilibrium was, in its initial formulation, little more than this insight adumbrated.
"Punctuated Equilibrium in Fact and Theory," In Albert Somit
and Steven Peterson The
Dynamics of Evolution. New York: Cornell University Press, 1992, pp. 56-57.
I emphatically do not assert the general ‘truth’ of this philosophy
of punctuational change. Any attempt to support the exclusive validity of such a grandiose
notion would border on the nonsensical. [
] Nonetheless, I will confess to a personal
belief that a punctuational view may prove to map tempos of biological and geographic
change more accurately and more often than any of its competitorsif only because
complex systems in steady state are both common and highly resistant to change. As my
colleague British geologist Derek V. Ager writes in supporting a punctuational view of
geologic change: ‘The history of any one part of the earth, like the life of a soldier,
consists of long periods of boredom and short periods of terror.’
"The Episodic Nature of Evolutionary Change,"
The Panda's Thumb,
New York: W. W. Norton, 1980, p. 185.
In my field of evolutionary biology, the most prominent urban
legendanother ‘truth’ known by ‘everyone’holds that evolution may well be
the way of the world, but one has to accept the idea with a dose of faith because the
process occurs far too slowly to yield any observable result in a human life-time.
Thus, we can document evolution from the fossil record and infer the process from the
taxonomic relationships of living species, but we cannot see evolution on human
timescales ‘in the wild.’ In fairness, we professionals must shoulder some blame
for this utterly false impression about evolution's invisibility in the here and now of
everyday human life. Darwin himselfalthough he knew and emphasized many cases
of substantial changes in human time (including the development of breeds in his beloved
pigeonstended to wax eloquent about the inexorable and stately slowness of
natural evolution. In a famous passage from the Origin of Species, he even
devised a striking metaphor about clocks to underscore the usual invisibility:
It may be said that natural selection is daily and hourly
scrutinizing, throughout the world, every variation, even the slightest; rejecting that
which is bad, preserving and adding up all that is good; silently and invisibly working. . . .
We see nothing of theses slow changes in progress until the hand of time has marked the
long lapse of ages.
Nonetheless, the claim that evolution must be too slow to see
can only rank as an urban legendalthough not a completely harmless tale in this
case, for our creationists incubi can then use the fallacy as an argument against
evolution at any scale, and many folks take them seriously because they just ‘know’ that
evolution can never be seen in the immediate here and now. In fact, a precisely opposite
situation prevails: biologists have documented a veritable glut of cases for
rapid and eminently measurable evolution on timescales of years and decades.
Paradox of the Visibly Irrelevant," Natural History 106 (December 2000): 12.
Since we proposed punctuated equilibria to explain trends, it is
infuriating to be quoted again and again by creationistswhether through design or
stupidity, I do not knowas admitting that the fossil record includes no transitional
forms. Transitional forms are generally lacking at the species level, but they are abundant
between larger groups.
"Evolution as Fact and Theory,"
Hen's Teeth and Horse's Toes, New York: W. W. Norton, 1994, p.
The anatomical transition from reptiles to mammals is particularly
well documented in the key anatomical change of jaw articulation to hearing bones. Only
one bone, called the dentary, builds the mammalian jaw, while reptiles retain several
small bones in the rear portion of the jaw. We can trace, through a lovely sequence of
intermediates, the reduction of these small reptilian bones, and their eventual
disappearance or exclusion from the jaw, including the remarkable passage of the reptilian
articulation bones into the mammalian middle ear (where they became our malleus and incus,
or hammer and anvil). We have even found the transitional form that creationists often
proclaim inconceivable in theoryfor how can jawbones become ear bones if
intermediaries must live with an unhinged jaw before the new joint forms? The transitional
species maintains a double jaw joint, with both the old articulation of reptiles (quadrate
to articular bones) and the new connection of mammals (squamosal to dentary) already in
place! Thus, one joint could be lost, with passage of its bones into the ear, while the
other articulation continued to guarantee a properly hinged jaw. Still, our creationist
incubi, who would never let facts spoil a favorite argument, refuse to yield, and continue
to assert the absence of all transitional forms by ignoring those that have been
found, and continuing to taunt us with admittedly frequent examples of absence.
"Hooking Leviathan by Its Past,"
Dinosaur in a Haystack, New York: Crown Trade Paperbacks, 1997, pp.
Scientific claims must be testable; we must, in principal, be able
to envision a set of observations that would render them false. Miracles cannot be judged
by this criterion, as Whitcomb and Morris have admitted. But is all creationists writing
merely about untestable singularities? Are arguments never made in proper scientific form?
Creationists do offer some testable statements, and these are amenable to scientific
analysis. Why, then, do I continue to claim that creationism isn't science? Simply because
these relatively few statements have been tested and conclusively refuted.
vs. Geology" In Ashley Montagu, ed., Science and Creationism, New York:
Oxford University Press, 1984, pp. 130-131.
Our creationist detractors charge that evolution is an unproved
and unprovable charadea secular religion masquerading as science. They claim,
above all, that evolution generates no predictions, never exposes itself to test, and
therefore stands as dogma rather than disprovable science. This claim is nonsense. We
make and test risky predictions all the time; our success is not dogma, but a highly
probable indication of evolution's basic truth.
"Magnolias from Moscow," Dinosaur
in a Haystack, New York: Crown Trade Paperbacks, 1997, p.
Well evolution is a theory. It is also a fact. And facts
and theories are different things, not rungs in a hierarchy of increasing certainty.
Facts are the world's data. Theories are structures of ideas that explain and interpret
facts. Facts do not go away when scientists debate rival theories to explain them.
Einstein's theory of gravitation replaced Newton's, but apples did not suspend themselves
in mid-air, pending the outcome. And humans evolved from apelike ancestors whether they
did so by Darwin's proposed mechanism or by some other yet to be discovered.
"Evolution as Fact and Theory,"
Hen's Teeth and Horse's Toes, New York: W. W. Norton, 1994, p.
‘Creation science’ has not entered the curriculum for a reason
so simple and so basic that we often forget to mention it: because it is false, and
because good teachers understand exactly why it is false. What could be more destructive
of that most fragile yet most precious commodity in our entire intellectual heritagegood
teachingthan a bill forcing honorable teachers to sully their sacred trust by granting
equal treatment to a doctrine not only known to be false, but calculated to undermine any
general understanding of science as an enterprise?
"Verdict on Creationism," The Skeptical
Inquirer, 1988, 12 (2): 186.
As a methodology for research, science adopts as its cardinal
postulate (proved fruitful by its enormous success since the time of Galileo, Newton
and Descartes) the commitment to explain empirical phenomena by reference to invariant
laws of nature and to avoid appeals to the miraculous, defined as a suspension of those
laws for particular events. The notion of ‘abrupt appearance,’ the origin of complex
somethings from previous nothings, resides in this domain of miracle and is not part of
Punctuated equilibrium, catastrophic theories of mass extinction,
hopeful monsters, and a variety of hypotheses about rapid rates of change in continuous
sequences, not about unintelligible abrupt appearances, are part of scientific debate and
bear no relationship to the nonscientific notion of abrupt appearance, despite pernicious
and willful attempts by many creationists to distort such claims by misquote and halfquote
to their alien purposes. Punctuated equilibrium, in particular, is a claim that
evolutionary trends have a geometry that resembles a climb up a staircase rather than a
slide up an inclined plane. It is, in other words, an alternate theory about the nature
of intermediate stages in evolutionary trends not, as creationists have claimed, a denial
of these stages. As a term, ‘creation science’ is an oxymoron, a self-contradictory and
meaningless phrase, a whitewash for a specific, particular, and minority religious view
in AmericaBiblical literalism.
Out of the Mainstream," The Scientist 1 (November 17, 1986): 10.
In their recently aborted struggle to inject Genesis literalism
into science classrooms, fundamentalist groups followed their usual opportunistic strategy
of arguing two contradictory sides of a question when a supposed rhetorical advantage
could be extracted from each. Their main pseudoargument held that Genesis literalism is
not religion at all, but really an alternative form of science (creation science) not
acknowledged by professional biologists too hidebound and dogmatic to appreciate the
cutting edge of their own discipline. When we successfully pointed out that creation
scienceas an untestable set of dogmatic proposalscould not qualify as science
by any standard definition, they turned around and shamelessly argued the other side.
(They actually pulled off the neater trick of holding both positions simultaneously.) Now
they argued that, yes indeed, creation science is religion, but evolution is equally
They then pointed out, as Hutton had, that questions of ultimate origins
are not resolvable by science. Thus, they claimed, creation science and evolution science
are symmetricalthat is, equally religious. Creation science isn't science because
it rests upon the untestable fashioning of life ex nihilo by God. Evolution science isn't
science because it tries, as its major aim, to resolve the unresolvable and ultimate
origin of life. But we do no such thing. We understand Hutton's wisdom‘he has
nowhere treated of the first origin
of any substance
but only of the
transformations which bodies have undergone
Scalia's Misunderstanding," Natural History 96 (October 1987): 18.
Two organisms may maintain the same feature because both
inherited it from a common ancestor. These are homologous similarities, and they
indicate ‘propinquity of dissent,’ to use Darwin's words. Forelimbs of people,
porpoises, bats and horses provide the classic example of homology in most textbooks.
They look different, and do different things, but are built of the same bones. No
engineer, starting from scratch each time, would have built such desperate structures
from the same parts. Therefore, the parts existed before the particular set of
structures now housing them: they were, in short, inherited from a common
"Inside a Sponge's Cell,"
Panda's Thumb, New York: W. W. Norton, 1980, p.
Orchids manufacture their intricate devices from the common
components of ordinary flowers, parts usually fitted for very different functions.
If God had designed a beautiful machine to reflect his wisdom and power, surely he
would not have used a collection of parts generally fashioned for other purposes.
Orchids were not made by an ideal engineer; they are jury-rigged from a limited set
of available components. Thus, they must have evolved from ordinary flowers.
Panda's Thumb," The Panda's Thumb, New York: W. W. Norton, 1980, p. 20.
Skepticism or debunking often receives the bad rap reserved for
activitieslike garbage disposalthat absolutely must be done for a safe and
sane life, but seem either unglamorous or unworthy of overt celebration. Yet the activity
has a noble tradition, from the Greek coinage of ‘skeptic’ (a word meaning ‘thoughtful’) to
Carl Sagan's last book,
The Demon-Haunted World.
] Skepticism is the agent of reason against organized irrationalismand is
therefore one of the keys to human social and civic decency.[
] Skepticism's bad rap
arises from the impression that, however necessary the activity, it can only be regarded
as a negative removal of false claims. Not so [
].Proper debunking is done in the
interest of an alternate model of explanation, not as a nihilistic exercise. The alternate
model is rationality itself, tied to moral decencythe most powerful joint instrument
for good that our planet has ever known.
Michael Shermer, Why
People Believe Weird Things, NY: Freeman & Company, 1997, pp. ix-xii.
It seems the height of antiquated hubris to claim that the
universe carried on as it did for billions of years in order to form a comfortable
abode for us. Chance and historical contingency give the world of life most of its
glory and fascination. I sit here happy to be alive and sure that some reason must
exist for ‘why me?’ Or the earth might have been totally covered with water, and an
octopus might now be telling its children why the eight-legged God of all things had
made such a perfect world for cephalopods. Sure we fit. We wouldn't be here if we
didn't. But the world wasn't made for us and it will endure without us.
"Pleasant Dreams," An Urchin in the
Storm, New York: W. W. Norton, 1987, p. 206.
History includes too much chaos, or extremely sensitive dependence
on minute and unmeasurable differences in initial conditions, leading to massively divergent
outcomes based on tiny and unknowable disparities in starting points. And history includes
too much contingency, or shaping of present results by long chains of unpredictable
antecedent states, rather than immediate determination by timeless laws of nature.
Homo sapiens did not appear on the earth, just a geologic second ago, because
evolutionary theory predicts such an outcome based on themes of progress and increasing
neural complexity. Humans arose, rather, as a fortuitous and contingent outcome of thousands
of linked events, any one of which could have occurred differently and sent history on an
alternative pathway that would not have led to consciousness.
of Life On Earth," Scientific American 271 (October 1994): 85-86.
If we must deal in metaphors [to characterize the Cambrian
Explosion and trends in the evolution of complexity], I prefer a very broad, low and
uniform slope. Water drops randomly at the top and usually dries before flowing
anywhere. Occasionally, it works its way downslope and carves a valley to channel
future flows. The myriad valleys could have arisen anywhere on the landscape. The
current positions are quite accidental. If we could repeat the experiment, we might
obtain no valleys at all, or a completely different system. Yet we now stand at the
shore line contemplating the fine spacing of valleys and their even contact with
the sea. How easy it is to be misled and to assume that no other landscape could
possibly have arisen.
the Midst of Life
Panda's Thumb, New York: W. W. Norton, 1980, p.
Yet, just as individual selection emerged relatively unscarred
after its battle with group selection from above, other evolutionists launched an attack
from below. Genes, they argue, not individuals are the units of selection. They begin by
recasting Butler's famous aphorism that a hen is merely the egg's way of making another
egg. An animal, they argue, is only DNA's way of making more DNA. Richard Dawkins has
put the case most forcefully in his recent book The Selfish Gene. ‘A body,’
he writes, ‘is the gene's way of preserving the gene unaltered.’ For Dawkins, evolution
is a battle among genes, each seeking to make more copies of itself. Bodies are merely
the places where genes aggregate for a time. Bodies are temporary receptacles, survival
machines manipulated by genes and tossed away on the geological scrap heap once genes
have replicated and slaked their insatiable thirst for more copies of themselves in
bodies of the next generation. He writes:
We are survival machinesrobot vehicles blindly
programmed to preserve the selfish molecules known as genes. . . . They swarm in huge
colonies, safe inside gigantic lumbering robots . . . they are in you and me; they
created us, body and mind; and their preservation is the ultimate rationale for our
Dawkins explicitly abandons the Darwinian concept of individuals
as the units of selection: ‘I shall argue that the fundamental unit of selection, and
therefore of self-interest, is not the species, nor the group, nor even, strictly, the
individual. It is the gene, the unit of heredity,’ Thus, we should not talk about kin
selection and apparent altruism. Bodies are not the appropriate units. Genes merely try
to recognize copies of themselves wherever they occur. They act only to preserve copies
and make more of them. They couldn't care less which body happens to be their temporary
] Still, I find a fatal flaw in Dawkins' attack from below. No matter
how much power Dawkins wishes to assign to genes, there is one thing he cannot give
themdiscrete visibility to natural selection. Selection simply cannot see genes
and pick among them directly. It must use bodies as an intermediary. A gene is a bit of
DNA hidden within a cell. Selection views bodies. It favors some bodies because they are
stronger, better insulated, earlier in their sexual maturation, fiercer in combat, or
more beautiful to behold.
"Caring Groups and Selfish Genes,"
Thumb, New York: W. W. Norton, 1980, pp. 89-90.
[S]ome evolutionists will protest that we are caricaturing their view
of adaptation. After all, do they not admit genetic drift, allometry, and a variety of reasons for
nonadaptive evolution? They do, to be sure, but we make a different point. In natural history,
all possible things happen sometimes; you generally do not support your favored phenomenon
by declaring rivals impossible in theory. Rather, you acknowledge the rival but circumscribe its
domain of action so narrowly that it cannot have any importance in the affairs of nature. Then,
you often congratulate yourself for being such an undogmatic and ecumenical chap. We maintain
that alternatives to selection for best overall design have generally been relegated to
unimportance by this mode of argument.
Spandrels of San Marco and the Panglossian Paradigm, Proc. R. Soc.
Lond. B 205 (1161): 585.
Developmental constraints, a subcategory of phyletic restrictions, may
hold the most powerful rein of all over possible evolutionary pathways. In complex organisms,
early stages of ontogeny are remarkably refractory to evolutionary change, presumably because
the differentiation of organ systems and their integration into a functioning body is such a delicate
process so easily derailed by early errors with accumulating effects. Von Baer's fundamental
embryological laws (1828) represent little more than a recognition that early stages are both
highly conservative and strongly restrictive of later development. Haeckel's biogenetic law, the
primary subject of late nineteenth century evolutionary biology, rested upon a misreading of the
same data (Gould, 1977). If development occurs in integrated packages and cannot be pulled
apart piece by piece in evolution, then the adaptationist programme cannot explain the alteration
of developmental programmes underlying nearly all changes of Bauplan.
Spandrels of San Marco and the Panglossian Paradigm, Proc. R. Soc.
Lond. B 205 (1161): 594.
As many scholars have pointed out (including yours truly in his
very first published paper of 1965) uniformitarianism is a complex term with multiple
meanings, some legitimate, but some potentially false and surely constraining. If we simply
mean that we will regard nature's laws as invariant in space and time, then we merely
state a general assumption and rule of reasoning in science. But if we falsely extend such a
claim to current phenomena (rather than universal law)and argue, for
example, that continents must always be separated because oceans now divide our major
land masses, or that mass extinction by meteritic bombardment cannot occur because we
have never witnessed such an event during the short span of recorded human historythen
we surely go too far. History does include aspects of directionality, and the present range
of causes and phenomena does not exhaust the realm of past possibilities.
"Unusual Unity," Natural History,
106 (April 1997): 71.
Charles Darwin viewed the fossil record more as an embarrassment
than as an aid to his theory. Why, he asked (1859, p. 310), do we not find the ‘infinitely
numerous transitional links’ that would illustrate the slow and steady operation of natural
selection? ‘Why then is not every geological formation and every stratum full of such
intermediate links? Geology assuredly does not reveal any such finely graduated organic
chain; and this, perhaps is the gravest objection which can be urged against my theory’
(1859, p. 280). Darwin resolved this dilemma by invoking the great inadequacy of surviving
evidence (1859, p. 342): ‘The geological record is extremely imperfect and this fact will to a
large extent explain why we do not find interminable varieties, connecting together all the
extinct and existing forms of life by the finest graduated steps. He who rejects these views
on the nature of the geological record, will rightly reject my whole theory.' Thus Darwin set
the path for the new science of evolutionary paleontology: to demonstrate evolution, search
the fossil record and extract the rare exemplars of Darwinian processinsensibly graded
fossil series, spared somehow from the ravages of decomposition, non-deposition,
metamorphism, and tectonism.
equilibria: an alternative to phyletic gradualism" In T. J. M. Schopf, ed., Models in
Paleobiology. San Francisco: Freeman, Cooper and Company, 1972, p.
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