Database entry #306
Quoted by: UCSD IDEA student club
Quoted in: The IDEA Club Fossil Record Quote Collection web page (Last accessed 2001/10/14).
Person quoted: (The New Evolutionary Timetable by Steven Stanley, Basic Books, Inc. Publishers, 1981. Pg 93-94)
"Given a simple little rodent like animal as our starting point, what does it mean to form a bat in less than ten million years, or a whale in little more time ... If an average chronospecies lasts nearly a million years ... then we have only ten or fifteen chronospecies to align, end -to-end, to form a continuous lineage connecting our primitive little mammal with a bat or a whale. This is clearly preposterous ... A chain of ten or fifteen of these might move us from one small rodent like form to a slightly different one ... but not to a bat or a whale!"
Citation as given by quoter:
(The New Evolutionary Timetable by Steven Stanley, Basic Books, Inc. Publishers, 1981. Pg 93-94)
Status of quote as given: misquote
Comments: Stanley's complaint is about the inadequacy of phyletic gradualism to account for the known facts of paleontology and the superiority of punctuated equilibria as an explanation for those facts. The misquote here concerns the omission of relevant context - the removal of any sense that what is being critiqued is a specific hypothesis of evolutionary change rather than whether evolutionary change happens. This comes through clearly when one examines the complete context of this quote.
Database entry #1171
Quoted by: Wesley R. Elsberry
Quoted in: NA
Person quoted: Steven M. Stanley
When the mammals inherited the Earth, the result was spectacular. Their great adaptive radiation was recent enough that the fossil evidence for it is impressive. Within perhaps twelve million years, most of the living orders of mammals were in existence, all having descended from simple, diminutive animals that might be thought of as resembling small rodents, though not all possessed front teeth specialized for gnawing. Among the nearly twenty new orders were the one that contains large carnivorous animals, including modern lions, wolves, and bears; the one that comprises horses and rhinos; and the one that includes deer, pigs, antelopes, and sheep. Most of the orders evolved in even less than twelve million years. Perhaps the most spectacular origins were of the bats, which took to the air, and the whales, which invaded the sea.
Darwin was spared a confrontation with the extraordinarily rapid origins of modern groups of mammals. He knew that the history of mammals extended back to the early part of the Mesozoic, but the record was not well enough studied in his day for him to recognize that the adaptive radiation of modern mammals did not commence until the start of the Cenozoic. Today, our more detailed knowledge of fossil mammals lays another knotty problem at the feet of gradualism. Given a simple little rodentlike animal as a starting point, what does it mean to form a bat in less than ten million years, or a whale in little more time? We can approach this question by measuring how long species of mammals have persisted in geological time. The results are striking; we can now show that fossil mammal populations assigned to a particular Cenozoic lineage typically span the better part of a million years without displaying sufficient net change to be recognized as a new species.
The preceding observations permit us to engage in another thought experiment. Let us suppose that we wish, hypothetically, to form a bat or a whale without invoking change by rapid branching. In other words, we want to see what happens when we restrict evolution to the process of gradual transformation of established species. If an average chronospecies lasts nearly a million years, or even longer, and we have at our disposal only ten million years, then we have only ten or fifteen chronospecies to align, end-to-end, to form a con- tinuous lineage connecting our primitive little mammal with a bat or a whale. This is clearly preposterous. Chronospecies, by definition, grade into each other, and each one encompasses very little change. A chain of ten or fifteen of these might move us from one small rodentlike form to a slightly different one, perhaps representing a new genus, but not to a bat or a whale!
What the gradualist must then postulate is an extraordinary acceleration of evolution within established species. In other words, he must claim that, in the lineage leading to the first bat or whale, chronospecies were actually of very short duration. This situation brings us to the essence of the gradualistic dilemma — a dilemma that holds for the adaptive radiations of Cambrian marine life and Cretaceous flowering plants as well. The first problem is that we have absolutely no fossil evidence for rapid transformation of chronospecies. On the contrary, early Cenozoic species of mammals appear to have had long durations, resembling those of younger species. The second problem relates not to fossil evidence, but to causal explanation. Why should well-established species suddenly undergo very rapid transformation? We know that after the demise of the dinosaurs the world was available for occupancy by mammals. Nonetheless, why should mere ecological opportunity cause any well-established species to abandon its way of life for an entirely new one? We might expect a broadening of the original way of life — of the niche, in the parlance of ecology—but not a desertion of what worked well before. Expanded ecological opportunity would be expected to permit great diversification, but no single species ever becomes very highly diversified. Rather, diversification proceeds by the sprouting off of new species from already established species — by adaptive radiation — and this, of course, brings us to the punctuational scheme of evolution.
Citation as given by quoter:Stanley, Steven M. 1981. The New Evolutionary Timetable. New York: Basic Books. pp.93-94.
Status of quote as given: verbatim
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