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Time Frames: The Re-Thinking of Darwinian Evolution and the Theory of Punctuated Equilibria

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Dr. Eldredge is a curator of paleontology at the American Museum of Natural History. He and Dr. Stephen J Gould developed what may be the most critical appendix to Darwin's theory of evolution through natural selection since Ernst Mayr's biological species concept. In short the theory of punctuated equilibria states that species are in evolutionary stasis for long periods of time and when a useful adaptation appears it will spread rapidly through the population. It is not the theory that makes this book a good read. It is the way that the author describes how he and Dr. Gould came to it. Dr. Eldredge is an expert on trilobites, a group of aquatic arthropods that went extinct before the dinosaurs appeared. Following him as he explorers the fossil record of these creatures is as much a lesson in perseverance and good science as it is in evolutionary theory. I would recommend this book to anyone interested in any field of organismal biology, it would be a "must read" for people who are particularly interested in evolution and or paleontology.

Niles Eldredge (born 1943) is an American paleontologist, who, along with Stephen Jay Gould, proposed the theory of punctuated equilibrium in 1972.

He states in the Preface to this 1985 book, "This book is my version of the story of 'punctuated equilibria'---what it is, how it came to be, and what I think it means for modern evolutionary thinking. The development of the theory of punctuated equilibria is, I believe, utterly symptomatic of a general upsurge of critical analysis going on in virtually every corner of biology, including systematics ... ecology and paleontology. In telling the story I have tried to capture the thought processes and the feelings that go into the formulation and execution of a fairly typical scientific study---as well as some of the more complex behavior that transpires once an idea begins to catch on, and once that idea requires further elaboration as its implications begin to emerge. It is a story, at the outset, of simply not finding the expected, and later, of the complex, if not totally tortuous, path that led on from there."

Interestingly, he also notes in the Preface that "From the very beginning ... Stephen Jay Gould and I have differed to some extent on the significance, the implications---and even, on occasion, some aspects of the basic content---of 'punctuated equilibria.' Though, of course, our positions are (and always have been) closely similar compared with opposing views..." He later states, "Stephen Jay Gould, of course, codeveloped the notion of 'punctuated equilibria'--and even coined the expression." (pg 49)

Concerning their groundbreaking first paper on punctuated equilibria, he writes, "Gould and I, after much discussion, each wrote roughly half... Gould edited the entire manuscript for better consistency. We sent it in, and Schopf reacted strongly against it--thus signaling the tenor of the reaction it has engendered, though for shifting reasons, down to the present day." (pg. 120)

In the concluding chapter, he notes, "The possibility that there exist these other, larger-scale entities is perhaps the major gift of punctuated equilibrium to the ongoing task of learning more about how the evolutionary process really works. The idea itself--that there are large-scale entities so vast in space in time that we, locked into our humanly scaled perceptions, are scarcely aware of them--has been around for a while.... Punctuated equilibria above all else suggests that species really do have a concrete reality." (pg. 185)