The New Evolutionary Timetable

The New Evolutionary Timetable, Steven M. Stanley, Basic Books Inc./ Harper, QH366.2.S69, $8.95 paperback, copyright 1981.

“This is a superb summary of current views on evolution by one of the leaders in the field. A brilliant exposition on the need for punctuated evolution in order to explain the fossil record, it is essential reading for biologists and paleontologists who want to be brought up-to-date on new discoveries in evolutionary science. The New Evolutionary Timetable is also vital for those confused by the claims of the creationists.”

— Porter M. Kier, Director Emeritus, U.S. National Museum of Natural History.

This is a very good book. It is readable, informative, and coherent. It covers punctuated equilibrium theory and places it in context in the history of evolutionary theory. Stanley is Professor of Paleobiology at John Hopkins and is one the leading theorists in modern evolutionary theory.

The first four chapters (of ten) are largely historical. They cover evolutionary theory, as it was conceived of by Darwin, to the “modern synthesis” of the 1950’s. They are strongly concerned the bases of reasoning and data used. Chapters 5, 6, 7, and 9 contain the meat of arguments for punctuated equilibrium. Chapters 8 and 10 discuss creationism and social implications.

The argument is not about the fact of evolution (which is extraordinarily well established) but is about the theory of evolution — i.e. what is the nature of the evolutionary process. The modern synthesis is a gradualist theory. It holds that species gradually transform into other species and that natural selection operating on individuals is the principal mechanism of species evolution. Punctuated equilibrium holds that species are stable once they are established, that natural selection operates principally to keep established species stable, that speciation occurs rapidly when it occurs, and that selection operates principally at the species level.

The chapter entitled “The Rapid Origin of Species” is of particular interest because it gives examples of species that are known to have come into being very recently. There are two species of moth in Hawaii that live on bananas; the point here is that bananas were introduced in Hawaii by the polynesians about a thousand years ago. The implication is that new species can arise in that short a time. There is a fish called the devil’s pupfish which lives solely in one thermal spring in death Valley. “The devil’s pupfish is very unusual. On the basis of form, it constitutes a new genus … [it] has reduced pelvic fins or none at all, but it is a more distinctive animal, bearing no close resemblance to any living species.” The point here is that a new genus can arise in no more than 30,000 years. Most examples of new species cited are fish that occur in young lakes or of birds (e.g. the Hawaiian honeycreeper variants) that occur in islands.