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No. 60: Nov-Dec 1988

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Lop-sided evolution

We risk supersaturating our readers with the anomalies of evolution, but we simply cannot bypass an article that is introduced as follows:

"An analysis of the fossil record reveals some unexpected patterns in the origin of major evolutionary innovations, patterns that presumably reflect the operation of different mechanisms."

The most interesting "unexpected pattern" is the gross asymmetry between the diversification of life in the Cambrian explosion (about 440 million years ago) and that following the great endPermian extinction (a little over 200 million years ago). Biological innovation was intense in both instances; both biological explosions burst upon a life-impoverished planet. Many niches were unoccupied. Even so, all existing (and many extinct) phyla arose during the Cambrian explosion and none followed the Permian extinction.

"...why has this burst of evolutionary invention never again been equaled? Why, in subsequent periods of great evolutionary activity when countless species, genera, and families arose, have there been no new animal body plans produced, no new phyla?"

Some evolutionists blame the asymmetry on the different "adaptive space" available in the two periods. "Adaptive space" was almost empty at the beginning of the Cambrian because multicellular organisms had only begun to evolve; whereas after the Permian extinction the surviving species still represented a diverse group with many adaptations. (Just how the amount of "adaptive space" available was communicated to the "mechanism" doing the innovation is not addressed.) Scientists contemplating these matters, however, seem to concur that microevolution, which supposedly gives rise to new species, cannot manage the bigger task of macroevolution, in particular the creation of new phyla at the beginning of the Cambrian.

(Lewin, Roger; "A Lopsided Look at Evolution," Science, 241:201, 1988.)

From Science Frontiers #60, NOV-DEC 1988. 1988-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987