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No. 33: May-Jun 1984

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The failure of two-dimensional life

The fossil record tells us that just prior to the Cambrian explosion of life, the earth was populated by a diverse assemblage of soft-bodied, shallow-water marine invertebrates, some with dimensions as large as 1 meter. This whole group of animals did not survive into Cambrian times, thus ending what has been termed The Ediacaran Experiment. Some paleontologists have tried to find similarities between the Ediacaran and Cambrian life forms to preserve the continuity of life. This has proved difficult, and some scientists now feel that The Edicaran approach to "largeness" was to increase surface area externally. The Ediacarans were therefore shaped like pancakes, tapes, fans, etc. This enabled them to present large areas to the environment for respiration, feeding, and other biological functions.

In contrast, many present life forms achieve "largeness" by increasing internal areas, as in the lungs, folded intestines, etc., along with the forced circulation of air, blood, and other sub stances. This latter approach survived, while the two-dimensional Ediacaran Experiment did not. The demise or extintcion of the Ediacarans led Gould, the author of this far-ranging article, to the influence of extinctions on life in general -- a hot topic these days. Gould stated that with natural selection operating, one would expect continual "improvement" in life forms, but that this had not happened.

"I regard the failure to find a clear 'vector of progress' in life's history as the most puzzling fact of the fossil record. But I also believe that we are now on the verge of a solution, thanks to a better understanding of evolution in both normal and catastrophic times. We need a twotiered explanation for patterns (or non-patterns) in the history of life."

The first tier of explanation involves the theory of punctuated equilibrium, as championed by Gould and Eldredge. Gould says he once thought that punctuated evolution would be sufficient to explain all of life's development, but that now a second tier seemed required; namely, a general theory of mass extinction or what catastrophism does to life and its development.

(Gould, Stephen Jay; "The Ediacaran Experiment," Natural History, 93:14, February 1984.)

Ediacaran life forms Ediacaran life forms were typically flattish to maximize external area.

From Science Frontiers #33, MAY-JUN 1984. 1984-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:

Quotes

  • "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