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Science Frontiers ONLINE No. 99: May-Jun 1995 |
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Did darwin get it all right?
Believe it or not, the above title appeared in Science rather than the Creation Research Society Quarterly. (We never thought we'd see the day!) And right beneath, in large type, is:
"The most thorough study yet of species formation in the fossil record confirms that new species appear with a most un-Darwinian abruptness after long periods of stability."
In the article that follows, R.A. Kerr reviews several recent studies of fossil bryozoans and snails. Some of these painstaking dissections of the fossil record were carried out by scientists initially committed to Darwinian gradualism. Even these researchers have been forced to acknowledge that much biological evolution proceeds not in minute steps but by large jumps or saltations. Such abrupt speciation is tough enough to explain, but even more daunting are those species untouched by change over millions, even hundreds of millions of years. Indeed, the major characteristic of the fossil record and, therefore, earth life as a whole, has been stasis rather than speciation, despite all manner of asteroid impacts and climatic traumas. Nevertheless, many biologists think that species are somehow frozen in time by environmental forces that keep them from straying from their little niches. This being so, paleontologist D. Jablonski, University of Chicago, asks:
If stability is the rule, how do you get large-scale shifts in morphology?How do you get from funny little Mesozoic mammals to horses and whales? From Archaeopteryx to hummingbirds?
(Kerr, Richard A.; "Did Darwin Get It All Right?" Science, 267:1421, 1995)
Comments. (1) The reality of sudden saltations in the fossil record or "punctuated equilibrium" implies that those unfound transitional fossils beloved by the gradualists are truly missing. (2) The higher the taxonomic level, the more silent the fossil record. There are few clues as to how the major divisions of life (the phylla) originated.