Thursday, March 11, 2004

Eldredge and Cornets From the New York Times comes this profile of paleontologist Niles Eldredge. After a career studying trilobites (anceint, obscure invertebrates that are so prolifically represented in the fossil record that they are useful tools for studyign evolution) Eldredge has turned his attention to studying the evolution of cornets (the horn, that is).

Eldredge, now 59 is the senior curator for invertebrates at the Museum of Natural History in New York. He is most famous for developing, with Stephen Jay Gould, the theory of punctuated equilibirum. This theory suggested that evolution is characterized by long periods of stasis, during which species evolve very little, punctuated by rapid bursts of change concentrated around speciation events (i.e. events during which a new species is produced.) This was in contrast to the steady gradualism emphasized by more orthodox Neo-Darwinians.

This talk about rapid change was eagerly siezed upon by creationists, since it smacks of the miraculous. Also, since natural selection is famous for the leisurely pace it takes to affect significant change, it seemed to be suggesting that natural selection was not the driving force behind evolution. This misconception was aided by the fact that Gould, in other contexts, had also been critical of the idea that natural selection was as ubiquitous as many biologists claimed. Gould's criticism was not that natural selection could not craft complex structures. Rather it was that other forces were at work in evolution as well, and that these forces had been slighted by the overemphasis on selection.

Like most creationist arguments, the idea that punctuated equilibirum posed any threat to evolution was based on a simple misunderstanding of the theory. Gould and Eldredge were completely unambiguous that natural selection should still be regarded as the dominant force in evolutionary change. They claimed merely that the tempo and mode with which this change took place was something different from what was previously thought. When they referred to ``rapid'' change, they meant rapid when measured on geological time scales. A transformation requiring fifty thousand years to occur would be considered rapid in this sense.

Anyway, nowadays punctuated equilibrium is regarded as an interesting variation on traditional Neo-Darwinism, but nothing revolutionary or shocking. Gould subsequently became so famous for his essays and popular writing that Eldredge was sometimes overlooked. It's nice to see him getting some well-deserved attention now.


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