Punctuated Equilibrium

From Conservapedia

The theory of Punctuated Equilibrium according to the American Museum of Natural History "asserts that evolution occurs in dramatic spurts interspersed with long periods of stasis".^[1] The theory is briefly outlined below:^[2][3]

• 1. A species exists in the environment with many generations going by with little change (and members of this species occasionally being fossilized)
• 2. Through interbreeding the change in the species is kept low
• 3. There is a population at the edge of the general area that the species inhabits.
• 4. This population becomes isolated
• 5. Because this is a new environment, there are new pressures on the population
• 6. As this is a smaller population, genetic drift is also increased
• 7. 5+6 mean a greater rate of evolution, and in a different direction
• 8. Over a long period of time, the population might no longer be able to interbreed (new species)
• 9. If circumstances change again (sea levels rise), these new mollusks may drive the other mollusks to extinction
• 10. This new population would grow, and become static once more

As the new population developed quickly (as little as 100,000 years^[4]) and was in an isolated area, they would leave few fossils.^[5] This, according to Dr. Niles Eldredge, who proposed the theory along with Stephen Jay Gould^[6], is consistent with the fossil record.^[7]

The theory caused much controversy and received much criticism, forming part of the "Darwin Wars" between such scientists as Steven Jay Gould and Richard Lewontin on one side and "Ultra-Darwinists" such as Richard Dawkins on the other. However, there was no controversy as to whether gradual change through natural selection was the most important evolutionary process. Gould argued for a greater rate of evolution, but not greater changes per mutation.

External Links

• PBS: Punctuated Equilibrium
• University of California Museum of Paleontology: More on Punctuated Equilibrium
• Punctuated equilibrium: come of age? by Dr Don Batten

Notes