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Punctuated Equilibrium
Stephen J. Gould and Niles Eldredge proposed the theory of punctuated equilibrium in 1972. This theory contradicts Darwin’s theory of evolution somewhat, in that when Darwin proposed evolution, there were many gaps in the fossil record. These leave the impression that species go unchanged for eons and then, in relatively few generations, change dramatically.
Darwin hoped that new fossils would be found to fill the gaps and prove or support his theory of gradual change. Gould and Eldredge, however, noted that the gaps were not filled. They proposed that the fossils should be taken for what they are, and not what they could be. Their theory proposed that species could go unchanged for very long periods of time, punctuated by periods of rapid change.
Research at Michigan State University with E.coli bacteria supported the theory of punctuated equilibrium. It showed that several hundred generations of E.coli went unchanged, but then their size suddenly increased 30%. Over the next 30 or 40 generations, E.coli grew only an additional several percent in size. After several other small size changes, no other changes occurred.
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