Scientific reasoning
GradualismGradualism is a model used to explain evolution given the fossil record. The fossil record shows large changes, such as speciation, which seem to appear suddenly. The thing about fossils is they are a glimpse into the past, they don't show everything. It is like reading pages 5, 10 and 35 of a book and then trying to write a book report. Gradualism suggests that speciation happens slowly and is just not captured in the fossil record. It happened on page 30 and we didn't read that page! The model is shown above.
Punctuated equilibrium is a model that suggests that change in fact happens abruptly and so we see it as such in the fossil record. It suggests that species have long periods of equilibrium with no change. For now, most scientists assume that both models have some validity, but new discoveries may someday disprove one or both models. Comments are closed.
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