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Relationships of Living Species: Calibrating Molecular Clocks

In the 1960s, researchers first observed that the number of amino acid differences among the hemoglobin molecules made by different species corresponded to the time, estimated from the fossil record, when those species had a common ancestor. Since then, steady, clocklike rates of change have been observed in many proteins.

Credits: The Human Evolution Coloring Book, Second Edition, by Adrienne Zihlman, produced by Coloring Concepts Inc. and published by HarperCollins, New York

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Evolution of Diversity

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