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Knowing how fast DNA changes over time gives biologists a “clock” for measuring evolution itself. One way to measure the speed of DNA change is to compare DNA from individuals of one species that lived at widely different times. Adelie penguins of Antarctica offer a unique laboratory for these experiments. Hundreds of generations return to the same rookeries to breed, and the voluminous remains resulting from the harsh conditions and severe predation are amazingly preserved in the cold, dry climate. The natural history of Adélie penguins, including colony movements over the past many thousands of years, gives a fascinating picture of life on a stark, dramatic continent. Precise aging of serially preserved ancient and modern penguin remains and careful analysis of coding and noncoding DNA of their mitochondrial and nuclear genome presents us with the evolutionary clock biologists seek.

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