Age isn't just a number for one of the ocean's top apex predators. It's a mystery University of Georgia researchers are solving. A new UGA study has determined how to estimate the age of sharks by analyzing changes to individual animals' DNA. Known as epigenetic clocks, these scientific age estimators focus on chemical alterations known as DNA methylation to measure wear and tear on an animal's cells, providing a noninvasive, fast and accurate assessment of an animal's age.