The melting of icebergs due to global warming is affecting the evolution of penguins, according to a fascinating new study based on analysis of DNA from a longstanding penguin colony in Antarctica. According to an article in the Independent, this particular colony of adelie penguins has bred at the same site for thousands of years, and remains of birds as old as 6,000 years were buried in the snow and ice. Scientists studied DNA of dead and living birds and found that melting icebergs caused changes in the gene pool of the colony—caused in turn by disturbances in the birds' breeding patterns. When icebergs break apart (called “calving”) and shift, it can seriously impact the penguins' movements, since they must travel long distances to feed. In 2001, for instance, penguins were forced to walk across the ice instead of swimming to reach their food source. These changes in movement impact which birds—and how many—can breed, which leads to changes in the colony's gene pool.