SEATTLE (AP) - Researchers say clean up of Lake Washington in the late 1960s forced a little fish into reverse evolution. A study led by Seattle's Fred Hutchinson Cancer Research Center compared samples of the threespine stickleback from the 1950s with current samples, and found the fish had evolved back into a more armored, ancestral version of itself.

One of the researchers, Catherine Peichel says that the fish had been able to hide from its predators in Lake Washington's murky water, but the clean up cleared the water and left the threespine stickleback easy prey for trout.

The findings are being published in an upcoming issue of Current Biology.