It might not seem like a revolutionary concept, but marine biologists have just made a claim that could shake up the way dolphins are identified in scientific studies: We humans can reliably identify these marine mammals the same way we identify each another, by simply looking at their faces. The idea has never been put to the test because scientists have almost always relied on their fins to tell the animals apart. But this can be tricky, since notches and marks can change with time, and calves tend to have “clean” fins. So researchers studying bottlenose dolphins (Tursiops truncatus) off the coast of Trieste, Italy, created a dolphin lineup. They photographed 20 dolphin faces from their left and right sides, and put the photos in three folders: one “reference folder” with left-side images of all 20 dolphins, and two that contained 10 images each of either the dolphins’ right or left sides. Then, 20 biologists, eight of whom had no experience with dolphins, were asked to identify the dolphins by matching the smaller set of photos to those in the reference group. They did significantly better than expected by chance, and three researchers who had experience with dolphins were able to correctly identify all the animals, the team reported last month in Marine Mammal Science. The facial features are recognizable for at least 8 years, giving scientists hope that this new method will make it easier to track and study marine mammals that lack dorsal fins. But what about the dolphins? Even though they rely primarily on sound to recognize one another, they might also get something out of swimming cheek-to-cheek.