The lead researcher of the study said the number of blue-eyed people is increasing because people think they are more attractive. People with blue eyes are more successful at finding a partner. He says having blue eyes is like a peacock's tail. A colourful tail will get a peacock more mates. The researcher says people are attracted to the sparkle in blue eyes. Light sparkles in blue eyes. Darker eyes generally have less sparkle. Another scientist explains why blue eyes are popular. He said: "There is something attractive about blue eyes, maybe because they used to be so rare."