Jack of all Days

Eyes allow us to process the images in our world and gives others a peek into our souls—and they come in a variety of colors, from blue to gray to violet to green to hazel to brown or black. Some people even have two different colored eyes.

Eye color is determined by the amount of melanin, a dark brown pigment, present in your irises. Blue eyes are due to a lack of melanin, while brown eyes indicate melanin-rich irises. But just because your eyes are one color today doesn’t mean they’ll stay that way. A surprising new study found that 10 percent to 15 percent of whites undergo changes in eye color during adolescence and adulthood, according to a report in the Archives of Ophthalmology. In the study of 693 sets of twins and their mothers (a total of 1,513 people), 17 percent of twins and 11 percent of mothers had eye color either lighten or darken by at least two shades over the years. The changes seem to be genetically determined because identical twins were more likely to both have a change in eye color, compared with fraternal twins, who are not genetically identical. The study participants were enrolled in the Louisville Twin Study, which began in 1957.

“Children with eyes that were hazel to light brown or darker at 6 years of age were more likely to experience a decrease in pigmentation by adulthood,” according to the report. Those with gray-green eyes at age 6 were more likely to have eyes get darker as they got older. About 20 percent of children with gray-green eyes had darkened by two shades by the time they reached adulthood. The opposite was true for the mothers with gray-green eyes, a shade that tended to lighten over time. Overall, about 2 percent of the mothers had darker eyes and 9 percent had lighter eyes when tested years later.

“The mechanisms that control these changes in iris color remain unknown,” the authors wrote. But they believe that it may be due to changes in production from melanocytes, cells found in the hair, skin and the eye that make melanin, a black or brown pigment.

Sp what to do on Different Colored Eyes Day? You may want to look at photos from your youth and see if your own eye color has changed, or simply make notice of the eyes of everyone you meet today to see how many colors you come across.