If you’ve gone shopping for a baby outfit anytime in the past sixty years, you know it’s virtually impossible to enter a children’s-clothing store without getting lost in a divided sea of pinks and blues. For girls, there are flowing pink dresses, fluffy pink sweaters, and floppy pink hats, all adorned with flowers, butterflies, rhinestones, and cutesy sayings. (“Precious” and “Little Princess” spring to mind.) For boys, there are blue shirts, sweat suits, jackets, and jeans featuring ruff-and-tuff images of trucks, airplanes, and jungle animals. Moms and dads who delight in color-coding their babies’ clothes (and nurseries) by gender often perceive the retail industry for kids as one big playground, but for parents seeking more neutral options, finding a happy medium can seem almost prohibitively elusive. The next time you find yourself navigating rack after rack of pink and blue clothes and accessories, take a moment to consider how this whole scenario came to be.

Hues in the News

Given the prevalence and rigidity of the “pink is for girls, blue is for boys” school of thought today, it’s difficult to imagine things being any other way. However, some evidence suggests that these color lines actually weren’t drawn until the middle of the twentieth century. In the 1800s, almost all babies wore white—in fact, parents back then were so unconcerned about distinguishing between the sexes that they outfitted their infant sons and daughters in dresses across the board. And even when babies started sporting colorful clothing in the mid-nineteenth century, specific hues were not identified as “male” and “female”; rather, an 1855 New York Times account of a P.T. Barnum–sponsored “baby show” described both sexes as wearing a wide and arbitrary array of colors.

In the early twentieth century, however, male and female children’s clothes began to differ stylistically—boys started wearing pants, while girls remained in dresses—and with those changes came more consistent color/gender associations. At first, though, pink was ascribed most often to boys, and blue to girls. In 1918, an article in the Ladies’ Home Journal declared, “There has been a great diversity of opinion on the subject, but the generally accepted rule is pink for the boy and blue for the girl. The reason is that pink being a more decided and stronger colour is more suitable for the boy, while blue, which is more delicate and dainty, is prettier for the girl.” Another theory holds that blue, associated frequently with the Virgin Mary, was believed to reflect little girls’ purity and goodness, while pink, a derivative of red, was seen as a better match for male children’s “fiery” temperament. But by the 1940s, the tables had turned, and society’s equating of pink with femininity and blue with masculinity has remained intact since then.

Baby’s Got His Blue Genes On

Despite these apparent connections between culture and color, one groundbreaking study—conducted by neuroscientists Anya Hurlbert and Yazhu Ling, of Newcastle University in the U.K.—suggests that females may actually have an innate biological preference for pink hues. The doctors surveyed a group of 208 men and women between ages twenty and twenty-six; thirty-seven of the subjects were native Chinese, and the others were British and Caucasian. In a battery of tests in which each participant had to choose his or her favorite shade from a series of colored rectangles on a computer screen, the overall preferred color was blue, but the female participants—regardless of their cultural or ethnic background—demonstrated a clear affinity for reddish tones. Hurlbert reported in the August 2007 issue of the journal Current Biology that “females have a preference for the red end of the red-green axis, and this shifts their colour preference slightly away from blue towards red, which tends to make pinks and lilacs the most preferred colours in comparison with others.” She also noted, “Although we expected to find sex differences, we were surprised at how robust they were, given the simplicity of the test.”

Hurlbert and Ling speculate that this biological divide is long-standing and rooted in evolution. Men’s and women’s shared inclination for the color blue, the doctors suggest, could be related to humankind’s beginnings on the plains of Africa, where vast blue skies indicated good weather. The female-specific predilection for shades of pink may have something to do with early civilizations’ division of labor, in which men hunted while women gathered fruits and berries, which are often red. In addition, early women may have cultivated an ability to quickly identify red on the color spectrum, because that skill would have rendered them more alert to the flushed faces of their sick children.

Nature or Nurture?

As diverse and intriguing as these theories are, the fact remains that the pink-and-blue phenomenon has no single point of origin. And no matter how the color designations for male and female children have evolved through the ages, the current incarnations appear to be here for the long haul. What’s more, the clothing retailers couldn’t care less about how all this came about. As long as baby-shower guests and excited new parents keep snatching up pink sleep sacks for baby girls and blue ones for infant boys, the manufacturers will make more and the stores will keep their aisles segregated. If you’re satisfied with the status quo, the work’s been done for you—go forth and shop. And if you just can’t stomach the thought of restricting your child to a monochromatic wardrobe, it might be time to invest in a sewing machine.