It's impossible to navigate virtually any kind of retail store in February without seeing displays of pink and red chocolate boxes around every corner. Chocolate has become a standard Valentine's Day gift, right up there with flowers and jewelry, but the treat didn't develop its romantic reputation overnight. It took centuries of myths, marketing, and traditions to write chocolate into Valentine's Day history.

The first people to connect love and chocolate were the Mayans. They started brewing drinks made from cocoa beans around 500 BCE—centuries before the first Feast of St. Valentine. This early hot chocolate was an important part of Mayan wedding rituals. The bride and groom would exchange sips of the beverage during the ceremony, foreshadowing chocolate's future status as a universal expression of love.

The Aztecs had a less wholesome view of the ingredient. According to legend, the emperor Montezuma II binged huge quantities of cocoa beans to fuel his romantic affairs. Chocolate does contain small amounts of tryptophan and phenylethylamine, two chemicals associated with feelings love and desire, but scientists say there isn't enough of either substance to make chocolate a strong aphrodisiac.

Stories of chocolate's effects in the bedroom persisted nonetheless, which might explain why candy-sellers embraced the sweet treats when Valentine's Day became popular. Cadbury debuted the first heart-shaped box of chocolates in 1861, and it was an instant success. The package was embellished with cupids and roses to appeal to customers shopping for Valentine's Day gifts. And once the box was empty, it could be used to store keepsakes like love letters and locks of hair.

Cadbury didn't patent the heart-shaped chocolate box, so the rest of the candy industry started manufacturing similar packaging of their own. It wasn't long before chocolates became synonymous with the newly-commercialized holiday.

Valentine's Day chocolates are exchanged around the world, but they're attached to interesting traditions in some countries. Thanks to a successful marketing campaign, women in Japan have to give "obligation chocolates" to all the men they know on February 14. Here are more international Valentine's Day customs.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.