The familiar double-lobed heart symbol seen on Valentine's Day cards and candy was inspired by the shape of human female buttocks as seen from the rear, according to a professor of psychology who studied the origin, history and symbolism of the Feb.14 holiday.

Galdino Pranzarone of Roanoke College in Salem, Va., told Discovery News that he analyzed "essential literary and speculative evidence from mythology and secondary sources," which led to his theory. He believes one rather obvious bit of evidence is that the heart symbol does not directly duplicate the heart human organ.

"The twin lobes of the stylized version correspond roughly to the paired auricles and ventricles (chambers) of the anatomical heart," Pranzarone said, but added that the organ "is never bright red in color" and its "shape does not have the invagination at the top nor the sharp point at the base."

Pranzarone indicated that the ancient Greeks and Romans could have originated the link between human female anatomy and the heart shape. The Greeks, he said, associated beauty with the curves of the human female behind.

"The Greek goddess of beauty, Aphrodite, was beautiful all over, but was unique in that her buttocks were especially beautiful," he explained. "Her shapely rounded hemispheres were so appreciated by the Greeks that they built a special temple Aphrodite Kallipygos, which literally meant, 'Goddess with the Beautiful Buttocks.' This was probably the only religious building in the world that was dedicated to buttock worship."

He admitted that it was possible that the heart symbol represented both male and female glutes (the group that includes the three large muscles of each buttock that control thigh movement), but he said, "I think the Valentine's heart more closely fits the rounded female anatomy rather than the angular, compact and slimmer male butt."

Valentine's Day-type heart symbols first became popular in 15th century Europe as a suit designation on playing cards. It is possible that the Renaissance fondness for classical literature and history brought forth the Greek interest in the female buttocks shape, which Pranzarone indicated also mirrors the basic outline of female breasts.