Nursery rhymes evolved into their current forms around the 19th century when rhyme books began to circulate. Before then, people passed on lullabies and children's songs orally. Many famous nursery rhyme characters may be based on historical figures and events, but evidence is mixed. In the 21st century, people still use rhymes to teach moral lessons to children and to introduce them to language and reading, as the rhymes contain repetitions of various letters and sounds.
Many nursery rhyme characters are personified with human characteristics given to animals or things in nature. In the nursery rhyme, "Hickory Dickory Dock," the mouse has a penchant for running up clocks, and in the tale of "The Three Little Kittens," the kittens -- not children -- are concerned with finding their lost mittens. Humpty Dumpty is not an animal, but an egg who sits atop a wall and falls, breaking apart. Other nursery rhymes focus on star characters, like "Twinkle, Twinkle Little Star" and "Star Light, Star Bright."
Though most nursery rhyme characters are animals or children, there are several famous adult characters, most with quirky personalities or strange habits. In "Old Mother Hubbard," Mother Hubbard will do anything for her almost-human dog, and the old woman living in a shoe has so many children that she feeds them only broth, whips them and sends them to bed, overwhelmed. "This Old Man" tells of a character in a famous counting nursery rhyme. At the end of each verse, he comes rolling home.
Many nursery rhymes center around a little boy. "Jack Be Nimble" tells the story of a little boy jumping over a candlestick and burning his toe in the process. Little Boy Blue falls asleep on the job while tending his sheep, and Little Jack Horner gets rewarded for good behavior by finding a plum in his mincemeat pie. Georgie Porgie centers around a little boy who makes girls cry with his kisses and runs away from the town boys when they come out to play. It may refer to George IV, who was seen as amorous and amoral. According to the nursery rhyme, "What Are Little Boys Made Of," boys are made of puppy dog tails, snips and snails.
Famous female nursery rhyme characters include Mary in "Mary Had a Little Lamb." Mary brings her faithful lamb to school and distracts the class with his presence. "Little Bo Peep" tells the story of a little girl whose flock of sheep disappears, only to find them with their tails missing. She finds the tails hung on a tree and tries to put them back on her beloved herd. "What Are Little Girls Made Of" addresses little girls in general, stating that they're made of sugar and spice and everything nice.