What is the origin of The Five Little Monkeys?

It derives from the original first verse of "Shortenin' Bread":

Two little (insert N-Word here)

Lyin' in bed

One of 'em sick

An' de odder mos' dead.

Call for de doctor

An' de doctor said,

"Feed dem darkies on shortenin' bread"

We all know the chorus:

Mammy's little baby loves

Shortenin', shortenin',

Mammy's little baby love shortenin' bread.

Unfortunate, but true. Like many children's rhymes and songs, the rhythm of the verse was too catchy for people to abandon, so parents/teachers simply changed the characters and the action. "Monkeys" belies this... unfortunately monkeys and apes have often been used as stand-in characters for African-Americans.

This rhyme was beginning to be cleansed as early as the late 1930s. My 77-year-old mother heard "Five Little Monkeys" on my child's Baby Genius CD recently and said "Monkeys? It's 'Five Little Darkies' and the doctor says to feed them shortenin' bread!" So the N Word was already out of favor in the northeast US by the time she was a child, and "darkies" was preferred for both the beginning and ending phrase.