Eros, the god of love, was represented by a strong, powerful young man in ancient Greece, but by the time ancient Rome depicted love, it was a little boy with a bow and arrow.
How that happened is what a six-month art exhibit in Athens seeks to illustrate. The heart of the answer lies in the exhibit's top floor, where children under 16 aren't allowed unattended. There three rooms illustrate sexual congress (what we know as intercourse), homoerotic love, and pederasty (a relationship between a man and young boy). Ancient Greeks thought it was normal to be drawn to the beauty of adolescent boys just as they were drawn to women, and homosexuality was considered part of coming of age.
So how did Eros, the athletic young man in art and literature, become a flying boy named Cupid? As time passed he became younger and younger until Hellenistic times when he was portrayed as a child or baby with a bow and arrow. When Romans created their god, they took the Greek's version and named him Cupid.
Good thing Valentine's Day is two months away. Maybe we can forget this, but probably not!
Source: Flickr User chicks57