In 1983, a medical doctor published an article about Sandro Boticelli's painting Portrait of a Youth (c. 1482/85), arguing that the youth's hand gesture was an indication of juvenile arthritis. See the article here
But why would Boticelli depict a physical defect in the young man? It seems odd that Boticelli would so prominently portray such a crippling handicap in a portrait. The look on the young man's face is one of confidence and ability, and contradicts the idea that he has a debilitating physical defect. Had the young man actually had juvenile arthritis, it would make sense that Boticelli would portray him without his hands, as in his other famous Portrait of a Young Man (c. 1480-5).
Portraiture was generally used to aggrandize patrons, and associate them with a particular family, class, or group. In another work, Portrait of a Man with a Medal of Cosimo the Elder (c. 1474-5), the young man, similarly dressed, is holding a medallion with the profile of Cosimo de' Medici, identifying him with Medici family.
Couldn't the hand gesture of the young man in Boticelli's later painting similarly connect the youth to a certain family or group in 15th century Florentine culture? Is this the original "Westside" gang sign? Is this work the inspiration for the hand gesture that later inspired Tupac Shakur, Snoop Dogg, countless rappers, gang-bangers, and white kids across the West coast?
While in prison, Tupac extensively read the writings of Niccolo Machiavelli. Several editions of The Prince have Boticelli's painting as the cover artwork.
Tupac was so inspired by Machiavell's writings he later used "Makaveli" as a pseudonym for his last album. Perhaps Tupac saw this hand gesture as a representation of the Machiavellian ideals that inspired him.
I haven't found any information on the exact origins of the modern "westside" sign. I first saw this connection during ArtHC 202 freshman year in 2006 as I explored Gardner's Art Through the Ages. I thought it was humorous and sent the image to some family and friends, but was again reminded of it with all the current discussions of hip-hop culture and art history. Apparently, I'm not the only one to make the connection, as I just saw on another blog this image of Snoop Dogg mimicking Boticelli's young man's confident look and hand gesture.
From Florence to the inner-mountain West, let's give it up for the West Side...