http://www.wonderwhizkids.com/golden-ratio

"In late 2005, Dutch researchers from the University of Amsterdam ran the painting's image through "emotion recognition" computer software developed in collaboration with the University of Illinois at Urbana-Champaign. The technology demonstration found the smile to be 83% happy, 9% disgusted, 6% fearful, 2% angry, less than 1% neutral, and 0% surprised."
https://en.wikipedia.org/wiki/Speculations_about_Mona_Lisa
The portrait of Mona (short for 'Madonna') Lisa was commissioned by her husband Francesco di Bartolomeo di Zanobi del Giocondo. Neither poor nor among the most well-to-do in Florence, the couple lived a middle-class life. They lived in shared accommodation until Francesco was able to buy a house. Leonardo is thought to have begun painting Lisa's portrait the same year.
The large painting fulfilled the requirements for portraying a fashionable woman of virtue.
Leonardo da Vinci was not paid for the work and did not deliver it to his client. The artist's paintings traveled with him throughout his life, and he may have completed the portrait many years later.
Decades afterwards the portrait got the Italian name La Gioconda that is the feminine form of her married name. Though derived from Lisa's married name it also derives from the word for "happy" (in English, "jocund").
https://en.wikipedia.org/wiki/Lisa_del_Giocondo