Outline for interview of Ben Sweeney on ABC PrimeTime “Medical Mysteries” November 28, 2006 at USC

Primary evidence:

Last supper depicts Syndactyl left hand for Christ

Drawing in his notebook of Leonardo’s left hand depicts same syndactyl anomaly

Young Leonardo wrote that his left hand was tired.

Leonardo wrote in his notebooks: (Cod. Arundel. Folio 155r) "Arching my back, I rested my tired hand (la stanca mano) on my knee and held my right hand over my lowered lids." (Brizio, 292) Written around 1478 when Leonardo was approximately 25 years old, this shows that he referred to his left hand as his tired hand much earlier than as would have been expected if it had been caused by a stroke. The subject of controversy, it is frequently translated to mean "left hand" (Brizio 292). The literal meaning of "stancare" is weary, exhausted, or tired and a review of Kate Steinitz's book "Leonardo da Vinci's Trattato della Pittura...A Bibliography" shows that John Spencer believes that the more appropriate translation is indeed "tired hand" (Spencer, 201).

The Madonna of the Yarnwinder 1504 (The Lansdowne Madonna)remarkably what is seen in the IR of the infant's left hand is an uncorrected synpolydactyly after early soft tissue separation but with no skeletal correction

Secondary evidence:

Leonardo depicted by Raphael, Botticelli, Botticini, Michelangelo with characteristics that confirm congenital anomalous hand

Leonardo is described by Luca Pacioli as being Il Mancino... Literal Latin translation consistent to congenital findings

Given the moniker "Il Mancino/The Left Handed One" (Bambach 31), Leonardo's namesake is a clawed, ferocious animal. Some suggest that he was dubbed "Il Mancino" simply because he continued to work primarily with his left hand and no mention of an anomaly is offered (Bambach 31). "La mano manca" literally refers to "the lacking or injured hand". However, according to lexicographic surveys in Battaglia, Italy from 1975 and 1998, it can also refer to the left hand (Bambach 52). "Mancare" is Italian for the verb "to need", while the Latin word "mancus" is translated as "defective in any limb" (Valpy, 248).

Tertiary Evidence:

Leonardo’s namesake is clawed; he was not born in sign of Leo and no immediate family with name ‘Leonardo”

Anecdotal stories by Vasari, Beattis describe a man with a problem of the hand likely from a stroke

Historical descriptions note his unique style dress that would also aid in hiding this hand

Summary:

Leonardo was potentially born with syndactyly or polysyndactyly left hand