Is That a Secret Michelangelo Selfie at the Sistine Chapel?

Michelangelo may have secretly painted himself onto the ceiling of the Vatican’s Sistine Chapel, portraying himself as God with arm outstretched to spark life in a lounging Adam.

The theory, if true, underscores Michelangelo’s outsize ego, or at least his cheeky sense of humour. The hunch, which is gaining traction among Italian Renaissance scholars, also places the artist’s self-portrait squarely at the center of one of the most famous images in Western art.

“Michelangelo saw himself as the Messiah of art, so it makes sense,” said Adriano Marinazzo, a curator of special projects at Virginia’s Muscarelle Museum of Art at The College of William & Mary who published the theory last December in the peer-reviewed Italian art journal Critica d’Arte.

Although the artist painted more than 300 biblical characters across 5,000 square feet of ceiling, the central action in Michelangelo’s masterpiece is “The Creation of Adam.” The section shows an elderly, bearded God twisting beneath a floating cloak so that the fingertips on his right hand nearly reach a lackadaisical Adam, who represents mankind.

Mr. Marinazzo, who has a record of Michelangelo-related discoveries, said he made the connection after studying a sheet of paper containing a sonnet Michelangelo wrote to his friend Giovanni da Pistoia between 1509 and 1511. In the sonnet, Michelangelo complains about the physical toll the job has taken on his health.

“My brush, above me all the time, dribbles the paint so my face makes a fine floor for droppings,” the artist wrote.

In the sonnet’s margins, the artist also drew a man, presumably himself, standing with legs slightly crossed while painting a ghoulish face on the ceiling with his right arm outstretched.

Scholars have long focused on how the poem now held in Florence’s Buonarroti Archive proves Michelangelo’s ornery attitude about the papal commission. Mr. Marinazzo said he instead fixated on the sketch, wondering why the artist would portray himself standing with one leg slightly crossing the other—a shaky stance for anyone standing on scaffolding.

Mr. Marinazzo rotated a digital image of the letter last year and had an epiphany: The posture and pose of the sketched man looked eerily similar to that of God on the ceiling, a move the historian is now convinced was intentional.

“He’s hidden himself in the ceiling,” he said. “The face is idealised because Michelangelo was self-conscious about his smashed nose, but this is the closest he’s ever come to presenting himself as divine.”

Not everyone is convinced. Paul Barolsky, a Renaissance art historian at the University of Virginia, said he needs corroborating proof that the sketch inspired the final product. Michelangelo left behind hundreds of letters, including several where he wrote self-deprecatingly about his looks after a rival painter punched and broke his nose. He also created preparatory drawings of the figures’ hands in that pivotal scene on the ceiling. Never once did the artist claim to have modelled the figure of God after himself. “Everybody’s got theories, but you’ve got to do better than that,” Mr. Barolsky said.

Yet other scholars who have read Mr. Marinazzo’s hypothesis see merit in the claim.

William Wallace, a historian at Washington University in St. Louis who has written eight books on Michelangelo, said Mr. Marinazzo has made a “clever connection” about an artist whose crackling sense of humor is often overlooked. Mr. Wallace said he could “totally entertain” a theory wherein the artist painted himself as God. “He liked to laugh at himself, so this could be a hint.”

Gary Radke, an Italian Renaissance expert at New York’s Syracuse University, said he is now equally curious about the artist’s stance in the sketch. “Who stands like that on scaffolding?” Mr. Radke said. “It raises questions about interpretation, and Adriano has seen something new.”

Mr. Radke thinks the artist, who prized his own skills, may have subconsciously related to the God figure he was painting at the time.

Certainly the task before him was gargantuan. At the time Michelangelo took the commission, he was in his 30s—far younger than the God he painted—and already deemed one of Florence’s greatest sculptors, having carved “David” in Florence and the “Pietà” of St. Peter’s a few years before. He famously preferred sculpting over painting and accused his peers of recommending him for the ceiling job so they could watch him fail, scholars say.

Pope Julius II only asked him to paint the 12 apostles in the triangular shapes lining the outer edges of the barrel-vaulted ceiling, leaving the centre painted like a night sky with gilt stars. Instead, Michelangelo took over the entire span, ultimately re-creating a vast, biblical story about man’s search for God and redemption.

The result was widely hailed the moment it was unveiled in 1512, with Michelangelo’s biographer Giorgio Vasari describing the artist as “something divine rather than mortal.”

Mr. Radke said it often takes time for scholars to accept new ideas involving Michelangelo’s masterpiece. Another theory gaining traction alleges that the artist modelled the billowing cloak surrounding God after the shape of a human brain, he said. Ditto the notion that the woman and toddler tucked under God’s left arm represent Christ and his mother, Mary.

When it comes to Michelangelo selfies, there’s also precedent: Two decades after the artist finished the Sistine Chapel ceiling, Michelangelo returned to the same room to paint a wall-spanning view of Christ’s Second Coming. In 1925, a scholar first suggested that Michelangelo likely painted himself in the flayed skin held by St. Bartholomew in that work, “The Last Judgment,” and the idea has since caught on.

“Michelangelo had an ego beyond belief,” Mr. Radke said, “so all his art was autobiography to him. He was a modern artist in that way.”