A group in Switzerland is claiming that Leonardo Da Vinci created an earlier version of his masterpiece "Mona Lisa."
The Mona Lisa Foundation, based in Zurich, announced its findings Thursday on its website. The group contends that the painting known as the "Isleworth Mona Lisa," which resembles the original but whose provenance has been contested for many years, is actually a Da Vinci work.
The foundation said it is basing its claim on mathematical analysis, historical research and other methods. It said the painting predates the "Mona Lisa" by about 11 years.
"Isleworth Mona Lisa" was discovered in the late 19th century in England and was once owned by Henry F. Pulitzer, who wrote a book about it. The woman depicted in the painting closely resembles the figure in "Mona Lisa," but there are significant differences between the works, such as the landscape in the background and the size of the canvas.
The foundation claims that Da Vinci "intended from the outset that the works would be different from each other" and that "both paintings are original works by the same artist, and neither could be a copy of the other."
It also contends that the portraits depict the same women at different ages.
The foundation's findings are published in a new book titled "Mona Lisa: Leonardo's Earlier Version."