We can thank the Vatican's 16th-century fresco painters for a food-history find.

Occasionally the tangents of a major newspaper article are at least as intriguing as the main topic. At least that's the case of the New York Times' reporting of the reopening of one of the great interiors of the Renaissance, four rooms in the Vatican with frescoes by Raphael:

Some beans found inside a small hole in the fresco of the Fire in the Borgo, painted from 1514 to 1517, suggests that it didn't take long for these legumes, indigenous to the Americas and imported by Columbus some 20 years earlier, to become part of the common man's diet in Europe.

"Sadly, they were cooked," making it impossible to replant them and replicate their taste, Professor Nesselrath said Thursday, during a preview tour of the frescoes.

The discovery, limited though it is, is more than a factoid of food history. It's actually connected with the transformation of the European diet that had already made the High Middle Ages and Renaissance possible even before Columbus. As Umberto Eco has written:

[W]hen, in the 10th century, the cultivation of legumes began to spread, it had a profound effect on Europe. Working people were able to eat more protein; as a result, they became more robust, lived longer, created more children and repopulated a continent.

We believe that the inventions and the discoveries that have changed our lives depend on complex machines. But the fact is, we are still here -- I mean we Europeans, but also those descendants of the Pilgrim Fathers and the Spanish conquistadors -- because of beans. Without beans, the European population would not have doubled within a few centuries, today we would not number in the hundreds of millions and some of us, including even readers of this article, would not exist.

We think of the speed of technological innovation and the spread of memes as a late 20th- and 21st-century phenomenon, but the Vatican discovery implies that European diet was changing literally at the grassroots within a generation of the first voyages. For this insight we should be grateful to the careful work of the Vatican's conservationists -- and the eccentric habits of Raphael's plasterers.