Ancient sculptors made magnetic figures from rocks struck by lightning

People living at least 2,000 years ago near the Pacific Coast of what’s now Guatemala crafted massive human sculptures with magnetized foreheads, cheeks and navels. New research provides the first detailed look at how these sculpted body parts were intentionally placed within magnetic fields on large rocks.

Lightning strikes probably magnetized sections of boulders that were later carved into stylized, rotund figures — known as potbellies — at the Guatemalan site of Monte Alto, say Harvard University geoscientist Roger Fu and his colleagues. Artisans may have held naturally magnetized mineral chunks near iron-rich, basalt boulders to find areas in the rock where magnetic forces pushed back, the scientists say in the June Journal of Archaeological Science. Predesignated parts of potbelly figures — which can stand more than 2 meters tall and weigh 10,000 kilograms or more — were then carved at those spots.

Potbellies represented dead but still revered ancestors of high-ranking families, suspects art historian Julia Guernsey of the University of Texas at Austin.  Sculptures that repelled magnetized objects would have been seen as demonstrating the presence and authority of deceased ancestors in rapidly expanding societies ( SN: 6/1/13, p. 12 ), she suggests. Fu’s results also indicate that Mesoamericans attributed special powers to certain body parts, such as the face and midsection, Guernsey adds.

The researchers studied 11 potbelly sculptures, six heads and five bodies, now displayed in a Guatemalan town. At least 127 such sculptures have been found at sites in Mesoamerica, an ancient cultural region that runs from central Mexico through much of Central America.

Handheld sensors confirmed a 1997 report that magnetic signals occurred over the right temple and cheek of three colossal heads from Monte Alto. Sensors also detected magnetism near the navels of four body sculptures. A portable, high-resolution magnetic sensor then precisely mapped magnetic fields on two head and two body sculptures.