The red pigment also contains traces of bird eggs
A 1,000-year-old mask found on the head of an ancient skeleton was painted with human blood, according to a new study.
Archaeologists from the Sikan Archaeological Project discovered the golden mask in the early 1990s while excavating an ancient tomb in Peru. The tomb, which dates from around 1000 AD, belonged to a noble middle-aged man from the ancient Sikan culture, who inhabited the northern coast of Peru from the 9th to the 14th century.
The skeleton, also painted bright red, was found sitting headless and facing down in the center of a 12-meter-deep square burial.
The head, which was intentionally separated from the skeleton, is placed with the right side up and covered with a red-painted mask. Inside the tomb, archaeologists found 1.1 tons of burial objects and skeletons of four others – two young women, arranged in the positions of midwife and woman in labor, and two squatting children, arranged at a higher level.
During the excavations, scientists identified the red pigment on the mask as cinnabar, a bright red mineral of mercury and sulfur. But even though it had been buried deep underground for a thousand years, somehow the red paint – a layer 1 to 2 millimeters thick – remained attached to the mask. “The identity of the binder that was so effective in the red paint remains a mystery,” the authors write.
In the new study, researchers analyzed a small sample of red dye to see if they could understand the secret ingredient responsible for effective binding.
First, with an infrared spectroscopy technique that uses infrared light to identify the components of the material, the researchers realized that there was protein in the red dye. They then use mass spectrometry, a method that can sort different ions into a material based on their charge and mass to identify specific proteins.
Red dye contains six proteins found in human blood, the researchers found. The dye also contains proteins derived from egg white. The proteins are highly degraded, so it’s not clear what kind of bird the eggs are, but researchers have suggested that it may have been the musk duck (Cairina moschata).
“Cinnabar-based paints are commonly used in the context of social elites and ritually important objects,” the study authors wrote.
While cinnabar is restricted for use by the nobility, the common people use another type of ocher-based paint to paint objects, the authors write.
Earlier, archaeologists hypothesized that the arrangement of the skeletons represented a desired “rebirth” of the deceased leader of Sikan. In order for this “desired” rebirth to take place, the ancients may have covered the entire skeleton with this bloody dye, probably symbolizing red, oxygen-saturated blood or “life force,” the authors write.
A recent analysis found that Sikans in human culture performed human sacrifices by cutting the neck and upper chest to increase bleeding, the authors write. So “from an archaeological point of view, the use of human blood in paint would not be surprising.”
Reference: Human Blood and Bird Egg Proteins Identified in Red Paint Covering a 1000-Year-Old Gold Mask from Peru
Elisabete Pires, Luciana da Costa Carvalho, Izumi Shimada, and James McCullagh
Cite this: J. Proteome Res. 2021, XXXX, XXX, XXX-XXX
Publication Date: September 28, 2021
© 2021 American Chemical Society