Red paint on 1,000-year-old gold mask from Peru contains human blood
proteins

Date:
October 27, 2021
Source:
American Chemical Society
Summary:
Thirty years ago, archeologists excavated the tomb of an elite
40--50- year-old man from the Sica'n culture of Peru, a society
that predated the Incas. The man's seated, upside-down skeleton
was painted bright red, as was the gold mask covering his detached
skull. Now, researchers have analyzed the paint, finding that,
in addition to a red pigment, it contains human blood and bird
egg proteins.



FULL STORY ========================================================================== Thirty years ago, archeologists excavated the tomb of an elite
40-50-year-old man from the Sica'n culture of Peru, a society that
predated the Incas. The man's seated, upside-down skeleton was painted
bright red, as was the gold mask covering his detached skull. Now,
researchers reporting in ACS' Journal of Proteome Research have analyzed
the paint, finding that, in addition to a red pigment, it contains human
blood and bird egg proteins.


==========================================================================
The Sica'n was a prominent culture that existed from the ninth to
14th centuries along the northern coast of modern Peru. During the
Middle Sica'n Period (about 900-1,100 A.D.), metallurgists produced
a dazzling array of gold objects, many of which were buried in tombs
of the elite class. In the early 1990s, a team of archaeologists and conservators led by Izumi Shimada excavated a tomb where an elite man's
seated skeleton was painted red and placed upside down at the center
of the chamber. The skeletons of two young women were arranged nearby
in birthing and midwifing poses, and two crouching children's skeletons
were placed at a higher level. Among the many gold artifacts found in the
tomb was a red-painted gold mask, which covered the face of the man's
detached skull. At the time, scientists identified the red pigment in
the paint as cinnabar, but Luciana de Costa Carvalho, James McCullagh
and colleagues wondered what the Sica'n people had used in the paint
mix as a binding material, which had kept the paint layer attached to
the metal surface of the mask for 1,000 years.

To find out, the researchers analyzed a small sample of the mask's
red paint.

Fourier transform-infrared spectroscopy revealed that the sample contained proteins, so the team conducted a proteomic analysis using tandem mass spectrometry. They identified six proteins from human blood in the red
paint, including serum albumin and immunoglobulin G (a type of human
serum antibody).

Other proteins, such as ovalbumin, came from egg whites. Because the
proteins were highly degraded, the researchers couldn't identify the exact species of bird's egg used to make the paint, but a likely candidate is
the Muscovy duck.

The identification of human blood proteins supports the hypothesis that
the arrangement of the skeletons was related to a desired "rebirth"
of the deceased Sica'n leader, with the blood-containing paint that
coated the man's skeleton and face mask potentially symbolizing his
"life force," the researchers say.

========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Related Multimedia:
* Mask_excavated_from_a_Sica'n_tomb_in_Peru ========================================================================== Journal Reference:
1. Elisabete Pires, Luciana da Costa Carvalho, Izumi Shimada, James
McCullagh. Human Blood and Bird Egg Proteins Identified in Red
Paint Covering a 1000-Year-Old Gold Mask from Peru. Journal of
Proteome Research, 2021; DOI: 10.1021/acs.jproteome.1c00472 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211027121956.htm

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