From sciencemag.org: Crimson Clues from the Ancient Past.
Chemists have confirmed something that archaeologists and art historians have long suspected: Ancient sculptures found in western Africa contain blood from ritual animal sacrifices in their patina. The study, which used new diagnostic techniques, should yield a greater understanding of the practices of artists from long ago, and it could open the way for more detailed analyses of the world’s most precious artifacts.
Anthropologists and ethnologists have uncovered much cultural evidence, from oral histories and illustrations, that ancient African artists often used ritual animal blood in their creations, generally as attempts to please or appease their deities. In the empire of Mali, for example, which flourished from the early 13th century to the late 15th century C.E., the Dogon people decorated or painted their sculptures with various pigments thought to be composed partly of blood. But because of the age of the artifacts, the composition of the patina has eluded standard chemical analyses.
So a team from the Centre for Research and Restoration of the Museums of France in Paris and other institutions in France employed a quartet of new techniques. [continue]