Metaproteomic analysis of King Ghezo tomb wall (Abomey, Benin) confirms 19th century voodoo sacrifices

The palace of King Ghezo in Abomey, capital of the ancient kingdom of Dahomey (present-day Benin), houses two sacred huts which are specific funerary structures. It is claimed that the binder in their walls is made of human blood. In the study presented here, we conceived an original strategy to analyze the proteins present on minute amounts of the cladding sampled from the inner facade of the cenotaph wall and establish their origin. The extracted proteins were proteolyzed and the resulting peptides were characterized by high-resolution tandem mass spectrometry. Over 6397 distinct molecular entities were identified using cascading searches. Starting from without a priori searches of an extended generic database, the peptide repertoire was narrowed down to the most representative organisms—identified by means of taxon-specific peptides. A wide diversity of bacteria, fungi, plants, and animals were detected through the available protein material. This inventory was used to archaeologically reconstruct the voodoo rituals of consecration and maintenance of vitality. Several indicators attested to the presence of traces of human and poultry blood in the material taken. This study shows the essential advantages of paleoproteomics and metaproteomics for the study of ancient residues from archaeological excavations or historical monuments.