Nearly 200 years ago, human blood was said to have been incorporated into a ceremonial tomb that legend has it built in a royal palace complex in what is now Benin. Now, an investigation into the proteins found within the tomb’s walls reveals evidence that the legend is true.
According to a new study, the tomb of Abomey, once the capital of the West African kingdom of Dahomey, contains proteins that could only have come from human blood, confirming the site’s grisly history.
It is one of the first times such a discovery has been made through ‘paleoproteomics’, the study of trace proteins left behind in archaeological contexts.
“This discovery is important because it provides concrete evidence of historical rituals and practices,” says biochemist Jean Armengaudan expert on ancient proteins at the French Commission for Alternative Energy and Atomic Energy told LiveScience.
Armengaud is the senior author of the new study, which was published May 29 in the journal Proteomics. He and his colleagues examined samples taken from the tomb between 2018 and 2022 during excavations at the site by archaeologists from France and Benin.
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According to local tradition, the grave is in the Abomey Palace Complex – built in the 19th century by King Ghezo of Dahomey, in honor of his brother, King Adandozan – used plaster containing the blood of 41 human sacrifices; 41 was considered a sacred number, the authors wrote in the study.
Dahomey King
Ghezo, who ruled from 1818 to 1858, famously led several military expeditions against the region’s powerful Yoruba state, or Oyo Empire, ending the Dahomey Kingdom’s annual tribute to slaves.
He was considered a powerful ruler and was said to have shown the death of his enemies to secure his rule. According to historical accounts, the path to his hut was paved with the skulls and jawbones of defeated enemies, and one of his thrones rested on the skulls of four enemy leaders.
Dahomey, now called Benin after the nearby bend (or bay) of Benin, is a center of the original African Vodun or Vodou religion that was developed in the Caribbean. Traditional Vodun often involves making sacrifices of animal blood.
Distinctive proteins
The researchers applied a technique called tandem mass spectrometry – on proteins found in samples from the tomb wall, which consists of two connected circular huts. The method breaks down ions into fragments to reveal their chemical structure.
Their research yielded more than 10,000 matches in a database of proteins that identified the presence of thousands of microorganisms, as well as human blood and chicken blood.
“Because proteins are more stable molecules compared to DNA, paleoproteomics can provide extensive information about the organisms that produced these proteins in ancient times,” Armengaud said.
The results clearly show that human blood was one of the substances in the wall – consistent with historical accounts, which have never been verified until now, which claimed that blood from human sacrifices was mixed with ‘red oil’ and holy water to to make plaster.
In this case, Armengaud said, the paleoproteomic study was preferable to a paleoproteomic study using ancient DNA, which could detect genetic material from individuals, such as the people who built the structure, without determining how they were involved.
But paleoproteomics and paleogenomics can also complement each other. Armengaud hopes that DNA sequencing of samples from the Abomey tomb can identify the number of victims sacrificed and their origins, providing more detailed historical context.
Matthew Collinsan archaeologist at the University of Cambridge who was not involved in the latest research, told LiveScience that the research showed how proteomics can be applied in complex and challenging situations.
“If you were to use DNA, you could see that certain species were present, but what you couldn’t determine is the type of tissue involved,” he said. “But here you have evidence that tissue proteins are associated with human blood.”