Really Old Indigo Dyeing.

Thanks for posting about this discovery.

I learned of the recent analysis of this find from a friend of mine, who read the article closely because she knows that tests for indigotin and indirubin, the active dye substances in the indiqo plant, are found in other plants (woad, for example) and that the tests for these substances cannot determine the specific plant from which they came. The scientific article about the dye analysis says: "The source of the indigoid dye at Huaca Prieta was most likely Indigofera spp.; however, other indigo-producing plants native to the tropics of South America are grown as dye plants today, including Justicia colorifera (cuaja tinta or tinta montes), Koanophyllon tinctorium Arruda, and Cybistax antisyphilitica Martius (yangua). These plants produce blues similar to those of Indigofera, and the dye produced by yangua, for instance, contains both indigotin and indurbin [sic] (22). Although these plants are not grown on the north coast of Peru today, their distribution 6000 to 7000 years ago is unknown."

So the news articles' claim that the Peruvian textile was an example of "indigo" dyeing might be technically incorrect depending on how one defines "indigo", but the find still is amazing and wonderful.