Courtesy Lauren A. Badams.

A team of scientists from the U.S., Belgium, Portugal, and the U.K. have pushed back the first use of Indigofera tinctoria as blue fabric dye in the world to South America 6,200 years ago. The previous oldest physical specimen was from Egypt 4,400 years ago, although there were written references to blue dye going back 5,000 years. The blue dyed cotton fabric was discovered in an archaeological site that has been studied for many years, Huaco Prieta, located in the northern coastal region of modern Peru.

Publication of the study by Jeffrey C. Splitstoser and his colleagues in Science Advances this month has set off wisecracks in popular science publications about Andean Indians inventing blue jeans, but it is a much bigger deal than that. Besides, what was new about blue jeans was the rivets, not the color.

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Indigo blue was highly prized long before the Americas were “discovered.” The ancient Greeks understood India to be the source of the dye and indigo—along with spices and silk—made up the trade goods the Europeans were seeking when they got sidetracked by Aztec and Incan gold.

Why is it a big deal that indigo appears in South America long before Asia or Africa? If the dye required nothing but mashing up something blue, then it might be found everywhere the plant grew, but it’s a bit more complicated than that.

Most ancient dyes were fairly simple. Flower petals were boiled to make them yield up their color. Ochre yielded reds and yellows, depending on the exact iron content. A bright white dye can be extracted from milkweed.

The first difference indigo presents is that the dye is not in the flowers. It’s in the leaves. To make the leaves yield the color, they first have to be fermented. The fermented solids are then dried. The fermented and dried indigo is light and easy to ship.

The indigo solids must then be treated with an alkaline substance, commonly urine, to produce a dye that is apparently white. Yarn treated with the reconstituted indigo comes out white but then turns to yellow, to green, and finally to the deep blue that makes the dye so valuable.

In an interview with Live Science, Splitstoser speculated, “This was probably a technology that was invented by women.” He noted that women were typically in charge of weaving and dying in Andean cultures.

The discovery at Huaco Prieta adds another example of cultural knowledge either purposely destroyed or ignored out of arrogance by conquistadors who believed they were doing God’s work in destroying non-Christian cultures. That destruction fed the myth that Europe represented science when the Americas represented superstition.

These people who were burning Mayan writings and destroying works of astronomy and mathematics and chemistry were burning human beings for heresy at the same time. Indians had science and Europeans had superstition. It ought to be possible to compare cultures in a more objective manner than the settlers have chosen when they wrote all the histories.

Full article here.