This ochre painting of an aurochs (an extinct species of large cattle) was painted above El Mirón Cave, in Spain, about 35,000 to 24,000 years ago.

Artists have been painting with ochre, a naturally occurring pigment, for hundreds of thousands of years. Their masterpieces range from prehistoric, ochre-pigmented images on cave walls to paintings on canvasses and other artwork from medieval times and onward.

Ochre (pronounced OAK-er) is clay pigmented by hematite, a reddish mineral that contains oxidized iron, which is iron that's been mixed with oxygen, said Paul Pettitt, a professor of paleolithic archaeology at Durham University in the United Kingdom.

Because ochre is a mineral, it doesn't wash away or decay, allowing it to persist through the ages. "Its vibrant color and ability to adhere to surfaces — including the human body — make it an ideal crayon or paint base," said April Nowell, a paleolithic archaeologist and professor and chair at the Department of Anthropology at the University of Victoria in Canada. [The Color of Blood: Here Are Nature's Reddest Reds (Photos)]

Where it's found

Ochre occurs naturally in rocks and soil — essentially in any environment where iron minerals have pooled and formed, Pettitt said. "It can be found in valley edges, eroding out of cliffs [or even] in caves eroding out of the bedrock," Pettitt told Live Science. In its more eroded form, ochre can be found in certain soils and then sieved out.

"It's actually very easy to obtain," Pettitt said. "Anybody who is using caves or operating in and around valleys will quite easily discover ochre."

People who pick up ochre will notice that it stains their hands a "nice red or yellow color," Pettitt noted. Once collected, ochre can easily be grated against a coarse piece of stone or ground by a mortar and pestle and then turned into a powder. Then, this powder can be mixed with a liquid, such as water, saliva or egg whites, and turned into pigmented paint.

Ochre can also be used as a crayon. "It is very pliable," Pettitt said. "You can break it into small lumps."

Ground ochre (Image credit: April Nowell)

History

The earliest evidence of ancient humans using ochre dates to the Paleolithic, about 285,000 years ago, at a Homo erectus site called GnJh-03 in Kenya. There, archaeologists found about 70 pieces of ochre weighing about 11 lbs. (5 kilograms).

However, more convincing evidence dates to about 250,000 years ago at the early Neanderthal site of Maastricht-Belvédère in the Netherlands, Pettitt said. During the 1980s, archaeologists in the Netherlands excavated small concentrates of the reddish mineral, according to a 2012 study in the journal PNAS. The Neanderthals may have powdered the ochre and mixed it with water so that they could paint their skin or clothing, Pettitt said.

Archaeologists have found a number of other Neanderthal ochre paintings in caves. These include linear fingerprint patterns in La Pasiega, in northern Spain; a hand stencil in Maltravieso, in west-central Spain; and red-painted stalactites that were originally sparkling white in Ardales, in northern Spain — all of which date to at least 64,000 years ago, according to a 2018 study in the journal Science. However, the dating of the ancient ochre in Spain may not be accurate, said Lawrence Straus, a distinguished professor emeritus of anthropology at the University of New Mexico. And while it's possible that Neanderthals used ochre to make lines and dots — that is, non-representational paintings — it's debatable whether they actually made complex cave paintings, such as illustrations of animals or human figures, Straus said.

Early Homo sapiens also illustrated with ochre. At Blombos Cave, in South Africa, archaeologists found an abalone shell containing finely ground ochre, charcoal and fat that may have made up a painting kit dating to about 100,000 years ago, Nowell said. The earliest human-made drawing is a red hashtag on small rock flake that dates to about 73,000 years ago, also at Blombos Cave.

Meanwhile, the oldest drawing is an image of a cow-like beast created with ochre on a cave wall in Borneo, Indonesia, dating to about 40,000 years ago. [Photos: Oldest Known Drawing Was Made with a Red Crayon]

After the time of these early sites, ochre paintings became more widespread, reaching Africa, Europe, the Middle East, Southeast Asia, Russia and Australia. When people crossed over the Bering Strait land bridge from Siberia and East Asia to the Americas, those people also used ochre, as evidenced by a burial covered in ochre in Alaska dating to about 11,500 years ago.

It's relatively common to find ochre-covered burials. It's likely that ochre colored the deceased's clothing, but as the clothing decayed, the ochre stained the grave and bones red, Pettitt said. One of these graves includes the famous Red Lady of Paviland in South Wales, in the United Kingdom, which is actually the burial of a young man who lived during the Paleolithic about 33,000 years ago. But when the burial was found in 1823, archaeologists thought that the stained-red grave must contain the remains of some sort of indecent, scarlet woman, Pettitt said.

Ochre continued to be used as a pigment throughout antiquity and was even used by artists in medieval times and the Renaissance, as well as in modern times, Pettitt said.

Prehistoric people created this ochre fingerprint artwork in Chufín, a cave in western Cantabria, Spain, about 24,000 to 20,000 years ago. (Image credit: Copyright Lawrence Guy Straus)

Uses and symbols

As a bright red pigment, it's possible that ancient people saw ochre as a symbol of life, in part because it is the color of blood, especially deep-red menstrual blood. "Some societies quite commonly associate the color red, and therefore ochre, with creation, life and fertility," Pettitt said. (However, not everyone agrees. See more below.)

Moreover, red is a striking color that's easy to see, especially in the low-light setting of a cave, Pettitt said.

Other than serving as paint, ochre had plenty of uses. People used it to tan hides, as mosquito repellent, for protection against the sun or cold, for medicinal purposes, for use in the extraction or processing of plants, and as an adhesive, such as attaching handles to stone tools, Nowell told Live Science in an email.

In art, "there is evidence that early peoples preferred certain colors," Nowell said.

For example, at the site of Qafzeh in Israel, archaeologists have found 84 lumps of ochre on layers dating between 100,000 and 90,000 years ago. About 95 percent of those lumps are red, even though yellow and brown ochre were also found in the area, she said. There's also evidence that ancient people heated ochre to turn it red. This may mean that early humans had a basic understanding of ochre's chemical properties, according to research by Francesco d'Errico, a professor of archaeology at the University of Bordeaux in France, Nowell said. [Photos: 2 Paleolithic Boys Were Buried with Fox Teeth and Spears]

In addition, about 266,000 years ago, early hominins at a site called Twin Rivers in Zambia collected a type of hematite that has reflective metallic flakes in it, which make it glitter.

With those finds taken together, "to me, it is very possible that, initially, ochre was used for some mundane purpose, but over time, it took on a symbolic dimension," Nowell said. "I think the evidence for heat treating and preferential color selection and the addition of 'glitter' to some of their pigment paints, as well as the inclusion of vast amounts of ochre in burials (at some times and places) suggests to me that ochre's vibrant color(s) had a visual salience for Upper Paleolithic peoples."

It's hard to say if ochre symbolized menstruation, because there is no evidence for that, she said

"What we can say, following colleagues like Steve Kuhn [a professor of anthropology at the University of Arizona], is that it is likely that ochre was a simple way of marking a body (living or dead) and that information about group membership or status or any number of other variables could be communicated easily and cheaply," Nowell said. "The fact that ochre stains easily and lasts for a very long time (and mixes well into paint) likely are other reasons why it was used a lot."

Additional resources:

Read more about ochre's use through history at ThoughtCo.

Get the definition of ochre at Encyclopedia Britannica.

Learn more about prehistoric pigments at the Royal Society of Chemistry.

Originally published on Live Science.