University of Missouri researcher Brandi L. MacDonald utilizes state-of-the-art technology available exclusively at Mizzou to assist scholars in deepening their knowledge of the evolution of human thought and intelligence throughout history.
In a recent investigation, a global group of researchers collaborated with MacDonald to utilize modern scientific facilities at the University of Missouri Research Reactor (MURR), Materials Science and Engineering Institute (MSEI), and Electron Microscopy Core (EMC).
With the resources and expertise from Mizzou, the group, headed by MacDonald, identified the location of the oldest ochre mine in the world and mapped out how ochre from the mine was distributed to surrounding communities.
World’s oldest ochre mine
Ochre is a naturally occurring pigment made from iron-rich materials. It is one of Earth’s oldest materials and has been used by people for thousands of years.
Known as a pigment for cave paintings and decoration of symbolic objects and personal ornamentation, it holds cultural, historical, and spiritual significance in many societies.
Its enduring presence offers scientists valuable insights into the growth of human society and self-expression.
“By comparing the ochre sources with the places where people lived, exchanged and used those ochres between 2,000 and 40,000 years ago, we can see how their choice of raw materials changed over long periods of time,” MacDonald said.
“This allows us to anchor human activities in time and show how human cognition and social networks developed alongside those activities. Understanding how these people mined, processed, transported and used ochre provides clues about early technological innovations and helps trace the history of human creativity and symbolism.”
Using new technologies
Provenance is an archaeological technique that helps identify an object’s historical path or origin. MacDonald’s primary area of expertise is this field at MURR’s Archaeometry Lab.
In that location, she and her colleagues employ neutron activation analysis, a method that uncovers the chemical makeup of artifacts. Afterward, they can juxtapose the findings with current data to determine the origin.
The Archaeometry Lab is linked to the nation’s most advanced university research reactor and employs experts who can utilize these techniques in this research field.
As a result, it is one of the rare facilities globally where this type of research can occur—and the sole one of its kind in the United States.
This intricate and deeply scientific procedure produces a distinctive geochemical signature that can disclose the material’s source, development, and background.
This study used ochre sampled from Lion Cavern and surrounding communities in Eswatini, a country in southern Africa.
“We take small samples of ochre artifacts and safely make them radioactive by exposing them to neutrons inside the reactor core,” said MacDonald, a chemistry professor in the College of Arts and Science with a joint appointment at MURR’s Archaeometry Lab.
“As these radioactive materials start to break down or decay, they emit characteristic energies in the form of radioisotopes — which we can measure using gamma ray spectrometry.”
Revealing Stone Age secrets
Creating the geochemical fingerprint at MURR was just the first step of this project. Additional cutting-edge tools found at MSEI and EMC helped researchers uncover a more complete history of how ochre was mined and used in this part of Africa.
Researchers used advanced laser technology at MSEI — Raman spectroscopy — to reveal the unique makeup of the ochre samples.
The laser makes the sample’s molecular bonds vibrate, and by measuring the energy from this vibration, they could identify the existence of specific minerals inside the ochre.
Meanwhile, at the EMC, the scientists were able to zoom in on samples of ochre with powerful imaging tools—including a scanning electron microscope—to examine the material’s chemical structure and elemental composition under high magnification.
This high-tech exploration allowed researchers to examine the composition and properties of ochre samples in-depth, uncovering new insights that connect the past to the present.
Together, these innovative techniques helped uncover the hidden secrets of ancient ochre.
Using modern science to analyze ancient history, they’re piecing together a vivid picture of the past, highlighting Mizzou’s role as a leader in innovative and transformative research.
