University of Missouri scientist Brandi L. MacDonald is utilizing advanced technology at Mizzou to enhance the understanding of human cognitive development over time. In collaboration with an international team, MacDonald accessed resources at the University of Missouri Research Reactor (MURR), Materials Science and Engineering Institute (MSEI), and Electron Microscopy Core (EMC) to confirm the location of the world’s oldest ochre mine and trace its distribution to nearby communities.
Ochre, a naturally occurring pigment from iron-rich materials, has been used for thousands of years in cave paintings and symbolic objects. Its historical significance provides insights into human society’s growth and self-expression.
MacDonald’s expertise in provenance, a method used in archaeology to trace an object’s history, plays a crucial role in this research. At MURR’s Archaeometry Lab, she employs neutron activation analysis to reveal artifacts’ chemical composition. This technique creates a geochemical fingerprint that can identify the material’s origin and history.
“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 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.”
The study also utilized Raman spectroscopy at MSEI to determine ochre samples’ unique makeup by measuring molecular bond vibrations. At EMC, powerful imaging tools like scanning electron microscopes allowed scientists to examine ochre’s chemical structure closely.
These techniques have uncovered new insights into ancient ochre use in Africa. The research highlights Mizzou’s leadership in innovative research by connecting past practices with modern science.
MacDonald’s work recently earned her a National Science Foundation CAREER Faculty Early Career Development Award. Her future research aims to expand studies in Eswatini and northern Australia, potentially reshaping our understanding of ochre throughout history.
“By comparing the ochre sources with the places where people lived, exchanged and used those ochres between 2,000 and 40,000 years ago,” MacDonald explained, “we can see how their choice of raw materials changed over long periods of time.” This research could provide clues about early technological innovations and human creativity.
The study titled “Ochre communities of practice in Stone Age Eswatini” includes co-authors from various international institutions.
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