For the very first time, scientists have successfully extracted DNA fragments from an ancient clay brick, shedding light on the potential use of these ancient building materials as archives of historical flora. This groundbreaking achievement showcases the ability to analyze millennia-old plant particles that remained embedded within the brick, revealing a snapshot of the environment from the time it was created.
Crafted around 2,900 years ago in what is now northern Iraq, the brick-making process involved mixing mud from the Tigris riverbanks with elements like chaff, straw, and animal dung. Remarkably, small plant remnants within this mixture have managed to endure, sheltered within the brick, for centuries. Researchers from the University of Oxford in the UK, the National Museum of Denmark, and the University of Copenhagen in Denmark undertook this innovative endeavor.
The research team employed a technique previously used on porous materials like bone to sequence and decode the DNA found in the preserved plant matter. The outcome was the identification of 34 distinct plant groups from this ancient DNA. Biologist Sophie Lund Rasmussen from the University of Oxford expressed excitement at the success of extracting ancient DNA that had remained shielded within the clay brick.
The brick that was subjected to analysis was discovered within the palace of Neo-Assyrian king Ashurnasirpal II in the ancient city of Kalhu. It was dated to the period between 879 and 869 BCE, coinciding with the palace’s construction years, thanks to an inscription on the brick itself that mentioned the palace.
Among the plant families identified from the genetic material were Brassicaceae (including cabbage and mustard), Ericaceae (heather), Betulaceae (birch), Lauraceae (laurels), Selineae (carrots and parsley), and Triticeae (cultivated grasses). The researchers concentrated on plant DNA due to its well-preserved state, though the same techniques could potentially unveil ancient animal DNA as well.
Clay bricks are widely found at archaeological sites globally, offering a wealth of insights into past ecosystems and environments. The fact that the examined brick was air-dried rather than fired played a crucial role in preserving its organic contents. The sample was extracted from the brick’s interior, which effectively safeguarded the material.
This breakthrough serves as a unique window into the world of ancient civilizations and the changes that have occurred over thousands of years. The collaborative nature of this study, encompassing diverse expertise, exemplifies the significance of interdisciplinary approaches in scientific research. Ultimately, this achievement holds the potential to unravel further mysteries concealed within the historical remnants of our world’s past.