This 2,900-year-old clay brick is an ancient life capsule

Thanks to the inscription on the brick, the researchers could pinpoint the clay's origins to quite a specific time in a particular region.

"Which means the brick serves as a biodiversity time-capsule of information regarding a single site and its surroundings. In this case, it provides researchers with a unique access to the ancient Assyrians," clarified Dr. Troels Arbøll, also the study's first author from the University of Oxford. 

This brick hails from the palace of Neo-Assyrian king Ashurnasirpal II, situated in the ancient city of Kalhu, better known as Nimrud, in modern-day northern Iraq. 

The brick bears an inscription in the extinct Semitic language Akkadian, allowing researchers to pinpoint its origin to a specific decade, between 879 BCE and 869 BCE.

The discovery took shape during a digitalization initiative at the museum in 2020. Researchers seized the opportunity to extract samples from the brick's inner core, ensuring minimal risk of DNA contamination. 

The team successfully extracted DNA from the ancient material by adapting a protocol designed for porous materials such as bone.

A biodiversity time-capsule

An intricate tapestry of 34 plant taxonomic groups emerged upon sequencing the extracted DNA. Prominent families like Brassicaceae (cabbage) and Ericaceae (heather) featured prominently. Birch, laurels, umbellifers, and cultivated grasses also made their presence felt. 

The brick's composition, largely mud collected from the Tigris River mixed with materials like straw or animal dung, presented an environment conducive to the preservation of genetic material within the clay. 

Unlike its counterparts, this brick was air-dried, bypassing the usual firing process, thereby ensuring the conservation of its genetic secrets.

While the study focused on the extracted plant DNA due to its prevalence and preservation, its potential ramifications extend further. Identifying various taxa, including vertebrates and invertebrates, remains possible depending on the sample. 

This capability could lead to constructing fine portraits of ancient biodiversity, offering insights into the past and perhaps lessons for the present.

The complete study was published in Nature Scientific Reports on August 22 and can be found here. 

Study abstract:

The recent development of techniques to sequence ancient DNA has provided valuable insights into the civilisations that came before us. However, the full potential of these methods has yet to be realised. We extracted ancient DNA from a recently exposed fracture surface of a clay brick deriving from the palace of king Ashurnasirpal II (883–859 BCE) in Nimrud, Iraq. We detected 34 unique taxonomic groups of plants. With this research we have made the pioneering discovery that ancient DNA, effectively protected from contamination inside a mass of clay, can successfully be extracted from a 2900-year-old clay brick. We encourage future research into this subject, as the scientific prospects for this approach are substantial, potentially leading to a deeper understanding of ancient and lost civilisations.