Mesopotamian Ancient DNA

Nestled within the fertile Shahrizor Plain of the Transtigris region, the ancient mound of Bakr Awa has long served as a vital cultural gateway connecting the worlds of Mesopotamia and Iran. From its earliest occupation during the Uruk period through the Akkadian and Ur III empires, the site’s material culture has mirrored the shifting geopolitical tides of Mesopotamia. Excavations led by the University of Heidelberg have revealed how the site's archaeological layers transition from the southern Mesopotamian-influenced Uruk Period (c. 4000-3100 BCE) to a more localized tradition during the Early Dynastic Period (c. 2900-2350 BCE). This local phase was followed by a distinct turn toward northern Mesopotamian architectural styles during the Akkadian Period (c. 2350-2150 BCE), before shifting back toward southern Mesopotamian administrative and cultural models with the rise of the Ur III kingdom in the late third millennium BCE. By the Middle and Late Bronze Age, Bakr Awa had evolved into a major administrative and trade center. This complexity is illustrated by a recovered tablet archive written in both Akkadian and Hurrian cuneiform, documenting a vibrant, linguistically diverse community. Following a catastrophic fire in the 15th–14th centuries BCE, the site lay abandoned until its Iron Age reoccupation, when the sudden appearance of reddish Slipped Ware connected the resettling population with northwestern Iranian Urartian and Median artistic traditions of the 8th–6th centuries BCE.

To explore these dynamics at a genomic level, our international research team—featuring scientists from the United States, Australia, Poland, and Germany—successfully sequenced genome-wide data from 17 ancient individuals excavated at Bakr Awa. Our study, published in Genome Biology (Williams et al., 2026), tracks a major genetic transition at this peripheral zone.

The Neolithic-to-Bronze Age Demographic Shift

By integrating our newly generated genomic data with published reference genomes, we identified a major genetic transition at the eastern periphery of Mesopotamia. During the Pre-Pottery Neolithic, the local Transtigris population—represented by previously published samples from the nearby site of Bestansur (33 km from Bakr Awa)—possessed a distinct genetic affinity to the central Zagros Mountains. However, by the Early Bronze Age, the inhabitants of Bakr Awa exhibited a highly shifted, heterogeneous ancestry profile.

This new genetic profile possessed strong affinities to northern Mesopotamian, Anatolian, and Levantine populations, marking a clear demographic shift. A key objective of our ongoing research is to identify the precise catalysts of this migration. We are now working to determine whether this genetic shift was associated with a parallel transition in regional material culture, and to pin down the exact geographical source of this Anatolian-like and northern Mesopotamian-like ancestry. By the Middle Bronze Age, Bakr Awa developed into a highly diverse genetic hub, displaying genetic ancestry linked to the Southern Caucasus (laced with the Yamnaya-related steppe ancestry), the northwestern Zagros, and the southern Levant. This high genetic heterogeneity was directly confirmed by runs of homozygosity (ROH) analyses conducted by WWU sophomore biology student Aidan Richards. Aidan's work demonstrated a lack of significant ROH, pointing to a diverse, outbred population.