Sheep have been interwoven with human civilization for over 11,000 years, serving not only as a vital source of meat but also yielding protein-rich milk and warm, resilient fabrics derived from their wool. The significance of this relationship is underscored by the latest groundbreaking research conducted by an international and interdisciplinary team, spearheaded by geneticists from Trinity College Dublin alongside zooarchaeologists from LMU Munich and the Bavarian State Collections of Natural History (SNSB). The team undertook an expansive genomic analysis of 118 ancient sheep genomes, extracted from archaeological bones that span over six millennia and cover a geographic range from Mongolia in the east to Ireland in the west.
Among the key findings of this study, the earliest sheep-herding settlement reflected in their genome remains is Aşıklı Höyük, located in central Türkiye. It presents a genetic blueprint that appears to be ancestral to later sheep populations across the surrounding areas. This remarkable evidence reinforces the hypothesis that these domesticated sheep trace their origins back to the initial captures of wild mouflon—a period that took place over 11,000 years ago within the western sectors of the northern Fertile Crescent.
By around 8,000 years ago, variations in sheep genomes reveal a pivotal moment in agricultural evolution, particularly in Europe. This phase marked the deliberate selection of sheep for specific traits, particularly coat color—a significant leap in the human-conducted domestication of animals. Alongside early modifications noted in goat populations, this development signifies the first known efforts of humanity to influence the genetic make-up of domesticated animals. The evidence points to a focused interest among early herders, akin to contemporary farmers, in enhancing the aesthetic and exotic qualities of their livestock.
Central to these genetic alterations was the identification of the gene known as “KIT,” which is linked to white coat coloration in various livestock species. This discovery provides insight into how early farmers may have prioritized visual traits in their herds, suggesting a complex interplay between agriculture and cultural aesthetic values well over millennia ago.
Interestingly, the research reveals that the genomes of the earliest domestic sheep from Europe and regions further east, including Iran and Central Asia, had diverged from one another during this time. However, this genetic separation was temporary.
As agricultural practices developed, driven by cultural influences radiating from the nascent cities of Mesopotamia, the movement of sheep genomes westward along the Fertile Crescent became apparent around 7,000 years ago. This movement of livestock is indicative of a broader pattern of economic and social transformation in ancient societies, where the management of domesticated animals became crucial to sustaining human populations.
Moreover, the emergence and spread of pastoralist societies across the Eurasian steppes approximately 5,000 years ago had a dramatic impact on the existing human populations in Europe, significantly altering their genetic makeup and cultural profiles. Notably, evidence suggests that this transformation changed the ancestry of British populations by approximately 90%. Furthermore, these migrations introduced early forms of the Indo-European languages that have since evolved into the diverse linguistic landscape present across Europe today.
The research dataset also illuminated how sheep herding practices, and the utilization of the full spectrum of sheep products—ranging from meat to dairy—fueled these extensive migrations. This aligns with changes in sheep genetic lineages, suggesting that pastoralism was not merely a domestic enterprise but also a sociocultural catalyst that reshaped landscapes and human societies. Thus, by the onset of the Bronze Age, it appears that sheep had developed a genetic ancestry that was composed of about 50% genetics from sources in the Eurasian steppes.
Dr. Kevin Daly, an Ad Astra Assistant Professor at UCD School of Agriculture and Food Science, highlighted one of the most intriguing findings of this research. He noted the substantial prehistoric migration of sheep from the Eurasian steppes into Europe during the Bronze Age, which mirrors our understanding of human migrations during the same epoch. His insights suggest that these migratory patterns of people were deeply intertwined with their livestock, reinforcing the idea that with each human movement came the accompanying flocks of sheep.
Dan Bradley, who leads the research project and serves as a Professor of Population Genetics in Trinity’s School of Genetics and Microbiology, emphasized the broader implications of this study. He remarked on how this evolution speaks to the intricate relationship between humans and sheep through various epochs. What began as a simple domestication has intricately evolved into a partnership that has been crucial for developing wool along with agricultural advancements, ultimately impacting cultural and economic trajectories across societies.
Co-corresponding author, Professor Joris Peters from LMU Munich elaborated on the study’s importance as it elucidates both morphological and genomic aspects of sheep domestication. He expressed a need for further interdisciplinary research to deepen our understanding of how various sheep breeds have been dispersed and selected across Eurasia and Africa. This acknowledgment reinforces an urgent call within the scientific community to collaborate across domains in order to appreciate the full complexity of domestication stories which entwine environmental conditions, cultural practices, and human innovation.
The findings presented in this research not only provide a historical backdrop for the progression of sheep domestication but also invite contemporaneous reflections on our ongoing interactions with livestock. Acknowledging the intricate ties between human civilization and our reliance on domesticated species could offer an enriched understanding for future agricultural practices and sustainability initiatives moving forward. Each of these discoveries serves as a testament to how intertwined our existence is with that of other species, emphasizing the shared evolutionary history that has shaped our past and continues to influence our future.
Subject of Research: Domestication and genetics of sheep
Article Title: Tracing the Genetic Journey of Domestic Sheep
News Publication Date: [Date not provided]
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Image Credits: Gift of Norbert Shcimmel Trust, 1989, open access Met Museum.
Keywords: Sheep domestication, genetic analysis, ancient DNA, agricultural evolution, Eurasian migrations, early livestock management.
