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10,000-Year-Old Goat DNA Holds Clues on Early Domestication and Evolution

The DNA samples were sourced from the remains of goats that lived 10,000 years ago in the Zagros Mountains of Iran.

(CN) — Researchers examining ancient DNA samples of goats that roamed the mountains of Iran uncovered genetic information on the earliest domesticated herds and clues on how agriculture shaped their evolution, according to a study released Monday.

The DNA samples examined by researchers were sourced from the remains of 32 goats that roamed the Zagros Mountains of western Iran at least 10,000 years ago. Historically, the region has provided key archaeological specimens on the earliest goat management practices.

Goats from that era had large, scimitar horns and more robust body sizes that more closely resembled their wild bezoars relatives than the goats we know today. The goats also had large, cloven hooves that left sizable imprints on both the region and the infrastructure of ancient villages.

Analysis of remains at an archaeological site in Ganj Dareh, Iran revealed evidence of an ancient practice of slaughtering male goats once they reached maturity.

Researchers also found that female goats were maintained even after they reached old age.

That strategy allowed early human communities to keep a high number of breeding female animals near them, a practice that continues today with goat herders.

"Ancient DNA continues to allow us to plumb the depths of ancient prehistory and examine the origins of the world's first livestock herds,” researcher Dan Bradley of Trinity College Dublin in Ireland said in a statement released with the study. “Over 10,000 years ago, early animal farmers were practicing husbandry with a genetic legacy that continues today."

The study’s lead author Kevin G. Daly of Trinity College said in the statement the findings reveal important clues on how the earliest goat herds evolved.

"Our study shows how archaeology and genetics can address highly important questions by building off ideas and results from both fields,” Daly said. “Our genetic results point to the Zagros region as being a major source of ancestry of domestic goats and that herded, morphologically wild goats were genetically on the path to domestication by about 10,200 years ago."

Researchers’ analysis of the goat’s DNA revealed the animals were fairly close to the genetic origin of the domestic herds, suggesting they were closely related to the first goats recruited for domestication, according to the study published Monday in the journal Proceedings of the National Academy of Sciences.

However, the genomes of a small number of goats from the larger sample more closely resembled that of their wild bezoar ibex relatives.

Daly said in the statement that finding likely means the early goat herders continued to hunt wild goats.

"This first livestock keeping shaped the goats' genomes. There were signs of reduced Y chromosome diversity - fewer males were allowed to breed, leading to an increased tendency of relatives mating. Surprisingly, the Zagros goat appeared to not have undergone a population bottleneck often associated with domestication and lacked strong signals of selection found in later domestic goats."

Researchers did not immediately respond to a request for further comment on the study.

Contributors and authors of the study include researchers at the National Museum of Iran, Trinity College Dublin, the Smithsonian Institution, the University of Copenhagen, the Centre national de la recherche scientifique and Muséum national d'Histoire naturelle in France.

Categories / Environment, Science

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