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Protected for over 1,000 years, Nara's sacred deer differ genetically from others in Japan

Deer in Nara Park, which are now known to possess a unique genotype, are seen in the city of Nara on Jan. 28, 2023. (Mainichi/Keiko Shioji)

NARA -- The deer inhabiting Nara Park, a symbol of this western Japan city, are genetically divergent from others in the area thanks to centuries of protection, researchers have announced.

    It's believed the animals have been able to preserve their genetic constitution by living alongside humans for over a millennium, protected as they were considered "divine messengers."

    Researchers from Fukushima University, Nara University of Education and elsewhere began a study in 2000, focusing on sika deer, also called Japanese deer, living in Japan's Kii Peninsula, which spans the prefectures of Nara, Wakayama, Mie, and the southern part of Kyoto.

    Mitochondrial DNA, the type of DNA passed only from mother to offspring, was sampled using the blood and muscle tissue of 294 animals. An analysis found 18 haplotypes, or groups of alternative forms of different genes that can usually be inherited as a unit. While the deer of Nara Park were closely related to the others, they alone were found to possess a specific haplotype.

    The researchers also compared the animals' nuclear DNA, which is passed to offspring from both parents. They found the deer of Kii Peninsula divide into three main genetic groups: one in Nara Park, an eastern group in Mie Prefecture and a western group in Wakayama Prefecture.

    Deer in Nara Park, now known to possess a unique genotype due to living closely with humans, are seen in the city of Nara on Jan. 28, 2023. (Mainichi/Keiko Shioji)

    The Nara Park deer are thought to have branched from a common ancestral herd with those in the rest of the peninsula over 1,000 years ago. The eastern and western groups are thought to have split from a common ancestor around 500 years ago.

    The research team's Toshihito Takagi, a student at Fukushima University's Graduate School, pointed out, "The specific genotype of the Nara deer was once common throughout the Kii Peninsula." As deer in the surrounding areas were being driven to extinction by hunting and habitat encroachment, humans preserved the uniqueness of this deer population, he said.

    At Kasugataisha Shrine in the city of Nara, legend has it that the deity of Ibaraki Prefecture's Kashima Jingu shrine rode there on a white deer about 1,300 years ago. Due to the legend, the animals were thought of as divine creatures and protected in the area. Kasugataisha's head priest, Hirotada Kasannoin, said, "We're surprised to hear that the animals are also scientifically considered a special kind of deer."

    As of July 2022, there were 1,182 deer in Nara Park, including on Kasugataisha Shrine's grounds.

    The researchers' findings were published in the American Society of Mammalogists' Journal of Mammalogy on Jan. 31.

    (Japanese original by Keiko Shioji, Nara Bureau)

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