Cannabis was one of the first plants domesticated by humans, and has a long history of being used in textiles, food, and oilseed as hemp, the study said.
Their genomic analysis separated the samples into four major groups, including basal cannabis, which is found in China and the United States.
Modern Chinese landraces — cultivated plants that have been altered through agriculture — and feral cannabis plants are now the closest descendents of the ancestors of hemp and marijuana, the study said.
After its domestication in the Neolithic period, the plant slowly spread across Europe and the Middle East in the Bronze Age, archaeological evidence shows.
In 2019, the excavation of a 2,500-year-old tomb in western China revealed the earliest clear evidence of humans using cannabis for its psychoactive properties.
However, it was unlikely that cannabis was smoked in the same way it is today.
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