Researchers discovered four charred seeds of a wild tobacco plant within the hearth contents, along with stone tools and duck bones left over from meals. So far, the earliest documented use of tobacco was in the form of nicotine residues in a pipe from Alabama dating back 3,300 years ago.
The researchers assume the nomadic hunter-gatherers at the Utah site may have smoked the tobacco or perhaps sucked wads of tobacco plant fibres for the stimulant qualities offered by the nicotine it contained, the report said.
"On a global scale, tobacco is the king of intoxicant plants, and now we can directly trace its cultural roots to the Ice Age," said archaeologist Daron Duke of the Far Western Anthropological Research Group in Nevada, lead author of the research published in the journal Nature Human Behaviour.
The seeds belonged to a wild variety of desert tobacco, named Nicotiana attenuata, which still grows in the area. "This species was never domesticated but is used by indigenous people in the region to this day," Duke said.
The hearth remnants were found during erosion of the barren mud flats where wind has been peeling away sediment layers since the marshlands dried up about 9,500 years ago.