WASHINGTON — Scientists have unearthed evidence of a milestone in human culture — the earliest-known use of tobacco — in the remnants of a hearth built by early inhabitants of North America's interior about 12,300 years ago in Utah's Great Salt Lake Desert.

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.

The researchers believe the nomadic hunter-gatherers at the Utah site may have smoked the tobacco or perhaps sucked wads of tobacco plant fiber for the stimulant qualities offered by the nicotine it contained.

"This species was never domesticated but is used by indigenous people in the region to this day," Duke said.

Evidence for the use of tobacco, both direct — seeds, residue — and indirect — such as pipes — increases during these times alongside the domestication of food crops," Duke added.