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 leftover from meals. Until now, the earliest documented use of tobacco came in the form of nicotine residue found inside a smoking pipe from Alabama dating to 3,300 years ago. 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. After tobacco use originated among the New World’s native peoples, it spread worldwide following the arrival of Europeans more than five centuries ago. Tobacco now represents a worldwide public …