The earliest evidence of tobacco use dates to over 12,000 years ago

Ancient North Americans started using tobacco around 12,500 to 12,000 years ago, roughly 9,000 years before the oldest indications that they smoked the plant in pipes, a new study finds.

This discovery replaces the pipe-smoking report as the oldest direct evidence for the human use of tobacco anywhere in the world.

Excavations at the Wishbone site in Utah’s Great Salt Lake Desert uncovered four charred seeds of wild tobacco plants in a small fireplace, say archaeologist Daron Duke of Far Western Anthropological Research Group in Henderson, Nev., and colleagues.

Those seeds, dated based on radiocarbon dates of burned wood in the fireplace, likely came from plants gathered on foothills or mountains located 13 kilometers or more from the Wishbone area, Duke’s team reports October 11 in Nature Human Behavior.

The site was located in a sprawling marshland at the time of its occupation. Finds in and around the fireplace include bones of ducks and other waterfowl, a long, intact stone point and another point broken in two, a bone implement and seeds of several edible wetland plants.

It’s unclear how ancient North American hunter-gatherers used the tobacco, Duke says. Wads of tobacco leaves, stems and other plant fibers may have been twisted into balls and chewed or sucked, with attached seeds spit out or discarded. Ancestors of Pueblo people in what’s now Arizona chewed wild tobacco between around 1,000 and 2,000 years ago. Tobacco smoking can’t be ruled out at the Wishbone site, Duke adds.

The earliest evidence of domesticated tobacco, which comes from South America, dates to only about 8,000 years ago (SN: 10/29/18). Duke suspects various ancient American populations independently tamed the plant at different times. “Certain groups wound up domesticating particular [tobacco] species, typically alongside food crops,” he suggests.

Earth’s lower atmosphere is rising due to climate change

Global temperatures are rising and so, it seems, is part of the sky.

Atmosphere readings collected by weather balloons in the Northern Hemisphere over the last 40 years reveal that climate change is pushing the upper boundary of the troposphere — the slice of sky closest to the ground — steadily upward at a rate of 50 to 60 meters per decade, researchers report November 5 in Science Advances.

Temperature is the driving force behind this change, says Jane Liu, an environmental scientist at the University of Toronto. The troposphere varies in height around the world, reaching as high as 20 kilometers in the tropics and as low as seven kilometers near the poles. During the year, the upper boundary of the troposphere — called the tropopause — naturally rises and falls with the seasons as air expands in the heat and contracts in the cold. But as greenhouse gases trap more and more heat in the atmosphere, the troposphere is expanding higher into the atmosphere (SN: 10/26/21).

Liu and her colleagues found that the tropopause rose an average of about 200 meters in height from 1980 to 2020. Nearly all weather occurs in the troposphere, but it’s unlikely that this shift will have on a big effect on weather, the researchers say. Still, this research is an important reminder of the impact of climate change on our world, Liu says.

“We see signs of global warming around us, in retreating glaciers and rising sea levels,” she says. “Now, we see it in the height of the troposphere.”