The researchers had gathered together to dig up part of an experiment: an unusual long-term experiment that started in 1879 on the campus of what is now Michigan State University.

A botanist named William Beal wondered how long seeds could remain viable underground. So he designed an audacious study to find out, knowing full well that the answer might not come in his lifetime.

Frank Telewski, a professor of plant biology at the university, explains that Beal got 20 glass bottles. "Those 20 bottles, he filled up with a sandy seed mixture," says Telewski. "And the sandy seed mixture contained 21 species of plants, with 50 seeds per plant."

The plants were just common weeds. The idea was to find out, if farmers faithfully weeded their plots, how long these annoying plants could keep coming up from seeds already in the dirt.

Beal buried the bottles in the ground, keeping the location private so it wouldn't get disturbed. Every five years, he dug up one bottle and checked to see if the seeds inside would germinate. In 1910, when Beal retired, he passed on the experiment to a colleague, who later passed it on to a colleague and so on.

The study has lasted far longer than Beal intended because its caretakers decided to stretch it out. Instead of every five years, they switched to digging up a bottle every 10 years. Then, every 20 years. Telewski helped unearth a bottle in 2000, when he took over the experiment from a colleague. That year, only a couple of different weeds were still able to sprout. //

The researchers waited and waited for about a week. Then, on the afternoon of Friday, April 23, Lowry checked the tray of seeds and saw one tiny green seedling. That means at least one old seed could still germinate, and more could sprout in the days to come.

"We know that seeds can last a really long time in perfect conditions, like in seed storage vaults or the permafrost," says Weber, who notes that Beal's original question is still relevant. "We don't really know how long seeds can last in the soil. And that's where most of the seeds are." //

With four bottles left in the ground, the study should go on for another 80 years.