So what specifically killed Into the Wild subject Christopher McCandless in the Alaskan wilderness back in 1992? In 2013, author Jon Krakauer blamed toxic seeds from the Eskimo potato plant. After the theory met with skepticism from scientists and non-scientists alike, Krakauer investigated further. His new conclusion: It was indeed those seeds, but for a different reason than he first suggested. This time, his research is backed up by a study he co-authored in the peer-reviewed journal Wilderness & Environmental Medicine, reports NPR. In 2013, Krakauer postulated that the seeds contained a toxin known as ODAP. But subsequent studies at a Michigan lab show that the seeds have a different toxin, called L-canavanine.
"It wreaks havoc," says Krakauer of the amino acid. "It screws up your ability to metabolize, so you essentially starve. It short-circuits your metabolism." His co-author, a biochemist, notes that a 1960 paper first identified the toxin in the plant, so their new work is more about confirmation of that finding than breaking new ground. Krakauer wrote about the update in the New Yorker, and explains why it matters: "Because many people—both admirers of McCandless and his detractors—regard Into the Wild as a cautionary tale, it’s important to know as much as possible about how McCandless actually may have died." (McCandless' sisters say abuse at home drove their brother into the wild.)