Nearly 20 years after publishing Into the Wild, the life and death of a wandering young man named Chris McCandless still captivates author Jon Krakauer.

McCandless trekked into the wilderness near Fairbanks and lived more than 100 days in an abandoned school bus before succumbing to what officials at the time deemed starvation. Krakauer’s 1996 book about the young man led to a movie in 2007 of the same name.

Krakauer had always suspected that the 23-year-old died from eating potato seeds, but exactly what was it in those potato seeds that technically killed him was a debate. The author who is well known for his outdoor exposes, published an article in The New Yorker in 2013 supposing the seeds contained a toxin known as ODAP.

Krakauer was led to the conclusion from a writer who had heard the Nazis used the substance in concentration camps. So Krakauer had a sample tested and discovered its presence. But the story wasn’t over yet.

Another writer, this time in Fairbanks, called his research into question and challenged Krakauer to put his work up to a scientifically reviewed panel. And so this year Krakauer and coauthor Jonathan Southard published the results of a peer reviewed study on the matter in Wilderness & Environmental Medicine. His findings were also followed-up in another article in The New Yorker earlier this year.

With the help of a laboratory in Michigan, the pair determined the seeds contained a different toxin, an amino acid called L-canavanine.

The seeds McCandless ate supposedly came from a plant called the Eskimo potato or Hedysarum alpinum. Native Alaskans typically eat the carrot-like root, but there is no record of anyone eating the seeds. The amino acid in question is apparently used to ward off predators by tricking the body into thinking it’s good for you.

“And then it wreaks havoc,” Krakauer told NPR. “It screws up your ability to metabolize, so you essentially starve. It short-circuits your metabolism.”

It’s the same toxin found in alfalfa and jack bean Krakauer suspects may have permanently paralyzed 100,000 people in the 20th century.

“Through all these twists and turns, now, finally, I think we have figured out what is in those plants,” Southard offers. “There’s millions of plants out there, and they make lots of strange compounds that we don’t know about yet.”

Photo credit: Bus used in the movie Into the Wild Flickr Creative Commons

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