Chris McCandless, a young man who gave up his possessions and hiked into the Alaskan wilderness to live in solitude — only to be found dead four months later — was immortalized in the 1996 book Into the Wild by Jon Krakauer and later by a movie of the same name (image above) directed and written by Sean Penn. But until this week, the true reason why McCandless starved to death has long been up for debate. In a New Yorker article this week, Krakauer explains how the now over 20-year mystery was solved. The author theorized in Into the Wild that wild potato seeds, which were found all over McCandless' shelter, were the culprit, even though they weren't believed to be toxic. He pointed toward a diary entry written a couple of weeks before the hiker's death, which said, "Extremely weak. Fault of pot[ato] seed. Much trouble just to stand up. Starving. Great jeopardy."

Experiments in the '90s could find no conclusive evidence for this claim, but it turns out after all this time that they were looking for the wrong toxic ingredient. After a fan published a paper online earlier this year linking the conditions of the hiker's death to ghastly experiments at a Nazi concentration camp that saw Jewish prisoners paralyzed by a toxic plant, Krakauer had new research done to show that wild potato seeds contained a neurotoxin. The disease it causes is known as lathyrism, which can reduce already weakened people (like McCandless) to little more than a crawl. There was no way McCandless could have known the dangers of the seed, since even the science community was unaware of its toxic nature until now. For the full story, be sure to check Krakauer's New Yorker article.