How Chris McCandless Died

An update to ‘Into the Wild’

The debate over what killed Chris McCandless, and the related question of whether he is worthy of admiration, has been smoldering and occasionally flaring for more than two decades now. Shortly after the first edition of Into the Wild was published in January 1996, University of Alaska chemists Edward Treadwell and Thomas Clausen shot down my theory that the cause of McCandless’s death was a toxic alkaloid contained in the seeds of the Eskimo potato plant, Hedysarum alpine, also known as wild potato. When Treadwell and Clausen completed chemical analyses of the Eskimo potato seeds I’d sent them, they found no trace of any poisonous compounds. “I tore that plant apart,” Dr. Clausen explained to Men’s Journal in 2007. “There were no toxins. No alkaloids. I’d eat it myself.”

My theory about the seeds was based on the alarming entry McCandless wrote in his journal on July 30, 1992:

EXTREMELY WEAK. FAULT OF POT[ATO] SEED. MUCH TROUBLE JUST TO STAND UP. STARVING. GREAT JEOPARDY.

Assuming that McCandless must have had a good reason to believe the seeds were to blame for his failing health, when Treadwell and Clausen proclaimed that H. alpinum seeds are completely benign, I proposed a new hypothesis to explain his demise, which I included in an updated edition of Into the Wild printed in 2007: It wasn’t the seeds that killed McCandless, but rather a mold growing on the seeds, which produced a toxic alkaloid called swainsonine.

Eskimo potato seeds (Hedysarum alpinum) harvested by McCandless for food on July 18, 1992, in a 0ne-gallon Ziploc bag. Estimated dry weight 600 grams. Photo courtesy of the Chris McCandless Memorial Foundation

I had no hard evidence to support this hypothesis, however, so I continued searching for information that would allow me to reconcile McCandless’s unambiguous journal entry — stating he had become physically incapacitated because he ate Eskimo potato seeds — with the equally unambiguous results of the chemical analyses performed by Treadwell and Clausen. These results were reinforced in 2008, moreover, when they published a peer-reviewed paper titled, “Is Hedysarum mackenziei (Wild Sweet Pea) Actually Toxic?” in the journal Ethnobotany Research & Applications. Upon completing “an exhaustive comparison of the secondary chemistry between the two plants [H. mackenzii and H. alpinum are closely related] as well as a search for nitrogen containing metabolites (alkaloids) in both species,” Treadwell and Clausen wrote, “no chemical basis for toxicity could be found.”

In August 2013, I happened upon a paper titled “The Silent Fire: ODAP and the Death of Christopher McCandless,” by Ronald Hamilton, which appeared to solve the conundrum. Hamilton’s essay, posted online, presented hitherto unknown evidence that the Eskimo potato plant was in fact highly toxic, contrary to the assurances of Treadwell, Clausen, and apparently every other expert who had ever weighed in on the subject. According to Hamilton, the toxic agent in H. alpinum was not an alkaloid, as I had speculated, but rather an amino acid, and it was the ultimate cause of McCandless’s death.

“I now walk into the wild.” Postcard that Chris McCandless sent to his friend Wayne Westerberg the day before he headed down the Stampede trail on his fatal journey. Photo © Jon Krakauer

Hamilton is neither a botanist nor a chemist; he’s a writer who until recently worked as a bookbinder at the Indiana University of Pennsylvania library. As Hamilton explains it, he became acquainted with the McCandless story in 2002, when he happened upon a copy of Into the Wild, flipped through its pages, and suddenly thought to himself, “I know why this guy died.” His hunch derived from his knowledge of Vapniarca, a little-known World War II concentration camp in what was then German-occupied Ukraine.

“I first learned about Vapniarca through a book whose title I’ve long forgotten,” Hamilton told me. “Only the barest account of Vapniarca appeared in one of its chapters…. But after reading Into the Wild I was able to track down a manuscript about Vapniarca, which has been published online.” Later, in Romania, he located the son of a man who served as an administrative official of the camp, and who sent Hamilton a trove of documents.

In 1942, as a macabre experiment, an officer at Vapniarca started feeding the Jewish inmates bread and soup made from seeds of the “grasspea,” Lathyrus sativus, a common legume that has been known since the time of Hippocrates to be toxic. “Very quickly,” Hamilton writes in “The Silent Fire,”

a Jewish doctor and inmate at the camp, Dr. Arthur Kessler, understood what this implied, particularly when within months, hundreds of the young male inmates of the camp began limping, and had begun to use sticks as crutches to propel themselves about. In some cases inmates had been rapidly reduced to crawling on their backsides to make their ways through the compound…. [O]nce the inmates had ingested enough of the culprit plant, it was as if a silent fire had been lit within their bodies. There was no turning back from this fire — once kindled, it would burn until the person who had eaten the grasspea would ultimately be crippled…. The more they’d eaten, the worse the consequences — but in any case, once the effects had begun, there was simply no way to reverse them…. Even today, at this moment, Lathyrus sativus is maiming [and] crippling…. It is currently estimated that [throughout the twentieth century] more than 100,000 people worldwide [suffered] from irreversible paralysis due to the consumption of the plant. The disease is called, simply, neurolathyrism, or more commonly, “lathyrism.” Dr. Arthur Kessler, who… initially recognized the sinister experiment that had been undertaken at Vapniarca, was one of those who escaped death during those terrible times. He retired to Israel once the war had ended and there established a clinic to care for, study, and attempt to treat the numerous victims of lathyrism from Vapniarca, many of whom had also relocated in Israel.

The injurious substance found in grasspea plants turned out to be a neurotoxin, beta-N-oxalyl-L-alpha-beta diaminoproprionic acid, a compound commonly referred to as beta-ODAP or, more often, just ODAP. According to Hamilton, ODAP

affects different people, different sexes, and even different age groups in different ways. It even affects people within those age groups differently…. The one constant about ODAP poisoning however, very simply put, is this: those who will be hit the hardest are always young men between the ages of 15 and 25 and who are essentially starving or ingesting very limited calories, who have been engaged in heavy physical activity, and who suffer trace-element shortages from meager, unvaried diets.

ODAP was identified in 1964. It brings about paralysis by overstimulating nerve receptors, causing them to die. As Hamilton explains,