As with Aron Ralston, the story of Chris McCandless has sharply divided observers, between those who see him as a hero for eschewing a materialistic, traditional western life and those who think he was an idiot who got in over his head and then paid the ultimate price in the Alaskan bush. There’s also been disagreement over precisely what caused McCandless’s death, but new evidence assembled by curious writer and then chronicled by Into the Wild author Jon Krakauer points a likely final verdict: poisoning from a toxin unknown to be in the wild potato seeds he consumed, which led to McCandless’s weakening, paralysis, and starvation.
In a piece in the New Yorker, Krakauer spins a detective tale of chemistry and curiosity. McCandless foraged and ate wild potato seeds in his last months spent just north of Denali National Park, which contained no known toxins or harmful substances but that he suspected were killing him. “EXTREMELY WEAK. FAULT OF POT[ATO] SEED. MUCH TROUBLE JUST TO STAND UP. STARVING. GREAT JEOPARDY,” he wrote on July 30, a few weeks before he died.
Krakauer’s first writing on McCandless, an article in Outside, speculated that the wilderness pilgrim had mistaken the seeds of wild potato, hedysarum alpinum, with the seeds of wild sweet pea, hedysarum mackenzii, a plant thought to be toxic and that was strikingly similar to hedysarum alpinum. By the time he’d spun the article into the book, Krakauer changed his mind. McCandless would not have mistaken the two plants, he thought, and Krakauer now speculated that wild potato seeds contained an alkaloid called swainsonine. Tests by a top chemist, Dr. Thomas Clausen, turned up nothing problematic. “I tore that plant apart,” Clausen said. “There were no toxins. No alkaloids. I’d eat it myself.”
It’s been 21 years since McCandless died, and people remained interested in him, including Ronald Hamilton, an author and employee at Indiana University of Pennsylvania, who stumbled upon Into the Wild and immediately suspected he knew how McCandless died.
Hamilton had read a book about a World War II concentration camp in Ukraine called Vapniarca, where Jewish inmates were fed bread made with flour from pea grass, lathyrus satius, which has been known for at least 2,000 years to lead to weakening and paralysis in the legs, especially in young men. The effect is even named after the plant and is called neurolathyrism, or lathryism. Pea grass, it turns out, contains a neurotoxin called beta-N-oxalyl-L-alpha-beta-diaminoproprionic acid, or ODAP for short.
Hamilton posted a paper to a Chris McCandless website speculating that wild potato also contains ODAP and that the reason previous efforts to find a toxin in the plant failed because chemists were looking for alkaloid-based poisons, not proteins like ODAP. He had contacted Clausen’s chemistry team, who agreed they might have missed a protein-based toxin, and the convinced the chemistry department at Indiana University, to test his theory with seeds and roots of both hedysarum alpinum and hedysarum mackeniei, plus lathyrus satius and pure ODAP. The results were a smoking gun.
“The seeds of both of the hedysarum plants showed even higher concentrations of the deadly protein toxin ODAP than was contained in the tissues and fibers of the lathyrus sativus plant itself,” wrote Hamilton. “Only purified ODAP showed a higher concentration of the toxin.
“It might be said that Christopher McCandless did indeed starve to death in the Alaskan wild, but this only because he’d been poisoned, and the poison had rendered him too weak to move about, to hunt or forage, and, toward the end, “extremely weak,” “too weak to walk out,” and, having “much trouble just to stand up.” He wasn’t truly starving in the most technical sense of that condition. He’d simply become slowly paralyzed. And it wasn’t arrogance that had killed him, it was ignorance. Also, it was ignorance which must be forgiven, for the facts underlying his death were to remain unrecognized to all, scientists and lay people alike, literally for decades.”