In 1845, the ships HMS Erebus and HMS Terror under the command of English rear admiral Sir John Franklin sailed from the United Kingdom to northern Canada in search of the mythical Northwest Passage. The ships were lost and over several decades searchers scoured the area looking for survivors, or at least their remains. Some of those searchers disappeared themselves. It wasn’t until September 2014 that the Erebus was located in Nunuvut. The Terror was found two years later in Terror Bay.
While those mysteries have finally been solved, researchers are still interested in answering another question—what actually killed Franklin’s crew? Though no survivors remained, the crew did abandon ship in 1848, leaving notes and ships logs in rock cairns that were found by later searchers. The remains of some of the 129 sailors were found as well. According to Kate Dailey at the BBC, the ships were stocked with enough food to last seven years. So, why exactly did the men die?
A study led by Jennie Christensen, CEO and technical director of the toxicology firm TrichAnalytics, set out to discover just that. According to Megan Gannon at LiveScience, Christensen and her colleagues examined a thumbnail and toenail from John Hartnell, a crewmember whose mummified remains were found with others on Beechey Island. Previous studies suggested that many of the Franklin crew died of lead poisoning and were possibly exposed to the metal from their food tins or drinking water system.
Christensen and her team wanted to look at the nails since, according to Alexandra Pope at Canadian Geographic, the nails retain the nutrients and metals in a person's body, creating a chart of an individual's health over the period of several months. Using a synchrotron micro-x-ray, the team mapped the metal content on the underside of Hartnell’s nails.
“We were expecting to see elevations in the lead content [of the nail] over time, but it was a flatline, right through the early voyage on the sea and the Beechey Island timeframe,” Christensen tells Pope. Hartnell’s lead levels only began to spike in the last couple weeks of his life, when he was in the final stages of tuberculosis. Christensen says the lead was probably released from his tissues as his starving body began to break down bone, fat and tissue. “He contaminated himself, essentially.”
The researchers also focused on the zinc and copper content in Hartnell’s nail. Both of those metals are highly linked with nutrition and indicate access to fresh meat. For instance, in mid-July 1845, the crew is known to have eaten oxen found in Greenland, which corresponds with a zinc spike in the nails. But over time, his zinc levels slowly diminished to the point where, Pope explains, he could no longer absorb vitamin A which supports the immune system. The tuberculosis already present in his body would have flared up, leading to his demise.
A press release explains that malnutrition and zinc deficiency lead to similar unusual behavior as lead poisoning, which would explain some of the strange encounters Inuit people described after encountering some members of the starving crews.
“That zinc deficiency would explain that he had a very low immune function,” Laurie Chan, from the University of Ottawa who also worked on the research tells Bob Weber at The Canadian Press. “In the tough environment, he probably contracted infections and died from (tuberculosis).”
The research may also partially explain why, despite having ships full of food, that the crew suffered from malnutriton. “We see a clear decline of meat consumption,” Chan tells Weber. “If all the canned food (had lasted) he should not have that problem. It’s probably because some of the canned food was spoiled.”
In their paper, which appears in The Journal of Archaeological Science: Reports the researchers conclude, “Given Hartnell's nail zinc concentration pattern, it is probable that the tinned food was not appreciably zinc-rich and/or fresh arctic meat was not available to supplement the crew's diet. While these speculations are based on only a single crewman, Hartnell's nail suggests other men on the Franklin Expedition may have shared a similar fate.”
“This is kind of like a Canadian myth,” Chan tells Weber. “I get excited at the opportunity to work on it and talk about it.” The researchers say if possible they’d like to use the same technique on other members of the Franklin crew to broaden and confirm their findings.