English explorer Sir John Franklin sailed to Canada in 1845 with two centrally heated ships, a crew of 128 and a three-year supply of food, hoping to find an Arctic route connecting the Atlantic and Pacific oceans (what we now refer to as the Northwest Passage). Instead, Franklin and his crew vanished. More than 30 expeditions looked for them — so many that the death toll for searchers actually exceeded the lost Franklin crew [source: RMG].
Finally, in 1859, skeletal remains were found, along with a log that stopped in April 1848. After Franklin's ships had become stuck in the ice, the crew spent nearly two years trying to get them free, but after Franklin and 23 members died, the remainder set out on a doomed march across the Canadian tundra. Some resorted to cannibalism [sources: Gillis and Sorensen, RMG].
So, what went wrong? In the 1980s, a study by Canadian anthropologist Owen Beattie concluded that the explorers succumbed not to starvation or cold, but to diseases such as tuberculosis, after being weakened by poisoning from food cans with high lead content [source: Bayliss].
A subsequent 2013 study dissented in part, arguing that the high lead content in the bones probably came from lifelong exposure in cluelessly toxic mid-1800s England, not just from the cans. A 2018 study reached the same conclusion. These researchers reasoned that if the lead in food cans was the cause of death, then the ones who survived longest should have had the highest levels of lead. Also, the members of the expedition should have had higher levels of lead than a similar sample of British sailors living in Antigua at the same time. Neither was found to be true [source: Solly].
So, what was the cause of their demise if not lead poisoning? Researchers from the 2013 study speculated it was ice. "The surviving men had no option but to desert the ships and trek south to the mainland. But they were ill-equipped, and probably in poor health, so escape was beyond them. Their plight was desperate and all died in the attempt," researcher Keith Millar told the Guardian.
Another part of the mystery was resolved in 2014, when a Canadian robotic submarine located the wreckage of one of Franklin's ships under the Arctic ice [source: Gillis and Sorensen]. Divers are still excavating that ship every summer.