Thanks to Linode, a top rated cloud computing company, for supporting this episode of SciShow.

Click the link in description or head to linode.com/scishow to learn more and get a $100 60-day credit on a new Linode account. [ INTRO ] The history books are full of fascinating mysteries. Many of these are lost to the passage of time.

The historical record is never perfect, and some details can never be recovered. But new technology can also unlock new clues. The better our techniques get, the more information we can wring from the historical and physical evidence to unlock long-dormant secrets.

So here are five fascinating historical cold cases that once seemed unsolvable, but have been cracked – or at least cracked open – by modern science. In 1959, a group of nine hikers died under strange circumstances in the Ural Mountains. And The condition in which they were found was… a bit disturbing.

They cut themselves out of their tent and fled into the minus 25 degree nigh t wearing only their underwear and socks, some even barefoot. The bodies were over a kilometer downhill from where they had cut into the snow and pitched their tent. And somehow, they had sustained bizarre injuries, including impact to their chests, cracked skulls, and a missing tongue or eyes.

Traces of radioactivity were even found on their clothes. This is known as the Dyatlov Pass Incident, and many ideas have been proposed to explain it, from nuclear weapons, to aliens, to Yetis! But it remained officially unsolved for decades.

In 2019 and 2020, a Russian government investigation concluded an avalanche was the most likely explanation, but gave few details about how it occurred. Which means not everyone was totally convinced. You see, scientists had previously dismissed the avalanche theory.

There wasn’t much avalanche debris, and the injuries weren’t consistent with avalanche victims. The group was camped on a slope less than 30º. Such an incline is often considered too flat for an avalanche.

And whatever happened, happened in the middle of the night. An avalanche would be more likely to happen as soon as the hikers cut into the snow. If this was an avalanche, it would be a pretty weird one.

It wasn’t until 2021 that scientists published a plausible scenario for an avalanche… thanks to the movie Frozen. Using the same method Disney used to simulate snow in the movie, researchers recreated the conditions on the mountain that night to see what would happen. First of all, they found that a combination of a buried layer of weak snow and strong winds blowing snow down the mountain could trigger an avalanche, even on a gentle slope.

Second, they also found that slow accumulation of snow due to the winds could trigger the avalanche many hours after the hikers cut into the snow to make their camp — a delayed reaction. Finally, they calculated that when the slab of snow slammed into the tents, it wouldn’t have had enough force to kill the hikers inside. But it would have crushed the hikers against the compacted snow and skis underneath the tent.

It’s rare for avalanches to trap people against hard objects like skis, which could explain the uncommon injuries. What exactly happened next? We can’t be sure what decisions the hikers made and why.

They likely fled into the night, unable to dress properly in the chaos. As for the radiation, At the time, hikers often carried lamps with the radioactive element thorium in them, so a broken lantern could have explained that. It doesn’t explain what happened after the hikers fled their tent.

But it’s clear that an avalanche, even a bizarre one, is a plausible first step. And simulating strange events like this could be an essential step to figuring out how to be safer in dangerous alpine terrain, and avoid tragedies in the future. In May 1821, the famous French emperor Napoleon Buonaparte died while in exile on the remote island of St Helena in the middle of the Atlantic.

Newspapers reported that an autopsy concluded the cause of death was stomach cancer. But that didn’t stop speculation that foul play was involved. The conspiracy goes something like this: Napoleon had escaped an island exile once before to take over France.

So what was stopping him from doing it again? Maybe a group of powerful, shadowy figures had conspired to poison him with arsenic, and stop him for good. And Some evidence seemed to support this idea.

An analysis of Napoleon’s hair in 1961 found elevated levels of arsenic. But arsenic was pretty common in some everyday items at the time. It could have even come from the wallpaper at his house on St Helena, and a 2004 paper found arsenic in his hair from before then.

So in 2008, a study took a careful look through that original autopsy and the medical records leading up to his death. The researchers reanalyzed these in the context of modern medical knowledge and compared them with those of stomach cancer patients. They found no evidence that Napoleon had the symptom of gradual arsenic poisoning.

But he did have symptoms consistent with an infection of the bacterium H. pylori. This is significant because we know the inflammation from this infection increases someone’s risk of stomach cancer. In fact, it’s responsible for 95% of stomach cancer cases.

As Napoleon's symptoms worsened, they followed the expected course for an infection leading to stomach cancer and the growth of a large, 10 centimeter tumor. The conclusion is clear: the initial diagnosis was indeed correct. He may have even had a family history of stomach cancer.

Records aren’t definitive, but it appears his father may have died of something similar. The Romanov family were the last Russian monarchs. They were executed in 1918 after the Bolshevik Revolution began a year earlier.

This was an attempt to discourage their remaining loyal supporters and prevent any hope of rescue. The entire family was killed by firing squad and buried nearby. This included Tsar Nicholas, his wife Tsarina Alexandra, their five children and four members of their staff: 11 people in total.

But since then, rumors have swirled that one or two of the children just might have escaped alive. In fact, over 200 people have come forward claiming to be those long-lost royal children. Clearly they can’t all be right!

The mass grave was discovered in the 70s, but kept a secret until 1991 when the Soviet Union fell and the remains could be exhumed. But in many ways, this only added to the rumors. The grave contained only nine bodies.

Notably, two of the children were missing. The Crown Prince Alexei was unaccounted for, as was one of his sisters. Likely one of the younger two, either Princess Maria or Princess Anastasia.

DNA couldn’t narrow down which sister was missing, and experts from Russia and the United States fell into two camps. A Russian team attempted to reconstruct facial features using the skulls and concluded Maria was missing. But an American team focused on figuring out the ages of the remains from physical features on the skeletons and concluded the missing princess was the youngest, Anastasia.

A breakthrough came in 2007 when amateur archaeologists found a second grave nearby with the remains of two children in it, one boy and one girl. DNA analysis confirmed the boy was the Crown Prince Alexei, and the girl was one of his sisters. We still can’t definitively say which sister is which, but we now know that all family members are accounted for, and sadly, they all perished in 1918.

Now, this one isn’t wrapped up with a shiny bow yet – but thanks to science and some recent discoveries, it’s getting closer. Sir John Franklin and his crew of 128 sailed to the Canadian Arctic in 1845 aboard two ships. Their goal was to search for a Northwest Passage, or shortcut from Europe to Asia.

But their ships ended up caught in the ice for 19 months until the crew abandoned them in an attempt to make their way south and find help. None survived. So why didn’t they make it back? 105 of them made it to the point of abandoning ship.

Many have proposed that lead poisoning is what doomed the expedition. Their food was stored in cans sealed with lead solder. A 2018 study analyzed bones and teeth from crew members to figure out if this was indeed to blame.

And while the researchers did find high levels of lead compared to modern standards, or to the contemporary Inuit living nearby, they don’t think it’s what ultimately did the sailors in. They found crew members who died early in the expedition had similar lead levels to those who died later. This suggests the high levels might have resulted from a lifetime of exposure, not just the time spent on the expedition.

So to confirm this, they tested the remains of British navy sailors who lived at a similar time but were not on the expedition. And they found similar lead levels. So it’s likely this expedition didn’t face any unique risk from lead.

Just being a sailor at the time exposed you to a lot in the first place. What did end up killing them? Probably various factors.

The Arctic is a tough place to live if you don’t know how to survive there. One other mystery was what happened to the two ships they abandoned, since they didn’t remain stuck in the ice forever. After over 150 years of searching, the first was found on the seafloor in 2014 and the second two years later.

As scientists explore these wrecks, what they find should help us further understand what happened on this tragic expedition. Marie Antoinette was the last Queen of France who famously met her end during the French Revolution. She was married to Louis the Sixteenth, but there are long-standing rumors of a possible affair with a Swedish count, Axel von Fersen.

The two wrote letters back and forth from 1791 to 1792, but the surviving copies have sections of text redacted. Someone has scribbled over them, leaving historians to speculate about what they say and who censored them. But a study published in 2021 successfully used some clever science to see through the ink and reveal what’s underneath!

But a study published in 2021 successfully used some clever science to see through the ink and reveal what’s underneath! The researchers used x-ray fluorescence. This works by hitting an atom with x-rays, causing a low-energy electron to be ejected from the atom.

When that electron drops down, it releases x-rays unique to that particular atom. By detecting this energy, the machine can determine what element that atom is. In this case, the atoms in question make up the ink on the page of the letter.

So by scanning the ink, the researchers can make a map of each element on the page. The ink used to black out the letters had a slightly different composition than the ink used to write them. So mapping the copper, iron, and zinc in the ink revealed the words underneath.

Of course, the real question is what they said! The team is still working on that. The text is pretty distorted and the scientists are working with historians to be sure they get it right.

But they did reveal that the reacted sections tended to be the more sentimental ones, and the language used, words like be-loved, tender friend, adore, and madly tend to imply a very close relationship between the Queen and the Count. The study also figured out who censored the letters. It was Count Axel von Fersen himself!

From handwriting analysis, they knew he made a copy of each letter he received. The ink analysis revealed that the redacting ink was always similar to, but not quite the same as, the ink used to recopy them. That suggests it came from the same source shortly after.

Ink composition can change slightly even from the start to the end of a letter as the liquid level goes down in the inkwell. The ink used to redact the letters was different enough in composition that this method could see through it, but similar enough that it’s clear it came from the same source. We’re not entirely sure why the Count copied and then redacted the letters he received.

But it’s likely he could have been trying to protect Marie Antionette or himself. And it goes to show how future technology can undo security measures that were probably pretty effective at the time! Though the composition of the ink does change after a while, and on some of the letters the original writing is too similar to the redactions to make out.

So if you don’t want your letters read by gossipy scientists in a couple hundred years, maybe consider burning them instead. So there you have it: five cases that have been cold for decades, even centuries. All it took was some modern analysis to reveal critical clues that crack them open, or at least make good progress!

But these only scratch the surface — the history books are still full of unsolved cases just waiting for a resourceful scientist to come along and crack. And if you have unsolved mystery data, or any other kind of computer data, that you need to protect, this episode’s sponsor, Linode, can help you out. Linode is a cloud computing company, which means they provide additional storage space, databases, analytics and more to you or your company, all over the internet.

With cloud computing, everything is online when you need it so there’s no equipment setup and you only use what you need. If your company sends emails, streams movies, or stores files on a computer, then you’re probably already using cloud computing. And Linode is the largest independent cloud for developers.

You can check out Linode by clicking the link in the description or heading to linode.com/scishow. You’ll get a $100 60-day credit on a new Linode account. And thanks for watching this episode of SciShow! [ OUTRO ]