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What’s the weirdest thing you learned this week? Well, whatever it is, we promise you’ll have an even weirder answer if you listen to PopSci’s hit podcast. The Weirdest Thing I Learned This Week hits Apple, Spotify, YouTube, and everywhere else you listen to podcasts every-other Wednesday morning. It’s your new favorite source for the strangest science-adjacent facts, figures, and Wikipedia spirals the editors of Popular Science can muster. If you like the stories in this post, we guarantee you’ll love the show.
FACT: Leprosy is back. So where did it come from?
By Rachel Feltman
In early August, a case report in the CDC’s Emerging Infectious Diseases journal sounded the alarm on, you guessed it, an emerging infectious disease. But instead of a new strain of bird flu or some exotic new mosquito-borne parasite, the researchers were warning the medical community about the return of a real throwback: leprosy. Cases in the southeast have doubled over the last decade. Central Florida has such a disproportionate share of reported cases—81% of the 159 cases in 2020, to be exact—that the researchers suggest leprosy might now be endemic there, which means there’s a consistent, ongoing presence of the disease, as opposed to occasional outbreaks when someone brings it in from somewhere else.
Like news reports on cases of the plague, which yes, people still get, this one set off a lot of frantic headlines about “biblical diseases” being back on the rise. Leprosy, which is officially called Hansen’s disease these days, is probably the most commonly referenced and least understood infectious disease in history. So let’s talk about how it got that way.
First, the facts: Yes, Hansen’s disease, which is caused by the bacteria Mycobacterium leprae and M. lepromatosis, is contagious. But it’s extremely hard to catch. We aren’t even exactly sure how it’s transmitted, because we know casual contact, like sitting next to someone on public transportation or shaking hands with them, isn’t enough. Leprosy has been called a “wimp of a pathogen,” because it dies pretty much instantly once it’s outside of the body. It’s possible that the bacteria spreads through droplets from coughs and sneezes, but in any case, it seems like you only run the risk of catching it from someone if you have really prolonged close contact.
Side note: You can also catch leprosy from touching or eating an infected armadillo. The nine-banded armadillo is known to carry the disease. Humans are thought to have transmitted it to them about 500 years ago. Red squirrels were recently found to carry it too, and the trade of their fur in medieval Europe may have fueled an epidemic at that time.
Even if you’re in close contact with a person (or armadillo) with Hansen’s disease, you’re extremely unlikely to contract it. Only five percent of people who are exposed actually become infected, because most people’s immune systems are able to brush these bacteria off. Certain genetic variations are thought to play a role in determining susceptibility. Even then, the bacteria grows so slowly that it can take years or decades for you to develop symptoms.
The first noticeable sign of leprosy is often the development of pale or pink coloured patches of skin that may be insensitive to temperature or pain. The loss of fingers and toes often associated with untreated Hansen’s disease isn’t because leprosy makes tissue fall off; it’s because it can cause nerve damage, and without pain receptors in fingers and toes, it’s very common to injure them without realizing and get infections, similar to what happens in people with severe and untreated diabetes.
Luckily the disease is easily treated with antibiotics, and you stop being contagious within days of starting treatment.
So how did we get our overblown idea of what leprosy is?
Our oldest physical evidence of Hansen’s disease dates back to 4,000 years ago. A skeleton was found in India that showed signs of the bone lesions that can occur if the disease is left untreated. While there are lots of earlier historical references to leprosy, it’s likely that these descriptions referred to all sorts of conditions that affected the skin, including syphilis, which actually is highly contagious.
So: Conflation of many diseases, lack of certainty about how and when someone might contract Hansen’s disease, plus the very real issue of serious disease in a few folks led to an outsized fear of the relatively benign ailment.
This stigma peaked in Western Europe during the Middle Ages, when people with Hansen’s disease were said to literally be doing their time in purgatory while still alive, and were banished to the edge of town to beg for alms.
But this ridiculous stigma also has a pretty recent history. In 1865, Hawaii introduced laws allowing the arrest and removal of people with leprosy, and began housing them in isolation on the island of Molokai. Those laws weren’t lifted until 1969. As of 2015, there were still 16 former patients living there.
If you live in an area where leprosy is on the rise, keep an eye out for symptoms and see your doctor about any mysterious rashes. But don’t be weird about it! Hansen’s disease is no reason to treat humans (or armadillos) with fear or disgust.
FACT: Ancient people made high-tech tools out of space rocks
By Sara Kiley Watson
The Bronze Age, which lasted from around 3000 BCE to 1000 BCE was a step up, at least engineering wise, from the Stone Age. Humans essentially graduated from rock tools to metal tools—namely, duh, bronze. Bronze was made from melting tin and copper together, and could be made to use some pretty neat stuff, especially when it comes to weaponry.
As we know today, there are even stronger materials than bronze, and one of those is iron. And we still use a whole lot of iron in the modern world. The problem here is that to turn iron ore, which is relatively common throughout the world into usable iron, you need to know what you’re doing. So how did iron end up in a rare selection of Bronze Age tools, long before the art of smelting was commonplace? Meteors. Yep, some of the biggest and baddest characters of the ancient era, King Tut included, had superstrong tools made from space rocks long before humans really got the hang of iron.
FACT: Ancient tweezers made people scream so loud, people wrote noise complaints
By Laura Baisas
If you think waxing is bad, try plucking your armpit hair. That was par for the course in Roman Britain. A recent archaeological dig in the UK uncovered more than 50 tweezers dating back to the Roman occupation that were used to tweeze armpit hair. Roman author and politician Seneca once wrote a letter complaining about the noise coming from from the public baths, noting “the skinny armpit hair-plucker whose cries are shrill, so as to draw people’s attention, and never stop, except when he is doing his job and making someone else shriek for him.” Learn more about this agonizing fact in today’s episode.
