The following is an encore presentation of Everything Everywhere Daily. One of the most important substances throughout world history has been salt. Salt might seem mundane, but it's actually necessary for the functioning of life. For millennia salt has been used as a preservative, a seasoning, and even a medium of exchange.
Salt is one of the universal things that has remained the same throughout history and everywhere on Earth. Learn more about salt and its importance in human history on this episode of Everything Everywhere Daily. This episode is sponsored by Planet Money. Tariffs, meme coins, Girl Scout cookies, what do they all have in common? Money.
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Tune in to Planet Money every week for entertaining stories and insights about how money shapes our world. Stories that can't be found anywhere else. Listen now to Planet Money from NPR. History is complicated. The story of human progress is long, messy, and riddled with controversies big and small. On Conflicted, we dive headfirst into history's most infamous events and contentious figures. We try and untangle the good from the bad The fact from the fiction.
and the monsters from the misunderstood. Was Genghis Khan a murderous butcher, or a civic pioneer? Did the Allied powers go too far in firebombing the German city of Dresden at the twilight of World War And how did the Marquis acquire such a sinister reputation. And was any of it true? These are just a few of the tough questions we wrestle with So if you love history, Please join me.
fascinating new topic each and every month conflicted a history podcast is available on spotify apple or wherever else you get your podcasts I hope to see you soon. Before I get into the historical use of salt, I should probably start with what salt is. Salt is simply a chemical compound consisting of one sodium atom and one chlorine atom bound together with an ionic bond.
An ionic bond simply means that each atom is an ion with a positive or negative charge. In the case of salt, the sodium atom has a positive charge, and the chlorine atom has a negative charge. The chemical name is sodium chloride, and it has a chemical symbol of NaCl. It should be noted that any ionic solid is considered to be a salt. This can be confusing because when used generically, salt simply refers to NaCl, or what we would call table salt.
However, other compounds can form a salt, which is just something to keep in mind if you ever hear someone use the term salt in a way that might not immediately make sense. For the rest of this episode, when I refer to salt, I will be referring to table salt. Salt, when found in its mineral form, is known as halite. It forms crystals and can be mined like other minerals. Salt is the only mineral that humans consume as food.
Today, most people might only be familiar with salt as a condiment or a seasoning for food, but salt is actually vital for human survival. That's right. If you didn't consume salt, you would eventually die. Salt is necessary for a host of functions in your body, including electrolyte balance, nerve function, blood pressure regulation, nutrient absorption and transport, as well as body fluid regulation.
I'm not going to get into too much detail about how the body uses salt, but we need salt. Other animals will actually seek out salt as well which is why salt licks are used to attract deer. The necessity of salt to humans is really the crux of this episode. It allows us to look at history through a unique lens. Other products I've done episodes on like bread, beer, and cheese have changed dramatically over time.
Salt because it's a simple chemical is exactly the same today as it was for our early human ancestors Furthermore, because salt is an essential nutrient for all humans, every society and culture in history, wherever on earth, including our own today, has had to procure and find sources of salt.
So this isn't the case of a technology that began in one part of the world and spread. This is something that had to have occurred simultaneously everywhere, with everyone using the exact same chemical throughout all of history up until the present day. So, how did our earliest ancestors get solved? If they live near the sea, the answer is pretty obvious. You could just get salt from seawater. Just get some water in a shallow pool, let it evaporate, and you will eventually be left with salt.
This technique is still practiced today. In many places around the world, so long as it's next to a body of salt water, you will find salt production. But what about people who didn't live next to saltwater? There, it gets tricky, and it depends on the particular geography of where people might have lived. If there was a salt deposit, then it could have been mined, and people could have used rock salt. Likewise, there are sometimes salt springs where water percolates through salt deposits.
Many people got their salt from animals. Other animals have sodium in their blood and meat. This is why where you see salt licks or salt sources, it usually attracts herbivores, not carnivores. Many nomadic people with meat-rich diets would often consume an animal's blood, if nothing else than for the salt content. Other people had to go through much more elaborate procedures in order to get solved. According to the anthropologist Jared Diamond, in the highlands of Papua New Guinea,
People, quote, gathered leaves of certain plant species, burned them, scraped up the ash, percolated water through it to dissolve the solids, and finally evaporated the water just to obtain small amounts of bitter salt. End quote. Needless to say, these methods were highly elaborate, but they showed just how far people would go to acquire salt.
Finally, one of the most popular methods that eventually developed was simply trade. Those with easy access to salt would trade it with those who didn't have access, but might have other goods. Salt was probably the very first product that was traded amongst humans. When civilization started to arise, an agricultural surplus allowed for dedicated salt production. Again, it's hard to say who developed a salt industry first because it appeared all over the world.
The first documentation we have of salt production comes from China. The Chinese, like most cultures, had multiple sources of salt, including sea salt and salt mining. However, they also pioneered the use of salt wells in the province of Sichuan. They would literally bore wells into subterranean salt pools to harvest what came up. There were reports of wars being fought over a salt lake known as Yunchen in China's Shang-Chi region as early as 6,000 years ago.
In Africa, there were salt deposits in the Sahara Desert. If you remember back to my episode on the richest people in history, one person who was a claimant for that title was the 14th century ruler of the Mali Empire, Mansa Musa. Much of his wealth derived from salt, which he traded for gold. There are reports of salt caravans with as many as 40,000 camels carrying salt out of the Sahara to be traded in the Sahel. The ancient Egyptians got their salt from brackish marshes in the Nile Delta.
In India, one of their sources was rock salt, which was found in what is today the Punjab province of Pakistan. This is the same salt that you can buy today that goes by Himalayan salt. In the Americas, sea salt production facilities were developed around what is today Mexico to augment diets of corn, squash, and beans that were otherwise low in salt.
As salt production developed, other uses for salt came to the forefront. Simple consumption of salt actually became rather minor and the dominant use for salt was as a preservative. Prior to the development of refrigeration, salt was the primary way to preserve meat. Salt is hygroscopic, meaning it attracts and retains water molecules. When a microbe encounters a grain of salt, it will usually result in its death because water is removed from the cell.
Dry salting, brining with salt water, and pickling were all techniques to preserve beef, pork, and fish, which allowed them to be stored for months and transported long distances. Salted fish and birds have been found in ancient Egyptian tombs. Moreover, salting meat was also a roundabout way for people to consume salt.
This made salt an extremely valuable commodity, and not surprisingly, many governments used salt as a means of control. Either they outright owned and controlled the major sources of salt production, and or they taxed salt heavily. Salt was really a perfect substance to tax because it only came from a few locations and it was absolutely necessary.
Salt roads, which were major trading routes between salt-producing regions and major population centers, eventually developed. The Greek historian Herodotus wrote of salt roads that crossed Libya. The first road from Rome to the port city of Assia was supposedly to bring imported salt into the city. The Romans eventually developed a network for the transportation of salt known as the Via Salaria. The Via Salaria ran across the Italian peninsula from Rome to the Adriatic Cove.
Because of the depth and temperature of the Adriatic, the salinity there is slightly higher, which makes for better salt production. One legend which has floated around for years is that Roman soldiers were paid in salt. And there is actually no basis for this story. Roman soldiers were paid in hard money. However, the English word salary does come from the Latin word for salt, and it might come from the word salarium, which was a stipend given to soldiers for the purchase of salt.
Likewise, the English word salad comes from the Latin word for salted, as Romans often ate green leafy vegetables with salt. The rise and fall of empires really didn't affect salt production very much, which is one of the reasons why salt is such a fascinating lens through which you can view history.
Many major world cities that you're familiar with were founded because of salt production. Salzburg, Austria was named after salt. Liverpool, England became the port for exporting salt from the Cheshire salt mines. Krakow, Poland became a flourishing city due to the Wieliczka salt mine, which is today a UNESCO World Heritage Site.
And just as an aside, if you're ever in Krakow, I highly recommend visiting the Wieliczka salt mine. Over the years, the miners carved elaborate sculptures, chapels, and other structures out of pure rock salt. Even as the modern world developed, salt never lost its importance. Venice had a dominant trading empire, and part of that empire included the salt trade.
They would purchase salt from all over the Mediterranean and the Black Sea, including Egypt, Algeria, the Crimean Peninsula, Sardinia, Ibiza, Crete, and Cyprus. They also produced their own salt in the Venice Lagoon. They had a monopoly on the salt trade in much of Italy. And Venice fought wars with Genoa and Padua in order to preserve their salt monopoly. In France, the Gabel was a salt tax that lasted from the 14th century to the end of World War II.
And during that time, the tax was almost universally hated. Salt wasn't just taxed, but government salt purchases were mandatory, which was an incredible burden on the poor. During the American Revolutionary War, salt became a strategic asset. The British blocked all salt imports, which ushered in the development of American salt works along the Atlantic coast.
In the 20th century, the British salt tax in India played an important role in the Indian independence movement. Mahatma Gandhi led a group of 100,000 people on a march to the sea known as the Salt Satyagraha, where they would collect salt in defiance of the British tax. Salt is still produced, although it isn't as important as it once was. Mechanization has made salt incredibly cheap and refrigeration has all but eliminated the use of salt as a preservative.
Just as there were in the past, there are still multiple methods of salt production, and many of the ancient methods are still used today in almost the exact same manner. Today, the biggest use of salt in the modern world isn't for consumption, but rather for melting ice on roads.
One of the properties of salt is that it lowers the melting point of water when it comes in contact with it through a process known as eutectic melting. This allows ice to melt at temperatures where it would normally freeze. If you live in a cold climate, you've probably seen entire trucks full of salt that just spread it over frozen roads.
There is of course a problem with this. Over time salt will build up in the soil alongside of roads which makes it difficult for plants to grow. The second biggest use is in the chemical industry which uses salt as a source of sodium and chloride. There are several misconceptions and misunderstandings that people have about purchasing salt for cooking and the different types of salt that can be purchased.
For starters, all salt is chemically exactly the same. Even Himalayan salt, which has a pinkish hue, is just regular salt with some trace elements. And the thing that gives it its color is iron oxide, otherwise known as rust. Kosher salt isn't called kosher because it's kosher. It's called kosher because it's used in the preparation of kosher foods. Kosher salt is just a larger grain version of salt with nothing added.
And grain size is actually something that we can taste. Popcorn salt is just plain old salt that's been ground down to have smaller salt crystals. Sea salt will often form into flakes as it condenses out of evaporating seawater, but outside of some trace elements, it too is the same as regular salt. In the early 20th century, many people began suffering from iodine deficiency, especially people living in inland regions.
In 1922, Switzerland began adding iodine to salt as a way to deliver iodine to people, and the United States followed suit in 1924. The addition of iodine to salt has largely solved the problem of iodine deficiency in most countries to the point where salt without iodine is now regularly sold in stores. I've done many episodes where I've talked about some technology or some product that was pivotal to the rise of civilization in the modern world.
However, some things are more important than others. In the case of salt, it is probably the most pivotal thing right after food itself. If it weren't for salt, our world simply wouldn't exist. The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Austin Oakton and Cameron Kiefer. I want to thank everyone who supports the show over on Patreon. Your support helps make this podcast possible.
I'd also like to thank all the members of the Everything Everywhere community who are active on the Facebook group and the Discord server. If you'd like to join in the discussion, there are links to both in the show notes. And as always, if you leave a review or send me a boostagram, you too can have it right on the show.