The History of Salt

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Podcast Transcript

One of the most important substances throughout world history has been salt. 

Salt might seem mundane, but it is 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.

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 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 refers to NaCal, 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 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 it 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 vital for human survival. That’s right, if you didn’t consume salt, you’d 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, and 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 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 entire 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 is 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, everywhere on Earth, including our own today, has had to procure and find sources of salt.

So this isn’t a case of a technology that began in one part of the world and spread. This is something that 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 salt? If they lived near the sea, the answer is pretty obvious. You could 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 is next to a body of salt water, you will find salt production. 

But what about people who didn’t live next to salt water? There, it gets tricky, and it depends on the particular geography 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, 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 measures to procure salt. According to the anthropologist Jerrod Diamond, in the highlands of Papua New Guinea, people “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 to obtain small amounts of bitter salt.”

Needless to say, these methods were highly elaborate, but they show just how far people would go to acquire salt.

Finally, one of the most popular methods that developed was simply trade. Those with easy access to salt would trade it with those who didn’t have access but might have had other goods. Salt was probably the very first product that was traded amongst humans.

When civilizations started to arise, an agricultural surplus allowed for dedicated salt production. Again, it is 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 Yuncheng, in China’s Shanxi region as early as 6000 years ago.

In Africa, there were salt sources in the Sahara Desert. If you remember back to my episode on the richest people in history, one person who is 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 and into the Sahel. 

The ancient Egyptians got 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 Egyptian tombs. 

Moreover, it 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 was absolutely necessary. 

Salt roads, which were major trading routes between salt-producing regions and major population centers, developed. The Greek historian Herodotus wrote of salt roads that crossed Libya.

The first road from Rome to the port city of Ostia 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 Coast. Because of the depth and temperature of the Adradiac, 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. There is 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. 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 the Romans often at green leafy vegetables with salt. 

The rise and fall of empires didn’t really 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 are 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 (Vee-a-leech-ka) salt mine, which is today a UNESCO World Heritage Site.

…and just as an aside, if you are 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 purchased 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 had a monopoly on the salt trade in much of Italy. 

Venice fought wars with Genoa and Padua in order to preserve their salt trade.

In France, the gabelle was a salt tax that lasted from the 14th century to the end of World War II. During that entire 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 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 it would normally freeze. 

If you live in a cold climate, you have probably seen entire trucks full of salt that spread over frozen roads. 

There is, of course, a problem with this. Over time, salt will build up in the soil alongside 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 people have about purchasing salt for cooking and the different types of salt that can be purchased. 

For starters, all salt is chemically the same. Even Himalayan salt, which has a pinkish hue, is just regular salt with some trace elements. The thing that gives it its color is iron oxide, also known as rust.

Kosher salt isn’t called kosher because it’s kosher. It’s called kosher because it is used in the preparation of kosher foods. Kosher salt is just a larger grain of salt with nothing added. 

Grain size is actually something that we can taste. Popcorn salt is just plain old salt that has 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 regularly sold in stores. 

I’ve done many episodes where I talked about some technology or some product that was pivotal to the rise of civilization and 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 Peter Bennett and Cameron Kieffer.

Today’s first review comes from listener Green Nolan over on Patreon. They write:

I’m a huge fan. I have a lot of time to listen to podcasts during work, and I always look forward to yours! Even if I think I know a topic very well, you always provide a tidbit I missed. At first, I couldn’t understand why you are a Packers fan because you are so logical and rational. Then I heard your promo where you said that you don’t sauce your chicken wings and everything made sense. Much love from Chicagoland my confused yet wonderful rival.

Thanks, Nolan. I think your confusion comes from a condition medical researchers call championship asphyxiation. Because your baseball teams went over a century between titles and because you have the Chicago Bears in town, the lack of championships can cause confusion and befuddlement.

Thankfully, the condition can be cured by simply turning your loyalties to the north. 

Remember, if you leave a review or send me a boostagram, you too can have it read on the show.