Salt makes you Thirst

This post contains reviews of a couple of history books that I read this fall: Salt and Thirst. The former is about salt as an ingredient, preservative, and commodity; the latter is about approaches to water management in various ancient societies.


Salt: A World History by Mark Kurlansky looks at the history of obtaining, trading, and using salt around the world (it focuses on one region and one era at a time—some regions come up for discussion in more than one era—and the regions considered come from four different continents). It reveals just how important the simple substance was prior to modern means of food preservation. Here are some things that stood out to me from Salt (plus other ideas and random links that the reading inspired):

  • Salt is a necessity in everyone's diet to replace what is lost in sweat. It also is an effective preservative for many foods: "Proteins unwind when exposed to heat, and they do the same when exposed to salt. So salting has an effect resembling cooking." For these reasons, every culture since the agricultural revolution (the flesh of animals contains some salt, so hunting tribes would get enough from eating meat) has needed to obtain salt, either by mining, gathering (from salt flats), evaporating seawater, or trading.

Salt is so common, so easy to obtain, and so inexpensive that we have forgotten that from the beginning of civilization until about 100 years ago, salt was one of the most sought-after commodities in human history.

  • The salt trade across the Sahara desert was historically important. Camel caravans would stock up at salt mines like Taoudenni and Taghaza.

  • The city of Sfax is mentioned in an early chapter while discussing early Mediterranean salt production; in one of the final chapters it is mentioned again since there is now a big modern saltworks. It's interesting how some of the choices the Phoenicians and Romans made on where to obtain salt have proved so enduring:

About 800 B.C., when the Phoenicians first settled on the coast of what is today Tunisia, they founded a seaport, Sfax, which still prospers today. Sfax became, and has remained, a source of salt and salted fish for Mediterranean trade. ...
Inland from the port of Sfax are dried desert lake beds where salt can be scraped up in the dry season. This technique, the same as was used 8,000 years ago on Lake Yuncheng in China, and referred to as “dragging and gathering,” was the original Egyptian way of salt gathering, the method used for harvesting natron in the wadi of Natrun. The Arabs called such a saltworks a sebkha, and on a modern map of North Africa, from the Egyptian-Libyan border to the Algerian-Moroccan line, from Sabkaht Shunayn to Sebkha de Tindouf, sebkhas are still clearly labeled.

  • Celtic peoples were apparently known for salt mining, and many place-names in Europe are rooted in that activity:

The Romans, finding them less mysterious, called them Galli or Gauls, also coming from a Greek word, used by Egyptians as well, hal, meaning “salt.” They were the salt people. The name of the town that sits on an East German salt bed, Halle, like the Austrian towns of Hallein, Swäbisch Hall, and Hallstatt, has the same root as do both Galicia in northern Spain and Galicia in southern Poland, where the town of Halych is found. All these places were named for Celtic saltworks.

  • Towns in England that end in -wich also have links to historical salt production in some cases. A number of examples are found in Cheshire (where the extent of salt extraction has actually caused ground subsidence). Cheshire is also known for its cheese—cheese-making requires salt, so it is logical for the same region to produce both.
  • Parma in Italy is another place that produces both salt and cheese, plus prosciutto, a salt-cured meat:

In Parma, the production of cheese, ham, butter, salt, and wheat evolved into a perfect symbiotic relationship. ...
Heating the mixed milk, they added rennet and a bucket of whey, the leftover liquid after the milk curdled in the cheese making the day before. They then heated the new mixture to a higher temperature, still well below boiling, and left it to rest for forty minutes. At this point the milk had curdled, leaving an almost clear, protein-rich liquid, and this whey was fed to pigs. It became a requirement of prosciutto di Parma that it be made from pigs that had been fed the whey from Parmesan cheese.

  • Kurlansky's book has lots to say about various foods that require salt, including sharing medieval recipes. Pickling is a preservation process that relies on salt and it has been applied to many different foods in various cultures. Sichuan in China is a salt-producing region, and Sichuan cuisine features a lot of pickled vegetables and salty pastes/sauces, for example.

  • Salt also goes into the history of Tabasco sauce.

  • One food for which preservation in salt or brine has been perhaps more important than any other is fish. Mark Kurlansky has written a whole book about cod, so the chapter that dealt with that was very detailed. Ships that went fishing for cod carried a lot of salt so that they could preserve their catch for transportation back to Europe.
  • Herring is another fish that has commonly been preserved with salt. They are plentiful in the cold waters of the North Sea and the Baltic, and conveniently come close to shore in enormous numbers to spawn. However, the Baltic is low in salinity, so it is not a good place for salt production. One of the factors behind the success of the Hanseatic League was bringing salt to where herring was being caught:

The salt shortage of the northern fisheries was solved by a commercial group that organized both herring and salt trades. Between 1250 and 1350, a grouping of small associations in northern German cities formed. Known as the Hanseatic League, from the Middle High German word Hanse, meaning “fellowship,” these associations pooled their resources to form more powerful groups to act in their commercial interests. They stopped piracy in the Baltic, initiated quality control on traded items, established commercial laws, provided reliable nautical charts, and built lighthouses and other aids to navigation.

  • In the Mediterranean, too, salt was important for preserving the anchovy and tuna catches. Those fisheries have declined in modern times, and the author notes poignantly how the colourful boats that artists like Matisse painted in the town of Collioure are no longer there (of course fisheries collapse is a sadly familiar theme in my part of the world).

With the once precious salt crystals so common they are dumped onto roads, today there is a scarcity of tuna, anchovies, herring, Great Lakes carp, Caspian caviar, even cod.

  • One chapter in Salt was about the chemistry of salts (not just NaCl) and brines. I'm now interested in trying a little experiment at home to supersaturate brine (to > 26%), drop in a seed crystal, and watch it crystallize.

The long practiced principle of evaporating brine was that when brine becomes supersaturated—when it is at least 26 percent salt, which is considerably more than the 2.5 or 3 percent salt of seawater—sodium chloride crystalizes and falls out, or precipitates, from the liquid. But slowly it was discovered that after the sodium chloride, the salt of primary interest, precipitates, a variety of other salts crystalize at even denser saturation.

  • Historically, the salt trade relied on (and spurred the construction of, especially where canals are concerned) cost-effective transportation. At the present time, things have come full circle and transportation relies on salt—around half of the annual salt production in the United States is used for de-icing. However, preserved food was certainly important for long-distance travel in the past (salted fish was a common naval ration), so salt's enabling of transportation is not entirely a new phenomenon:

Because a profitable salt shipment is bulky and heavy, accessible transportation has always been the essential ingredient in salt trade.

  • Salt became less important for preserving food with the invention of canning and pasteurizing and fast-freezing (Birdseye method), but some pickled/salt-cured foods are still very popular (although often made less salty than they were in the past).

  • Because it was so essential, many governments in the past exercised monopolies over salt as a source of revenue. In the book, Kurlansky discusses the impact of these laws in France, China, and British-ruled India.

  • There has been a lot of consolidation in salt production, and now a few big companies dominate the industry. Big players include Morton and Cargill (Cargill is a big player in many food-related commodities; I listened to a really interesting podcast with their former CEO once).
  • I think it would be interesting to go see saltworks somewhere someday. Algae and shrimp make the solar evaporation ponds brightly coloured. Around Guérande in Western France it sounds like some of the traditional culture around salt-making is still alive, which would be cool to see, too.

Earlier this year, I read another book that delved into a single commodity: Uncommon Grounds (about coffee). If this review piqued your interest, you might want to check out that one as well.


Thirst: Water and Power in the Ancient World by Steven Mithen is well-researched and heavily foot-noted—I'd say it's on the border of popular and scholarly works. Like Salt, it draws examples from four continents (South America instead of Africa in this case; Asia, Europe, and North America are featured in both). Here are some of the things I found notable from Thirst:

  • Dr. Mithen is an archaeology professor (here are some of his publications) and brings his extensive knowledge base to Thirst. He also personally visited many of the sites he describes, and the writing slips into first person as he shares his own impressions. In my opinion, the balance between thorough research and first-hand experience makes for an effective writing style.
  • Following an introduction, the book starts in the neolithic era (which is where much of the author's own research has been focused). One of the things I really appreciated about Thirst is that each chapter includes a map of the sites discussed.

  • Crete and Mycenaea had some impressive early examples of sanitation and drainage—which can be as important as water supply. Mycenaeans and later Greeks appear to have been some of the first to get into diverting rivers and reclaiming land.

  • The Nabateans, most famous for their capital at Petra, had to be experts at water management in the arid desert. They made use of secret bottle-shaped cisterns to resupply with water on desert trips; knowing the cistern locations gave them protection from enemies and an advantage in handling trade passing through their territory. In the city of Petra itself, water features such as fountains and pools flaunted the Nabateans' water management skills. Mithen refers to the work of Ortloff, a hydraulic engineer, in describing Petra's water system.
  • The Nabateans were also skilled at managing water for agriculture.
    They used terraces (to retain runoff), with small rock walls marking out catchment areas that could be twenty times larger than the cultivated area (effectively assigning property rights to the rainfall that could be collected in that area, if I understand correctly), concentrating the available water to the point that crops could grow. The author refers to some really cool experimental archaeology in the Negev to figure out how the Nabateans managed to farm in such a dry place.
  • Roman aqueducts are probably the most familiar image of ancient water infrastructure. One thing I learned from the chapter on Rome was that there is a surviving report from a Roman water commissioner in 96 A.D.

  • The chapter on China had a lot of familiar content from another book I've read (indeed, it cites Water: The Epic Struggle) such as the story of Yu. Some new things I learned about were the irrigation works at Dujiangyan by Li Bing and modern efforts to conserve the Yellow River that were awarded the Lee Kuan Yew water prize.

  • Before reading Thirst, I didn't realize that the Angkor civilization had done some serious hydraulic engineering. Near their famous temples, they had massive (kilometers long) reservoirs, most notably the West Baray. There is debate about what their purpose was: irrigation/flood control or religious/symbolic? Mithen lays out the different perspectives and supporting evidence in detail.
  • Hohokam was a culture I hadn't even heard of before reading this book. They lived in what is now Arizona, and built canals for irrigation along the Salt and Gila rivers. Like Mesoamerican cultures further south, they had ceremonial ballcourts. As discussed below, there is debate in archaeology about the link between irrigation projects (which require coordinated labour) and the development of social hierarchies. From the Hohokam, high status buildings (e.g. higher mounds or multi-storey) date to after irrigation was well-established.
  • The decline of Mayan city-states has often been linked to drought. Thirst discusses the environmental archaeology of Richardson Gill who correlated periods of drought with the timeline for decline. The author discusses how the lack of water could have eroded the ritual authority of Mayan lords.

  • The final case study in Thirst is of the Incas. Their famous ruins at Machu Picchu are still standing after six centuries because of the care they took with providing good drainage. There and elsewhere (e.g. Tipón) they constructed terraces for agriculture; after putting in drain tiles they moved fertile soil to the terraces (which must have been a lot of work in the mountainous terrain). The Incas were also attuned to the aesthetics of water (flowing in fountains or cascades—so more similar to Rome or Petra than the mirror-like expanses of Angkor). Mithen mentions an engineer named Wright who became interested in paleo-hydrology and did a lot of research in Peru

  • I've written about the "hydraulic hypothesis" before so I was really interested by the discussion about it in the final chapter of Thirst:

Has controlling water always been a pathway to power, or perhaps even the predominant route? If so, what form has this taken? Was water the cause of conflict in the past between competing city-states or was it a medium for cooperation and mutual growth? Archaeologists have previously addressed such questions. Karl Wittfogel’s 1957 volume entitled Oriental Despotism: A Comparative Study of Total Power argued that ancient civilisations were dependent upon large-scale irrigation works. He proposed the ‘hydraulic hypothesis’ that such works required forced labour and a large bureaucracy, both of which were features of ‘despotic rule’.


The scale of such hydraulic engineering implies a considerable degree of centralised planning and control. The reservoirs, dams and canal systems had required vast quantities of building material, labour and time to complete. ...
It does appear, however, that contra the 1957 arguments from Karl Wittfogel no such centralised control was necessary for the initial development of irrigation systems ...
[R]elatively small communities appear to have worked cooperatively in the planning, construction and maintenance of irrigation systems without any overarching authority. Strikingly similar developments happened around the world in ignorance of each other and at quite different times throughout the last 4,500 years. Similar developments most likely happened in many other regions, notably in the Yellow River valley of China; my guess is that they also occurred in locations we were unable to visit within this book, such as Sub-Saharan Africa and Australia. ...
[I]t appears to have been the canal systems that enabled particular communities, families or individuals to develop a power base, ...
So we have a [bootstrapping] process: hydraulic-engineering projects enabled certain families/individuals to secure a power base. With their new authority, they were able to control labour and materials to extend the scale of the hydraulic engineering and so on, ...
Power lay in controlling access to water.

(as the ellipses show, I've condensed the text above, but I think I've preserved the flow of the argument).

  • Steven Mithen points out how convergent designs for water engineering emerged around the world (because hydraulics are the same everywhere, not a cultural construct):

Those who built the canals in the Yellow River Valley of China, the Salt River Basin of Arizona, in the rainforests around Edzná and Angkor, and on the Tigris–Euphrates alluvial plain did so thousands of years apart, with no knowledge of each other and within completely different cultures. But they all shared similar ideas, plans and physical labours; they addressed the same questions about gradients and where to place head-gates; they found the same solutions imposed by the common properties of water and then engaged in the same fights against the accumulation of silt and protection against floods.

  • Many of the places discussed in Thirst are accessible to the public, not just archaeologists. Steven Mithen has good advice for anyone who has the opportunity to visit them:

So if you wish to appreciate the Nabataean achievement when visiting Petra, ensure that you pay attention to the discreetly hidden water channels and drains as well as the ostentatious rock-cut tombs. When in Rome, leave the city and go to the Parco degli Acquedotti and if in Arizona search out the Hohokam equivalent at the Park of the Canals in Phoenix. Similarly, when in Constantinople, don’t just visit the Hagia Sophia but also enjoy the Basilica Cistern and Aetius reservoir; if you really wish to appreciate the Byzantine achievement take a trip to the Kurşunlugerme

  • I'd like to visit some of these places someday. I'd also be interested in reading a sequel to Thirst (e.g. one that covers new sites and civilizations, such as in Africa or Oceania, or time periods closer to the present*). It seems that Mithen might eventually have material for a sequel, based on the way he concludes his book:

I am not sure whether it is with regret or pleasure that I now must inform you that the more I have seen and read, the thirstier I have become; the more that I have learned about the past the more I need to know. I now feel compelled to explore those civilisations not covered within this book, to visit many more archaeological sites around the world and continue with my own excavations in Wadi Faynan. While I hope you have learned something about the past from the pages of my book, I also hope that your thirst has remained equally unquenched.

*I recently got an e-book called Designed for Dry Feet about land reclamation and flood control works in the Netherlands so I do have something to read in that direction.

Another book I read recently was the novel Artemis by Andy Weir (author of The Martian). I don't plan to write a full review—I'll just note that I read it cover-to-cover in a single day—but I do want to draw attention to this interview. In it, Weir talks about the moon colony setting that he developped for Artemis, including creative details like the currency they use and the flag that they're under. (The conversation contains mild spoilers but mainly about the setting rather than the plot).