Wednesday, November 21, 2012
The craving for salt
The craving for salt
Human beings have an intimate relationship with salt. Our tears, blood and sweat taste of salt.
The chemical reactions inside our bodies need sodium - one of the two components that make up salt (with chloride).
We can't survive without sodium, but it was about five million years before humans began to eat their sodium as salt.
Hunters in Greenland ate no salt until they were introduced to it by whaling Europeans in the 17th century. Like our prehistoric forebears, Lapps, Samoyeds, Kirghiz, Bedouin, Masai and Zulus used to consume all the sodium they needed from the animals and fish they ate.
Agriculture and salt
Archaeologists believe that salt eating developed as humans learned how to keep animals and grow crops in the years after 10,000 BC. As the proportion of meat in their diet fell, people had to find salt for themselves and for their domesticated animals.
Salt has another crucial property that made it important for the development of human society. By 2000 BC, people knew that adding salt to food stopped it going off. Salt was used to preserve meat, fish and vegetables, and to create delicacies such as salted olives, which added variety to the diet.
The buying and selling of salt became one of the most important trading activities in the world.
Salt is one of the most common minerals on the earth. Salty springs and lakes dry out to leave salt crystals that can be collected. Salt can be extracted from sea water by boiling or leaving it to evaporate. In some places, solid salt appears on the surface of the earth and can be collected or mined. Wells can be dug down to tap underground supplies of salty water.
The ancient Chinese and Egyptians, the Celts, the Romans and others discovered how to make salt from these sources. But despite their efforts, salt remained in short supply until modern times.
The trade in salt
Salt was expensive because of the work needed to extract it and the high cost of carrying it by river, by sea and overland. Trading in salt made the traders rich. Roman and Chinese rulers introduced taxes on salt or took over the trade for themselves 2,500 years ago. When countries wanted to go to war, they raised taxes on salt. British taxes and control of the salt trade lit the fuse of India's successful independence movement.
Salt and ritual
Salt has had an important place in people's imaginations through the centuries. In many religions, salt was given as a blessing. It was thought to drive out evil spirits and was linked to fertility and sexual desire.
There are echoes of salt's history in the English language today. You are paid a 'salary' because Roman soldiers were partly paid in salt ('salarium' in Latin). A juicy piece of gossip is 'salacious' because an ancient Roman in love was said to be 'salted'.
New uses for salt
Until the 19th century, the most important use of salt was in food, though it was also used to treat leather, dye textiles and in making pottery. In the 19th century, chemists discovered ways of using salt to make a whole range of new chemicals. Manufacturers today claim there are more than 14,000 uses for salt.
This industrial demand for salt caused a growth in the industry and much more extensive deep mining and drilling of salt. Salt shortages effectively ended by the middle of the 19th century.
Salt in processed food
Salt has always been a key component in preserved food. Salt consumption probably peaked in Europe in the 19th century when people ate as much as 18g a day, much of it in the form of ham, bacon and other salted meats and fish.
The invention of refrigeration meant meat could be transported across the world without the need for salting.
As people began to eat less salted meat and fish, new preserving techniques were being introduced in industrial countries. Tins, packets, ready-made biscuits, cakes, snacks and later whole meals revolutionised our eating habits. Salt was added to help preserve the food and improve the taste. Now, 75% of the salt we eat in the UK is already in the food we buy.