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Beyond Stone & Bone

Prozac Nation, 4000 B.C.
by Heather Pringle
March 13, 2009

768px-prozacIn the hills of Catalonia, some 50 miles northwest of Barcelona,  small bands of people began mining a spectacular reddish-blue outcrop of rock some 6000 years ago.  With broken, polished stone ax blades, they hammered at the steep slopes of Muntanya de Sal—one of only two salt domes in all Europe—breaking off large chunks of rock and hammering it into ever smaller pieces.  This precious commodity they traded among their neighbors for some of the finest ornaments of the age:  bracelets of shimmering sea shells and beads of a beautiful turquoiselike stone known as variscite.

Muntanya de Sal is the earliest-known rock-salt mine in Europe, and a lasting testament to the ancient hunger for salt.  And it raises a fascinating question.  Why were early coastal dwellers of Catalonia willing to part with their most beautiful and precious ornaments for a chunk of sodium chloride?  Did they intend to use the costly commodity as a salt lick for their herds, or a preservative for their fish catch?   

An intriguing new study out of the University of Iowa, which will be published in the July issue of Physiology & Behavior, puts a very new spin on the matter.  A team of psychologists led by Alan Kim Johnson has just suggested that salt acts very much like a drug—specifically a natural version of Prozac—on rats.  When the psychologists deprived lab rats of salt, the rodents began avoiding activities that they normally loved, such as slurping up a sugary fluid.  Such avoidance of pleasure, notes the team, is one of the key features of psychological depression, suggesting that the rats felt blue without their regular salt fix. 

Did farmers in Catalonia 6000 years ago crave salt as a mood-elevating drug?  It’s a very intriguing idea.  Modern nutritional studies have shown that salt is an addictive substance among humans.  While we need less than 2 grams of sodium chloride daily (to regulate the flow of fluids in and out of cells, and to pass information from one nerve cell to another), we consume on average worldwide five times that amount each day.  And even when doctors instruct patients with high blood pressure to throw out their salt shakers, they struggle mightily to comply—just as smokers wrestle with giving up cigarettes.   

Moreover, Johnson and his colleagues have found another intriguing piece of the puzzle.  The team’s studies show  that rats deprived of salt develop brain-activity patterns resembling those of rats deprived of drugs.  Such resemblances, Johnson explains, suggests “that salt need and cravings may be linked to the same brain pathways as those related to drug addiction and abuse.” 

Were ancient well-to-do Catalonians hooked on a natural version of Prozac?  I’m sure we’ll never know,  but it’s an interesting idea to play with.   


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7 comments for "Prozac Nation, 4000 B.C."

  • Reply posted by Dan Hilborn (March 13, 2009, 10:41 am):

    And ever since the French Revolution, decent societies have learned to keep the price of salt at a minimum.


  • Reply posted by Daniel Molitor (March 20, 2009, 6:43 am):

    I suspect this will turn out to be a case where there are many answers to the question of why the Catalonians “craved” salt. Possibly it’s mood-altering properties added some incentive, but probably it was a mix of all the factors you mentioned. Preserving food so you don’t starve is a pretty strong motivator…


  • Reply posted by Erik Nelson (March 22, 2009, 10:33 pm):

    Dear Heather Pringle,

    The “Late Neolithic”, beginning about 4000 BC, coincides with the quick collapse of Hunting & Gathering, in favor of Farming:

    The close of the 5th millennium BC [~4000 BC] saw further development in the process begun with the first farming settlements in the 7th millennium BC: the transformation of Europe from a continent of Hunter-Gatherers to one of Farmers. From around 4000 BC, there was a marked change in northern & eastern Europe. Mesolithic [Hunter-Gatherer] communities that had long been familiar w/ the products of Farming while pursuing their traditional Hunter-Gatherer economy rapidly shifted to economies dominated by farming. Agriculture also became the dominant way of life in Britain from southern England to the Shetlands in the far north [1].

    In turn, Farmers consumed less meat, making it necessary to seek special sources of salt:

    Increased reliance on cereals, at the expense of meat, made it necessary to supplement the salt naturally occurring in the diet, and a number of sites started to produce salt by evaporating saline [salt-] water; blocks of salt were among the goods that moved along the trade networds [2].

    Thus, the Muntanya de Sal rock-salt mines, beginning operations about 4000 BC, precisely compliment this picture.

    Moreover, this rapidly burgeoning preference for Farming also coincides with a Global Climate Cooling, occurring around 4000 BC, which “triggered world-wide migrations to river valleys” and the adoption of Farming [3].

    Thus, Global Climate Cooling apparently compelled the adoption of Agriculture, which cut back dietary intakes of salt, and caused cravings for the commodity.


    Erik Nelson

    [1] Jane McIntosh. Handbook to Life in Prehistoric Europe, pg. 47.
    [2] ibid., pg. 49.
    [3] ; cf.


  • Reply posted by Heather (March 23, 2009, 7:22 am):

    Thanks very much, Erik, for laying all this out so clearly and concisely. But I think it’s still possible that at least one reason Late Neolithic farmers craved salt was for this proposed mood-elevating property. Wouldn’t the collapse of the old hunting and gathering way of life and the transition to farming have been stressful on early groups? Again, this is just a speculation.


  • Reply posted by Erik Nelson (March 30, 2009, 5:59 pm):

    Dear Heather,

    Wine making may have begun about the same time (5th Millennium BC):

    A modest Neolithic house in northern Greece burned down in the fifth millennium B.C., preserving wild grape seeds and skins that look as though they had been crushed to extract their juice, perhaps to make wine. It is the earliest evidence of wine production in the Aegean region, and shows that wine could have been made before grapes were domesticated. [1]

    Perhaps, then, the demise of the Mesolithic “Golden Age of Hunter-Gatherers” witnessed widespread stress-reactions, from the sudden social changes, w/ corresponding solace-seekings in various psychedelic substances.


    Erik Nelson

    [1] Archaeology Magazine (July/Aug. 2007) ; Cf.


  • Reply posted by Erik Nelson (March 30, 2009, 6:50 pm):


    Vast Flint Mining operations also began, across western Europe, about 4000 BC [1]. For,

    Flint Mining was becoming a major industry, to supply the growing demand for axes, to clear woodlands [for farm-fields]… Flint had been mined earlier, but [now] production greatly increased to satisfy increased demand [2].

    So, as everybody began clear-cutting forests for farm-fields, vast Flint Mining operations opened up, to meet the mushrooming market demand. Meanwhile, eastern Europeans began pioneering Copper Mining operations about the same time:

    Later in the 5th Millennium BC, [metal] smelting — the extraction of the metal from its ore — was introduced… In the [Balkan] highlands, Copper Mines have been found, at Aibunar in Bulgaria & Rudna Glava in Yugoslavia, which were already being exploited around 4500 BC. [3]

    So, Mankind apparently began operating many Mines, for various rocky ores (Copper, Flint, Salt), in the late 5th Millennium BC. This “proto-Industrial Revolution” (as it were) ended the Neolithic, and ushered in the Metal Ages (Copper, Bronze).

    [1] (Collins Atlas of Archaeology) Past Worlds, pp. 13,107.
    [2] Jane McIntosh, ibid., pp. 48,51.
    [3] Past Worlds, ibid., pg. 110.


  • Reply posted by Bretlee (July 20, 2009, 8:42 am):

    Hello, Superb blog post, really well compiled.


About Our Blogger:

Heather Pringle is a freelance science journalist who has been writing about archaeology for more than 20 years. She is the author of Master Plan: Himmler's Scholars and the Holocaust and The Mummy Congress: Science, Obsession, and the Everlasting Dead. For more about Heather, see our interview or visit

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