Numerous other methods of food preservation didn’t involve drying. A simple method in Arctic and northern European areas with sub-zero winter temperatures was to freeze food in the winter and bury it in the ground or in subterranean ice-filled chambers where the food would remain frozen into the next summer. I stumbled upon a vestige of that practice when, as a university student at Cambridge, England, I went on a sight-seeing drive through the East Anglian countryside with British friends with whom I shared the hobby of spelunking (exploring caves). While we were chatting with a local land-owner, he invited us to see a strange building on his land whose purpose nobody understood. It proved to be a brick dome constructed of beautifully set courses of old brick, and with a locked door that our new acquaintance opened for us. Inside, we saw in front of us a brick-lined vertical hole 10 feet in diameter, with a wooden ladder disappearing into it, and so deep that we couldn’t see a bottom.
On the following weekend, we returned with our cave-explorers’ belaying ropes, acetylene torches, helmets, and single-piece overalls. Of course, we were hoping for a deep shaft, side galleries, and a forgotten treasure hoard. As the only American and the lightest member of our group, I was the one selected by my British friends to be the first to risk descending the rotting wooden ladder. To my disappointment, the ladder reached a dirt floor at a depth of only 30 feet, with neither side galleries, treasure, nor any other hint of function except for more beautiful courses of old brick. On my return to Cambridge that evening, I recounted our mysterious discovery over dinner. One of my table companions, an elderly engineer who spent his weekends taking walks through the countryside, exclaimed, “That’s obviously an ice-house!” He told me that such buildings used to be regular features of British estates until refrigerators began to supplant them in the late 19th century. They were excavated to a depth far below the warm surface soil layer, were filled with food and blocks of ice in the winter, and maintained food frozen into the next summer. The quantity of food that our re-discovered ice-house must have been capable of holding was huge.
Another traditional method of food preservation is to boil food so as to kill microbes, then to seal the container while it is still hot and sterile. As recently as World War II, American city-dwellers were urged by the United States government to spare food supplies for our soldiers by patriotically planting backyard victory gardens and storing the boiled produce in air-tight vacuum jars. In the house in Boston where I grew up, my parents maintained a basement room that my mother filled with jars of tomatoes and cucumbers harvested in the autumn, and that my parents and sister and I consumed throughout the winter. My childhood was repeatedly punctuated by explosions of the antiquated pressure cooker in which my mother boiled produce before jarring it, spraying vegetable mush over our kitchen ceiling. New Zealand Maoris similarly preserved meat by cooking it and transferring it still hot into containers sealed with melted fat that kept out microbes. Without knowing about microbes, Maoris somehow discovered this method.
The remaining class of methods preserves food without either drying or freezing or boiling, by pickling and/or fermenting with substances that prevent microbial growth. These substances include salt or vinegar added to the food, or else alcohol, vinegar, or lactic acid developing during fermentation of the food itself. Examples include beer, wine, and other alcoholic beverages; the Korean staple of kimchee served with every Korean meal, and commonly including cabbage, turnips, and cucumbers fermented in brine; the fermented mare’s milk of Asian herders; Polynesia’s fermented taro and breadfruit; and the fermented fish of Kamchatka’s Itenm’i people.
Finally, one can achieve the purpose of storing surplus food by converting it into some non-food item that is convertible back into food during a subsequent hungry season. Farmers in our modern cash economy do this by selling their produce for money when they harvest or slaughter, banking the money, and eventually converting the money back into other foods at a supermarket. Pig husbandry by New Guinea Highlanders in effect constitutes food banking, because the staple Highland crop of sweet potatoes can be stored as is for only a few months. However, by feeding sweet potatoes to pigs and waiting several years before slaughtering the pigs, Highlanders bank the sweet potatoes, transform them into pig meat, and effectively preserve them for much longer than a few months.
Diet broadening
Another strategy besides food storage for coping with seasonal food scarcity is to broaden one’s diet and consume foods scorned during seasons of food plenty. In Chapter 6 I mentioned an example from Rennell Island, where people classify edible wild plants in two categories: those eaten normally, and those eaten only in desperation after a cyclone destroyed gardens. But Rennell Islanders usually obtain most of their plant food from gardens, and their classification of wild plants is not elaborate. Preferences for wild plant foods are classified much more finely among the !Kung, because traditionally they were hunter-gatherers and did not farm. They name at least 200 local wild plant species, of which they consider at least 105 edible, and which they divide along a preference hierarchy with at least six categories. Most preferred are plants that are superabundant, widely distributed, available in all months of the year, easy to collect, tasty, and considered nutritious. Number one in the hierarchy, because it meets all of these criteria, is the mongongo nut, which provides nearly half of all plant calories consumed by the !Kung and is rivaled in popularity only by meat. Lower in preference are plants that are scarce, found only locally, available only in certain months, unpleasant-tasting, hard to digest, or considered un-nutritious. When the !Kung move to a new camp, they begin by collecting mongongo nuts and their 13 other favorite plant species, until these become depleted in the vicinity. The !Kung then have to move down their food preference ladder and content themselves with less and less desirable foods. In the hot dry months of September and October, when the least food is available, the !Kung stoop to collecting fibrous tasteless roots that are ignored at other times of year, and that now are dug out and eaten without enthusiasm. About 10 species of trees exude edible resins that are rated low, considered hard to digest, and collected only incidentally as the occasion arises. At the bottom of the ladder are foods eaten only a few times a year, such as an abundant fruit thought to cause nausea and hallucinations, and meat from cows that died from eating toxic leaves. Lest you think that these food preference ladders of the !Kung are irrelevant to the lives of modern First World citizens, many Europeans adopted similar practices during the food shortages of World War II: for example, British friends told me of eating mice then, which they served up as creamed mouse.
Within 300 miles east of the !Kung, at population densities 100 times those of the !Kung, are Gwembe Tonga farmers. When the farmers’ crops fail, the farmers’ high numbers place much greater pressure on the environment’s wild plants than do the relatively few !Kung, and so the Tonga have to reach farther down the preference ladder than do the !Kung. They then consume 21 plant species that also occur in the !Kung area but that the !Kung don’t even consider edible. One of those plants is an acacia tree whose abundant seed pods are toxic. The !Kung could collect tons of those pods each year but choose not to. However, at times of famine the Tonga do collect them and soak, boil, and leach them for a day to wash out the toxins, then eat the pods.