On the average, Goland’s 20 families actually planted two or three more fields than the number of fields that she calculated that they had to plant in order to avoid starvation. Of course, that field scattering did force them to burn more calories while walking and transporting things between their scattered fields. However, Goland calculated that the extra calories thereby burned up were only 7% of their crop calorie yields, an acceptable price to pay for avoiding starvation.
In brief, through long experience, and without using statistics or mathematical analyses, Goland’s Andean peasants had figured out how to scatter their land just enough to buffer them against the risk of starvation from unpredictable local variation in food yields. The peasants’ strategy fits the precept “Don’t put all your eggs in one basket.” Similar considerations probably also explain field scattering by medieval English peasants. The same considerations may explain why the Lake Titicaca peasants so harshly criticized by exasperated agricultural development researchers for appalling inefficiency were actually smart, and why it was actually the researchers’ land-swapping advice that was appalling. As for my New Guinea friend whose isolated garden several miles from his other gardens initially puzzled me, his people mentioned five reasons for scattering their gardens: to reduce the risks of all their gardens simultaneously being devastated by a wind-storm, crop disease, pigs, or rats, and to obtain a wider variety of crops by planting at three different elevations in different climatic zones. Those New Guinea farmers are similar to Goland’s Andean farmers, except for planting fewer but larger gardens (on the average, 7 gardens with a range from 5 to 11 for the New Guineans, instead of 17 fields with a range from 9 to 26 for the Andean farmers).
Far too many American investors forget the difference, recognized by peasant farmers around the world, between maximizing time-averaged yields and making sure that yields never drop below some critical level. If you are investing money that you are sure you won’t need soon, just to spend in the distant future or for luxuries, it’s appropriate to aim to maximize your time-averaged yield, regardless of whether yields become zero or negative in occasional bad years. But if you depend on your investment earnings to pay current expenses, your strategy should be that of the peasants: make sure that your annual earnings always remain above the level necessary for your maintenance, even if that means having to settle for a lower time-averaged yield. As I write these lines, some of the smartest investors in the United States are suffering the consequences of ignoring that difference. Harvard University has the largest endowment, and has had the highest time-averaged endowment earnings rate, of any American university. Its endowment managers became legendary for their skill, success, and willingness to explore profitable types of investments previously shunned by conservative university investment managers. The salary of a Harvard manager was linked to the long-term average growth rate of the portion of Harvard’s portfolio for which that manager was responsible. Unfortunately, Harvard’s investment income is not reserved for luxuries or a rainy day but contributes about half of the operating budget of Harvard College. During the worldwide financial meltdown of 2008–2009, Harvard’s endowment principal and income crashed, as did so many other investments aimed at maximizing long-term yields, so Harvard was forced to impose a hiring freeze and to postpone indefinitely its billion-dollar plan for a new science campus. In retrospect, Harvard’s managers should have followed the strategy practised by so many peasant farmers (Plate 45).
Seasonality and food shortage
We have been discussing how traditional peoples cope with the danger of starvation arising from unpredictable fluctuations in food supply. Of course, there are also predictable seasonal fluctuations. Inhabitants of the temperate zones are familiar with the differences between spring, summer, fall, and winter. Even today, when food storage and long-distance food transport have evened out most seasonal variation in food availability in supermarkets, local fresh fruits and vegetables still become available on a predictable schedule. For example, near my home in Los Angeles is a farmers’ market that stocks only locally grown seasonal produce, such as asparagus in April and May, cherries and strawberries in May and June, peaches and apricots in June and July, squashes from July through January, and persimmons from October through January. In the temperate zones of North America and Eurasia, availabilities of other foods besides fresh fruits and vegetables also used to fluctuate seasonally, until modern storage and transport eliminated the fluctuations. There was an abundance of meat in the fall, when farm animals were culled and slaughtered; of milk in the spring and summer, when cows and sheep gave birth; of fish such as salmon and herring, which have predictable times of fish runs up rivers and along the coast; and of hunted migratory wild animals such as reindeer and bison at certain seasons.
As a result, some months of the temperate-zone year were times of plenty, and other months were predictable lean times when people knew that stored food might run out and that they would at least have to tighten their belts and at worst risk starvation. For the Greenland Norse, that lean season came each year at the end of winter, when they were close to eating up the cheese, butter, and dried meat stored from the previous year, but when their cows and sheep and goats had not yet given birth and so were not yet producing milk, the herds of migratory harp seals had not yet arrived along the coast, and the resident common seals had not yet landed on beaches to give birth. It appears that the inhabitants of one of Norse Greenland’s two settlements all starved to death at the end of such a winter around 1360.
Americans, Europeans, and other residents of the temperate zones tend to assume that tropical regions, especially near the equator, lack seasonality. While temperature is of course much less variable from month to month in the tropics than in the temperate zones, most tropical areas do have marked wet seasons and dry seasons. For instance, the town of Pomio in Papua New Guinea lies only a few hundred miles south of the equator, is very wet (260 inches of rain a year), and receives 6 inches of rain even in the driest month. However, the wettest months at Pomio (July and August) are 7 times wetter than the driest months (February and March), and that has big consequences for food availability and living conditions at Pomio. Hence people resident at low latitudes or even on the equator face predictable lean seasons, just as do traditional temperate-zone peoples. In many cases that lean season falls during the local dry season, which variously comes during the months of September and October for the !Kung of the Kalahari and for the Daribi people in the hills of Papua New Guinea, December to February for Mbuti Pygmies of the Congo’s Ituri Forest, and January for the Kaulong people of New Britain. But some other low-latitude peoples experience instead a lean season during their wettest months, which are December to March for the Ngarinyin Aborigines of Northwest Australia, and June to August for the Nuer of the Sudan.