by Brian Fagan
The same strategies of broad-based diet and mobility worked well over thousands of years of climate change, but just how severe were conditions in the Mojave a thousand years ago? Here, too, climatologists rely on an esoteric data source, the tiny middens accumulated by pack rats (Neotoma). Between A.D. 600 and at least 1200, the middens contain vegetation from arid surroundings, with few signs of water-loving plants. Furthermore, between 900 and 1300 there are virtually no records of increased spring activity or high lake levels, both characteristic of the Little Ice Age that followed. There was certainly less winter rainfall than in earlier and later times.
Extended droughts in the Mojave after A.D. 800 would have abridged water sources of all kinds and reduced spring discharge. The shallow desert playa lakes, normally magnets for game and waterfowl, would have dried up. Water supplies would have been scarce and widely dispersed, and the risks of traveling to locate them in an arid landscape correspondingly larger. The few archaeological sites that date from A.D. 800 to 1300 lie near major springs and in perennial oases along the Mojave River, where the groundwater was close to the surface even during sustained droughts. Elsewhere, the desert was effectively uninhabitable, except, perhaps, for a few weeks after rare major rainstorms. Life during the Medieval Warm Period was difficult, existence often marginal, but for those adapted to the environment, the droughts were survivable.
Nothing demonstrates the volatility of life in the desert better than the life and death of Lake Cahuilla.11 Every spring, the Colorado River to the east of the Mojave rose in flood, alternating among channels in its enormous delta. Sometime around A.D. 700, a prolonged shift of the river caused water to flow into the low-lying Salton basin, which filled like a bathtub to a height of about 42 feet (13 meters). At its height, this inland sea was 115 miles (185 kilometers) long, up to 35 miles (56 kilometers) across, and 314 feet (96 meters) deep, one of the largest lakes in North America. The great lake survived for more than six centuries as an overflow for the Colorado, until rising silt levels blocked the entry channel. The lake became a closed basin and dried up within a half century or so.
Thanks to the Colorado floods, Lake Cahuilla remained relatively stable for hundreds of years, its water level varying by 3 feet (1 meter) or so. Geological surveys have shown that the lake was full during most of the warm centuries. The sudden appearance of a huge lake in the midst of an extremely arid landscape was a godsend to local hunter-gatherer groups during a period of persistent drought, but, unfortunately, the water was too saline to drink. Numerous short-term camps flourished along the lakeshore, occupied when people caught fish or trapped and hunted the waterfowl that abounded there.
Throughout the Mojave and the Great Basin, the warmer centuries rendered much of the landscape uninhabitable. Food was less readily available; bands foraged over much smaller areas, only within walking distance of water. Competition for food intensified, and social relationships came under severe stress. Small bands would have coped with reduced nut harvests, families elbowing out their neighbors at the few stands of wild grasses in spring. Words would be exchanged, curses would lead to blows and perhaps even to sneak attacks with clubs and spears. In the end, the group would split up as one party to the dispute would move away to camp with relatives or to found a new settlement. The social environment would have been volatile, charged with anxiety and stoic acceptance of hunger and thirst.
Survival in the arid American West depended on cooperation and, above all, on intelligence about water supplies and food resources scattered over enormous, harsh landscapes. These landscapes were inconspicuously edible living environments when there was water, but utterly devoid of food when drought came and the desert pump expelled animals, people, and plants to the margins. What was for Europe and the Arctic a time of relative climatic benevolence was for vast areas of the arid American West a time of deprivation and suffering, even among peoples who knew that flexibility and mobility were the elixirs of life. But their environmental knowledge and opportunism helped them survive, perpetuating a lifeway that had survived extremes of flood and drought for many thousands of years in some of the toughest environments on earth.
CHAPTER 7
Acorns and Pueblos
If the drought withered the corn shoots, if the buffalo unaccountably shifted, or if the salmon failed to run, the very existence of people in other regions was shaken to its foundations. But the manifold distribution of available foods in California, and the working out of corresponding means of reclaiming them, prevented a failure of the acorn crop from producing similar effects. It might produce short rations and racking hunger, but scarcely starvation.
—Alfred Kroeber, Handbook of the Indians of
California (1925)1
THE CHANNEL IS GLASSY SMOOTH, the ridges of the snowcapped mountains razor clear against the sharp blue sky of the winter day. The crews paddle in the lightest of southeasterly airs, relishing the calm after the strong northwesterlies of the day before that had followed the rain and snow of a strong winter storm. The ocean slowly turns a gorgeous, roseate pink with the westering sun, a color that lingers long after sunset. Basking sharks move lazily close to the surface, their fins and tails moving imperceptibly in the calm. The weathered, planked canoes glide swiftly over the mirrorlike water, taking advantage of the calm instead of “the very high waves of the Pacific Sea, which, at times, seem to lift them as far as the clouds and at other times to bury them in the bottom of the sea.”2 The paddlers crouch on sea grass pads, paddling steadily, hour after hour, chanting the same canoe song over and over again, as a boy huddled in the bottom of the boat bails with an abalone shell. The echoes of the canoe chant float on the still air as the afterglow of sunset fades and the men come close to land.
The great droughts of the warm centuries in the American West tested ancient strategies of movement to the limit. People died; there was certainly hunger; in some areas, such as southern California, there were startling changes in the nature of society itself, which became more hierarchical, even more despotic. But, through it all, the inhabitants of the West quietly survived. Their traditional lifeways would have continued indefinitely, had not European explorers, then missionaries and settlers, introduced new, totally unfamiliar factors into cultural equations that had thrived for centuries, even millennia.
By no means all western societies lived in desert landscapes. As one moved west toward the Pacific, the varied terrain of what is now California supported some of the most diverse environments on earth—small mountain valleys, local wetlands, and lush valleys with shallow lakes. In some areas—San Francisco Bay and the Santa Barbara Channel for instance—rich maritime fisheries, shellfish beds, and sea mammal rookeries provided so much food that many groups could remain in one place for most of the year if not all. Away from the ocean or permanent rivers and lakes, people relied heavily on wild plants, on widely scattered foods that came into season at different times of the year. Every forager, young or old, male or female, had an encyclopedic knowledge of edible environments, but people were constrained to move constantly to exploit them. This mobility reduced some of their vulnerability to drought cycles, but, with the notable exception of the drought-susceptible piñon, few plant foods could be stored for any length of time. Bands living in some parts of the Great Basin and over much of California came to rely on a surprisingly nutritious staple: the carbohydrate-rich acorn.
Acorns came into use wherever oaks grew in California after about 2000 B.C., at first as a supplemental food. This was a time when the climate was cooler and wetter than today and California’s population was rising steadily. Both grass seeds and other long-utilized plants became scarcer as a result. We know there was hunger, because human skeletons dating to earlier than 1000 B.C., before acorns came into widespread use, display many more signs of malnutrition, such as Harris lines (lines that appear in limb bones as a result of temporary retardation of growth) and dental hyperplasia (layers of defective tooth enamel in children) than later burials. The chan
geover to intensive acorn consumption may well have resulted from overcrowding, more frequent food shortages, and malnutrition episodes. Interestingly, once acorns became a staple, the incidence of dental caries increased dramatically, owing to a carbohydrate-rich diet.3
Once the changeover took place, each band readily accepted the extra labor involved in processing and storing acorns, which provided much more abundant and nutritious food. The staple could be stored in quantities so large that many harvesters collected a full year’s supply in a few weeks. The only other solution to recurring hunger would have been to start growing maize and beans, just as people were doing in the Southwest. The acorn foragers were well aware of agriculture, but why take the trouble of clearing fields and growing crops when acorns are ready to hand? By the time of Christ, the acorn was a staple of California life from Oregon to the southern deserts.
The acorn did not revolutionize life in the California of a thousand to fifteen hundred years ago. This humble nut merely made food supplies more predictable for people living in a more crowded and territorially circumscribed world. But, during the prolonged droughts of the Medieval Warm Period, heavy dependence on acorns increased the risk of famine, for the acorn harvest was seriously affected by dry conditions.
A.D. 1100. A grove of California oaks on a hot fall day. The bright sunlight casts fretted shadows on the ground during the hectic weeks of the ancient acorn harvest. The band has carried stacks of empty baskets to the trees early in the day. While the older men hunt for deer that feed on the rich mast from the oak groves, young boys leap into the branches and shake the boughs gently. Ripe acorns shower the women and elders. They laugh as they gather the plump nuts into baskets, combing the ground carefully, quickly discarding cracked or rotten nuts, keeping only those that will store well. As the youths climb more trees, the women carry the full baskets back to camp, where they dump the acorns on dry hides. The harvest continues from dawn until dark, for there are only a few days in the year when the acorns are easily harvested.
Early Californians were by no means the first people in history to rely on acorns. Entire villages in Syria subsisted off acorns fourteen thousand years ago. Medieval European farmers consumed bushels of acorns; so did native Americans in the Midwest.4 As late as the nineteenth century, acorns provided about 20 percent of the rural diet in Italy and Spain. But acorns were nowhere so important as they were in California, with its highly varied environment and endemic droughts. They have excellent nutritional value and are also highly tolerant of storage. Under favorable circumstances, they will keep for up to two years in large baskets or specially built granaries, a priceless quality for people who lived in unpredictable environments. By A.D. 500, thousands of California Indians depended heavily on the immense acorn harvest. At Spanish contact in the sixteenth century, native Californians harvested more than 66,000 tons (60,000 metric tons) of acorns a year— more than the industrialized sweet corn crop in the state today. For many groups, acorns constituted over half the diet. The ancient precaution of a broadly based diet had yielded in the face of abundance.
We know a great deal about acorn consumption, thanks to finds of acorn fragments in numerous archaeological sites, also the grinders and pounders used to process them. Fortunately, too, we have an archive of information about the harvesting, processing, and storage of acorns from both observations of traditional societies and modern-day consumption practices. Balanophagy, acorn eating, flourishes, for many people swear by tasty acorn bread. As a result, we have a great deal of information on this all-important ancient (and modern) food.
Fifteen species of oaks grow from Oregon to California. In good years, California oaks could yield as many as 1,728 pounds/2.5 acres (784 kilograms/hectare), a yield rivaling that of medieval agriculture in Europe and sufficient to support fifty to sixty times more people than lived in California when the Spanish arrived. Unfortunately, however, the harvest fluctuated from grove to grove, even from tree to tree, and most oak species produced a good crop only every two or three years. The ancient foragers, well aware of this, responded by harvesting acorns from different areas. The long storage life of acorns helped compensate for irregular harvests, but acorns have other serious disadvantages. They are a labor-intensive crop, not so much to harvest as to process. Shelling and pounding them is just the beginning, for because of the bitter-tasting tannic acid they contain, they are inedible unless soaked in water.5 Processing acorns took far longer than grinding seeds, by one estimate about four hours to produce 2.4 pounds (about 1 kilogram) of meal from 5.9 pounds (2.7 kilograms) of pounded acorns. But the effort was well worth it, for the nuts or processed flour could be carried on long journeys or in canoes, as well as used to make nourishing breads and gruels.
By the time the Medieval Warm Period began, around A.D. 900, most forager groups spent more and more of their time in permanent base camps within narrow compasses of territory, in many cases traveling no more than some 5 miles (8 kilometers) from their homes during their entire lives. The small sizes of tribal territories also made each group dependent on others. When droughts reduced the productivity of the environment, kin ties with other groups became very important as a way of acquiring food. Each group had control over local food supplies, such as, for example, acorn groves, fishing pools, or reliable stands of edible seeds. These they exploited more intensively than they would for their own needs, passing food to widely separated communities as part of a complex web of interconnectedness that linked dozens of small villages and the individuals who presided over them.
One could not survive in California’s highly localized and varied environments without the help of others. The range of artifacts and commodities exchanged between communities takes one’s breath away—all kinds of foodstuffs from acorns and game meat to mollusk flesh, as well as other essentials such as salt and medicinal plants. Asphaltum, for waterproofing baskets, changed hands, as did basketmaking materials and bow wood. Obsidian, a volcanic glass, was highly prized and found at only a few locations, for example Medicine Lake Highlands in northern California. Fortunately, obsidian from different locations has distinctive trace elements that can be identified by spectrographic analysis, so we know that obsidian from Medicine Lake traveled over 50 miles (80 kilometers) from its source.6 Millions of abalone and Olivella seashell beads circulated through California during the warm centuries, as populations rose and territories became smaller. The ancient Mojave trail carried Pacific shell beads as far as agricultural communities in the Southwest. Other bead strings passed from hand to hand deep into the Great Basin. But most trade was purely local, between people who depended on one another for essential commodities in increasingly circumscribed environments.
The prolonged droughts of the Medieval Warm Period played havoc with long-established trading arrangements. Live oaks are susceptible to drought, which reduced acorn harvests considerably over and above the normal interannual fluctuations. We know little about the effects of long-term drought on these trees, which are well adapted to long dry seasons, but seasonal aridity and multiyear dry cycles are different matters. For instance, between 1986 and 1992, a six-year drought killed thousands of oak trees in coastal central California, especially those growing on south-facing slopes, which tend to be drier and with less fertile soils. About 10 percent of all oaks, regardless of species, had perished by 1992.7 Had not 1993 and later years been wetter, the mortality would have increased dramatically, well above the normal casualty rates from fires, insects, and other causes. Project the 10 percent figure back a thousand years and factor in prolonged, repeated droughts, and the effects on acorn harvests must have been brutal.
Unfortunately, archaeology is an anonymous record of history, so the voices of those who lived through the dry centuries are silent. Only a few shreds of evidence come down to us, including some skeletons from two Yokut Indian cemeteries from the San Joaquin Valley discovered during the construction of the Interstate 5 freeway. The burial places bracket the medieval droughts and were
used by people who relied heavily on acorns. Using computer tomography, the biological anthropologist Elizabeth Weiss measured the cortical thickness of femurs, a cumulative dimension that reflects changes in diet and nutrition over a person’s lifetime.8 She found that the individuals buried in the earlier cemetery, which dated to about two thousand years ago had thicker cortical bone and fewer pathologies or traumatic injuries than those from the burial ground dating to between eleven hundred and twelve hundred years ago, the time of prolonged drought. These people had thinner cortical bone, lived shorter lives, and manifested many more injuries, as well as showing evidence of malnutrition.
Acorns were certainly inadequate protection against prolonged drought for people who relied on little else for their diet, but we need another generation of research to fill in the details.
THE SITUATION WAS somewhat different in areas around San Francisco Bay and in the Santa Barbara Channel region, where rich marine environments allowed people to settle in the same place for long periods of time. In the case of the Santa Barbara Channel, natural upwelling close inshore provided rich anchovy harvests, except in occasional El Niño years, when rising sea surface temperatures affected marine productivity. But even in these favored areas, life was uncertain, especially when drought affected drinking water supplies.
The Santa Barbara Channel, south of Point Conception, is another climatic Rosetta stone, site of an exquisitely precise 656-foot (200-meter) deep-sea core that extends 160,000 years into the past.9 The uppermost 56 feet (17 meters) represent the past eleven thousand years, and rapid sedimentation rates on the sea floor provide fine-grained climatic information. We actually have a record of temperature change at 82-foot (25-meter) intervals over the past three millennia. The core abounds in two species of planktonic foraminifera, one that dwelled close to the surface, the other inhabiting a depth of about 197 feet (60 meters). By analyzing the oxygen isotope content of these organisms and radiocarbon-dating twenty samples of the tiny shells, the oceanographer James Kennett has been able to reconstruct cycles of changing sea surface temperatures within a regimen that was generally reasonably warm, around 54.5 degrees F (12.5 degrees C) on average.9 From the Kennett temperature curve, we learn that there were warmer sea temperatures between about 2,900 and 1,500 years ago, with a colder cycle following between 1,500 and 500 years before the present, after which the temperature warms until modern times. The coldest sea surface temperatures since the Ice Age fell between 1,500 and 500 years ago, centuries that included the Medieval Warm Period.
