inherently contradictory hereditary and achieved status positions.74 The result was an involuted cycle of prestige rivalry and competition that led as often to the destruction of the very means of production which were the objects of competition.”75
Easter Island is only the radical nightmare scenario of population “overshoot” of scarce resources leading to social collapse; to lesser degrees this process was ongoing in much of Polynesia by the eighteenth century. Fortunately, in only a handful of them had conditions worsened to such a grim point. These few, extreme examples naturally come from islands with marginal environments, whether due to makatea geology, remoteness, and/or small size—as with Henderson, Pitcairn, or the ten other small islands that Polynesians once inhabited but had abandoned by the time of European contact.76 This can help explain the rapidity of their transit through the phases Kirch catalogs—which we might better call socioenvironmental involution. Other places in Polynesia, with fewer obvious environmental limitations, appeared to be pushing against the door of involution in late prehistory: Tonga, the Societies, and other islands in the Cooks among them. While not every case of environmental vulnerability produced competitive involution, much less crash, the record promises some ability to predict these trajectories based on geography; after all, as Braudel formulized, “living standards are always a question of the number of people and the total resources at their disposal.”77 A bigger question is: What can the record of how they choose to dispose of their resources teach us?
EXPANSION INTO THE DRYLANDS
A new agricultural form appeared in Hawai‘i around AD 1400: intensive cultivation of ‘uala and other crops in unirrigated field systems constructed on broad slopes, mostly in leeward areas. Like the other Hawaiian farming types, this intensive rain-fed, or dryland, cultivation was unevenly distributed across the islands, being possible only where the right conditions existed: rocks old enough to form soils but not so old as to be leached and nutrient-poor, combined with enough rainfall to grow crops of mainly ‘uala, supplemented with dryland taro and kō but not so much as to leach away necessary nutrients. This “sweet spot” for sweet potatoes can be found only on the eastern islands—Kaua‘i and O‘ahu are too old geologically—and principally on the broad, unincised leeward slopes of Hawai‘i and East Maui running in horizontal bands between the dry coastline makai (below) and the wet forest mauka (above).78 On Maui, the Kahikinui and Kaupo field systems wrapped around the southeastern, leeward slopes of Haleakala; on Hawai‘i, traces of extensive field systems have been found in Kohala, Waimea, Kona, and Ka‘u. The best-preserved and most extensively studied, the Lower Kohala field system, covered sixty square kilometers over parts of thirty ahupua‘a and large ‘ili ‘āina with a dense, reticulate grid of stone walls delineating terraced gardens, water catchments, planting mounds, and trails, which also formed field boundaries. Interspersed among the productive infrastructure were house platforms, burial platforms, temples, and middens.79
The dryland fields were by nature less reliable food producers than irrigated pondfields, depending as they did on the vagaries of rainfall in a marginal environment where drought is a regular occurence. Kirch has suggested that farming families coped with the risks of variable climate by employing “bet-hedging agronomic strategies,” planting crops at several locations up and down the slope and thus, the rainfall gradient, to maximize their chances of a return.80 They also required more labor for weeding and especially mulching, including for “lithic” mulch, stones used to slow wind- and water-driven erosion and evaporation of moisture.81 On Maui and Hawai‘i, the women joined the men in the fields—something unknown on the other islands.82 The native Hawaiian historian David Malo wrote: “On lands supplied with running water, agriculture was easy and could be carried on at all times . . . On the kula lands farming was a laborious occupation and called for great patience, being attended with many drawbacks.”83 Areas of dryland culture, with unreliable water and thin, volcanic, chemically impoverished soils in place of the rich valley soils, were inherently marginal and more vulnerable to drought, fire, erosion, and soil exhaustion. Beyond these physical difficulties were social ones: Samuel Kamakau noted that “the women worked outside as hard as the men, often cooking, tilling the ground, and performing the duties in the house as well. This is why the chiefs of Hawai‘i imposed taxes on men and women alike and got the name of being oppressive to the people, while the chiefs of O‘ahu and Kaua‘i demanded taxes of the men alone.”84 Nevertheless, the enormous size of the larger field systems supported large populations: the Lower Kohala system may have been capable of supporting 15,480 to 30,960 persons, while the Kona field system’s population has been estimated at between 47,300 and 94,600.85 From its initial appearance, dryland cultivation on the eastern islands exploded, feeding populations that may have doubled in a single lifetime.86 By the end of the precontact period, Maui depended on rain-fed crops for 70 percent of its food, while the percentage on Hawai‘i reached 94 percent.87 On Molokai, soils on the leeward slopes with the correct rainfall were too old—most had formed from volcanic eruptions up to 1.4 million years earlier—and thus too mineral-poor for extensive field systems. But at Kalaupapa Peninsula, the “stone leaf” formed at the base of the windward sea cliffs by an eruption 330,000 years ago, ideal soil conditions combined with a rainfall band between nine hundred and thirteen hundred millimeters to allow a very productive ‘uala field system, begun about 1400 and encompassing at its zenith in the nineteenth century a grid of up to four thousand walls covering a combined 230 kilometers, according to partial surveys.88
Studies of the dryland field systems indicate that they, like the irrigated valleys but in an accelerated amount of time, followed the path of intensification. Likely beginning as long fallow swidden areas carved out of the mesic forest to help support small numbers of people, they gradually became more permanent and more intensive, with labor needs and population growth rising reciprocally, leading to the rapid expansion of the area under cultivation but also to increased subdivisions within the fields.89 Productivity also trended downward as nutrients were depleted, spurring farmers to shorten fallow periods and increase mulching.90 Robert Hommon summarized the probable net effect on the dryland farmers: “Increased labor requirements, the addition of field work to women’s traditional tasks, diminished productivity, rapid population growth, reduced soil fertility resulting from shortened fallow, government levies, and finally infrastructure development that reached the limits of cultivable land—probably led to an increased frequency and degree of food stress among the commoners who were dependent on rain-fed systems.”91
Even so, the inherent instability of the dryland field systems slowed neither their expansion nor the increase in overall average production as well as population. This is in contrast to the situation in the older, western islands of Kaua‘i, O‘ahu, and probably Molokai, where the population, after expanding enormously from 1400 to 1650, reached a peak in 1650 and then went into a slow but steady decline.92 Yet on Maui and Hawai‘i, population continued to grow from 1650 to contact.93 Had population in the western islands reached the limits of their environment’s carrying capacity, or were other processes at work?
Patrick Kirch outlined a theory of why population growth in Polynesia slowed, oscillated, or even reversed in many places at or about the same time: the “full land” scenario, where population pressure was felt first in a lack of access to land, not in constrained food supply, “which could often be offset through” intensification. Population densities of one hundred people per square kilometer or higher were not uncommon on many Polynesian islands, without causing famine. Instead, “cultural controls on population growth began to be implemented,” including “means of reducing fertility (celibacy, contraception, abortion), as well as of increasing mortality (infanticide, suicide voyaging, war, expulsion of certain groups, ritual sacrifice, and even cannibalism).94 The most successful of these societies self-regulated to adapt to their resource base before their diminishing resource base did the regulating for them.
The fact that agricultural intensification is, if not entirely independent of demography, at least not deterministically produced by population pressure is one of the most interesting discoveries of Pacific anthropology. Instead, it is dependent on social variables. There is a primary relationship between production and power. In anthropological theory