erosion.62 Based on these and similar geomorpholical changes seen on O‘ahu and elsewhere from prehistory and documented on Molokai in the historic period (detailed in chapter 3), it is reasonable to assume that the same processes were at work on Molokai prior to European contact in 1778, especially on the kona shore, with its shallow reef flats stretched out below the steep, dry, easily eroded southern slopes of the ancient volcanoes.
Polynesian expansion brought equally massive impacts to the biota. The fossil record shows wholesale extinctions of land snails and birds (these are far more easily preserved than insects and other invertebrates, about which little is known). Recent, startling discoveries in dunes at Mo‘omomi, Molokai, and in limestone sinkholes near Barber’s Point, O‘ahu, have revealed that the Hawaiians’ hunting and habitat destruction pushed at least one-half of the known land bird species, at minimum thirty-eight previously unknown birds, and between one-third and one-half of the land mollusks into extinction.63
With the depletion of easily obtainable wild foods came a greater reliance on agriculture, setting in motion a cycle of cropland expansion, agricultural intensification, and population growth, which in turn had their feedback regime in deforestation, followed by erosion, which affected nearshore reefs and bays, decreasing the productivity of the marine environment and in turn forcing an ever-greater reliance on agriculture.64 For Hawaiians, it was a mixed bag: there was less wild food but more farmed from pondfields, terraces, and fishponds—more reliable and less vulnerable to drought, weather, and pests. A fragile environment had been transformed into a rich agricultural landscape. However, this change came at a price—one perhaps higher in social terms than in environmental losses.
PATTERNS FROM PACIFIC ANTHROPOLOGY
Events in Hawai‘i were part of a broad pattern across Polynesia of anthropogenic environmental change, almost always following a version of the same script: early exploitation of wild foods, leading to extinctions, especially of birds; deforestation for swidden agriculture aided by fire and introduced animals, leading to erosion and dessication; and agricultural intensification in response to slope erosion, population growth, and decreasing productivity of the nearshore marine environment. The transformation of once-forested landscapes on Pacific islands following Polynesian settlement into treeless grasslands or fernlands dominated by pyrophytic plants has been extensively documented. It was especially emphatic in New Zealand, Mangaia, Easter Island, and the Marquesas, as well as Hawai‘i.65
Across the Pacific, archaeologists have found evidence of colonization: charcoal and fossilized bones, shells, nuts, and pollen well preceding the first dated habitation sites.66 This is an indication of both the odds against the preservation of early coastal sites on unstable, flood-prone sand dunes and the odds against successfully locating and excavating them. But in significant part, this is because the environmental degradation set in motion by the arrival of humans was devastatingly rapid. This fact is due to Polynesian practices, as we have seen, but also, significantly, to the structure of island biogeography that gives island biotas “their extreme vulnerability, or susceptibility, to disturbance,” in the words of botanist Raymond Fosberg.67 In remote Polynesia—and nowhere there more so than Hawai‘i—island biogeography reaches its apogee. Just as the forests had evolved without fire, rooting pigs, or dessication, birds—whether seabirds nesting on the exposed ground by the millions or geese that had actually lost their ability to fly—had never been hunted, by humans or rats, and quickly succumbed to both. The Polynesians in their march encountered flightlessness on nearly every major island they settled; the record of extinctions in Hawai‘i is matched generally by all major Pacific island groups so far adequately studied. In New Zealand, for example, the thirteen species of moa (in Maori, as in Hawaiian, meaning chicken or chicken-like running birds) were virtually all eliminated by Polynesian settlers. A poignant detail is provided by the fact that Polynesian sailors knew that unusual concentrations of seabirds over the open ocean indicated the proximity of uninhabited islands. “It is no exaggeration,” Kirch writes, “to say that among the Remote Oceanic islands, the ‘biodiversity crisis’ began not recently but 3,500 years ago with the Lapita expansion.”68
These outcomes are not cases of environmental determinism in history but the complex and dynamic interaction between Polynesian social structures, economies, introduced organisms, and a series of similar yet unique island environments—outcomes predictable, to some extent, based on the variables involved yet different on every island. Patrick Kirch invoked Charles Tilly’s concept of “historically grounded huge comparisons of big structures and large processes” to “help establish what must be explained” and to shine light back on the human, contingent, and social causes.69 Historical environmental change visible to the techniques of anthropology is one such large process, played out at the level of the island: “An ecological process with enormous consequences for island landscapes and for island cultures . . . In these large environmental ‘structures’ one seeks clues to certain big processes of political economy.”70
One such locus is how population growth interacts with the environment. Archaeological evidence sketches a series of similar progressions across most of the Pacific that accord with mathematical models of demographic increase. Most every place in Remote Oceania, on the eve of European contact, had reached a near-maximum population density.71 Remote Oceania (Polynesia, Micronesia, and extreme eastern Melanesia) had much higher growth rates than Near Oceania (most of Melanesia and insular Southeast Asia) for several conditions and reasons. The first was a better disease environment, with no mosquitoes capable of carrying malaria east of the Solomons, due to the same dispersal difficulties encountered by other immigrants to remote islands. Next in importance were plentiful marine and terrestrial foods, at least initially; the lack of competing human inhabitants on arrival; and the cultural reasons for high fertility and voyaging already discussed.72
In every case, there is a familiar relationship between population increase, agricultural expansion and intensification, and environmental degradation. Equally strong is a corollary relationship between environmental stress and increasing social hierarchy. Kirch in On the Road of the Winds uses as his textbook case that of the island of Mangaia, in the southern Cook Islands, because of its extreme geological features and history of environmental and social disaster. It is an ovoid island, fifty-two square kilometers, with an eroded volcanic core surrounded by makatea ramparts as much as two kilometers wide. This is a limestone karst landscape riddled with caves and sinkholes and deeply cut by small streams that nearly disappear into the ground before ponding against the ramparts near the coast and dropping their sediment load. At these edges are swampy basins ideal for irrigated kalo culture but that account for just 2 percent of the total land area, with no more than another 18 percent available for dryland agriculture. Pollen coring and stratigraphy indicate that the island possessed extensive forests and marine and terrestrial resources, including a rich bird fauna, prior to human colonization about twenty-five hundred years ago. These resources were heavily exploited and crashed, resulting in faunal extinctions and the replacement of the forest with a pyrophytic landscape of scrub ironwood and ferns. The human population, divided into six districts with each ruled by a hereditary chief, eventually reached 150 persons per acre—very high even in Polynesian terms. Over time, competition for land became so severe that the political economy devolved into a permanent state of intertribal raiding and war, with victors seizing irrigated bottomlands and defeated groups taking refuge in cave systems on the upland makatea. There is plentiful evidence of human sacrifice and potentially outright cannibalism. In Kirch’s words, “Late precontact Mangaian society became . . . a society based on terror.”73 Similar trajectories are visible in the Marquesas; parts of New Zealand; Mangareva, which has some of the worst land degradation in Polynesia; and, most famously, Rapa Nui (Easter), where total deforestation led to spectacular social collapse, descent into warfare, cannibalism, and population crash.
In each case of environmental degradation, there was a parallel political evolution from a social hierarchy based on rigid hereditary chiefships to a more fluid one based on earned status, typically in the military sphere. In Mangaia and elsewhere, this transition proceeds in lockstep with the progress of environmental degradation. Kirch has described the process as “competitive involution” (borrowing and enlarging a concept from Clifford Geertz) where rapid population growth