Prehistoric extinction of birds on Mangaia, Cook Islands, Polynesia.

Mangaia (Cook Islands) consists of a weathered volcanic interior encircled by limestones known as the makatea. Excavations at Tangatatau Rockshelter (site MAN-44), located on the inner cliff of the makatea, produced a stratified sequence of Polynesian artifacts and faunal remains ranging from A.D. 1000-1100 to A.D. 1500-1600. Resident species of birds represented at MAN-44 include nine seabirds (at least three extirpated on Mangaia) and 12 land birds (eight extirpated or extinct). Seven of the extinct/extirpated land birds are confined to the site's four lowest stratigraphic zones, which represent the first 200-300 yr of human occupation at MAN-44. During this time, human exploitation of vertebrates switched from primarily native land birds to almost exclusively small reef fish, domesticates (chickens, pigs), and commensals (rats). Sediment cores from a lake 0.9 km from MAN-44 show clear palynological and stratigraphic signals of human presence on Mangaia, especially forest clearance of the volcanic interior, beginning at 1600 yr B.P. The rugged makatea must have provided a forest refuge for birds during the first 700 yr of human presence, after which Mangaians exploited the previously little used makatea because forest resources (trees, other plants, birds) had been depleted on the now badly eroded volcanic interior. MAN-44 is the oldest archaeological site known on Mangaia. Whether other species of birds were lost in the period of human activity that preceded occupation of MAN-44 remains to be seen.

Prehistoric agricultural depletion of soil nutrients in Hawai'i.

We investigated the fate of soil nutrients after centuries of indigenous dryland agriculture in Hawai'i using a coupled geochemical and archaeological approach. Beginning approximately 500 years ago, farmers began growing dryland taro and sweet potato on the leeward slopes of East Maui. Their digging sticks pierced a subsurface layer of cinders, enhancing crop access to the soil water stored below the intact cinders. Cultivation also catalyzed nutrient losses, directly by facilitating leaching of mobile nutrients after disturbing a stratigraphic barrier to vertical water movement, and indirectly by increasing mineral weathering and subsequent uptake and harvest. As a result, centuries of cultivation lowered volumetric total calcium, magnesium, sodium, potassium, and phosphorus content by 49%, 28%, 75%, 37%, and 32%, respectively. In the absence of written records, we used the difference in soil phosphorus to estimate that prehistoric yields were sufficient to meet local demand over very long time frames, but the associated acceleration of nutrient losses could have compromised subsequent yields.

Late Holocene human-induced modifications to a central Polynesian island ecosystem.

A 7000-year-long sequence of environmental change during the Holocene has been reconstructed for a central Pacific island (Mangaia, Cook Islands). The research design used geomorphological and palynological methods to reconstruct vegetation history, fire regime, and erosion and depositional rates, whereas archaeological methods were used to determine prehistoric Polynesian land use and resource exploitation. Certain mid-Holocene environmental changes are putatively linked with natural phenomena such as eustatic sea-level rise and periodic El Niño-Southern Oscillation events. However, the most significant changes were initiated between 2500 and 1800 years and were directly or indirectly associated with colonization by seafaring Polynesian peoples. These human-induced effects included major forest clearance, increased erosion of volcanic hillsides and alluvial deposition in valley bottoms, significant increases in charcoal influx, extinctions of endemic terrestrial species, and the introduction of exotic species.

On the genetic and cultural relationships of certain Polynesian outlier populations.

The results of a population genetic study of several Polynesian Outlier and Melanesian populations are compared with recent findings from archaeology. Certain remarkable correspondences offer independent confirmation of particular inter-island contacts and prehistoric population movements.

Interisland and interarchipelago transfer of stone tools in prehistoric Polynesia.

Tracing interisland and interarchipelago movements of people and artifacts in prehistoric Polynesia has posed a challenge to archaeologists due to the lack of pottery and obsidian, two materials most readily used in studies of prehistoric trade or exchange. Here we report the application of nondestructive energy-dispersive x-ray fluorescence (EDXRF) analysis to the sourcing of Polynesian artifacts made from basalt, one of the most ubiquitous materials in Polynesian archaeological sites. We have compared excavated and surface-collected basalt adzes and adze flakes from two sites in Samoa (site AS-13-1) and the Cook Islands (site MAN-44), with source basalts from known prehistoric quarries in these archipelagoes. In both cases, we are able to demonstrate the importing of basalt adzes from Tutuila Island, a distance of 100 km to Ofu Island, and of 1600 km to Mangaia Island. These findings are of considerable significance for Polynesian prehistory, as they demonstrate the movement of objects not only between islands in the same group (where communities were culturally and linguistically related) but also between distant island groups. Further applications of EDXRF analysis should greatly aid archaeologists in their efforts to reconstruct ancient trade and exchange networks, not only in Polynesia but also in other regions where basalt was a major material for artifact production.

Human skeletal and dental remains from Lapita sites (1600-500 B.C.) in the Mussau Islands, Melanesia.

The Lapita Cultural Complex, radiometrically dated to between 3,600 and 2,500 B.P., is regarded on archaeological evidence as ancestral to modern Austronesian-speaking cultures of eastern Melanesia and Polynesia. To date, there has been a lack of human skeletal and dental material from Lapita sites; thus, the present sample from Mussau Island, although small, offers an opportunity to present some preliminary observations of their importance to Oceanic prehistory. The present analysis, based mainly on teeth, suggests that the Mussau Island Lapita people had slightly closer affinities with Indonesian than with Melanesian populations. These results correspond well with linguistic and archaeological evidence regarding the origin of the Lapita Cultural Complex.

Soils, agriculture, and society in precontact Hawai'i.

Before European contact, Hawai'i supported large human populations in complex societies that were based on multiple pathways of intensive agriculture. We show that soils within a long-abandoned 60-square-kilometer dryland agricultural complex are substantially richer in bases and phosphorus than are those just outside it, and that this enrichment predated the establishment of intensive agriculture. Climate and soil fertility combined to constrain large dryland agricultural systems and the societies they supported to well-defined portions of just the younger islands within the Hawaiian archipelago; societies on the older islands were based on irrigated wetland agriculture. Similar processes may have influenced the dynamics of agricultural intensification across the tropics.

Environment, agriculture, and settlement patterns in a marginal Polynesian landscape.

Beginning ca. A.D. 1400, Polynesian farmers established permanent settlements along the arid southern flank of Haleakala Volcano, Maui, Hawaiian Islands; peak population density (43-57 persons per km(2)) was achieved by A.D. 1700-1800, and it was followed by the devastating effects of European contact. This settlement, based on dryland agriculture with sweet potato as a main crop, is represented by >3,000 archaeological features investigated to date. Geological and environmental factors are the most important influence on Polynesian farming and settlement practices in an agriculturally marginal landscape. Interactions between lava flows, whose ages range from 3,000 to 226,000 years, and differences in rainfall create an environmental mosaic that constrained precontact Polynesian farming practices to a zone defined by aridity at low elevation and depleted soil nutrients at high elevation. Within this productive zone, however, large-scale agriculture was concentrated on older, tephra-blanketed lava flows; younger flows were reserved for residential sites, small ritual gardens, and agricultural temples.