Environment

Micronesian islands have a tropical climate with small seasonal changes. However, there are some marked differences in rainfall patterns. Islands in the western part of Micronesia frequently have a higher precipitation in June and July and a drier season between February and April. Larger volcanic islands to the east such as Pohnpei and Kosrae receive more rainfall annually than the others. In fact, Pohnpei is considered to be one of the wettest places on earth, with an astonishing 300-400 inches of rainfall every year. The southern Marshall Islands, for example, typically receive more rainfall than the northern ones, and the opposite is true for the Gilberts (Kiribati).

There are four main island types in Micronesia - high volcanic (e. g., Pohnpei, Kosrae), island-arc (e. g., Palau, Yap), raised coral or limestone (e. g., Fais, Satawal, Rock Islands), and coral atoll (e. g., Kayan-gel, Ulithi, the Marshalls). The western part of Micronesia (Western Carolines, Marianas) lies west of the Andesite Line, which separates the deeper, igneous rock of the Central Pacific Basin from the partially submerged continental areas of acidic igneous rock on its margins. Japan, the Philippines, Indonesia, New Guinea, and New Zealand are all eastward extensions of the continental blocks of Australia and Asia and lie outside the Andesite Line. Within the closed loop of the Andesite Line are most of the deep troughs, submerged volcanic mountains, and oceanic volcanic islands that characterize the Central Pacific Basin. Here, basaltic lavas gently flow out of rifts to build huge dome-shaped volcanic mountains whose eroded summits form island arcs, chains, and clusters. Outside the Andesite Line, volcanism is more explosive, and the so-called Pacific rim of fire is the world’s foremost belt of volcanic activity.

The most prevalent island type in Micronesia is the coral atoll. These are remnants of submerged volcanic peaks that have emergent coral reefs developed on the uppermost fringe of the peaks. They usually have a deep lagoon or several smaller ones with coral sand beaches. Freshwater must either be collected from rainwater in some type of catchment or from wells dug into the island’s interior to tap what is known as the Ghyben-Herzberg lens (a lens of freshwater that lays atop the denser saltwater). The majority of coral islands extend in an arc east to southeast from the Caroline Islands through the Marshalls, Kiribati, Tuvalu, Tokelau, and Tuamotu. Chuuk, for example, primarily consists of coral atoll reef islets that surround an immense lagoon approximately 2125 km2 in area, although there are a few volcanic islands found in the southern half of this group. Studies on climate changes during the Late Holocene have shown that atolls in Micronesia were not able to form until sea level, which was steadily rising, had begun to stabilize to its present-day height.

Because of their insular nature, islands in Micronesia have an impoverished fauna, especially in terms of terrestrial species. A number of these, including the fruit bat (Pteropus spp.), coconut crab (Burgis latro), and various species of crabs, were eaten in the past and are still relished today. Archaeological evidence suggests that pigs (Sus scrofa), dogs (Canis famil-iaris), two different species of rats (Rattus rattus mansorius and Rattus exulans), and possibly chicken (Gallus gallus) were introduced by native peoples.

But, these were typically not aLl present on every island. Prior to the historic period, a variety of bat, bird, crab, frog, and snake species were present.

Marine resources such as fish and shellfish played a more prominent role in the diet of prehistoric Micro-nesians compared to terrestrial animals. The green (Chelonia mydas) and hawksbill turtles (Eretmo-chelys imbricata) were important for their meat and carapaces and shellfish were heavily exploited for both food and manufacturing tools. Of these, giant clams (tridacnids) was preferred for their meat, dense shell for making tools (particularly adzes), and probably as containers. Other species such as Terebra, Conus, Mitre, Anadara, Cassis, Trochus, and Pinctada shells were important for producing adzes, fishhooks, graters, beads, or ornaments. Other invertebrates used by Micronesians as food include sea urchins (Echinoidea), the sea worm (Sipuncula), starfish (Asteroidea), sea cucumbers (Holothurioidea), octopus (Cephalopoda), shrimp (Natantia), and various crustaceans. Animals transported by humans to the islands such as pigs (identified only from Palau and Fais) and dogs may have supplemented the diet, although neither seems to be found in any great quantities at archaeological sites.

Although marine foods were abundant and an important source of protein and calories, plants introduced by humans were critical to the long-term survival of human groups. These crops included bananas (Musa spp.), coconuts (Cocos nucifera), taro (Colocasia esculenta and Cyrtosperma chamissoni; rarely Alocasia macrorrhiza), breadfruit (Artocarpus altilis), yams (Dioscorea alata, D. nummularia, D. pentaphylla or cumingi), and pandanus (Pandanus tectorius). The Polynesian chestnut (Inocarpus edulis) also provided an additional source of food for some peoples. In general, taro and yam are most preferred in the west, while breadfruit was more of a staple in the east (Figure 2).