User:M.Grotz

Introduction
The archeology of the Arenal region of northwestern Costa Rica is defined by a unique dynamic between people, time, and the Arenal Volcano. The region is situated within the greater cultural context of the Isthmo-Colombian area. This area is characterized by extraordinary diversity and, while greater cultural patterns are in play, the highly variable topography, ecology, and climate of the area tends to resist broad generalization and therefore, in as much as environmental and physical factors have a role in shaping culture, cultural features are often quite unique. This holds true for the Arenal region as well, which in itself can be divided into four river systems with their own distinctive spatio-temporal archeological characteristics: the Rio Santa Rosa Valley, the Rio Canas Valley, the Cuenca de Arenal, and the Rio Arenal Valley. Yet, the influence of the larger cultural and ecological contexts of Greater Nicoya and the Atlantic Watershed also can be detected in the material cultural of the Arenal region during the Arenal and Silencio phases. Evidence of expansive cultural diffusion after AD 500 has been linked with volcanism and, consequently,  the  Arenal region may be viewed as an representative abbreviation of the Isthmo-Colombian area from the paleo-indian diffusion to the emergence of social complexity.

Terrestrial Features
The region is comprised of multiple microenvironments, a phenomenon which Sheets (1994) adds likely influenced land use and the choice of the locations of settlements in order to take advantage of each environment in line with their respective strengths and weaknesses. The Holdridge life zones can be used to interpret this feature of the region as it would pertain to the projected prehistoric and archaic environment. The five life zones of the region include: the Tropical Wet Forest, probably avoided by early peoples who preferred dryer climates; the Wet Tropical Forest, in which three sites have been found, but in which the climate is detrimental to seed crops; the Premontane Wet Forest, in which thirty-two sites and the Silencio area are located; the Tropical Moist Forest, in which twenty-three sites have been found, the soil being the most fertile of the zones and less susceptible to erosional hazards; and the Humid Premontane Forest, provisionally investigated, where soils would require irrigation during the dry season. The heavy winds of the Tilaran-Arenal area come from a northeasterly direction and range from speeds up to 14.5-30 Km per hour. Wind severely deforms large scale mono-cropping to this day, yet strategies of intersylvian farming were developed by early Arenal peoples as an adaptation to these windy conditions. The Arenal area is also cloudy much of the time especially in the eastern half of the area, another factor that can hinder the growth of cultigens. Nonetheless, researchers have found macrofossils, phytoliths, and pollens of many useful wild and domesticated species including: nance, avocado, coyol and corozo palms, maize, squash, and jícaro (Crescentia alata), which indicate that early inhabitants developed a highly successful subsistence pattern skillfully utilizing the diversity and particularities of the environment to their advantage.

Settlement within the reach of an active volcano provided benefits as well as dangers for early peoples. The earliest settlers in the region predated volcanic activity, but soon afterward the activity of the volcano became a dominating feature of the environment. Tephra, initially ruinous to the affected flora and fauna, would eventually degrade into a rich source of carbon to be utilized by plants and these by animals and so on up the chain. Erupted material in the form of basalts, andesites, and obsidian are ideal for the creation of projectile points and other stone tools. Volcanic materials also may become, though weathering, excellent clays for pottery or construction. Of course, detrimental factors also exist such as tectonic disruptions that may cause earthquakes, noxious emissions of poisonous gasses and explosive eruptions (which occurred on average every four centuries).

Proyecto Prehistorico Arenal
The project's objectives were 1) to uncover the stratigraphic relationships between layers of tephra and time of human occupation of the area, 2) to determine the subsistence strategies of the peoples that inhabited the Arenal area, 3) to determine variations between sites in terms of locale, chronology, and function. Sheets (1994) takes the area to be an "excellent laboratory in which to study human adaptation to volcanically active areas, as it provides a significant range of climates, many active volcanoes, and the full range of human societies from hunter-gatherer bands to highly centralized, stratified states" (1). The Proyecto Prehistorico Arenal seeks to utilize this "laboratory" to investigate how, for instance, the periodic presence of tephra shapes ecologies and the societies that depend on those ecologies.

Remote Sensing of the Arenal Region
Remote sensing is defined as "the observation of phenomena at a distance" and employs technologies that showcase the unique talents nearly all of the electromagnetic spectra (135). These technologies can provide an invaluable source of information to archeologists. Serendipitously, "laser profiler (Lidar), radar, Landsat Thematic Mapper (TM), and Multispectral Scanner (TIMS) data, as well as color and infrared photography" of the region had been gathered by NASA in order to inform the construction of the Sangregado Dam. Arenal archeologists were allowed to access this rich source of data (135). This data "has aided in the study of environmental variation and in the identification and recognition of a network of prehistoric foot paths. . . direct evidence of interaction between sites and sources of raw materials" in the Arenal region (141).

The Pivotal Date of A.D. 500 and the Emergence of Social Complexity in the Isthmo-Colombian Area
Around A.D. 500, lower Central American peoples underwent substantial changes in their subsistence, settlement, and demographic patterns (7). Studies in the Arenal highlands indicate that population peaked in the area during the Zoned Bichrome period (500 B.C. - 500 A.D) and fell sharply thereafter; whereas on the Pacific coast the reverse is true, with little occupation before and heavy occupation after the Middle and Late Polychrome periods (800-1520 A.D.) (7). Volcanism may be responsible for this change. Subsequently, the archeological record of the Arenal region displays a curious bivalent quality: on one hand the region can be viewed as principally autochthonous and, on the other hand, as the result of a cross-pollination of multiple cultural influences that lead to a regional self-actualization. (Though, this duality is not contradictory as the former characterization most essentially reflects the earlier epochs; and the latter, the later epochs after AD 500 and the Tilaran Phase). For example, Hoopes (1994) relates that the reason why the Arenal region never "attained the social complexity evident in Mesoamerica and the Andes is that advanced systems of resource exchange and interregional resource exploitation were unnecessary" due to the high degree of self-sufficiency that the environment allowed. Yet the period after the Tilaran Phase is quite different, and deserves a separate assessment. To elucidate, Hoopes (2005) offers that a "catastrophic environmental crisis" may have precipitated the emergence of social complexity in the Isthmo-Colombian region though the activities of "pan-tribal sodalities" that underwent a process of "'routinization,'" which produced a "widespread horizon of common practices and beliefs despite variations in their specific manifestations". "Routinization," coined by Weber (1963), is defined as "the development of a patterned iconographic and material expression of ritual". Oyuela (2001) suggests that the transition from "shaman" to "priest," effectively the transition from archaic society to social complexity, was driven by eschatological concerns engendered by environmental catastrophe, which in turn prompted a "routinization" of the numinous practices of certain timely and charismatic individuals who sought to address those eschatological matters, a process presenting a recursivity which could only ingrain the routine. Hoopes (2005) astutely applies this conceptual background to the Chibchan or Isthmo-Colombian world (to which the Arenal region belongs) in connection with geological evidence for volcanic activity coincident with time of cultural transition, thereby explaining the far-reaching paradigmatic societal and cosmological transformation evident in the archaeological record of the region during the Late Arenal phase, ca. AD 300-600.

An Ethnographic Analog
Sheets (1994) proposes that Posey's (1983) ethnography of the Kayapo may offer a model for imagining the early inhabitants of the Arenal region. Sheets writes that the Kayapo are an "egalitarian" society who live interspersed among nine sedentary villages within the ecologically diverse tropical rain forest of central Brazil. Sheets relates that "the Kayapo perceive their environment in terms of a series of ecological zones and subzones" and are "very sensitive to natural hazards and plant in a variety of areas to minimize risk" (21). The Kayapo settle in the interstitial zones between the elemental ecological zones in order to play off the potentiated diversity. The Kayapo position themselves so as to be able to approach their environment as a synchronization of zones of different ecological dynamics, so as to have a situation in which scarcity/abundance and seasonal variations alternately offset, creating the most stable outcome allowable. This potentiated diversity is also a source for a vast array of plant species; as many as 250 species alone are utilized for their fruits, which is not to mention the hundreds more used for other gastronomic, artisanal, and medicinal purposes. The Kayapo are not simply passive extractors of natural resources, but engage in a complex system of "nomadic agriculture." Such subsistence strategies of the Kayapo resonate with those likely to have been practiced by early Arenal inhabitants giving the similarities in the diverse nature of their ecologies, the persistent threat of natural disaster, and the requisite adaptations to a complex matrix of microclimates.