By Eric J. White and Robert A. Benfer

Peru’s Chilca valley is fertile ground for testing hypotheses central to our understanding of the character of Andean prehistory. The Chilca Valley Archaic provides a view of early human settlement and adaptation in a variety of environmental settings within a relatively circumscribed geographic area. Research in the valley provides valuable information on processes of sedentism, domestication and land use.

The Middle Archaic (8000-4500 BP) of central Peru is the period when mobile hunter gathers began the processes that eventually led to civilization. The beginnings of the Middle Archaic are marked by humans entering and adapting to a sedentary lifestyle in extreme environments; the high sierra and the desert coast. There is also the somewhat enigmatic spread of a relatively uniform chipped stone industry across environments. In the Puna zone, deer and camelid hunters become camelid hunters. This specialization on camelids set up the preconditions for domestication and the adoption of a pastoral adaptation. At the same time along the coast, Middle Archaic peoples quickly become sedentary fishermen.


Paloma
Frederick Engel (1978, 1980) first directed extensive excavations at the preceramic site of Paloma, in the Chilca Valley, Peru in 1973 and 1975. Initial excavations indicated that Paloma was a deeply stratified village dating from Middle Archaic times. The large number of burials and conditions of excellent preservation motivated Engel to enlist Robert A. Benfer, an archaeologist and physical anthropologist from the University of Missouri-Columbia. In 1976, new excavations by MU and the Center for the Study of Arid Zones (C.I.Z.A) of the National Agrarian University of Peru at La Molina began.

Two five-month field seasons in 1976 and 1979 were followed by more limited excavations and rechecking of stratigraphy in 1982 and 1990. With its deep stratigraphy and incredible preservation Paloma offered a glimpse into the world of Middle Archaic fishermen. The Paloma project was designed to provide an interdisciplinary analysis of adaptation to sedentism and food production at this important site (Benfer 1982, 1986, 1991). The focuses of these investigations were paleodemography, stress and diet. In addition, ethnobotanical studies (Dering and Weir 1982, 1986; Weir et al. 1988) and zooarchaeological studies (Reitz 1976, 1986, 1987) were conducted, and the mortuary patterns (Quilter 1980) and technological organization (White 1992) have been described.

The Investigation of Paloma
Life expectancy increased over the centuries at the site, or fertility decreased, or possibly both (Benfer 1991). Significant differences were found in age category distributions among stratigraphic levels with later levels exhibiting lower mortality of both the young as well as the adults (Benfer 1984). There was evidence of a decrease in non-specific stress as population increased. Delayed marriage and possibly infanticide was used as a population control. In other words while people are getting healthier and healthier they are having fewer children. This is counter to the assumption that healthy well -fed people should be having lots of children. Also somewhat counter-intuitive is the fact that sexual division of labor and diet diminished over time at the site. This means that in the time period immediately preceding the advent of complexity and inequality society was in some respects becomming more egalitarian. Sexual dimorphism did not change in either the maximum diameter of the head of the femur or in stature, although stature increased over time (Benfer 1984). Bony response to musculature, however, showed a regular change toward diminished sexual dimorphism over time (Benfer 1984). The study found that there is no convincing evidence of significant status differences, based upon anything but sex and age, between the inhabitants of the site (Quilter 1980). The project showed that during the final village occupation there was a clear shift toward marine resources, however food from the sea was always of critical importance (Benfer 1990). Microwear studies show that the rate of dental wear was decreasing through time, which lends support to a shift from a more broad-based subsistence towards a more specialized diet (Moore-Jansen 1982; Edwards 1983). White (1992) found the technological organization of stone tools at Paloma consistant with a sedentism. Twenty-five to thirty percent of all archaeological sediments were comprised of shellfish (Weir, Benfer and Jones 1988). The Palomans were also heavily dependent upon marine mammals fish, including anchovies, and sea birds (Reitz 1988). The abundance of the Pacific biomass contributed heavily to the caloric requirements of the site's prehistoric inhabitants (Reitz 1976,1988; Jones 1988; Weir, Benfer and Jones 1988). Benfer (1986) points out that through careful population control or emigration of surplus population and by careful monitoring of the resources of the lomas, the prehistoric inhabitants of the Chilca-Lurin catchement area could have lived comfortably at Paloma most, if not all of the year. The reason the loma was abandoned is deforestation. Ultimately, the Palomans ran out of firewood.


The Altitudes
The sites of Tres Ventanas and Kiqche are found on the rim of the Puna, but within walking distance of the desert coast. Kiqche and Tres Ventanas are situated at about 3900 meters above sea level. The Chilca valley has been an important route from the coast to the highlands from Middle Archaic times through the present . Small amounts of shell were recovered from matrix samples from both sites. The now-excavated caves are currently used as base camps for pastoralists. Both are found adjacent to rich pastures and streams that flow year round. The inverse relationship between altitude and temperature make life at high altitude challenging. In biological terms the cost of living at altitude is great. Tres Ventanas and Kiqche are located at a extreme altitude but within two days walk of the extremely protein abundant Pacific Ocean. Kiqche and Tres Ventanas are located at the upper end of the same valley that has the low elevation sites of Chilca 1 and Paloma (Engel 1980; Quilter 1980; Benfer 1982; Benfer 1984; Engel 1984; Benfer 1986; Weir and Dering 1986; Quilter 1989; Benfer 1990) .

Before coca became widely available, hypoxia was resistant to cultural response. The problem is that migrants to high altitudes simply require more oxygen than permanent residents. Permanent residents of high altitude environments are protected from hypoxia by developmental acclimatization. One strategy for overcoming this stress would be to initially make short forays into high altitudes. This would allow for developmental acclimatization, particularly among children. Rick (1980; 1988) hypothesized that the Early Archaic hunters in the Mantaro Valley initially made short visits to the Puna to extract key subsistence and lithic resources. Over time people became better adapted and better equipped to life at high altitudes and settled permanently on the high Puna grasslands. Depth of stratigraphy, lithic reduction and microwear data all suggest that similar processes may have operated during the initial phase of exploitation of the Puna rim of the Chilca Valley.

Heat loss and increased basil metabolic rates are more amenable to cultural response than hypoxia. The inverse relationship between air temperature and altitude means that any high altitude adaptation, must include a cultural response to mediate the impact of cold stress. Perhaps the most obvious cultural response to cold stress is warm tightly fitted clothing. The insulation provided with tailored clothing curbs heat loss and theoretically, would slightly decrease basil metabolic processes.

The most abundant material for clothing at high altitudes would have been hides of deer and camelids. Both of these animals would have been relatively abundant during Archaic times. The tanned-hides of both kinds of animals are excellent insulators. The problem is that a coastal population, relocating to higher altitudes would have to develop tanning technology. Lithic evidence and actual clothing recovered from cave burials indicate the importance of this kind of insulation to people living along the rim of the Chilca Valley.

Kiqche and Tres Ventanas are deeply stratified cave sites that provide continuous records from the earliest human occupation of the high sierra through the Late Formative period. The residents of these supplemented their diet of wild foods with gardening. The abundance of camelid remains at both sites indicate that people initially hunted, and later likely herded these animals. Despite the importance of camelids to these early peoples, they maintained a broad-based hunting strategy throught the site’s lengthy occupations. Deer were an important resource along the rim of the Chilca Valley even after camelids were certainly domesticated. Viscacha (Lagidium peruanum) were taken in numbers that suggest the rodent was economically important (Reitz 1980).