During Middle Holocene times, archaeological evidence is still scarce. This period is characterized by environmental changes related to what is known as the Hypsitermal. In the pampas, during this period the sea-level rose above current level at around 7000 BP. However there is no agreement about the magnitude of this rise (between 2.2 to 12 m depending on the author) and the chronology of the maximum ingression (see revisions in Aguirre and Whatley 1995; Melo et al. 2003). Climate conditions were warmer and probably humid during this time period, although short periods of aridity might have occurred during this interval. In the campos the sea level reached the current level at ca. 7000 BP and subsequently reached +5 m at around 6000 BP. After this, it started a progressive fall to the present sea level (Martin and Suguio 1989). At around 5000 to 4500 BP (the post Hypso-thermal) there is a period of increased aridity in most areas of this region.
The archaeological record for the Middle Holocene in the pampas is relatively scarce. Paso Otero 1, one of the sites repeatedly mentioned, is probably a natural accumulation of guanaco bones due to water transportation (Gutierrez and Kaufmann 2004). The other sites are basically in the interserrana area (Arroyo Seco 2), the Tandilia Hills (Cueva Tixi and Cerro La China) and Ventania (Avestruz and Caverna El Abra), and the Colorado and Salado-Curaco rivers (Casa de Piedra and Tapera Moreira) (see summary in Politis and Madrid 2001). These sites suggest an economy based on the guanaco. Technology shows few chronological changes through this period but rather a great intra-regional variation. Several types of medium-size triangular stemless projectile points, bola stones, as well as grinding stones are the basic hunting and processing tools and are found in various sites. For this Middle Holocene period, Martinez and Guiterrez (2004) proposed the existence of a specialized regional economy (this contrasts with the Late Holocene diversification, discussed below).
Among 34 taxa recovered in the archaeological record, only 10 were exploited. The sites of Paso Otero 3 and Nutria Mansa are good examples of this pattern.
In the pampas, the main evidence comes from the multi-component sites of Fortin Necochea and Arroyo Seco 2, both interpreted as open air campsites representing residential bases of hunter-gatherers (Crivelli Montero et al. 1987/88; Politis and Gutierrez in press). In the first site, there is a good Middle Holocene record dated between 6010 BP and 3630 BP. The archaeological sequences of Fortin Necochea and Arroyo Seco 2 indicate the reoccupation of the same localities throughout the Middle Holocene and suggest technological continuity (unifacial artifacts made from quartzite flakes and secondarily with chalcedony and chert flakes—basically side and end-scrapers, stemless triangular
Projectile points, mortars and pestles made from granite and granodiorite, bola stones, etc.), a comparable economy (based on guanaco as a principal resource and pampean deer, rhea, and armadillos as secondary or complementary resources), and a similar settlement pattern (re-occupation events on lagoon borders).
One of the best records for the transition between the Early and Middle Holocene is the human burials from Arroyo Seco 2. To date, 45 human skeletons have been uncovered and dated with 19 dates from ca. 7800 to 4500 years BP (Politis et al. in press). The burials occur as both single-individual and multi-individuals of adults and children. The earliest level of inhumation is represented by four burials of skeletons with bifacial triangular stemless projectile point within the bodies and dated between 7800 and 7615 BP (Figure 14.6). A secondary burial with a similar date (ca. 7600 BP), which is the earliest burial of this type in the whole region, was also recovered at the site. Grave goods consisting of marine shell beads and necklaces of canid canines and powdered red ocher occurred in 12 skeletons, indicating an early and complex funerary treatment of the dead. Moreover, the abundance of canid canines in a funerary context and the absence of other skeletal parts of canids in the site suggest that this animal would have had a strong symbolic connotation to mediate the relation between human and supernatural spirits or beings. The date span from the burials (both primary and secondary) of Arroyo Seco 2 suggest the site was used for inhumation for about 3,000 years during the Middle Holocene; use of the site was not continuous but redundant.
The cluster of summarized archaeological evidence does not support the model of Barrientos (2001; Barrientos and Perez 2005) who proposed that a population replacement took place in the southeastern pampas and probably that a new biological population entered the region sometime between 6000 to 5000 BP, after the “emigration or local extinction” of the Early and Middle Holocene population. Although it seems clear that there are some cranio-facial differences between the Middle Holocene and the early Late
Figure 14.6. Human skeleton of Arroyo Seco 2 with two projectile points between the ribs. (Gustavo Politis)
Holocene samples, why these difference should be only the result of two different populations has not been proven. Alternative explanations such as micro-evolutionary processes or changes in the original population due to genetic flux from neighboring peoples have not been explored by the authors. Moreover, other assumptions raised by Barrientos to support his model, such as the lack of secondary burials in Early and Middle Holocene times, have been proven to be incorrect (i. e., the consistent dates of ca. 7600 BP for the secondary burial of Arroyo Seco 2). Although it is true that up until today there is less archaeological visibility during the Middle Holocene in the pampas, the available evidence suggests continuity of several patterns (technology, subsistence, burial places, use of space) rather than a disruption, as the local extinction or emigration of the local population would have produced.
In the eastern campos of Uruguay and southern Brazil, the Middle Holocene human occupation is characterized by hunter-gatherer-fishers who specialized in the exploitation of the fruit of the butia palm (Butid capitata). On the Atlantic coast subsistence was complemented with the hunting of seals and the gathering of mollusks. The first evidence of a shell midden on the coast of Uruguay is the La Esmeralda site, dated to Middle Holocene times, which would suggest an incipient adaptation in the exploitation of marine resources.
On the inland grasslands hunting was oriented toward deer and complemented with coypo. Alochtonous siliceous raw material was used to produce distinctive mid-size stemmed triangular projectile points (Bracco et al. 2005; Lopez 2001).
During this period the first evidence of mounds are recorded in the eastern sector of the campos, mostly in the Laguna Merim basin. The mounds, locally called cerritos de indios (in Uruguay) or aterros (in Brazil), are circular or elliptical earth structures of about 20 to 40 m in diameter and up to 7 m high, which occur isolated (Figure 14.7) or in clusters
Figure 14.7. Areal view of a cerrito from the Department of Rocha (Uruguay) during excavation. (photo courtesy Jose M. Lopez Mazz)
With up to fifty in the same locality (Bracco et al. 2005; Lopez 2001). Radiocarbon chronology indicates that the construction of cerritos involved extensive time periods (in some cases ca. 3,000 years). Lopez identified four phases in the development of the cerritos: (1) an Early and Middle Holocene (ca. 8000 to 5000 BP) pre-cerritos level, represented by “archaic” hunter-gatherers; (2) a first stage of cerritos construction, between 5000 to 4000 BP, when monumentality appeared in the area; (3) a second stage, between ca. 3000 to 1000 BP when the construction of cerritos increased. During this stage pottery came into use (ca. 3000 BP) as well as horticultural practices involving squash, maize and beans (Iriarte et al. 2001); and (4) a final stage with differentiation of patterns and intense funerary activity a few centuries before the European conquest.
The function and construction process of these mounds are currently under strong debate. A few decades ago, Brazilian archaeologists (Schmitz 1976; Schmitz et al. 1991) proposed that mounds were some kind of platform constructed to inhabit seasonal flooded areas by people adapted to this environment. These mounds were associated with what was called the Vieira Tradition, especially with the ceramic phases (Torotama, Vieira and Cerritos) of the Late Holocene hunter-gatherers and would have functioned as “lacustrine hunting camps”. More recently, Uruguayan researchers maintained that the mounds were mainly funerary structures of complex hunter gatherers, taking into account the recurrence of human burials in several of them (Bracco et al. 2005; Lopez 2001, inter alia). For Consens (2003) the cerritos correspond to a “Formative” period. For Lopez Mazz (2001) the first structures (ca. 4000 to 3000 BP) seem to be oriented toward marking and ordering the territory and to legitimating the exclusivity of the resources, while after ca. 2500 BP some structures began a specialization toward ceremonial activity and funerary practices. Dillehay (in Lopez 2001) believes that some clusters of cerritos would be part of a planned village associated with middle rank tribal societies. Recently this idea has been supported by Iriarte et al. (2004) who proposed, based on the excavation of the Los Ajos mounds, that as early as 4190 BP the site became a circular plaza village which grew as a result of multiple overlapping domestic occupations associated with a wide range of activities. In this site, as well as in Punta de San Luis, Potrerillo and Isla Larga, Iriarte et al. (2004) found phytoliths and starch grain of squash (Cucurbita sp.), maize (Zea mays), beans (Phaseolus sp.), and Canna sp. rhisomes, which indicate an early domestication at ca. 3600 BP. For Iriarte et al. (2004) this cluster of evidence would indicate an independent architectural tradition in lowland South America.
In the rest of the campos, and in the southern planalto the archeological record of hunter-gatherers during the Early and Middle Holocene was subsumed under the concept of Umbu Tradition (Noelli 1999-2000). This concept encompasses a variety of lithic material, which includes some distinctive projectile points and an economy based on hunting, gathering, fishing and mollusk collection. Since nuts of two genera of palms, Arescastrum and Butid, have been consistently recovered in these sites, Noelli (1999-2000) proposes that this species would have been “managed” by these populations. The Humaita tradition was also proposed to integrate a group of sites, basically located in the forest of the planalto, with a distinctive technology of big bifacial artifacts, including the curved “cla-vas” (Rodriguez 2001). However, for some authors both traditions seem to be very similar and differences would be related to site functionally rather than representing two different populations (Hoeltz 1995).
In general terms, the archaeological evidence shows continuity between the Early to Middle Holocene population and intra-regional differentiation. This would be the result of evolutionary and historical processes, which produced different adaptive patterns during
The Early and Middle Holocene. Most researchers (Lopez 2001; Noelli 1999-2000; Iriarte et al. 2004; Politis and Madrid 2001) are interpreting the main changes that occurred in the Middle Holocene as the result of transformation in several dimensions that happened within the Early Holocene populations. This has been the process to explain the emergence of the cerritos and the continuity of the basic adaptive patterns and technology of the hunter-gatherers of the pampa and campos.
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