South American Sites Research Articles

Evolutionary and ecological implications of primate seed dispersal

In this paper, we evaluate patterns of fruit eating and seed dispersal in monkeys and apes and draw an important distinction between 1) the ecological consequences of primates as seed dispersers and 2) the evolutionary implications of primates on the seed and fruit traits of the plant species they exploit. In many forest communities, primates act as both seed predators and seed dispersers and are likely to have an important ecological impact on patterns of forest regeneration and tree species diversity. Evidence from Kibale National Park, Uganda, and Manu National Park, Peru, as well as several other South American sites indicates that monkeys and apes display a wide range of fruit-processing behaviors, including spitting seeds, dropping seeds, masticating seeds, and swallowing seeds. Differences in consumer body size, diet, ranging patterns, and oral and digestive morphology result in different patterns in the distance and distribution of seeds from the parent plant. In the case of South American monkeys, for example, despite their relatively small body size, platyrrhines were found to exploit larger fruits and swallow larger seeds on average than did Old World monkeys and apes of the Kibale forest. We found little evidence to support the existence of a coevolutionary relationship between a single or set of primate dispersers and the particular plant species they disperse. This is due to variability in the manner in which monkeys and apes select fruits and treat seeds, the fact that many species of primates and nonprimates exploit and disperse the same fruit species, and the fact that extremely high levels of postdispersal seed, seedling, and sapling mortality serve to dilute the influence that any primate species may have on the recruitment of the next generation of adult trees. It is apparent that many primate lineages exhibit dental, digestive, and/or sensory adaptations that aid in the exploitation of particular food types and that many lineages of flowering plants have evolved characteristics of fruits and seeds that facilitate seed dispersal. However, in light of currently available data, we argue that these represent evolutionary rather than more strictly defined coevolutionary relationships. Am. J. Primatol. 45:9–28, 1998. © 1998 Wiley-Liss, Inc.

South American Site of Auger Project Is Still Up in the Air

South American Site of Auger Project Is Still Up in the Air

New Perspectives on the Clovis vs. Pre-Clovis Controversy

We consider the Clovis vs. pre-Clovis debate from three perspectives: migration models; petroglyph and surface-artifact ages; and scientific method. First, we test the hypothesis that a Clovis migration can account for the temporal and spatial distribution of South American Paleoindian sites “accepted” by Clovis-first advocates. Using a Clovis-first model, site ages are underpredicted by approximately 1,500 years, suggesting that the Clovis hypothesis cannot be reconciled with accepted empirical data. Second, we present North American accelerator mass spectrometry (AMS)14C minimum-limiting ages from petroglyphs and surface artifacts that demonstrate continued support for a pre-Clovis occupation of the dryland west, as well as a Beringian entry into the hemisphere. Third, the debate has been confounded by a widespread misstatement of the problem. Though Clovis occupation is a “solved” issue, the competing hypotheses are whether the first migration was Clovis or pre-Clovis; the presence of Clovis sites is simply a necessary prediction of both migration theories. The empirical implications of the Clovis-first hypothesis are virtually untested. Scientifically evaluating the first peopling controversy requires scrutinizing the empirical test implications and logical coherency of both competing hypotheses.

A 14 300‐Yr Paleoecological Profile of a Lowland Tropical Lake in Panama

The first paleoecological analysis of a complete sedimentary record spanning the period from the late Pleistocene to the present from lowland Panama, documents changes in lowland vegetation communities through major climatic change and the onset of human disturbance. Past sympatry is found among presently allopatric species, suggesting that tropical forest communities are not species—stable through time. Late Pleistocene floras at Lake La Yeguada (elevation 650 m), Panama, had high relative abundance of montane forest elements, e.g., Quercus and Magnolia, existing some 900 m below their present range, suggesting a climatic cooling of ≈5°C below present. This descent of montane forest taxa onto lowland hilltops denied the ground to postulated lowland rain forest refugia. The late Pleistocene (14 350—11 050 yr BP) was not uniformly cool and was interrupted by brief phases of near present—day warming. The onset of the Holocene was abrupt, taking <100 yr, and was almost coincidental with the start of human forest disturbance. Changes in climate at La Yeguada were found to be largely synchronous with those documented at Lake Valencia, Venezuela, but no fine—scale climatic synchrony was apparent with South American or European sites, and significant departures from the predictions of published climatic circulation models are found.

A Review of Lynch's Descriptions of South American Pleistocene Sites

The description of major South American Pleistocene sites by Lynch (1990) contains significant errors and omissions. The artifact assemblage at the Colombian site of Tibitó, dated at 11,740 ± 140 B.P., is much larger than indicated by Lynch and well represents the Abriense industry, which features small unifacially retouched flake tools and core tools, with no stone projectile points. Lynch did not describe the 1976 stratigraphic profile at the Venezuelan site of Taima-Taima, and he failed to refer to the evidence for butchering of the juvenile mastodon with which an El Jobo projectile point fragment and a utilized flake were associated directly. The descriptions of Brazilian sites also feature serious mistakes. For the site of Alice Boër, Lynch overlooked a thick sterile stratigraphic unit (Bed IV) that intervenes between Bed III, with its thermoluminescence dates as early as 10,970 ± 1020 B.P. and radiocarbon dates as early as 14,200 ± 1150 B.P., and the artifact-bearing surface of Bed V. For Lapa Vermelha, Lynch failed to indicate that several artifacts were recovered from an older cemented cave fill that yielded radiocarbon dates of 22,410 B.P. and > 25,000 B.P. Lynch’s description of the site of Toca do Boqueirào da Pedra Furada does not correspond to eyewitness reports, and his description of the nearby Toca do Sitio do Meio was incomplete and confused. Finally, in his description of the stratigraphy of the Patagonian site of Los Toldos, Cueva 3 Lynch misquoted and misconstrued the original reports, which indicate clearly the stratigraphic priority and integrity of the Level 11 industry. For accurate descriptions of early South American archaeological sites, readers are urged to examine the original sources.

A “marginality” model to explain major spatial and temporal gaps in the old and new world Pleistocene settlement records

AbstractA key argument currently invoked to cast skepticism on certain South American sites, that suggest a first peopling of the New World by ca. 35,000 B.P., is the perplexingly low visibility of the archaeological record until 12,000 B.P. But, contrary to a popular misconception, great spatial and temporal discontinuities are common in the Old World Paleolithic settlement record. In Southern Africa, carefully controlled archaeological stratigraphies show that the now semiarid interior was unoccupied for 50,000 and more years at a time. Episodes of widespread settlement in marginal environments were relatively brief, limited to periods of substantially wetter climate, and closely linked with moist habitats. A risk‐minimization model is proposed to explain these discontinuities. Plant and animal resources in the region, given a climate as dry or drier than today, were of low productivity and low reliability for unspecialized hunter‐gatherers during the dry seasons of poor years. This would require large foraging territories and very wide spacing of proximal bands, so that the exchange of vital information on temporary or migratory resources was minimal. Finally, during extended droughts, fat‐depleted animals provided an unsatisfactory source of food. These variables suggest that environments with low productivity and predictability were too risky for unspecialized hunter‐gatherers with a pre‐Upper Paleolithic technology, such as those who would have been able to enter the New World 35,000 B.P. Major spatial and temporal gaps in the New World settlement record should therefore be expected prior to the appearance of specialized Paleoindian hunter‐gatherers ca. 12,000 B.P. Implications for geoarchaeological strategies are discussed.

Flakes, Breaks and the First Americans

T o many archaeologists, the contention that humans first trooped into North America 200,000 years ago or more is outrageous at worst, an interesting but unproven assumption at best. But evidence for this controversial view from two archaeological sites located just east of the Calico Mountains in southern California's Mojave Desert, the other straddling the Old Crow River in Canada's Yukon Territory is, after more than two decades, undergoing a rigorous analysis that is sure to stoke up further debate over when the first Americans arrived. my opinion, we're at a critical turning point, says archaeologist Alan L. Bryan of the University of Alberta in Edmonton, Canada. We no longer have any logical basis for proclaiming an arbitrary limit beyond which people could not have entered For the last half century, that limit has generally been agreed to be about 12,000 years ago, or 2,000 years before the end of the Ice Age. Radiocarbon dates of stone spear or arrowhead points found near Clovis and Folsom, N.M., in the 1920s laid the foundation for this view. Some of the stones, carefully flaked on both sides to form sharp edges, were found among the bones of mammoth and extinct bison. It appeared that hunters with advanced methods of tool-making had migrated from Siberia to North America across a land bridge where the Bering Straits are now located and rapidly filtered southward in their search for big game. It is becoming increasingly clear, however, that there were earlier settlers whose way of life was a far cry from biggame hunting on the High Plains, says Bryan. Human occupation at two South American sites was recently shown to extend back at least 33,000 years (SN:6/28/86,p.405). Since migration via the Bering land bridge is, he contends, the most plausible route for the first immigrants, there must be earlier human occupation sites in North America. His view is supported by the 19,600-year-old radiocarbon date for a braided fragment, apparently a remnant of a woven basket or mat, found at the Meadowcroft Rockshelter near Pittsburgh. Furthermore, explains Bryan, the majority of early Americans may have been hunter-gatherers who used simple (not necessarily human-made) stone flakes, broken animal bones and wood implements to obtain and prepare food. Artifacts such as these do not preserve well and are often difficult to recognize as tools if they survive the millennia. Waterlogging of the 13,000-year-old Monte Verde village site in Chile protected an abundance of these simple tools and demonstrates that the inhabitants were foragers, not predatory hunters with sophisticated stone weapons. Indians whose hunting tools were found at Clovis and Folsom had one of the most highly specialized ways of making a living that developed anywhere in the says Bryan. The forests surrounding Monte Verde, on the other hand, were a bountiful source of perishable materials such as bone and wood that could be used in gathering and preparing various foods, including the occasional kill of a large animal. If perishable bone and wood tools were once used at the arid Calico Mountains site in California, they did not have the benefit of a protective liquid bath. Yet thousands of flaked stones excavated from several pits appear to have been modified by humans and, according to a preliminary analysis in a book edited by Bryan (New Evidence for the Pleistocene Peopling of the Americas, Center for the Study of Man, University of Maine, 1986), some of the stones are from a layer of earth that is at least 200,000 years old. A more extensive examination of the Calico stones will appear later this year in the JOURNAL OF FIELD ARCHAEOLOGY. Early man appears to have crossed over to North America in the midPleistocene and to have used a variety of simple stone tools, says archaeologist and Calico project director Ruth D. Simpson of the San Bernardino County Museum in Redlands, Calif. The Pleistocene epoch stretched from 1.6 million to 10,000 years ago. It is difficult to tell if the new reports out of Calico will meet with the approval of skeptical archaeologists. In the past, some of the stones have been described by Calico investigators as human-produced tools when, to many outside observers, they appeared to have been shaped by natural forces. Another concern with the site, says Dennis J. Stanford of the Smithsonian Institution in Washington, D.C., is the lack of additional signs of human occupation, such as hearths. Several stone arrangments resembling hearths have been

Observations on Copulation and Seasonal Reproduction of Two Species of Spider Monkeys, Ateles belzebuth and A. geoffroyi

Observations on the sexual behavior of 2 species of spider monkeys, Ateles belzebuth and A. geoffroyi indicate that primary sexual behavior is diurnal and, in contrast to groups of Saimiri sciureus sympatric with A. belzebuth at a South American study site, non-seasonal. The copulatory posture taken by the male spider monkey during penile insertion is different from that described for any other primate. Behavioral data strongly support the hypothesis that the transmission of information concerning female sexual receptivity is via chemical stimuli, and that the primary function of the female spider monkey’s hypertrophied clitoris is the deposition of urinary scents.