Given the environmental conditions described above, it is not surprising that the oldest traces of human presence, prior to the definitive retreat of the glaciers, were detected in moderate altitude regions that were never directly affected by glaciations. These were either regions where the glaciers were small, such as on the Colombia plateaus, or valleys and intra-mountainous basins not attained by the extremities of the glaciers, all located at an altitude below 3000 m. The first traces date to around 15 000 BP: Pikimachay Cave (2850 m), in the Ayacucho basin of Peru, yielded an occupation sequence that appears to begin around 14 000 BP with the Ayacucho phase (14150 ± 180 BP). We must note, however, that Richard MacNeish wanted to push the occupation nearly 10 000 years back. According to him, during a first Paccaicasa phase (25 000-15 000 BP), crude stone tools (choppers and large flakes) associated with Quaternary fossil fauna (toothless Scelidotherium and Megatherium, horse Equus Amerhippus, fossil cervidae and a large carnivore) indicate the passage of small bands of hunters that would have tracked down this large prey in their den before butchering and consuming them. However, this phase remains very hypothetical for several reasons. First, the C14 dates were obtained, not from charcoal (the level contained no evidence for the use of fire), but from the bone of a Scelidotherium, a large toothless animal that inhabited the cave at the time, as is proved by the presence of its excrements. This evidence shows that the carcasses could have been present there without necessarily being brought in by humans, and perhaps even long before the passage of humans. Second, the ‘tools’ attributed to this phase (with the exception of four objects that could have fallen from the upper levels) consist of more or less amorphous, chipped fragments of volcanic tuff, which is the same material in which the cave is hollowed out and which is not apt for stone knapping. According to numerous specialists, these unlikely tools are probably no more than simple flakes detached from the cave wall. During the following Ayacucho phase (14150 ± 180 BP), on the other hand, a more abundant and clearly identifiable lithic industry - more than 200 tools, including choppers, crude bifacial pieces, and large flakes, sometimes retouched (but no projectile points) - made on exogenous (thus imported) materials indicates that the site was occupied by hunters whose prey still included not only a few Pleistocene species (mega-theridae, horse and the fossil camelidae, Palaeolama), but also, already, smaller, modern species (camelidae and rodents). Meanwhile, in this phase, as in the precedent, no traces of fire were discovered.
One other site that must be noted is Guitarrero Cave, also in the Peruvian Andes, at 2580 m, in the Callejon de Huaylas. At this site, Thomas Lynch established one of the longest sequences in Peruvian prehistory. However, the oldest date obtained for the lower occupation level - complex I, 12 560 ± 360 BP - is still strongly debated since the two other dates obtained for the same complex do not exceed 9500 BP. Moreover, this deep level yielded only modern fauna, to the exclusion of all Pleistocene megafauna species. For these reasons, we do not retain this site among those occupied 10 000 years ago.
At Pikimachay Cave, on the other hand, Pleistocene megafauna, which begins to disappear at 11 000 BP and whose extinction is complete in the Andes at 9000 BP, is well represented. At present, this site is thus the only one that could attest to a peopling of the Andean mountains during the Final Pleistocene, as well as the utilization of a tool industry lacking projectile points. However, both of these propositions are strongly contested by many specialists of prehistory in the Americas. This extreme rarity of ancient sites in the central Andes (as in the northern Andes of Colombia and Ecuador), despite a recent multiplication of research projects, thus tends to indicate that the Cordillera was peopled relatively late and that the population density remained low for a long time. This is also true on the Pacific coastal plain where, as we will see later, the first traces of occupation also do not exceed 10 000 years. It is still surprising that if humans were indeed present in Brazil more than 20 000 years ago, they did not reach the Andean regions until 10 000 years later. Specialists have not yet found a satisfactory explanation for this, except perhaps - and this remains hypothetical - that movements along the low zones of the Atlantic coastal plain, after an obligatory passage by the Panama isthmus, would have presented fewer natural obstacles than a passage along the Andean Cordillera or by a maritime route along the coast. Another possibility is that over thousands of years, the sporadic passage of probably very small human groups left only scarce traces in the Andes, which are today barely perceptible.
The lifeways of this period remain difficult to characterize. Current evidence indicates the presence of small, very mobile groups with relatively crude tools reflecting the use of simple techniques. The use of projectile points, and thus of projected arms, seems to have been unknown (or perhaps forgotten?), unless only clubs or wooden spears with fire hardened points, or bone points, were used. It is also probable, though we have no preserved evidence, that humans knew very early on how to successfully exploit a natural environment rich in diverse resources. Depending on the season, they could have complemented hunted resources with trapped ones, as well as with the collection of edible berries, seeds, and tubers where they could be found.
Finally, no human skeleton or skeletal part older than 11 000-10 000 BP has been discovered in the Andean zone (as is also true in the rest of Latin America), and the physical appearance of these first occupants thus remains unknown.
World History
