Most rock paintings and rock carvings or petroglyphs were created by ancient and prehistoric societies. Archaeologists have long used them to gain clues to the way of life of such peoples. In Peru, where many sites have already been located, mystery still cloaks the signification and role of these concentrations of cave paintings and petroglyphs. One of these sites, Toro Muerto, contains over 4000 carved blocks scattered over several dozen hectares. Discoveries made in different areas of the country over recent years by Peruvian and international researchers are keys to improved understanding of the meaning behind these artistic representations which were realized over a long period from 8000 BCE.
     Analysis of the distribution and characteristics of these sites brought out a distinction between the art produced in the coastal valleys from that of the Andean Cordillera uplands. The extensive sites with rocks carved in the open air are concentrated mainly on the Pacific facing slopes, whereas the scenes painted in caves or under shelters predominate in the high regions and on the Amazon side. These preferences as to the supports and techniques used reflect associated ritual practices which are probably rather different.
     Study of the oldest rock paintings and their dating by indirect methods (carbon 14 dating of remains of in situ burnt charcoal) showed them to be the work of hunter-gatherers who occupied the region between 7000 and 3000 BCE. The motifs are small, most often painted in red, and they depict hunting scenes. The most ancient sites show a predominance of naturalistic representations of dead or wounded animals. However, a second set dated at 4000 to 5000 years BCE eulogizes fertility. This time the images are large, drawn with the abdomen enormously swollen, sometimes containing a foetus. This stylistic development, which seems to coincide with the beginnings of animal husbandry in the high upland regions of Peru, appear to symbolize the emergence of pastoralism and the change in man—animal relationships that came along with this practice.
     These research studies also brought into relief periods that were quite distinct in terms of stylistic evolution of carved figures. Whereas the most ancient motifs, associated with the rise of the first great Andean civilizations (2500-300 BCE) essentially reproduced complex figures bearing high symbolic and spiritual content, the later carvings characteristically appear in abundance and testify to a simplification of morphological features. The simplicity and relative abundance of these petroglyphs suggest a degree of generalization of rock carving practices to further sections of the society. The largest sites dating from this era, which contain several hundred carved rocks with dozens of motifs, probably played a significant role in societies' cultural and social life, both at local and regional level. Their location, and some of the rituals that took place, may have been linked to areas of production and trade routes of prized commodities such as coca or salt.    

Source: Science Daily (6 August 2008)