The Appearance of Settled and More Highly Structured Groups

Prehistoric hunters became increasingly proficient after the development of sharpened stone weapons. A similar result occurred when the domestication of wild plants was facilitated by tools created for harvesting of food crops and grinding of grains into flour. However, not until around 5000 B.C. were maize and beans domesticated by the tribes of the Tehuacan Valley (Mexico), providing them with a balanced supply of proteins, carbohydrates and amino acids. Surplus crops eventually enabled groups in the southern hemisphere to settle for several years in one location, until their slash and burn form of agriculture depleted the soil of fertility.

As in Eurasia, the earliest settled communities were populated by clans of related families. Leadership generally rested with the eldest productive members of the clan. Administration of the clan's territorial holdings was normally directed by the elders on the basis of communal ownership. Hierarchical structure on the Eurasian model first appeared around 1500 B.C. in the southern hemisphere. As described by historians Swanson, Bray and Farrington, the changes parallel those of earlier Eurasian experiences:

Some tribal communities developed into chiefdoms, characterized by the beginnings of class distinction and by an increasing separation between the rulers and the common people. Certain clans or families gained the power and status at the expense of others, leading eventually to the emergence of a hereditary elite. ... In Mesoamerica and the central Andes the more advanced chiefdoms were gradually transformed into states. States have populations measured in tens or even hundreds of thousands, with strong centralized government, specialized professions (administrators, priests, craftsmen, traders, lawyers and bureaucrats), and a hierarchy of social classes. The governing class gets more than its fair share of the produce of the community, may control the distribution of goods or land, and has few links with the common people. Class distinctions may be deliberately fostered by government policy through the granting of special insignia or privileges.

The three great examples of these American civilizations were the Aztec of Mexico, the Mayan in Guatemala and the Inca of Peru. The rise of the Aztec civilization in the high Valley of Mexico began somewhat later than that of the Incas in Peru, however. The Aztec decision to settle where they did centered on the existence of several large lakes, formed during a prehistoric era of greater rainfall. Their numbers increased over time, as did their impact on the fragile environment in which they lived, as described here by historian Jonathan Leonard:

...perhaps as much as 2,000 years ago ... the population on the shore of these lakes evidently grew to the extent that the farmers began to feel pinched for land, so they encroached on the lakes. Starting in the shallowest places, they drove stakes into the soft bottom and connected them with wickerwork to form small enclosures. Then they scooped up mud and dumped it into the enclosures until they created a scrap of new land rising a foot or so above the water. These always-moist floating gardens proved enormously productive and could be planted to crops several times a year. As the population of the Valley of Mexico continued to increase, more and more of them were built. The islands coalesced into blocks of land separated by canals; trees were planted on them so their maze of roots would stabilize the mushy soil, and silt scooped out of the canals was spread on their surfaces to preserve their fertility.

In their peak period, before the Spanish conquest, the floating gardens were the economic base of the Aztec empire. The gleaming white capital, Tenochtitlan, was itself built mostly on floating gardens, and food for its estimated 300,000 inhabitants was brought in from other floating garden areas by canoes that plied the canals.

Necessity had stimulated discovery under societal conditions that apparently fostered experimentation. Thus, Aztec socio-political arrangements were for a relatively long period cooperatively-based; at the same time, their settled existence eventually resulted in the same hierarchical socio-political structure that shaped the destiny of similarly developed civilizations in Eurasia. Yet, the Aztec understanding of the natural environment, the discovery of practical knowledge and conversion of that knowledge into technologies and the pursuit of knowledge for its own sake proceeded at a pace consistent with the internal and external pressures of their civilization. Given sufficient time, this would have led them along a path of technological advance closely resembling that of their European conquerors. The evidence to support this conclusion comes from the tendency of very divergent groups to find very similar solutions to organizational challenges they face over time. Traditions, rituals, and social mores do differ by degree; however, our species-specific powers of self-contemplation serve us in a universal fashion and have done so independent of time and place. What differentiates societies from one another is the stage of development, the extent of knowledge accumulation (i.e., of discoveries), the pressures from the external environment and the presence of competing groups.

Defying what would seem most logical, the appearance of settled and more highly structured groups in the northern hemisphere of the Americas appeared in much more recent times than in the southern hemisphere and in regions one might not anticipate would have been viewed as hospitable for large-scale human habitation. These tribal groups (primarily the Hopi and Zuni tribes), settling in the southwestern regions of what is now part of the United States, constructed adobe-walled towns and engaged in a highly developed form of agriculture. Their socio-political structure was also highly advanced and included a formal court system within which disputes and the interpretation of law was adjudicated.

Tribes living east of the Rocky Mountains continued at this time to live primarily as hunters, although few were nomadic as that term is normally used. They constructed villages and engaged in horticulture but periodically moved when game and soils became depleted. The Algonquin and other tribes occupying the northeastern part of the Americas were semi-sedentary and depended more extensively on agriculture, while to their immediate south (from Lake Champlain to the Genesee River and from the Adirondack Mountains to central Pennsylvania) five independent tribes had long before the arrival of European challenges united to form a powerful confederation, the Iroquois League, to govern this large territory and protect one another from attack by non-member tribes.