The three-age system of archaeology was a classical form of dividing the theoretical progression of human societies, beginning with pre-Homo sapiens advanced hominid cultures (over two million years ago) and continuing throughout the prehistoric period, that is, until a given culture's invention of literacy and writing. Prehistoric cultures were said to progress through three distinct phases, or "ages," based on the most common raw material used to build their tools and implements: the Stone Age, the Bronze Age, and the Iron Age.
The three-age system dates to the work of Jens Jacob Worsaae in the 1850s. Originally, it was simply used as a helpful classification system for types of artifacts in museums, before being developed into a general historical model of the evolution of human culture.
- Stone Age (beginning 2.5 million years ago) -
The Stone Age refers to the period in which human societies make their tools from stone, especially types of stone which can be easily chipped and manipulated like flint and sandstone. During this period, a large number of tools are also made from bone, wood, and eventually clay, leading to pottery.
In many ways, the Stone Age is the most diverse in terms of the types of cultures and tool uses it encompasses; it is also chronologically the longest. It begins with the Paleolithic, in which Homo habilis, Homo ergaster, and eventually Homo sapiens used increasingly complex tool sets in Africa, Asia, and Europe. In the beginning, the primitive stone tools used by Homo habilis, known as the Oldowan tool set, was used for chopping. The Middle Paleolihthic featured more advanced tool use by the Neanderthals and then by early Homo sapiens, while the Upper Paleolithic involved the spread of Cro-Magnon (Homo sapiens) humans through Europe and, eventually, the Americas, up to about ten thousand years ago.
The next period of the Stone Age, the Neolithic, saw the development of agriculture, pottery (made from clay), and the first city-states, like Jericho and Catul Huyuk (sometimes spelled Catal Huyuk as well). Neolithic does not mean "primitive," though this is the classic formulation: technically, indigenous cultures which never developed bronze or iron should still be classified as stone-working cultures, although they could be highly complex and sophisticated. Civilizations in South America, for example, existed despite the absence of advanced metallurgy.
- Bronze Age (since 3000 B.C.) -
The Bronze Age begins with the first metal-working, which historically involved bronze in most areas outside of sub-Saharan Africa. (Some areas worked with copper first, and then bronze.) In the ancient Middle East, the Bronze Age is said to stretch from roughly 3000 B.C. to 1200 B.C., and is divided into the early, middle, and late Bronze Ages.
This period saw the rise of the major ancient civilizations of that region of the planet, like Mesopotamia, Egypt, the Levantine civilizations, Anatolia, and the ancient Persians. One of the first bronze-working civilizations was in the Indus valley (present-day India). In parts of Europe, the Bronze Age came substantially later; bronze-working in the British Isles, for example, began in roughly 2000 B.C., and lasted for about 1250 years, and Ireland lasted even longer. It is more difficult to develop generalizations about Bronze Age civilizations than about ancient Stone Age civilizations, both because the archaeological record is much richer and because of the extremely diverse civilizations which developed across Eurasia.
In the Americas, there was limited bronze-working in pre-contact Central and South America.
- Iron Age (since 1200 B.C.) -
The Iron Age is the final phase in classical prehistorical archaeology, followed by literacy and steel refining. Long before the Iron Age, a large number of ancient cultures had been aware of iron-nickel, found at meteor impact sites, and used it without refinement. Some iron smelting also can be found throughout the Mediterranean, Middle East, and India after 2000 B.C. However, bronze was generally dominant because of its lower melting point and therefore easier application to tool-making. Not all areas, and within all areas only a minority of Iron Age tools, actually were made of steel, which is lighter but more difficult to produce than wrought iron.
The Iron Age, in the areas to which the term was first applied, saw the rise of the first modern state-based societies: groups defined by a fixed sovereign or monarchical ruler over a territory, rather than a tribal or clan-based system of leadership. Cheap iron weapons allowed for greater militarization, while the spread of the state arguably resulted in a substantial decrease in equality. (One can trace the rise in authoritarian political organization, and decline in individual freedom, from hunter-gatherer societies through the rise of agriculture and then the rise of the first states.)
- After the Three-Age System -
Aside from general public discussion of ancient eras, the three-age system no longer occupies much importance in contemporary archaeological or anthropological research. This is because anthropologists and historians generally recognize that the three-age system is less of a general law of human society than it is a specific, historical description of how cultures tended to develop in the Middle East and the Mediterranean. Elsewhere, the three-age system was less useful in understanding cultural development. Many indigenous cultures never moved from stone to bronze; in a few cases, they even skipped bronze altogether and developed iron.
The three-age system was designed to describe ancient cultures prior to history (i.e. prior to the dawn of writing, which was seen as the classic transition from prehistoric "archaeology," dependent upon artifacts, to historic "history," dependent upon writing. Obviously, again, contemporary academics realize that the distinction is not so clearcut: the historical record is biased, while the archaeological record is spotty. Where possible, each must be used to supplement the other. However, we frequently refer to other "ages" coming and passing since, like the Industrial Age of the nineteenth century, the Atomic Age of the second half of the twentieth century, and the Information Age, since the dawn of personal computers and the Internet.