ice age

or glacial age

Any geologic period during which thick ice sheets cover vast areas of land. Such periods of large-scale glaciation may last several million years and drastically reshape surface features of entire continents. A number of major ice ages have occurred throughout the Earth's history; the most recent periods were during the Pleistocene Epoch (1.8 million–10,000 years ago).

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Formally organized social group consisting of every male (or female) of comparable age. In societies where the practice traditionally occurs (e.g., the Nuer of the southern Sudan or the Masai of Kenya and Tanzania), a person belongs, either from birth or from a determined age, to a named age set that passes through a series of life stages, or age grades, each of which has a distinctive status or social and political role. Seealso rite of passage; social status.

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Gradual change in an organism that leads to increased risk of weakness, disease, and death. It takes place in a cell, an organ, or the total organism over the entire adult life span of any living thing. There is a decline in biological functions and in ability to adapt to metabolic stress. Changes in organs include the replacement of functional cardiovascular cells with fibrous tissue. Overall effects of aging include reduced immunity, loss of muscle strength, decline in memory and other aspects of cognition, and loss of colour in the hair and elasticity in the skin. In women, the process accelerates after menopause. Seealso gerontology and geriatrics.

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First known period of prehistoric human culture, characterized by the use of stone tools. The term is little used by specialists today. See Paleolithic Period; Mesolithic Period; Neolithic Period; stone-tool industry. Seealso Bronze Age; Iron Age.

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European intellectual movement of the 17th–18th century in which ideas concerning God, reason, nature, and man were blended into a worldview that inspired revolutionary developments in art, philosophy, and politics. Central to Enlightenment thought were the use and celebration of reason. For Enlightenment thinkers, received authority, whether in science or religion, was to be subject to the investigation of unfettered minds. In the sciences and mathematics, the logics of induction and deduction made possible the creation of a sweeping new cosmology. The search for a rational religion led to Deism; the more radical products of the application of reason to religion were skepticism, atheism, and materialism. The Enlightenment produced modern secularized theories of psychology and ethics by men such as John Locke and Thomas Hobbes, and it also gave rise to radical political theories. Locke, Jeremy Bentham, J.-J. Rousseau, Montesquieu, Voltaire, and Thomas Jefferson all contributed to an evolving critique of the authoritarian state and to sketching the outline of a higher form of social organization based on natural rights. One of the Enlightenment's enduring legacies is the belief that human history is a record of general progress.

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or Old Stone Age

Ancient technological or cultural stage characterized by the use of rudimentary chipped stone tools. During the Lower Paleolithic (circa 2,500,000–200,000 years ago), simple pebble tools and crude stone choppers were made by the earliest humans. About 700,000 years ago, the first rough hand ax appeared; it was later refined and used with other tools in the Acheulean industry. A flake-tool tradition emerged in the Middle Paleolithic, as exemplified by implements of the Mousterian industry. The Upper Paleolithic (40,000–10,000 BC) saw the emergence of more complex, specialized, and diverse regional stone-tool industries, such as the Aurignacian, Solutrean, and Magdalenian. The two principal forms of Paleolithic art are small sculptures—such as the so-called Venus figurines and various carved or shaped animal and other figures—and monumental paintings, incised designs, and reliefs on the walls of caves such as Altamira (in Spain) and Lascaux Grotto (in France). The end of the Paleolithic is marked by the emergence of the settled agricultural villages of the Neolithic Period.

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or New Stone Age

Final stage of technological development or cultural evolution among prehistoric humans. It is characterized by the use of stone tools shaped by polishing or grinding, the domestication of plants or animals, the establishment of permanent villages, and the practice of such crafts as pottery and weaving. The Neolithic followed the Paleolithic Period (and in northwestern Europe the Mesolithic) and preceded the Bronze Age. Its beginning is associated with the villages that emerged in South Asia circa 9000 BC and flourished in the Tigris and Euphrates river valleys from circa 7000 BC. Farming spread northward throughout Eurasia, reaching Britain and Scandinavia only after 3000 BC. Neolithic technologies also spread to the Indus River valley of India by 5000 BC and to the Huang Ho valley of China by circa 3500 BC. The term is not applied to the New World, though Neolithic modes of life were achieved independently there by circa 2500 BC.

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Final technological and cultural stage in the Stone–Bronze–Iron-Age sequence (or Three-Age System) in which iron largely replaced bronze in implements and weapons. The start of the Iron Age varied geographically, beginning in the Middle East and southeastern Europe circa 1200 BC but in China not until circa 600 BC. Though the large-scale production of iron implements brought new patterns of more permanent settlement, use of iron for weapons put arms in the hands of the masses for the first time and set off a series of large-scale movements and conquests that did not end for 2,000 years and that changed the face of Europe and Asia. Seealso Bronze Age.

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In the eastern Mediterranean and the Middle East, the period between the death of Alexander the Great (323 BC) and the conquest of Egypt by Rome (30 BC). Alexander and his successors established Greek monarchies that controlled the area from Greece to Afghanistan. The Macedonian Antigonid kingdom, the Middle Eastern Seleucid kingdom, and the Egyptian Ptolemaic kingdom spread Greek culture, mixed Greek and non-Greek populations, and fused Greek and Oriental elements. They produced effective bureaucracies and a common, creative culture based at Alexandria. A great flowering of the arts, literature, and science occurred particularly in the period 280–160. The decline of the Hellenic states occurred as Rome gained strength and won wars against Macedonia and against Mithradates VI Eupator, turning the kingdoms and their allies into Roman provinces. Egypt was the last to fall, after having been drawn into the civil war between Mark Antony and Octavian (Augustus).

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Third phase in the development of material culture among the ancient peoples of Europe, Asia, and the Middle East, following the Paleolithic and Neolithic periods and preceding the Iron Age. The term also denotes the first period in which metal was used. The date at which the age began varied by region; in Greece and China it began before 3000 BC, in Britain not until circa 1900 BC. The beginning of the period is sometimes called the Chalcolithic (Copper-Stone) Age, referring to the initial use of pure copper (along with its predecessor, stone). By 3000 BC the use of copper was well known in the Middle East, had extended westward into the Mediterranean area, and was beginning to infiltrate Europe. Only in the 2nd millennium BC did true bronze come to be widely used. The age was marked by increased specialization and the invention of the wheel and the ox-drawn plow. From circa 1000 BC the ability to heat and forge iron brought the Bronze Age to an end.

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Age may refer to:

The length of time that an organism has lived:

• aging, for the social, cultural, and economic factors of age and aging.
• senescence, for the biology and science of aging.

A period of history:

• list of time periods
• three-age system
• geologic timescale
• astrological age

Other:

• Agé, a god from the mythology of the Fon people; the son of Mawu-Lisa;
• One of the D'ni Ages, the fictional universe in the Myst series of games.
• Agenore Incrocci, an Italian screenwriter.
• Age (Model theory), the class of all finitely generated structures which are embeddable in a structure A in mathematics.
• âge Japanese company
• The Age is a daily newspaper published in Melbourne, Australia.

AGE is a three-letter acronym that may refer to:

• Advanced glycation endproduct, a class of spontaneously modified molecules whose modification begins with an initial glycation
• A. G. Edwards, a brokerage firm
• Agarose gel electrophoresis, a method used in molecular biology
• American Aging Association (abbreviated AGE, although not an acronym)
• Applied general equilibrium
• Arterial gas embolism
• Agricultural & General Engineers, a group of companies
• The Age (band), rock band from Warren, Michigan