Human history

The history of the world, by convention, is human history, from the first appearance of Homo sapiens to the present. Human history is marked both by a gradual  accretion of discoveries and inventions, as well as by quantum leaps — revolutions — that comprise epochs in the material and spiritual evolution of humankind.

Human history, as opposed to prehistory, has in the past been said to begin with the invention, independently at several sites on Earth, of writing, which created the infrastructure for lasting, accurately transmitted memories and thus for the diffusion and growth of knowledge. Writing, in its turn, had been made necessary in the wake of the Agricultural Revolution, which had given rise to civilization, i.e., to permanent settled communities, which fostered a growing diversity of trades.

Such scattered habitations, centered about life-sustaining bodies of water — rivers and lakes — coalesced over time into ever larger units, in parallel with the evolution of ever more efficient means of transport. These processes of coalescence, spurred by rivalries and conflicts between adjacent communities, gave rise over millenia to ever larger states, and then to superstates (empires). The fall of the Roman Empire in Europe at the end of antiquity signalled the beginning of the Middle Ages.

In the mid-15th century, Johannes Gutenberg's invention of modern printing, employing movable type, revolutionized communication, helping end the Middle Ages and usher in modern times, the European Renaissance and the Scientific Revolution.

By the 18th century, the accumulation of knowledge and technology, especially in Europe, had reached a critical mass that sparked into existence the Industrial Revolution. Over the quarter-millennium since, knowledge, technology, commerce, and — concomitantly with these — war have accelerated at a geometric rate, creating the opportunities and perils that now confront the human communities that together inhabit a finite planet.

Paleolithic Period
"Paleolithic" means "Old Stone Age." This was the earliest period of the Stone Age.

Scientific evidence based on genetics and the study of fossils, places the origin of modern Homo sapiens in Africa. This occurred about 200,000 BP during the Palaeolithic period, after a long period of evolution. Ancestors of humans, such as Homo erectus, had been using simple tools for over a thousand millennia, but as time progressed, tools became far more refined and complex. Humans also developed language sometime during the Paleolithic period, as well as a conceptual repertoire that included systematic burial of the dead. The latter suggests a development of foresight after consistent exposure to rotting bodies.

The first signs of prehistoric art also appear during this period. During the Paleolithic, all humans lived as hunter-gatherers, who were generally nomadic.

According to the Toba catastrophe theory, the Lake Toba supereruption, which occurred 75,000 years ago, may have had global effects, killing off as many as 59 million people, and creating a population bottleneck.

Modern humans spread rapidly over the globe from Africa and the frost-free zones of Europe and Asia. The rapid expansion of humankind to North America and Oceania took place at the climax of the most recent Ice Age, when today's temperate regions were extremely inhospitable. Yet, by the end of the Ice Age some 12,000 BP, humans had colonised nearly all the ice-free parts of the globe.

Hunter-gatherer societies have tended to be very small, though in some cases they have developed social stratification; and long-distance contacts may be possible, as in the case of Indigenous Australian "highways."

Eventually most hunter-gatherer societies have either developed into, or have been absorbed into, larger agricultural states. Those that have not, have either perished or have remained in isolation, as is the case with the small hunter-gatherer societies that are still present in remote regions today.

Mesolithic Period
The "Mesolithic," or "Middle Stone Age" (from the Greek "mesos," "middle," and "lithos," "stone") was a period in the development of human technology between the Paleolithic and Neolithic periods of the Stone Age.

The Mesolithic period began at the end of the Pleistocene epoch, some 10,000 BP, and ended with the introduction of agriculture, the date of which varied by geographic region. In some areas, such as the Near East, agriculture was already underway by the end of the Pleistocene, and there the Mesolithic is short and poorly defined. In areas with limited glacial impact, the term "Epipaleolithic" is sometimes preferred.

Regions that experienced greater environmental effects as the last ice age ended have a much more evident Mesolithic era, lasting millennia. In Northern Europe, societies were able to live well on rich food supplies from the marshlands fostered by the warmer climate. Such conditions produced distinctive human behaviours which are preserved in the material record, such as the Maglemosian and Azilian cultures. These conditions also delayed the coming of the Neolithic until as late as 4000 BCE in northern Europe.

Remains from this period are few and far between, often limited to middens. In forested areas, the first signs of deforestation have been found, although this would only begin in earnest during the Neolithic, when more space was needed for agriculture.

The Mesolithic is characterized in most areas by small composite flint tools — microliths and microburins. Fishing tackle, stone adzes and wooden objects, e.g. canoes and bows, have been found at some sites. These technologies first occur in Africa, associated with the Azilian cultures, before spreading to Europe through the Ibero-Maurusian culture of Spain and Portugal, and the Kebaran culture of Palestine. Independent discovery is not always ruled out.

Neolithic Period
"Neolithic" means "New Stone Age." This was a period of primitive technological and social development, toward the end of the "Stone Age." Beginning in the 10th millennium BCE, the Neolithic period saw the development of early villages, agriculture, animal domestication and tools.

Development of agriculture
A major change, described by prehistorian Vere Gordon Childe as the "Agricultural Revolution," occurred about the 10th millennium BCE with the adoption of agriculture. The Sumerians first began farming ca. 9500 BCE. By 7000 BCE, agriculture had spread to India; by 6000 BCE, to Egypt; by 5000 BCE, to China. About 2700 BCE, agriculture had come to Mesoamerica.

Although attention has tended to concentrate on the Middle East's Fertile Crescent, archaeology in the Americas, East Asia and Southeast Asia indicates that agricultural systems, using different crops and animals, may in some cases have developed there nearly as early.

A further advance in Middle Eastern agriculture occurred with the development of organised irrigation, and the use of a specialised workforce, by the Sumerians, beginning about 5500 BCE. Stone was supplanted by bronze and iron in implements of agriculture and warfare. Agricultural settlements had until then been almost completely dependent on stone tools. In Eurasia, copper and bronze tools, decorations and weapons began to be commonplace about 3000 BCE. After bronze, the Eastern Mediterranean region, Middle East and China saw the introduction of iron tools and weapons.

The Americas may not have had metal tools until the Chavín horizon (900 BCE). The Moche did have metal armor, knives and tableware. Even the metal-poor Inca had metal-tipped plows, at least after the conquest of Chimor. However, little archaeological research has so far been done in Peru, and nearly all the khipus (recording devices, in the form of knots, used by the Incas) were burned in the Spanish conquest of Peru. As late as 2004, entire cities were still being unearthed. Some digs suggest that steel may have been produced there before it was developed in Europe.

The cradles of early civilizations were river valleys, such as the Yellow River valley in China, the Nile valley in Egypt, and the Indus Valley in the Indian subcontinent. Some nomadic peoples, such as the Indigenous Australians and the Bushmen of southern Africa, did not practice agriculture until relatively recent times.

Before 1800, many populations did not belong to states. Scientists disagree as to whether the term "tribe" should be applied to the kinds of societies that these people lived in. Large parts of the world were "tribal" territories before Europeans began colonizing them. Many tribal societies, in Europe and elsewhere, transformed into states when they were threatened, or otherwise impinged on, by existing states. Examples are the Marcomanni, Poland and Lithuania. Some "tribes," such as the Kassites and the Manchus, conquered states and were absorbed by them.

Agriculture made possible complex societies — civilizations. States and markets emerged. Technologies enhanced people's ability to control nature and to develop transport and communication.

Development of religion
It is to the Neolithic that most historians trace the beginnings of complex religion. Religious belief in this period commonly consisted in the worship of a Mother Goddess, a Sky Father, and of the Sun and Moon as deities. (see also Sun worship). Shrines developed, which over time evolved into temple establishments, complete with a complex hierarchy of priests and priestesses and other functionaries. Typical of the Neolithic was a tendency to worship anthropomorphic deities.

The earliest surviving religious scriptures are the Pyramid Texts, produced by the Egyptians (dating back to 3100 B.C.E).

State
The first Agricultural Revolution led to several major changes. It permitted far denser populations, which in time organised into states. There are several definitions for the term, "state." Max Weber and Norbert Elias defined a state as an organization of people that has a monopoly on the legitimate use of force in a particular geographic area.



The first states appeared in western Iran, Mesopotamia, ancient Egypt and ancient India in the late 4th and early 3rd millennia BCE. In Mesopotamia and Iran, there were several city-states. Ancient Egypt began as a state without cities, but soon developed them.

A state ordinarily needs an army for the legitimate exercise of force. An army needs a bureaucracy to maintain it. The only exception to this appears to have been the Indus Valley civilization, for which there is no evidence of the existence of a military force.

States appeared in China in the late 3rd and early 2nd millennia BCE.

Major wars were waged among states in the Middle East. About 1275 BCE, the Hittites and Egyptians concluded the treaty of Kadesh, the world's oldest recorded peace treaty.

Empires came into being, with conquered areas ruled by central tribes, as in Persia (6th century BCE), the Mauryan Empire (4th century BCE), China (3rd century BCE), and the Roman Empire (1st century BCE).

Clashes among empires included those that took place in the 8th century, when the Islamic Caliphate of Arabia (ruling from Spain to Iran) and China's Tang dynasty (ruling from Xinjiang to Korea) fought for decades for control of Central Asia.

The largest contiguous land empire was the 13th-century Mongolian Empire. By then, most people in Europe, Asia and North Africa belonged to states. There were states as well in Mexico and western South America. States controlled more and more of the world's territory and population; the last "empty" territories, with the exception of uninhabited Antarctica, would be divided up among states by the Treaty of Berlin (1878).

City and trade
Agriculture also created, and allowed for the storage of, food surpluses that could support people not directly engaged in food production. The development of agriculture permitted the creation of the first cities. These were centers of trade, manufacture and political power with nearly no agricultural production of their own. Cities established a symbiosis with their surrounding countrysides, absorbing agricultural products and providing, in return, manufactures and varying degrees of military protection.

The development of cities equated, both etymologically and in fact, with the rise of civilization itself: first Sumerian civilization, in lower Mesopotamia (3500 BCE), followed by Egyptian civilization along the Nile (3300 BCE) and Harappan civilization in the Indus Valley (3300 BCE). Elaborate cities grew up, with high levels of social and economic complexity. Each of these civilizations was so different from the others that they almost certainly originated independently. It was at this time, and due to the needs of cities, that writing and extensive trade were introduced.

In China, proto-urban societies may have developed from 2500 BCE, but the first dynasty to be identified by archeology is the Shang Dynasty.

The 2nd millennium BCE saw the emergence of civilization in Crete, mainland Greece and central Turkey.

In the Americas, civilizations such as the Maya, Moche and Nazca emerged in Mesoamerica and Peru at the end of the 1st millennium BCE.

The world's first coinage was introduced around 625 BC in Lydia (western Anatolia, in modern Turkey).

Trade routes appeared in the eastern Mediterranean in the 4th millennium BCE. Long-range trade routes first appeared in the 3rd millennium BCE, when Sumerians in Mesopotamia traded with the Harappan civilization of the Indus Valley. The Silk Road between China and Syria began in the 2nd millennium BCE. Cities in Central Asia and Persia were major crossroads of these trade routes. The Phoenician and Greek civilizations founded trade-based empires in the Mediterranean basin in the 1st millennium BCE.

In the late 1st millennium CE and early 2nd millennium CE, the Arabs dominated the trade routes in the Indian Ocean, East Asia, and the Sahara. In the late 1st millennium, Arabs and Jews dominated trade in the Mediterranean. In the early 2nd millennium, Italians took over this role, and Flemish and German cities were at the center of trade routes in northern Europe. In all areas, major cities developed at crossroads along trade routes.

Religion and philosophy
New philosophies and religions arose in both east and west, particularly about the 6th century BCE. Over time, a great variety of religions developed around the world, with some of the earliest major ones being Hinduism and Buddhism in India, and Zoroastrianism in Persia. The Abrahamic religions trace their origin to Judaism, around 1800 BCE.

In the east, three schools of thought were to dominate Chinese thinking until the modern day. These were Taoism, Legalism and Confucianism. The Confucian tradition, which would attain dominance, looked for political morality not to the force of law but to the power and example of tradition.

In the west, the Greek philosophical tradition, represented by Plato and Aristotle, was diffused throughout Europe and the Middle East in the 4th century BCE by the conquests of Alexander of Macedon.

Major civilizations and regions
By the last centuries BCE, the Mediterranean, the Ganges River and the Yellow River had become seats of empires which future rulers would seek to emulate. In India, the Mauryan Empire ruled most of southern Asia, while the Pandyas ruled southern India. In China, the Qin and Han dynasties extended their imperial governance through political unity, improved communications and Emperor Wu's establishment of state monopolies.

In the west, the ancient Greeks established a civilization that is considered by most historians to be the foundational culture of modern western civilization. Some centuries later, in the 3rd century BCE, the Romans began expanding their territory through conquest and colonisation. By the reign of Emperor Augustus (late 1st century BCE), Rome controlled all the lands surrounding the Mediterranean.

The great empires depended on military annexation of territory and on the formation of defended settlements to become agricultural centres. The relative peace that the empires brought, encouraged international trade, most notably the massive trade routes in the Mediterranean that had been developed by the time of the Hellenistic Age, and the Silk Road.

The empires faced common problems associated with maintaining huge armies and supporting a central bureaucracy. These costs fell most heavily on the peasantry, while land-owning magnates were increasingly able to evade centralised control and its costs. The pressure of barbarians on the frontiers hastened the process of internal dissolution. China's Han Empire fell into civil war in 220 CE, while its Roman counterpart became increasingly decentralised and divided about the same time.

Throughout the temperate zones of Eurasia, America and North Africa, empires continued to rise and fall.

The gradual break-up of the Roman Empire, spanning several centuries after the 2nd century CE, coincided with the spread of Christianity westward from the Middle East. The western Roman Empire fell under the domination of Germanic tribes in the 5th century, and these polities gradually developed into a number of warring states, all associated in one way or another with the Roman Catholic Church. The remaining part of the Roman Empire, in the eastern Mediterranean, would henceforth be the Byzantine Empire. Centuries later, a limited unity would be restored to western Europe through the establishment of the Holy Roman Empire, comprising a number of states in what is now Germany and Italy.

In China, dynasties would similarly rise and fall. After the fall of the Eastern Han Dynasty and the demise of the Three Kingdoms, Nomadic tribes from the north began to invade in the 4th century CE, eventually conquering areas of Northern China and setting up many small kingdoms. The Sui Dynasty reunified China in 581, and under the Tang Dynasty (618-907) China entered a second golden age. The Tang Dynasty also splintered, however, and after half a century of turmoil the Northern Song Dynasty reunified China in 982. Yet pressure from nomadic empires to the north became increasingly urgent. North China was lost to the Jurchen in 1141, and the Mongol Empire conquered all of China in 1279, as well as almost all of Eurasia's landmass, missing only central and western Europe and Japan.

In these times, northern India was ruled by the Guptas. In southern India, three prominent Dravidian kingdoms emerged: Cheras, Cholas and Pandyas. The ensuing stability contributed to heralding in the golden age of Hindu culture in the 4th and 5th centuries CE. At this time also, in Central America, vast societies also began to be built, the most notable being the Maya and Aztecs of Mesoamerica. As the mother culture of the Olmecs gradually declined, the great Mayan city-states slowly rose in number and prominence, and Maya culture spread throughout Yucatán and surrounding areas. The later empire of the Aztecs was built on neighboring cultures and was influenced by conquered peoples such as the Toltecs.

In South America, the 14th and 15th centuries saw the rise of the Inca. The Inca Empire of Tawantinsuyu, with its capital at Cusco, spanned the entire Andes Mountain Range. The Inca were prosperous and advanced, known for an excellent road system and unrivaled masonry.

Islam, which began in 7th century Arabia, was also one of the most remarkable forces in world history, growing from a handful of adherents to become the foundation of a series of empires in the Middle East, North Africa, Central Asia, India and present-day Indonesia.

In northeastern Africa, Nubia and Ethiopia remained Christian enclaves while the rest of Africa north of the equator converted to Islam. With Islam came new technologies that, for the first time, allowed substantial trade to cross the Sahara. Taxes on this trade brought prosperity to North Africa, and the rise of a series of kingdoms in the Sahel.

This period in the history of the world was marked by slow but steady technological advances, with important developments such as the stirrup and moldboard plow arriving every few centuries. There were, however, in some regions, periods of rapid technological progress. Most important, perhaps, was the Mediterranean area during the Hellenistic period, when hundreds of technologies were invented. Such periods were followed by periods of technological decay, as during the Roman Empire's decline and fall and the ensuing early medieval period.

Background to European advance


Nearly all the agricultural civilizations were heavily constrained by their environments. Productivity remained low, and climatic changes easily instigated boom and bust cycles that brought about civilizations' rise and fall. By about 1500, however, there was a qualitative change in world history. Technological advance and the wealth generated by trade gradually brought about a widening of possibilities.

Even before the 16th century, some civilizations had developed advanced societies. In ancient times, the Greeks and Romans had produced societies supported by a developed monetary economy, with financial markets and private-property rights. These institutions created the conditions for continuous capital accumulation, with increased productivity. By some estimates, the per-capita income of Roman Italy, one of the most advanced regions of the Roman Empire, was comparable to the per-capita incomes of the most advanced economies in the 18th century. (see ) The most developed regions of classical civilization were more urbanized than any other region of the world until early modern times. This civilization had, however, gradually declined and collapsed; historians still debate the causes.

China had developed an advanced monetary economy by 1,000 CE. China had a free peasantry who were no longer subsistence farmers, and could sell their produce and actively participate in the market. The agriculture was highly productive and China's society was highly urbanized. The country was technologically advanced as it enjoyed a monopoly in piston bellows and printing. (see Joseph Needham). But, after earlier onslaughts by the Jurchens, in 1279 the remnants of the Sung empire were conquered by the Mongols.

Outwardly, Europe's Renaissance, beginning in the 14th century, consisted in the rediscovery of the classical world's scientific contributions, and in the economic and social rise of Europe. But the Renaissance also engendered a culture of inquisitiveness which ultimately led to Humanism, the Scientific Revolution, and finally the great transformation of the Industrial Revolution. The Scientific Revolution in the 17th century, however, had no immediate impact on technology; only in the second half of the 18th century did scientific advances begin to be applied to practical invention.

The advantages that Europe had developed by the mid-18th century were two: an entrepreneurial culture, and the wealth generated by the Atlantic trade (including the African slave trade). While some historians conclude that, in 1750, labour productivity in the most developed regions of China was still on a par with that of Europe's Atlantic economy (see Wolfgang Keller and Carol Shiue), other historians like Angus Maddison hold that the per-capita productivity of western Europe had by the late Middle Ages surpassed that of all other regions.

A number of explanations are proffered as to why, from the late Middle Ages on, Europe rose to surpass other civilizations, become the home of the Industrial Revolution, and dominate the world. Max Weber argued that it was due to a Protestant work ethic that encouraged Europeans to work harder and longer than others. Another socioeconomic explanation looks to demographics: Europe, with its celibate clergy, colonial emigration, high-mortality urban centers, continual warfare, and late age of marriage had far more restrained population growth, compared to Asian cultures. A relative shortage of labour meant that surpluses could be invested in labour-saving technological advances such as water-wheels and mills, spinners and looms, steam engines and shipping, rather than fueling population growth.

Many have also argued that Europe's institutions were superior, that property rights and free-market economics were stronger than elsewhere due to an ideal of freedom peculiar to Europe. In recent years, however, scholars such as Kenneth Pomeranz have challenged this view, although the revisionist approach to world history has also met with criticism for systematically "downplaying" European achievements.

Europe's geography may also have played an important role. The Middle East, India and China are all ringed by mountains but, once past these outer barriers, are relatively flat. By contrast, the Pyrenees, Alps, Apennines, Carpathians and other mountain ranges run through Europe, and the continent is also divided by several seas. This gave Europe some degree of protection from the peril of Central Asian invaders. Before the era of firearms, these nomads were militarily superior to the agricultural states on the periphery of the Eurasian continent and, if they broke out into the plains of northern India or the valleys of China, were all but unstoppable. These invasions were often devastating. The Golden Age of Islam was ended by the Mongol sack of Baghdad in 1258. India and China were subject to periodic invasions, and Russia spent a couple of centuries under the Tartar Yoke. Central and western Europe, logistically more distant from the Central Asian heartland, proved less vulnerable to these threats.

Geography also contributed to important geopolitical differences. For most of their histories, China, India and the Middle East were each unified under a single dominant power that expanded until it reached the surrounding mountains and deserts. In 1600 the Ottoman Empire controlled almost all the Middle East, the Ming Dynasty ruled China, and the Mughal Empire held sway over India. By contrast, Europe was almost always divided into a number of warring states. Pan-European empires, with the major exception of the Roman Empire, tended to collapse soon after they arose.

One source of Europe's success is often said to be the intense competition among rival European states. In other regions, stability was often a higher priority than growth. China's growth as a maritime power was halted by the Ming Dynasty's Hai jin ban on ocean-going commerce. In Europe, due to political disunity, a blanket ban of this kind would have been impossible; had any one state imposed it, that state would quickly have fallen behind its competitors.

Another doubtless important geographic factor in the rise of Europe was the Mediterranean Sea, which, for millennia, had functioned as a maritime superhighway fostering the exchange of goods, people, ideas and inventions.

By contrast to Europe, in tropical lands the still more ubiquitous diseases and parasites, sapping the strength and health of humans, and of their animals and crops, were socially-disorganizing factors that impeded progress.

Europe's mercantile dominance
In the fourteenth century, the Renaissance began in Europe. Some modern scholars have questioned whether this flowering of art and Humanism was a benefit to science, but the era did see an important fusion of Arab and European knowledge. One of the most important developments was the caravel, which combined the Arab lateen sail with European square rigging to create the first vessels that could safely sail the Atlantic Ocean. Along with important developments in navigation, this technology allowed Christopher Columbus in 1492 to journey across the Atlantic Ocean and bridge the gap between Africa-Eurasia and the Americas.

This had dramatic effects on both continents, in one of the most famous historic Outside Context Problems. The Europeans brought with them viral diseases that American natives had never encountered, and uncertain numbers of natives died in a series of devastating epidemics. The Europeans also had the technological advantage of horses, steel and guns that helped them overpower the Aztec and Incan empires as well as North American cultures.

Gold and resources from the Americas began to be stripped from the land and people and shipped to Europe, while at the same time large numbers of European colonists began to emigrate to the Americas. To meet the great demand for labour in the new colonies, the mass import of Africans as slaves began. Soon much of the Americas had a large racial underclass of slaves. In West Africa, a series of thriving states developed along the coast, becoming prosperous from the exploitation of suffering interior African peoples. Europe's maritime expansion unsurprisingly — given that continent's geography — was largely the work of its Atlantic seaboard states: Portugal, Spain, England, France, the Netherlands. The Portuguese and Spanish Empires were at first the predominant conquerors and source of influence, but soon the more northern English, French and Dutch began to dominate the Atlantic. In a series of wars, fought in the 17th and 18th centuries, culminating with the Napoleonic Wars, Britain emerged as the first world power. It accumulated an empire that spanned the globe, controlling, at its peak, approximately one-quarter of the world's land surface, on which the "sun never set".

Meanwhile the voyages of Admiral Zheng He were halted by China's Ming Dynasty (1368-1644), established after the expulsion of the Mongols. A Chinese commercial revolution, sometimes described as "incipient capitalism," was also abortive. The Ming Dynasty would eventually fall to the Manchus, whose Qing Dynasty at first oversaw a period of calm and prosperity but would increasingly fall prey to Western encroachment.

Soon after the invasion of the Americas, Europeans had exerted their technological advantage as well over the peoples of Asia. In the early 19th century, Britain gained control of the Indian subcontinent, Egypt and the Malay Peninsula; the French took Indochina; while the Dutch occupied the Dutch East Indies. The British also took over several areas still populated by Neolithic peoples, including Australia, New Zealand and South Africa, and, as in the Americas, large numbers of British colonists began to emigrate there. In the late 19th century, the European powers divided the remaining areas of Africa.

This era in Europe saw the Age of Reason lead to the Scientific Revolution, which changed man's understanding of the world and made possible the Industrial Revolution, a major transformation of the world’s economies. The Industrial Revolution began in Britain and used new modes of production — the factory, mass production, and mechanisation — to manufacture a wide array of goods faster and for less labour than previously.

The Age of Reason also led to the beginnings of modern democracy in the late-18th century American and French Revolutions. Democracy would grow to have a profound effect on world events and on quality of life.

During the Industrial Revolution, the world economy was soon based on coal, as new methods of transport, such as railways and steamships, effectively shrank the world. Meanwhile, industrial pollution and environmental damage, present since the discovery of fire and the beginning of civilization, accelerated drastically.

Twentieth Century onward


Following World War II the United Nations was founded, in the hope that it could allay conflicts among nations and prevent future wars. In 1991 the Soviet Union collapsed, leaving the United States in possession of the field as "the sole remaining superpower," termed by some a "hyperpower." (See "Pax Americana.")

The century had given rise to powerful secular ideologies. The first, after 1917 in the Soviet Union, was communism, which after 1945 spread to Central Europe, Yugoslavia, Bulgaria, Romania, Albania, North Vietnam and North Korea; in 1949, to China; and during the 1950s and '60s, elsewhere in the Third World. The 1920s and '30s saw militaristic fascist dictatorships gain control of Italy, Germany, Japan and Spain.



These transformations were linked to wars of unparalleled scope and devastation. World War I destroyed many of Europe's old empires and monarchies, and weakened France and Britain. World War II ultimately saw most of the militaristic dictatorships in Europe destroyed and communism advance into Eastern and Central Europe and into Asia.

This led to the Cold War, a forty-year stand-off between the United States, the Soviet Union, and their respective allies. All of humanity and complex life forms were put at risk by the existence of nuclear weapons. The nuclear powers understood the risks, especially after the Cuban Missile Crisis in 1962 nearly precipitated nuclear war. Such war being viewed as impractical, proxy wars were instead waged, at the expense of non-nuclear-armed Third World countries. In response to threatened and actual wars, a popular, youth-driven counterculture of the 1960s emerged in some countries, questioning the cold-war values of some elders.

In 1991 the world witnessed the disintegration of the Soviet Union, with some of its former republics rejoining Russia in a Commonwealth of Independent States, while other republics as well as several former Soviet "satellites" reached out toward western Europe and the European Union.

The same century saw vast progress in technology, and a large increase in life expectancy and standard of living for the majority of humanity. As the world economy switched from one based on coal to one based on petroleum, new communications and transportation technologies continued to make the world more united. The technological developments of the century also contributed to problems with the environment, though urban pollution is lower today than in the days of coal.

The latter half of the century saw the rise of the information age and globalization dramatically increase trade and cultural exchange. Space exploration reached throughout the solar system. The structure of DNA, the very template of life, was discovered, and the human genome was sequenced, promising to eventually change the face of human disease. The number of scientific papers published each year now far surpasses the total number published prior to 1900, and doubles approximately every 15 years. Global literacy rates have continued to increase, and the percentage of the global society's labor pool needed to produce  society's food has continued to decrease substantially (Kurzweil 1999).

The same period, however, raised prospects of an end to human history, precipitated by unmanaged global hazards: nuclear proliferation, the greenhouse effect and other forms of environmental degradation caused by the "fissile-fossil complex," international conflicts prompted by the dwindling of resources, fast-spreading epidemics such as HIV, and the passage of near-earth asteroids and comets.

The development of states had always taken impetus from hope of gain and fear of loss. The sense of national identity had always been forged in conflicts with outsiders who were perceived as a threat. As the 20th century closed, the world witnessed the rise of what some saw as a new superstate, the European Union. Tentative steps were also taken, at emulating the European Union, by states in Asia, Africa and South America. Meanwhile the growth, life and collapse of states, organized around various human populations and for the purpose of achieving various human goals, continued to be accompanied by wars, with concomitant loss of life, physical destruction, disease, famine and genocide.

As the 20th century closed and the 21st opened, an increasingly interdependent world faced common hazards that could be averted only by common effort. Some scientists referred to this as a shift to a Planetary Phase of Civilization. It more and more seemed that the world must either perish or survive as a whole. This was brought home on October 30, 2006, by the Stern Review, warning of the threat of global warming and rapid climate change. In the historic escalation of human perils, localized internecine and international conflicts began to be edged out, as a focus of dread, by common threats to all mankind — by mankind's global conflict with the natural environment.

The global threats posed by environmental degradation and by the exhaustion of material and energy resources were not the first "matergetic crisis" that the world had faced. One of many earlier ones had been triggered by Britain's deforestation to supply charcoal needed for the production of iron, and had led to the invention of coking by the Abraham Darbys, father and son, which helped spark the 18th-century Industrial Revolution. Similarly, as the 20th century yielded to the 21st, the world seemed again to be lodged at a historic bottleneck which might be opened up by new technological innovations — including research into fusion power (ITER), and greatly increased exploitation of solar-based renewable resources in the form of wind, tides, hydroelectric power and direct solar energy (e.g., photovoltaics).