Student's Friend, Part 1

LOCATIONS: Europe, Asia, Africa, Antarctica, Australia, North America, South America, Ural Mountains, Pacific Ocean, Atlantic Ocean, Indian Ocean, Arctic Ocean, Great Rift Valley, Bering Strait, the tropics, arctic and antarctic regions, temperate zones

World history is the story of human experience. It is a story of how people, ideas, and goods spread across the earth creating our past and our present. To help us better understand this experience, we will divide history into four main eras: prehistory, ancient times, middle ages, and modern times. Our story begins during prehistory in east Africa where human life began. From Africa humans spread to Eurasia (Europe and Asia), to Australia, and finally to the Americas. Human migration was one of the great waves of history.

During most of history, most humans made their living by hunting and gathering. Then about 12,000 years ago, people in the Middle East learned how to raise a wild wheat plant, and agriculture was born -- another great wave of history. No longer were humans constantly on the move searching for food. People could settle in one place, build cities, and make inventions like the plow, wheel, and writing. The complex societies that resulted are what we call civilization, another wave of history and the start of ancient times.
In terms of a human lifetime, waves of change moved slowly, and much stayed the same amid the changes.

Waves of history were channeled over the earth by geography. The first civilizations arose in river valleys where rivers provided fresh water for raising crops and transportation for moving crops to market. Beginning in Mesopotamia, civilization spread west to Egypt and east to India. These three civilizations formed an early international trading network that eventually extended across the connected lands of Eurasia and North Africa, a vast region that lies in a temperate climate zone where most of the world's people have lived since prehistoric times. More people meant more ideas, more inventions, and more diseases than in other parts of the world. Waves of change took longer to reach sub-Saharan Africa and the Americas because they were separated from Eurasia by physical barriers of desert and ocean.

As agriculture replaced hunting and gathering, human population increased. People in civilized societies divided themselves into unequal social classes with priests and kings at the top. Wealthy landowners collected rent payments from poor farmers, men came to dominate women, and slavery became common.
In the grasslands of central Eurasia, nomadic people chose not to settle down and raise crops. They lived by herding animals from pasture to pasture with the seasons. They learned to ride horses, developed cavalry skills, and attacked settled communities. Sometimes these nomadic raiders conquered great civilizations.

During ancient times people in Eurasia invented many things that still define civilization today such as money, armies, iron, math, literature, democracy, and major world religions -- to name a few. Ancient times lasted for roughly 4,000 years, ending about 500 AD after nomadic raiders brought down great classical civilizations in India, China, and the Mediterranean. The middle ages followed and lasted a thousand years.

Change spread to new places mostly through trading contacts. Some people welcomed change, while others avoided change and tried to maintain traditional ways. In the late middle ages, China was a superpower with the greatest navy in the world until China's rulers chose to reduce contact with the outside world and dismantled the fleet. This choice opened the door for Europeans to make the great voyages of discovery that connected the world and began the modern era around the year 1500. Change was moving faster now.

Three centuries later, Europeans learned how to power machines by burning fuels, unleashing the Industrial Revolution -- another great wave of history. Change moved even faster. At first, Europeans used their machines to dominate other peoples of the world who lacked advanced technology. Then Europeans turned their machines on each other, launching two suicidal world wars that ended European world dominance.

The stream of time flows on. As always, we humans face challenges to our survival, but in our time the challenges are global. The world is closely connected through communications and trade, but the world remains divided between the "haves" and the "have nots." Modern technology is consuming the world's resources, threatening the earth's environment, and it has produced weapons that could end human life.

History created our past and our present, but the future is up to us. There is no instruction manual for the future, but we do have a guide that shows how the world works and how humans behave. That guide is history.

1. primary and secondary sources
................We learn about the past from historians. But, where do historians get their information? Usually, they study primary sources, which are sources created at about the same time as the event being studied, often by people involved in the event. Examples of primary sources include artifacts uncovered by archeologists, art works, government records, diaries, letters, speeches, and newspaper articles.
Historians also study secondary sources. These are sources created after the event by people not involved in the event. Examples of secondary sources include history books, textbooks, encyclopedias, and the Student's Friend.
..............After historians examine their sources, they write histories based on their understanding of the truth. But, what they write may be influenced by their own opinions or by lack of information. It is not possible for historians to know everything about a past event, so they must rely on the evidence left behind in the form of primary and secondary sources. If new evidence is found, interpretations of history can change.

2. BC and AD
..............People in different parts of the world have adopted many ways to mark the passage of time. The Chinese calendar counts years from the reign of the mythical Yellow Emperor in 2698 BC. The Islamic calendar numbers years from 622 AD when Muhammad fled from Mecca. Both calendars are based on lunar cycles. The year 2000 in our calendar is 4697 in the Chinese calendar and 1421 in the Islamic calendar.
...............Our solar calendar comes from ancient Egypt. It was modified during the middle ages in Europe, and it has been adopted by most of the world for official purposes. Years are numbered from the birth of Christ: years before year 1 are designated BC for "Before Christ;" years after year 1 are designated AD, an abbreviation for the Latin term Anno Domini, which means "in the year of the lord." AD years are counted forward from year 1; BC years are counted backward from year 1. Thus, 500 BC was earlier than 200 BC.
...............In recent years, people who wish to avoid the reference to Christ have begun using the term BCE (Before the Common Era) to replace BC and CE (Common Era) to replace AD. The terms BCE and CE are used in some history books. The Student's Friend uses the traditional terms BC and AD because they are more widely known in our culture, because there was no Common Era in history, and because non-Christians may object to the suggestion that the Christian era is the "common era" of humankind.

3. hemispheres
...............A hemisphere is any half of earth's surface; the term comes from the Greek word for half a sphere. The equator (zero degrees latitude) divides the earth into the Northern Hemisphere and the Southern Hemisphere. The dividing line between the Eastern and Western Hemispheres is not so well defined, but it is usually placed at the Prime Meridian (zero degrees longitude) or at 20 degrees west longitude.
..............North and South America and surrounding waters are considered to be in the Western Hemisphere, while the continents of Europe, Africa, Asia, and Australia are considered to be in the Eastern Hemisphere.

4. climate zones
..............The earth has three main climate zones: the tropics, the temperate zones, and the arctic and antarctic regions. Although local climates can vary considerably within zones, the tropics are generally the warmest areas of the earth because they are near the equator where the sun's rays are most direct. The Tropic of Cancer is an imaginary line that circles the earth at 23-1/2 degrees north latitude, the northernmost point reached by the sun during our summer (on the summer solstice). The Tropic of Capricorn lies at 23-1/2 degrees south latitude, the farthest point south reached by the sun during our winter (on the winter solstice).
..............The arctic and antarctic regions are located near the earth poles where the sun's rays are least direct and weakest: thus these are the coldest areas of the earth. The Arctic Circle is an imaginary line that circles the earth at 66-1/2 degrees north latitude; the Antarctic Circle lies at 66-1/2 degrees south latitude.
..............Those areas of the earth that lie between the tropics and the arctic/antarctic regions are called the temperate zones, meaning areas where temperature and climate tend to be more moderate. Most of Asia, Europe, and North America lie within the northern temperate zone, which is a good place to grow crops. This is where most of the world's human population has been concentrated since prehistoric times.

5. Big Bang theory
...............Most astronomers agree the universe probably began with an event similar to an explosion, a big bang. The universe is a term for all of outer space including the planets, stars, and galaxies. Galaxies are clusters of hundreds of millions of stars, and there are hundreds of millions of galaxies in the universe. Our world, Earth, is located in the Milky Way galaxy, named after the milky-looking band of stars stretching across the night sky that is an edge-on view of our galaxy.
...............The Big Bang theory is supported by scientific observations that indicate galaxies in space are moving away from Earth. Astronomers use the speed of this movement to estimate the age of the universe at about 15 billion years. Many scientists accept a figure of about 5 billion years as the age of Earth.

6. continents
...............Geographers divide most of the land surface of the earth into seven large landmasses called continents. The continents are Europe, Asia, Africa, Antarctica, Australia, North America, and South America. Antarctica is the only continent not settled by humans. The Ural Mountains of Russia are considered the dividing line between Europe and Asia. Europe and Asia form a single large landmass called Eurasia.
................The continents, however, cover less than a third of the earth's surface. Earth is mostly a water planet, and 97% of that water is found in the earth's four oceans, the Pacific, the Atlantic, the Indian and the Arctic. Because ocean water is salty, it cannot be used for drinking, farming, or manufacturing. Far less than 1% of the earth's water is fresh water, water that is not salty and can be used to grow crops.

7. plate tectonics
...............According to the theory of plate tectonics, the earth's surface is composed of about a dozen plates of solid material that slowly move as they float on a bed of magma, or molten rock. In other words, the surface of the earth resembles a cracked eggshell, and the pieces of the shell are moving. These plates include both the ocean floor and the continents. The continents are simply high areas on the plates above sea level, so both the continents and the sea floor move with their plates.
................Earthquakes and volcanoes often occur at boundaries between plates as the plates push together, spread apart, or slide against one another. For example, the Pacific Plate is slowly grinding past the North American Plate in California creating enormous pressures along the San Andreas Fault that are expected to produce a major earthquake some time within the next few decades. Plate tectonics continues to shape the earth's surface, as does erosion caused by wind and water. Scientists believe all of the present continents might have been together in a single large landmass long ago before they broke apart and drifted to their present locations on the earth. This super continent of the past is called Pangaea.

8. Great Rift Valley
...............This is a valley in eastern Africa where two of the earth's plates are spreading apart exposing the fossil remains of early humans. Fossils are the remains of living organisms that have been left behind after the living tissue has slowly been replaced by stone-like material that preserves the form of the original organism. Scientists believe the Great Rift Valley might be where human life began and spread to other are of the earth, making humans the most widespread species in the world. If so, we are all Africans.
..............The Olduvai Gorge area of the Great Rift Valley has been the site of famous discoveries by the husband and wife team of Louis and Mary Leakey and other paleontologists. Until the 1960s, it was thought human life began in Asia until the Leakeys found older human fossils in Africa. (Paleontologists are scientists who study the fossils of plants and animals.) The Leakey's son, Richard, has written: "Humans are unique because they have the capacity to choose what they doThe most obvious product of our hands and brains is technology. No other animal manipulates the world in the extensive and arbitrary way that humans do." (Technology is a term for inventions and tools that help us do things better or more easily.)

9. Australopithecus
...............Australopithecus was an extinct member of the hominid family, the family tree that includes modern humans. Australopithecus lived in Africa from about 4 to 1 million years ago. The first discovery of an early Australopithecus was made in the Great Rift Valley, the skeletal remains of a female now called Lucy.
...............Because Australopithecus walked on two feet and had a relatively large brain, it might be considered an early human, although most scientists consider it prehuman. Walking upright was a big advantage; it gave Australopithecus a better view of the surrounding countryside, and it left both hands free to carry burdens and to use primitive tools and weapons. Australopithecus is Latin for "southern ape." (Many scientific terms in use today are derived from Latin, the language of the ancient Roman Empire.)

10. Culture
...............Culture is a term for the knowledge and achievements passed on from one generation to another to form the way of life shared by a group of people. Most people living in Europe and North America share a common culture known as Western Civilization, also called Western culture or simply the West. The East refers to Asia, Asian culture, or Eastern Civilization. (This use does not correspond to the hemispheres.)
..............Human culture may have begun with Homo erectus, another extinct member of the hominid family, who lived from about two million to a half-million years ago. Homo erectus is Latin for "upright human." Homo erectus was the first hominid to hunt large animals and the first to leave Africa, migrating first to Asia and then to Europe. Homo erectus adapted to warm tropical climates and to freezing cold temperatures.
..............Evidence from archeology indicates that Homo erectus developed a culture that included the construction of shelters and the use of hand axes and fire and maybe spoken language. Fire was powerful; it meant that humans could keep predators away, eat better by cooking their food, and extend their habitat into colder climates. If the definition of human is the ability to create new inventions, Homo erectus might qualify. (Archeology is the scientific study of the remains of past human life and human activities.)
...............Perhaps the most important invention ever created by humans was spoken language. Language is a set of symbols that gives humans the capacity to communicate, cooperate, organize, and plan for the future.

11. Homo sapiens
...............This is the biological classification for modern humans. The earliest Homo sapiens were Neanderthals (Homo sapiens neanderthalensis), who developed about 150,000 years ago and went extinct not long after encountering a human species with more advanced technology. The species that replaced Neanderthals was us, Homo sapiens sapiens. The term Homo sapiens is Latin for wise human.
...............From Africa, Homo sapiens spread over Eurasia and later reached Australia and America during Ice Ages when water locked in ice sheets lowered the level of oceans. Land exposed at the Bering Strait formed a "land bridge" where Asian peoples likely crossed to America while following wild game herds some 20,000 years ago. Others might have migrated to America from Europe along the edge of ice sheets.
...............These travelers became the Native Americans of North and South America, the last continents to be occupied by humans. The arrival of these skilled hunters was followed by a die-off of large animals including horses and camels. A strait is a narrow body of water connecting two larger bodies of water. The Bering Strait, 50 miles wide, connects the Pacific Ocean to the Arctic Ocean between Russia and Alaska.

12. Stone Age
...............History has been divided into three eras based on the kinds of tools, or technology, that people used during these periods: the Stone Age, the Bronze Age, and the Iron Age. By far the longest stretch of human history took place before and during the Stone Age, a period called prehistoric times, when people did not yet know how to read or write. The Stone Age began about 250,000 BC and ended about 4,000 BC when the Bronze Age began in the Middle East. (These ages began at different times in different places.) During the Stone Age, people learned to use fire and make stone tools and weapons; they also developed spoken language and farming. The earliest discoveries of human art are also from the Stone Age.
................Paleolithic is a scientific term applied to the early Stone Age when humans made their living mostly by hunting, scavenging, or gathering wild food such as nuts and berries. Neolithic means the late Stone Age when agriculture began, and copper tools were developed. (Neo means new; lithic means stone. Both terms come from Greek, another ancient language that contributed to the modern language we use today.)