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This National Geographic Article goes into depth on how geography has impacted human activity and migration to the Americas. It also includes 6 photos that explain multiple perspectives of migrating to the U.S., how human activity is impacting geography and political issues within the Americas.

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North America, the third-largest continent, extends from the tiny Aleutian Islands in the northwest to the Isthmus of Panama in the south.

North America's physical geography, environment and resources, and human geography can be considered separately.

North America and South America are named after Italian navigator Amerigo Vespucci. Vespucci was the first European to suggest that the Americas were not part of the East Indies, but an entirely separate landmass. The portions of the landmass that widened out north of the Isthmus of Panama became known as North America.

Today, North America is home to the citizens of Canada, the United States, Greenland, Mexico, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama, and the island countries and territories of the Caribbean Sea and western North Atlantic Ocean.

North America's human landscape closely mirrors that of its physical environment: varied, rich, and constantly changing. From their beginnings to the present day, the peoples of North America have worked with and against their surroundings in order to survive and prosper.

Historic Cultures

Indigenous cultures shaped, and were shaped by, the geography of North America. The first North Americans are believed to have migrated from Siberia, in northeast Asia, by crossing a land bridge over the Bering Strait. These populations fanned out southward, to present-day Florida, California, Mexico, and Central America.

The Olmec and the Maya, indigenous to Central America, built the first cities on the continent, eventually leading to the great urban areas of Tenochtitlan, Texcoco, and Tlacopan. These cities, in what is now central Mexico, boasted sophisticated engineering structures, such as canals, apartment buildings, and irrigation systems.

Many of these early North American cultures were scientifically and agriculturally advanced. Mayan calendars and almanacs recorded celestial events such as eclipses and seasonal changes. The Mayans were also mathematically advanced. Their counting system was able to represent very large numbers using only three symbols: dots, lines, and a football-shaped symbol that indicated a zero. The Mayans were, in fact, the first culture to have a written symbol for zero.

Cultures throughout southern North America harvested corn, squash, and beans in regular cycles. This sort of agriculture allowed major civilizations to develop. People were no longer bound to produce food and shelter for their families-some people could work in the food and construction industries while others became engineers, artists, and political leaders. Leading North American civilizations include the Maya and Aztec, in what is now Mexico, and the Iroquois, native to southeastern Canada and the northeastern United States.

The vastness of the northern part of the continent encouraged other indigenous communities to live nomadic lifestyles. These cultures did not establish urban areas or agricultural centers. Instead, they followed favorable weather patterns, natural agricultural cycles, and animal migrations.

The Plains Indians, for example, followed the seasonal grazing and migration of the American bison. Plains Indians include Lakota, Blackfoot, and Nez Perce. Plains Indians ate bison meat as their primary source of food, and used hides and bones to create dwellings, tools, and clothing. The range of the bison, which stretched from the southern Prairie Provinces of Canada, through the Great Plains, to the U.S.-Mexico border, coincided with the extent of Plains Indian communities. They were so interdependent that the eventual extinction of bison in many areas of the United States-through overhunting, development, and anti-indigenous federal policies-dramatically weakened the power and influence of the Plains people.

The environment also impacted the traditional beliefs and social structure of North American indigenous communities. For instance, the Inuit, native to the Arctic, were deeply influenced by the aurora borealis, or Northern Lights. They believed the amazing light displays were images of their family and friends in the afterlife, the souls of animals and spirits, and visual guides for hunting. Inuit also believed that all things have souls, and that spirits existed to protect those souls. By respecting the ecosystem (the living and nonliving things in an environment), Inuit communities aimed to maintain a balanced existence.

Contemporary Cultures

Contemporary North American societies are also greatly influenced by the continent's rich and varied environment. Our globalized world has pressed these societies to develop complex ways of interacting with, and profiting from, geographic resources.

North America's economic base is centered largely on the extraction, development, and trade of natural resources. Local communities, as well as national governments and regional organizations, also use natural resources. Guatemala, for example, has a traditional medicine system, which includes herbalists and spiritualists who use medicinal plants to treat ailments. Costa Rica has developed a network of sustainable and fair-trade coffee growers tailored to a growing international market.

Tourism is also an important part of North America's economy, especially for the small island nations of the Caribbean Sea. These island nations offer pristine tropical environments. Their multicolored coral reefs are one of the premier diving destinations in the world. The islands' historical ties to the United States and Europe ease travel arrangements and language barriers. The islands see about 20 million visitors every year. In 2010, tourism contributed more than $39 billion to the region's economy.

Some organizations promote tourism that is more beneficial to local economies and ecosystems. The Caribbean Alliance for Sustainable Tourism, for example, aims to promote the sustainable management of the region's natural resources. Sustainable tourism supports development of local businesses, as opposed to global corporations such as international hotel chains.

The Caribbean tourism industry is also developing more ecotourism opportunities for visitors. Ecotourism encourages tourists to have a minimal impact on the natural environment. Ecotourism promotes travel to natural destinations, such as coral reefs, instead of developed destinations such as casinos.

North America's multicultural history is another defining feature of the continent's human geography. Immigrants have sought opportunities, particularly in the United States and Canada, for hundreds of years. Immigrants from Europe, Asia, Africa, and South America have contributed to the development of the continent. Immigrants or children of immigrants to North America have become scientific, business, and cultural leaders.

The strong presence of immigrants is reflected in present-day ethnic neighborhoods: the Cuban "Little Havana" in Miami, Florida; the Somali "Little Mogadishu" in Minneapolis, Minnesota; the Korean "Koreatown" in Toronto, Ontario, Canada; and the North African "Little Maghreb" in Montreal, Quebec, Canada, are just a few. Mexico City's "Barrio Chino" is one of the smallest Chinatowns in the world, only two city blocks in length. Yet Barrio Chino counts 3,000 families of Chinese heritage within its boundaries.

Many immigrants are refugees. According to the United Nations, a refugee is a person who resides outside the country of their nationality for fear of being persecuted. Refugees may fear economic hardship, or political or social pressure. Refugees may also immigrate because of a natural disaster.

Major refugee populations in Canada include residents fleeing civil war in Sri Lanka, political oppression in Pakistan, and violence in Colombia. Major refugee populations in the United States include residents fleeing poverty in Ethiopia, political oppression in Vietnam and Cuba, and earthquakes in Haiti.

Since 2006, Ottawa, Canada, has been the site for World Refugee Week, which features the work of artists, academics, and activists from around the globe. This celebration of diversity is echoed in the many ethnic and cultural celebrations that take place across North America.

North America's history and development have been shaped by its political geography. Political geography is the internal and external relationships between its various governments, citizens, and territories.

Historic Issues
Contact between the indigenous people of North America and European explorers was the defining moment for the continent's political geography. Italian explorer Christopher Columbus' first landing on Caribbean soil in 1492 set in motion the voyages of other Europeans: Spanish explorers Hernando De Soto and Ponce de Leon; French explorer Jacques Cartier; and British explorers Sebastian Cabot and Henry Hudson.

The voyages of these explorers inspired various European countries to claim and colonize North American soil. European colonizers found different ways to work with and against North America's indigenous communities.

Colonizers in the present-day U.S. pushed native populations to the west. Through disease, war, and forced relocation, many native communities were exterminated. The large indigenous territories were reduced to isolated Political Geography reservations.

Colonizers in present-day Canada set up a reservation system that protected many Indian settlements but isolated them from development. Intermarriage between Europeans and natives created a French-Indian community known today as the Metis.

In Mexico, Central America, and the Caribbean, native populations were more fully integrated into the political and social systems. Mestizos, people of European and indigenous descent, have greatly contributed to the social structure and culture of Latin America.

Cooperation and conflict have dramatically affected the relationships between North American countries. The United States and Canada have the longest non-militarized border in the world, for instance. This peaceful border reflects a stable, cooperative relationship between the two countries.

North America's history is dotted with conflict, however. The Mexican-American War (1846-1848) resulted in the United States acquiring 1,294,994 square kilometers (500,000 square miles) of Mexican territory, extending from the Rio Grande to the Pacific Coast.

Conflicts have also caused tensions among residents of a single country. The Seven Years' War (1756-1763) resulted in all French territory east of the Mississippi River being ceded to Britain. This dramatically shifted Canada's political geography, creating divisions between French Canadians and those of the British Commonwealth. This division still influences Canadian politics.

North American countries have also suffered through civil wars. The civil wars that occurred in Honduras, Nicaragua, Guatemala, and El Salvador between the 1970s and 1990s killed tens of thousands of civilians and pushed many others to immigrate to Mexico, the United States, and Canada. The region also became a hotspot for foreign policy and financial assistance. The United States, for instance, aimed to protect its economic and political interests by backing various military governments and guerrilla groups.

Contemporary Issues
Today, North America's political geography is deeply influenced by economic and demographic trends. Two important policies-the North American Free Trade Agreement (NAFTA, signed in 1994) and the Dominican Republic-Central America Free Trade Agreement (CAFTA-DR, signed in 2004)-have affected trade between countries on the continent. Most significantly, the agreements have reduced or eliminated duties and tariffs. A duty is a kind of tax charged for items purchased outside the country. A tariff is another kind of tax, charged on imports and exports.

Both policies have eliminated duties on U.S. and Canadian agricultural exports, such as corn, wheat, and soybeans. The agreements have also reduced tariffs on goods like coffee, sugar, fruits, and vegetables. These are important exports for the rest of the continent.

While the agreements have eased trade between countries and regions of North America, they have also caused major political and economic problems. Corn imports to Mexico have impoverished many Mexican farmers, who cannot compete against the lower U.S. or Canadian prices.

NAFTA is also believed to have pushed many industries out of the United States and into the cheaper labor markets of Mexico, Central America, and the Caribbean. Companies find it less expensive to manufacture goods in these places for many reasons. Wages are lower and there are fewer health and safety regulations. Because there are often fewer restrictions on child labor and fewer opportunities for education, many companies find many more workers. These cheaper labor markets reduce the strength of the U.S. manufacturing sector.

Immigration is perhaps the most sensitive aspect of North America's political geography. Most immigration is fueled by poverty. People from North America's underdeveloped nations, such as Haiti, frequently immigrate to the continent's developed countries, such as the United States.

Immigration can be a long, difficult process. It involves more than just the physical migration from one nation to another. The governments of both countries must agree to the migration. Immigrants must often learn a new language and culture, including ways of dressing, eating, and socializing. Immigrants wishing to become citizens must also take classes to prove they are loyal to their new country. Often, immigrants must depend on luck: In the United States and Canada, lottery systems often determine which immigrants can legally migrate.

As a result of these difficulties, many impoverished immigrants from Mexico, the Caribbean, and Central America have illegally settled in developed countries. Illegal immigrants migrate for the same reasons legal immigrants do-to look for better economic and political opportunities.

Critics of illegal immigration say these immigrants are more likely to commit a crime and use public welfare programs, such as those that help pay for education and medical care. Critics say these immigrants do not contribute to society by paying taxes that fund these public programs.

Future Issues
After the terrorist attacks of September 11, 2001, the United States and all of North America became more concerned with safety. National security at the international, regional, and domestic level will continue to be an important issue. Internationally, the developed countries of North America, especially the United States, continue to negotiate their diplomatic presence in the world while protecting themselves from terrorist attacks at home.

Drug trafficking has become more pronounced regionally, especially along the Panama-Colombia border and the U.S.-Mexico border. This trade has been linked to the extreme violence that currently afflicts northern Mexico, damaging political relations between Mexico and the United States.

One of the most important aspects of North America's political and financial future rests largely on its efforts to minimize the effects of climate change.

The regulation or reduction of carbon emissions is perhaps the most important part of reducing global warming and minimizing the effects of climate change. As part of the 2009 international agreement known as the Copenhagen Accord, some North American countries agreed to reduce emissions. The United States, one of the world's largest producers of emissions, agreed to reduce greenhouse gas emissions by 17 percent below 2005 levels by 2020. Costa Rica pledged to be entirely carbon neutral by 2021.

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North America: Human Geography | National Geographic Society

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North America, the third-largest continent, extends from the tiny Aleutian Islands in the northwest to the Isthmus of Panama in the south. North America's physical geography, environment and resources, and human geography can be considered separately. North America and South America are named after Italian navigator Amerigo Vespucci.

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A 7 year journey tracing human migration by foot. 

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A 7 year journey tracing human migration by foot. 

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Paul Salopek goes on a 7 year journey, by foot. He traces the path of human migration from Ethiopia to the tip of South America.

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Impact

National Geographic Explorer Paul Salopek is on a 24,000-mile, multiyear odyssey, that began in Ethiopia, January 2013.

Pulitzer Prize-winner and National Geographic Fellow Paul Salopek is retracing our ancestors’ ancient migration on foot out of Africa and across the globe. His 24,000-mile, multiyear odyssey began in Ethiopia — our evolutionary “Eden ”— in January 2013 and will end at the tip of South America.

Supported by the National Geographic Society and the Knight Foundation, Paul is engaging with the major stories of our time, from climate change and technological innovation to mass migration and cultural survival.

Each chapter of his journey reveals the texture of the lives of the people he encounters — nomads, villagers, traders, farmers, and fishermen who seldom make the news.

Salopek is currently in the fifth chapter of his journey, traversing an emerging center of global power and navigating a maze of waterways across fertile South Asia.

When this journey ends, he will have pieced together a global mosaic of stories, faces, sounds, and sights — an unparalleled archive of our shared humanity at the start of a new millennium.

You can follow his journey on Instagram >>

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Paul Salopek: Retracing humanity’s ancient migration, on foot

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National Geographic Explorer Paul Salopek is on a 24,000-mile, multiyear odyssey, that began in Ethiopia, January 2013.

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Video: Human Migration and First Settlers to America

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Video: Human Migration and First Settlers to America

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This video gives students a good context of time when it comes to the chronological sequence of world migration. It would be a good unit introductory to get students thinking about how long ago migrations occurred, both globally and to the Americas.

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Unit 2 -  Human Migration and the First Settlers to North America

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Follow Paul's year journey through interactive maps, journal entries, photos and more. Each journey has its own maps, stories, photos, observations and more... incredible resource, very engaging!

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EthiopiaDjibouti / Red Sea Crossing

A motley camel caravan strikes out across the lands of the nomadic Afar toward the Indian Ocean and the "Strait of Tears."

Walking is falling forward. Each step we take is an arrested plunge, a collapse averted, a disaster braked. In this way, to walk becomes an act of faith.

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Try selecting a different part, location, language, or category in the "Explore" menu above, or see what Paul is doing now:

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EthiopiaDjibouti / Red Sea Crossing A motley camel caravan strikes out across the lands of the nomadic Afar toward the Indian Ocean and the "Strait of Tears." Walking is falling forward. Each step we take is an arrested plunge, a collapse averted, a disaster braked. In this way, to walk becomes an act of faith.

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Article from the Smithsonian Magazine, students will learn about the migration 80,000 years ago. They will follow the historical account of why humans left Africa and travelled to the Americas.

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Seventy-seven thousand years ago, a craftsman sat in a cave in a limestone cliff overlooking the rocky coast of what is now the Indian Ocean. It was a beautiful spot, a workshop with a glorious natural picture window, cooled by a sea breeze in summer, warmed by a small fire in winter. The sandy cliff top above was covered with a white-flowering shrub that one distant day would be known as blombos and give this place the name Blombos Cave.

The man picked up a piece of reddish brown stone about three inches long that he-or she, no one knows-had polished. With a stone point, he etched a geometric design in the flat surface-simple crosshatchings framed by two parallel lines with a third line down the middle.

Today the stone offers no clue to its original purpose. It could have been a religious object, an ornament or just an ancient doodle. But to see it is to immediately recognize it as something only a person could have made. Carving the stone was a very human thing to do.

The scratchings on this piece of red ocher mudstone are the oldest known example of an intricate design made by a human being. The ability to create and communicate using such symbols, says Christopher Henshilwood, leader of the team that discovered the stone, is "an unambiguous marker" of modern humans, one of the characteristics that separate us from any other species, living or extinct.

Henshilwood, an archaeologist at Norway's University of Bergen and the University of the Witwatersrand, in South Africa, found the carving on land owned by his grandfather, near the southern tip of the African continent. Over the years, he had identified and excavated nine sites on the property, none more than 6,500 years old, and was not at first interested in this cliffside cave a few miles from the South African town of Still Bay. What he would find there, however, would change the way scientists think about the evolution of modern humans and the factors that triggered perhaps the most important event in human prehistory, when Homo sapiens left their African homeland to colonize the world.

This great migration brought our species to a position of world dominance that it has never relinquished and signaled the extinction of whatever competitors remained-Neanderthals in Europe and Asia, some scattered pockets of Homo erectus in the Far East and, if scholars ultimately decide they are in fact a separate species, some diminutive people from the Indonesian island of Flores (see "Were 'Hobbits' Human?"). When the migration was complete, Homo sapiens was the last-and only-man standing.

Even today researchers argue about what separates modern humans from other, extinct hominids. Generally speaking, moderns tend to be a slimmer, taller breed: "gracile," in scientific parlance, rather than "robust," like the heavy-boned Neanderthals, their contemporaries for perhaps 15,000 years in ice age Eurasia. The modern and Neanderthal brains were about the same size, but their skulls were shaped differently: the newcomers' skulls were flatter in back than the Neanderthals', and they had prominent jaws and a straight forehead without heavy brow ridges. Lighter bodies may have meant that modern humans needed less food, giving them a competitive advantage during hard times.

The moderns' behaviors were also different. Neanderthals made tools, but they worked with chunky flakes struck from large stones. Modern humans' stone tools and weapons usually featured elongated, standardized, finely crafted blades. Both species hunted and killed the same large mammals, including deer, horses, bison and wild cattle. But moderns' sophisticated weaponry, such as throwing spears with a variety of carefully wrought stone, bone and antler tips, made them more successful. And the tools may have kept them relatively safe; fossil evidence shows Neanderthals suffered grievous injuries, such as gorings and bone breaks, probably from hunting at close quarters with short, stone-tipped pikes and stabbing spears. Both species had rituals-Neanderthals buried their dead-and both made ornaments and jewelry. But the moderns produced their artifacts with a frequency and expertise that Neanderthals never matched. And Neanderthals, as far as we know, had nothing like the etching at Blombos Cave, let alone the bone carvings, ivory flutes and, ultimately, the mesmerizing cave paintings and rock art that modern humans left as snapshots of their world.

When the study of human origins intensified in the 20th century, two main theories emerged to explain the archaeological and fossil record: one, known as the multi-regional hypothesis, suggested that a species of human ancestor dispersed throughout the globe, and modern humans evolved from this predecessor in several different locations. The other, out-of-Africa theory, held that modern humans evolved in Africa for many thousands of years before they spread throughout the rest of the world.

In the 1980s, new tools completely changed the kinds of questions that scientists could answer about the past. By analyzing DNA in living human populations, geneticists could trace lineages backward in time. These analyses have provided key support for the out-of-Africa theory. Homo sapiens, this new evidence has repeatedly shown, evolved in Africa, probably around 200,000 years ago.

The first DNA studies of human evolution didn't use the DNA in a cell's nucleus-chromosomes inherited from both father and mother-but a shorter strand of DNA contained in the mitochondria, which are energy-producing structures inside most cells. Mitochondrial DNA is inherited only from the mother. Conveniently for scientists, mitochondrial DNA has a relatively high mutation rate, and mutations are carried along in subsequent generations. By comparing mutations in mitochondrial DNA among today's populations, and making assumptions about how frequently they occurred, scientists can walk the genetic code backward through generations, combining lineages in ever larger, earlier branches until they reach the evolutionary trunk.

At that point in human history, which scientists have calculated to be about 200,000 years ago, a woman existed whose mitochondrial DNA was the source of the mitochondrial DNA in every person alive today. That is, all of us are her descendants. Scientists call her "Eve." This is something of a misnomer, for Eve was neither the first modern human nor the only woman alive 200,000 years ago. But she did live at a time when the modern human population was small-about 10,000 people, according to one estimate. She is the only woman from that time to have an unbroken lineage of daughters, though she is neither our only ancestor nor our oldest ancestor. She is, instead, simply our "most recent common ancestor," at least when it comes to mitochondria. And Eve, mitochondrial DNA backtracking showed, lived in Africa.

Subsequent, more sophisticated analyses using DNA from the nucleus of cells have confirmed these findings, most recently in a study this year comparing nuclear DNA from 938 people from 51 parts of the world. This research, the most comprehensive to date, traced our common ancestor to Africa and clarified the ancestries of several populations in Europe and the Middle East.

While DNA studies have revolutionized the field of paleoanthropology, the story "is not as straightforward as people think," says University of Pennsylvania geneticist Sarah A. Tishkoff. If the rates of mutation, which are largely inferred, are not accurate, the migration timetable could be off by thousands of years.

To piece together humankind's great migration, scientists blend DNA analysis with archaeological and fossil evidence to try to create a coherent whole-no easy task. A disproportionate number of artifacts and fossils are from Europe-where researchers have been finding sites for well over 100 years-but there are huge gaps elsewhere. "Outside the Near East there is almost nothing from Asia, maybe ten dots you could put on a map," says Texas A&M University anthropologist Ted Goebel.

As the gaps are filled, the story is likely to change, but in broad outline, today's scientists believe that from their beginnings in Africa, the modern humans went first to Asia between 80,000 and 60,000 years ago. By 45,000 years ago, or possibly earlier, they had settled Indonesia, Papua New Guinea and Australia. The moderns entered Europe around 40,000 years ago, probably via two routes: from Turkey along the Danube corridor into eastern Europe, and along the Mediterranean coast. By 35,000 years ago, they were firmly established in most of the Old World. The Neanderthals, forced into mountain strongholds in Croatia, the Iberian Peninsula, the Crimea and elsewhere, would become extinct 25,000 years ago. Finally, around 15,000 years ago, humans crossed from Asia to North America and from there to South America.

Africa is relatively rich in the fossils of human ancestors who lived millions of years ago (see timeline, opposite). Lush, tropical lake country at the dawn of human evolution provided one congenial living habitat for such hominids as Australopithecus afarensis. Many such places are dry today, which makes for a congenial exploration habitat for paleontologists. Wind erosion exposes old bones that were covered in muck millions of years ago. Remains of early Homo sapiens, by contrast, are rare, not only in Africa, but also in Europe. One suspicion is that the early moderns on both continents did not-in contrast to Neanderthals-bury their dead, but either cremated them or left them to decompose in the open.

In 2003, a team of anthropologists reported the discovery of three unusual skulls-two adults and a child-at Herto, near the site of an ancient freshwater lake in northeast Ethiopia. The skulls were between 154,000 and 160,000 years old and had modern characteristics, but with some archaic features. "Even now I'm a little hesitant to call them anatomically modern," says team leader Tim White, from the University of California at Berkeley. "These are big, robust people, who haven't quite evolved into modern humans. Yet they are so close you wouldn't want to give them a different species name."

The Herto skulls fit with the DNA analysis suggesting that modern humans evolved some 200,000 years ago. But they also raised questions. There were no other skeletal remains at the site (although there was evidence of butchered hippopotamuses), and all three skulls, which were nearly complete except for jawbones, showed cut marks-signs of scraping with stone tools. It appeared that the skulls had been deliberately detached from their skeletons and defleshed. In fact, part of the child's skull was highly polished. "It is hard to argue that this is not some kind of mortuary ritual," White says.

Even more provocative were discoveries reported last year. In a cave at Pinnacle Point in South Africa, a team led by Arizona State University paleoanthropologist Curtis Marean found evidence that humans 164,000 years ago were eating shellfish, making complex tools and using red ocher pigment-all modern human behaviors. The shellfish remains-of mussels, periwinkles, barnacles and other mollusks-indicated that humans were exploiting the sea as a food source at least 40,000 years earlier than previously thought.

The first archaeological evidence of a human migration out of Africa was found in the caves of Qafzeh and Skhul, in present-day Israel. These sites, initially discovered in the 1930s, contained the remains of at least 11 modern humans. Most appeared to have been ritually buried. Artifacts at the site, however, were simple: hand axes and other Neanderthal-style tools.

At first, the skeletons were thought to be 50,000 years old-modern humans who had settled in the Levant on their way to Europe. But in 1989, new dating techniques showed them to be 90,000 to 100,000 years old, the oldest modern human remains ever found outside Africa. But this excursion appears to be a dead end: there is no evidence that these moderns survived for long, much less went on to colonize any other parts of the globe. They are therefore not considered to be a part of the migration that followed 10,000 or 20,000 years later.

Intriguingly, 70,000-year-old Neanderthal remains have been found in the same region. The moderns, it would appear, arrived first, only to move on, die off because of disease or natural catastrophe or-possibly-get wiped out. If they shared territory with Neanderthals, the more "robust" species may have outcompeted them here. "You may be anatomically modern and display modern behaviors," says paleoanthropologist Nicholas J. Conard of Germany's University of Tübingen, "but apparently it wasn't enough. At that point the two species are on pretty equal footing." It was also at this point in history, scientists concluded, that the Africans ceded Asia to the Neanderthals.

Then, about 80,000 years ago, says Blombos archaeologist Henshilwood, modern humans entered a "dynamic period" of innovation. The evidence comes from such South African cave sites as Blombos, Klasies River, Diepkloof and Sibudu. In addition to the ocher carving, the Blombos Cave yielded perforated ornamental shell beads-among the world's first known jewelry. Pieces of inscribed ostrich eggshell turned up at Diepkloof. Hafted points at Sibudu and elsewhere hint that the moderns of southern Africa used throwing spears and arrows. Fine-grained stone needed for careful workmanship had been transported from up to 18 miles away, which suggests they had some sort of trade. Bones at several South African sites showed that humans were killing eland, springbok and even seals. At Klasies River, traces of burned vegetation suggest that the ancient hunter-gatherers may have figured out that by clearing land, they could encourage quicker growth of edible roots and tubers. The sophisticated bone tool and stoneworking technologies at these sites were all from roughly the same time period-between 75,000 and 55,000 years ago.

Virtually all of these sites had piles of seashells. Together with the much older evidence from the cave at Pinnacle Point, the shells suggest that seafood may have served as a nutritional trigger at a crucial point in human history, providing the fatty acids that modern humans needed to fuel their outsize brains: "This is the evolutionary driving force," says University of Cape Town archaeologist John Parkington. "It is sucking people into being more cognitively aware, faster-wired, faster-brained, smarter." Stanford University paleoanthropologist Richard Klein has long argued that a genetic mutation at roughly this point in human history provoked a sudden increase in brainpower, perhaps linked to the onset of speech.

Did new technology, improved nutrition or some genetic mutation allow modern humans to explore the world? Possibly, but other scholars point to more mundane factors that may have contributed to the exodus from Africa. A recent DNA study suggests that massive droughts before the great migration split Africa's modern human population into small, isolated groups and may have even threatened their extinction. Only after the weather improved were the survivors able to reunite, multiply and, in the end, emigrate. Improvements in technology may have helped some of them set out for new territory. Or cold snaps may have lowered sea level and opened new land bridges.

Whatever the reason, the ancient Africans reached a watershed. They were ready to leave, and they did.

DNA evidence suggests the original exodus involved anywhere from 1,000 to 50,000 people. Scientists do not agree on the time of the departure-sometime more recently than 80,000 years ago-or the departure point, but most now appear to be leaning away from the Sinai, once the favored location, and toward a land bridge crossing what today is the Bab el Mandeb Strait separating Djibouti from the Arabian Peninsula at the southern end of the Red Sea. From there, the thinking goes, migrants could have followed a southern route eastward along the coast of the Indian Ocean. "It could have been almost accidental," Henshilwood says, a path of least resistance that did not require adaptations to different climates, topographies or diet. The migrants' path never veered far from the sea, departed from warm weather or failed to provide familiar food, such as shellfish and tropical fruit.

Tools found at Jwalapuram, a 74,000-year-old site in southern India, match those used in Africa from the same period. Anthropologist Michael Petraglia of the University of Cambridge, who led the dig, says that although no human fossils have been found to confirm the presence of modern humans at Jwalapuram, the tools suggest it is the earliest known settlement of modern humans outside of Africa except for the dead enders at Israel's Qafzeh and Skhul sites.

And that's about all the physical evidence there is for tracking the migrants' early progress across Asia. To the south, the fossil and archaeological record is clearer and shows that modern humans reached Australia and Papua New Guinea-then part of the same landmass-at least 45,000 years ago, and maybe much earlier.

But curiously, the early down under colonists apparently did not make sophisticated tools, relying instead on simple Neanderthal-style flaked stones and scrapers. They had few ornaments and little long-distance trade, and left scant evidence that they hunted large marsupial mammals in their new homeland. Of course, they may have used sophisticated wood or bamboo tools that have decayed. But University of Utah anthropologist James F. O'Connell offers another explanation: the early settlers did not bother with sophisticated technologies because they did not need them. That these people were "modern" and innovative is clear: getting to New Guinea-Australia from the mainland required at least one sea voyage of more than 45 miles, an astounding achievement. But once in place, the colonists faced few pressures to innovate or adapt new technologies. In particular, O'Connell notes, there were few people, no shortage of food and no need to compete with an indigenous population like Europe's Neanderthals.

Modern humans eventually made their first forays into Europe only about 40,000 years ago, presumably delayed by relatively cold and inhospitable weather and a less than welcoming Neanderthal population. The conquest of the continent-if that is what it was-is thought to have lasted about 15,000 years, as the last pockets of Neanderthals dwindled to extinction. The European penetration is widely regarded as the decisive event of the great migration, eliminating as it did our last rivals and enabling the moderns to survive there uncontested.

Did modern humans wipe out the competition, absorb them through interbreeding, outthink them or simply stand by while climate, dwindling resources, an epidemic or some other natural phenomenon did the job? Perhaps all of the above. Archaeologists have found little direct evidence of confrontation between the two peoples. Skeletal evidence of possible interbreeding is sparse, contentious and inconclusive. And while interbreeding may well have taken place, recent DNA studies have failed to show any consistent genetic relationship between modern humans and Neanderthals.

"You are always looking for a neat answer, but my feeling is that you should use your imagination," says Harvard University archaeologist Ofer Bar-Yosef. "There may have been positive interaction with the diffusion of technology from one group to the other. Or the modern humans could have killed off the Neanderthals. Or the Neanderthals could have just died out. Instead of subscribing to one hypothesis or two, I see a composite."

Modern humans' next conquest was the New World, which they reached by the Bering Land Bridge-or possibly by boat-at least 15,000 years ago. Some of the oldest unambiguous evidence of humans in the New World is human DNA extracted from coprolites-fossilized feces-found in Oregon and recently carbon dated to 14,300 years ago.

For many years paleontologists still had one gap in their story of how humans conquered the world. They had no human fossils from sub-Saharan Africa from between 15,000 and 70,000 years ago. Because the epoch of the great migration was a blank slate, they could not say for sure that the modern humans who invaded Europe were functionally identical to those who stayed behind in Africa. But one day in 1999, anthropologist Alan Morris of South Africa's University of Cape Town showed Frederick Grine, a visiting colleague from Stony Brook University, an unusual-looking skull on his bookcase. Morris told Grine that the skull had been discovered in the 1950s at Hofmeyr, in South Africa. No other bones had been found near it, and its original resting place had been befouled by river sediment. Any archaeological evidence from the site had been destroyed-the skull was a seemingly useless artifact.

But Grine noticed that the braincase was filled with a carbonate sand matrix. Using a technique unavailable in the 1950s, Grine, Morris and an Oxford University-led team of analysts measured radioactive particles in the matrix. The skull, they learned, was 36,000 years old. Comparing it with skulls from Neanderthals, early modern Europeans and contemporary humans, they discovered it had nothing in common with Neanderthal skulls and only peripheral similarities with any of today's populations. But it matched the early Europeans elegantly. The evidence was clear. Thirty-six thousand years ago, says Morris, before the world's human population differentiated into the mishmash of races and ethnicities that exist today, "We were all Africans."

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Why humans left their African homeland 80,000 years ago to colonize the world

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Students can explore the 6 accompanying photos and this article to learn how early human settlement was possible in places that are now no longer existing due to geographical changes such as erosion.

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Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. A similar process, weathering, breaks down or dissolves rock, but does not involve movement. Erosion is the opposite of deposition, the geological process in which earthen materials are deposited, or built up, on a landform. Most erosion is performed by liquid water, wind, or ice (usually in the form of a glacier). If the wind is dusty, or water or glacial ice is muddy, erosion is taking place. The brown color indicates that bits of rock and soil are suspended in the fluid (air or water) and being transported from one place to another. This transported material is called sediment. eroded through physical erosion often form clastic sediments. Clastic sediments are composed of fragments of older rocks that have been transported from their place of origin. Landslides and other forms of mass wasting are associated with physical weathering. These processes cause rocks to dislodge from hillsides and crumble as they tumble down a slope. Plant growth can also contribute to physical erosion in a process called bioerosion. Plants break up earthen materials as they take root, and can create cracks and crevices in rocks they encounter. Ice and liquid water can also contribute to physical erosion as their movement forces rocks to crash together or crack apart. Some rocks shatter and crumble, while others are worn away. River rocks are often much smoother than rocks found elsewhere, for instance, because they have been eroded by constant contact with other river rocks. Erosion by Water Liquid water is the major agent of erosion on Earth. Rain, rivers, floods, lakes, and the ocean carry away bits of soil and sand and slowly wash away the sediment. Rainfall produces four types of soil erosion: splash erosion, sheet erosion, rill erosion, and gully erosion. * Splash erosion describes the impact of a falling raindrop, which can scatter tiny soil particles as far as .6 meters (2 feet). * Sheet erosion describes erosion caused by runoff. * Rill erosion describes erosion that takes place as runoff develops into discrete streams (rills). * Finally, gully erosion is the stage in which soil particles are transported through large Physical Erosion Physical erosion describes the process of rocks changing their physical properties without changing their basic chemical composition. Physical erosion often causes rocks to get smaller or smoother. Rocks channels. Gullies carry water for brief periods of time during rainfall or snowmelt but appear as small valleys or crevasses during dry seasons. Valley erosion is the process in which rushing streams and rivers wear away their banks, creating larger and larger valleys. The Fish River Canyon, in southern Namibia, is the largest canyon in Africa and a product of valley erosion. Over millions of years, the Fish River wore away at the hard gneiss bedrock, carving a canyon about 160 kilometers (99 miles) in length, 27 kilometers (17 miles) wide, and 550 meters (1,084 feet) deep. The ocean is a huge force of erosion. Coastal erosion-the wearing away of rocks, earth, or sand on the beach-can change the shape of entire coastlines. During the process of coastal erosion, waves pound rocks into pebbles and pebbles into sand. Waves and currents sometimes transport sand away from beaches, moving the coastline farther inland. Coastal erosion can have a huge impact on human settlement as well as coastal ecosystems. The Cape Hatteras Lighthouse, for example, was nearly destroyed by coastal erosion. The Cape Hatteras Lighthouse was built on the Outer Banks, a series of barrier islands off the coast of the U.S. state of North Carolina, in 1870. At the time, the lighthouse was nearly 457 meters (1,500 feet) from the ocean. Over time, the ocean eroded most of the beach near the lighthouse. By 1970, the pounding surf was just 37 meters (120 feet) away and endangered the structure. Many people thought the lighthouse would collapse during a strong storm. Instead, thanks to a significant engineering feat completed in 1999, it was moved 880 meters (2,900 feet) inland. The battering force of ocean waves also erodes seaside cliffs. The action of erosion can create an array of coastal landscape features. For example, erosion can bore holes that form caves. When water breaks through the back of the cave, it can create an arch. The continual pounding of waves can cause the top of the arch to fall, leaving nothing but rock columns called sea stacks. The seven remaining sea stacks of Twelve Apostles Marine National Park, in Victoria, Australia, are among the most dramatic and well-known of these features of coastal erosion. Erosion by Wind Wind is a powerful agent of erosion. Aeolian (wind-driven) processes constantly transport dust, sand, and ash from one place to another. Wind can sometimes blow sand into towering dunes. Some sand dunes in the Badain Jaran section of the Gobi Desert in China, for example, reach more than 400 meters (1,300 feet) high. In dry areas, windblown sand can blast against a rock with tremendous force, slowly wearing away the soft rock. It polishes rocks and cliffs until they are smooth-giving the stone a so-called "desert varnish." Wind is responsible for the eroded features that give Arches National Park, in the U.S. state of Utah, its name. Wind can also erode material until little remains at all. Ventifacts are rocks that have been sculpted by wind erosion. The enormous chalk formations in the White Desert of Egypt are ventifacts carved by thousands of years of wind roaring through the flat landscape. Some of the most destructive examples of wind erosion are the dust storms that characterized the "Dust Bowl" of the 1930s in North America. Made brittle by years of drought and agricultural mismanagement, millions of tons of valuable topsoil were eroded away by strong winds in what came to be known as "black blizzards." These dust storms devastated local economies, forcing thousands of people who depended on agriculture for their livelihoods to migrate. Erosion by Ice Ice, usually in the form of glaciers, can erode the earth and create dramatic landforms. In frigid areas and on some mountaintops, glaciers move slowly downhill and across the land. As they move, they transport everything in their path, from tiny grains of sand to huge boulders. Rocks carried by glaciers scrape against the ground below, eroding both the ground and the rocks. In this way, glaciers grind up rocks and scrape away the soil. Moving glaciers gouge out basins and form steep-sided mountain valleys. Eroded sediment called moraine is often visible on and around glaciers. Several times in Earth's history, vast glaciers covered parts of the Northern Hemisphere. These glacial periods are known as ice ages. Ice Age glaciers carved much of the modern northern North American and European landscape. Ice Age glaciers scoured the ground to form what are now the Finger Lakes in the U.S. state of New York, for example. They carved fjords, deep inlets along the coast of Scandinavia. The snout of a glacier eroded Cape Cod Bay, Massachusetts, and formed the recognizable fishhook shape of Cape Cod itself. Today, in places such as Greenland and Antarctica, glaciers continue to erode the earth. Ice sheets there can be more than a mile thick, making it difficult for scientists to measure the speed and patterns of erosion. However, ice sheets do erode remarkably quickly-as much as half a centimeter (.2 inch) every year. Other Forces of Erosion Thermal erosion describes the erosion of permafrost along a river or coastline. Warm temperatures can cause ice-rich permafrost to break off coastlines in huge chunks, often carrying valuable topsoil and vegetation with them. These eroded "floating islands" can disintegrate into the ocean, or even crash into another piece of land-helping spread new life to different landscapes. Mass wasting describes the downward movement of rocks, soil, and vegetation. Mass wasting incidents include landslides, rockslides, and avalanches. Mass wasting can erode and transport millions of tons of earth, reshaping hills and mountains and, often, devastating communities in its path. Factors Impacting Erosion Some of the natural factors impacting erosion in a landscape include climate, topography, vegetation, and tectonic activity. Climate is perhaps the most influential force impacting the effect of erosion on a landscape. Climate includes precipitation and wind. Climate also includes seasonal variability, which influences the likelihood of weathered sediments being transported during a weather event such as a snowmelt, breeze, or hurricane. Topography, the shape of surface features of an area, can contribute to how erosion impacts that area. The earthen floodplains of river valleys are much more prone to erosion than rocky flood channels, which may take centuries to erode. Soft rock like chalk will erode more quickly than hard rocks like granite. Vegetation can slow the impact of erosion. Plant roots adhere to soil and rock particles, preventing their transport during rainfall or wind events. Trees, shrubs, and other plants can even limit the impact of mass wasting events such as landslides and other natural hazards such as hurricanes. Deserts, which generally lack thick vegetation, are often the most eroded landscapes on the planet. Finally, tectonic activity shapes the landscape itself, and thus influences the way erosion impacts an area. Tectonic uplift, for example, causes one part of the landscape to rise higher than others. In a span of about 5 million years, tectonic uplift caused the Colorado River to cut deeper and deeper into the Colorado Plateau, land in what is now the U.S. state of Arizona. It eventually formed the Grand Canyon, which is more than 1,600 meters (1 mile) deep and as much as 29 kilometers (18 miles) wide in some places. Erosion and People Deposition, Soils, and SedimentsEroded sediments have profoundly influenced the development of civilizations around the world. Agricultural development is often reliant on the nutrient-rich soils created by the accumulation of eroded earth. When the velocity of wind or water slows, eroded sediment is deposited in a new location. The sediment builds up in a process called sedimentation and creates fertile land. River deltas are made almost entirely of sediment that has eroded from the banks and bed of a river. The rich delta soils of the San Joaquin and Sacramento rivers in northern California, for example, have created one of the most agriculturally productive areas in the world. Loess is an agriculturally rich sediment made almost entirely of wind-blown, eroded sediment. The Yellow River in central China gets its name from the yellow loess blown into and suspended in its water. The fertile lands around the Yellow River have been among China's most productive for thousands of years. forests or plow up grasses for agriculture and development, the soil is more vulnerable to washing or blowing away. Landslides become more common. Water rushes over exposed soil rather than soaking into it, causing flooding. Global warming, the current period of climate change, is speeding erosion. The change in climate has been linked to more frequent and severe storms. Storm surges following hurricanes and typhoons can erode kilometers of coastline and coastal habitat. These coastal areas are home to residences, businesses, and economically important industries, such as fisheries. The rise in temperature is also quickly melting glaciers. The slower, more massive form of glacial erosion is being supplanted by the cumulative impact of rill, gully, and valley erosion. In areas downstream from glacial snouts, rapidly melting glaciers are contributing to sea level rise. The rising sea erodes beaches more quickly. Erosion control is the process of reducing erosion by wind and water. Farmers and engineers must regularly practice erosion control. Sometimes, engineers simply install structures to physically prevent soil from being transported. Gabions are huge wireframes that hold boulders in place, for instance. Gabions are often placed near cliffs. These cliffs, often near the coast, have homes, businesses, and highways near them. When erosion by water or wind threatens to tumble the boulders toward buildings and cars, gabions protect landowners and drivers by holding the rocks in place. Erosion control also includes physically changing the landscape. Communities often invest in windbreaks and riparian buffers to protect valuable agricultural land. Windbreaks, also called hedgerows or shelterbelts, are lines of trees and shrubs planted to protect cropland from wind erosion. Riparian buffers describe plants such as trees, shrubs, grasses, and sedges that line the banks of a river. Riparian buffers help contain the river in times of increased stream flow and flooding. Living shorelines are another form of erosion control in wetland areas. Living shorelines are constructed by placing native plants, stone, sand, and even living organisms such as oysters along wetland coasts. These plants help anchor the soil to the area, preventing erosion. By securing the land, living shorelines establish a natural habitat. They protect coastlines from powerful storm surges as well as erosion. Erosion Control Erosion is a natural process, but human activity can make it happen more quickly. Human activity altering the vegetation of an area is perhaps the biggest human factor contributing to erosion. Trees and plants hold soil in place. When people cut down

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Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. A similar process, weathering, breaks down or dissolves rock, but does not involve movement. Erosion is the opposite of deposition, the geological process in which earthen materials are deposited, or built up, on a landform.

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10 Early Civilizations and their lasting Impact

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10 Early Civilizations and their lasting Impact

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Students will examine the 10 photos of ancient civilizations, and can learn about each one, why they settled where they did, their contributions and how they impacted future human settlement.

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Gonzalo Azumendi/Getty Images

The continents of North and South America were "discovered" by the European civilizations in the late 15th century A.D., but people from Asia arrived in the Americas at least 15,000 years ago. By the 15th century, many American civilizations had come and gone long before but many were still vast and thriving. Sample a taste of the complexity of the civilizations of ancient America.

Caral Supe Civilization, 3000-2500 BC

Imágenes del Perú/Getty Images

The Caral-Supe civilization is the oldest known advanced civilization in the American continents discovered to date. Discovered only as recently as the 21st century, the villages of the Caral Supe were located along the coast of central Peru. Nearly 20 separate villages have been identified, with a central place at the urban community at Caral. The city of Caral included enormous earthen platform mounds, monuments so large that they were hidden in plain sight (thought to be low hills).

Olmec Civilization, 1200-400 BC

Mesoamerican/Wikimedia Commons/CC BY 4.0

The Olmec civilization flourished on the gulf coast of Mexico and constructed the first stone pyramids in the North American continent, as well as the famous stone "baby-faced" head monuments. The Olmec had kings, built enormous pyramids, invented the Mesoamerican ballgame, domesticated beans, and developed the earliest writing in the Americas. The Olmec also domesticated the cacao tree and gave the world chocolate!

Maya Civilization, 500 BC-800 AD

The circular object in front of the Maya ruins at Kabah is a chultun, part of the Mayan water control system.
Witold Skrypczak/Getty Images

The ancient Maya Civilization occupied much of the central North American continent based on the gulf coast of what is now Mexico between 2500 B.C. and 1500 A.D. The Maya were a group of independent city-states, which shared cultural qualities. This includes their amazing complex artwork (particularly murals), their advanced water control system, and their graceful pyramids.

Zapotec Civilization, 500 BC-750 AD

Craig Lovell/Getty Images

The capital city of the Zapotec Civilization is Monte Alban in the valley of Oaxaca in central Mexico. Monte Alban is one of the most intensively studied archaeological sites in the Americas, and one of the very few "disembedded capitals" in the world. The capital is also known for its astronomical observatory Building J and Los Danzantes, a stunning carved record of captive and slain warriors and kings.

Nasca Civilization, 1-700 AD

Chris Beall/Getty Images

The people of the Nasca civilization on the south coast of Peru are best known for drawing huge geoglyphs. These are geometric drawings of birds and other animals made by moving around the varnished rock of the vast arid desert. They were also master makers of textiles and ceramic pottery.

Tiwanaku Empire, 550-950 AD

Marc Davis/Flickr/CC BY 2.0

The capital of the Tiwanaku Empire was situated on the shores of Lake Titicaca on both sides of the border between what today is Peru and Bolivia. Their distinctive architecture shows evidence of construction by workgroups. During its heyday, Tiwanaku (also spelled Tiahuanaco) controlled much of the southern Andes and coastline of South America.

Wari Civilization, 750-1000 AD

Duncan Andison/Getty Images

In direct competition with Tiwanaku was the Wari (also spelled Huari) state. The Wari state was located in the central Andes mountains of Peru, and their impact on the succeeding civilizations is remarkable, seen at sites like Pachacamac.

Inca Civilization, 1250-1532 AD

The ancient Incan site of Machu Picchu.
Claude LeTien/Getty Images

The Inca civilization was the largest civilization in the Americas when the Spanish conquistadors arrived in the early 16th century. Known for their unique writing system (called the quipu), a magnificent road system, and the lovely ceremonial center called Machu Picchu, the Inca also had some pretty interesting burial customs and an amazing ability to build earthquake-proof buildings.

Mississippian Civilization, 1000-1500 AD

Michael S. Lewis/Getty Images

The Mississippian culture is a term used by archaeologists to refer to cultures inhabiting the length of the Mississippi River, but the highest level of sophistication was reached in the central Mississippi River valley of southern Illinois, near present-day St. Louis, Missouri, and the capital city of Cahokia. We know quite a bit about the Mississippians in the American southeast because they were first visited by the Spanish in the 17th century.

Aztec Civilization, 1430-1521 AD

Rita Rivera/Getty Images

The best-known civilization in the Americas, I'll wager, is the Aztec civilization, largely because they were at the height of their power and influence when the Spanish arrived. Warlike, intractable, and aggressive, the Aztecs conquered much of Central America. But the Aztecs are so much more than simply warlike.

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These 10 Ancient American Civilizations Were Vast, Incredible Empires

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Both North and South America were populated with vast and sophisticated civilizations when the Europeans arrived in the late 15th century.

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This map covers the globe, and you can view any areas specific topography. This could be useful for students to think about how human settlement was influenced by geographic and physical characteristics.

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Services Privacy Policies and Notices Accessibility Site Map Contact USGS U.S. Department of the Interior DOI Inspector General White House E-gov Open Government No Fear Act FOIA

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The Ancient World Part 1: The First Civilizations

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The Ancient World Part 1: The First Civilizations

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Part 1 of this free documentary on youtube. It tells the story of the first civilizations and empires around the world.

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The Ancient World Part 1: The First Civilizations | The History of the World

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These 6 photos of the oldest maps are great pieces for students to analyze and form questions about. These would be great engagement pieces to have students explore the history of maps and how they impacted human migration and where civilizations started.

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Humans have made maps for untold thousands of years. They're among the oldest modes of communication, predating written language. But, as cartographer Norman Thrower writes in Maps and Civilization: Cartography in Culture and Society, "Only a small fraction of the maps produced in earlier ages has survived."

A handful remain with us, though, including these examples drawn from vastly different times and places. Together they hint at the fascinating and diverse ways our ancestors located themselves and their worlds in space. "Viewed in its development through time," Thrower writes, "the map details the changing thought of the human race, and few works seem to be such an excellent indicator of culture and civilization."

The Imago Mundi

The earliest known attempt to show the Earth in its entirety was the Imago Mundi , or Babylonian map of the world, thought to date to around 600 B.C. The city of Babylon itself figures as a large rectangle, bisected by another rectangle representing the Euphrates River. A few neighboring cities dot the area nearby, and surrounding them all is a ring labeled the "Salt-Sea." Beyond this circular waterway lie eight islands inhabited by legendary beings.

The Imago Mundi is just one of many maps inscribed in the clay tablets of Mesopotamia. It seems to be unique, however, in its scope. "Most ancient clay maps are large-scale representations of small areas, showing irrigation, fields and, most surely, ownership," John O. E. Clark writes in Maps that Changed the World . They are also quite precise. "In contrast," Assyriologist Wayne Horowitz writes , "the relative size and location of many of the features on the World Map seem preposterous." But for its purpose - to mythologize, not to settle land disputes - it probably served just fine.

Anaximander's World

Meanwhile, in Greece, the Milesian philosopher Anaximander pursued a similar goal: to map the whole world. His original work is lost to history, but scholars have tried to reconstruct it using descriptions from the historian Herodotus. It was flat and circular like a disc, ringed by ocean in a similar way to the Imago Mundi. Three land masses - Europe, Asia and Libya - fill the center, with the Nile River and the Mediterranean and Black seas separating them. Anaximander is considered one of the founders of geography, together with Hecataeus, a fellow Milesian who improved his map with far more detail.

The Bedolina Petroglyph

Around the same time, the mountain-dwelling people of northern Italy etched the Bedolina map into glacially polished granite in Valcamonica, a valley that contains one of the world's greatest collections of rock art. The 8-by-14-foot petroglyph stands among hundreds of thousands of others, likely created in the first millennium B.C. It's many abstract symbols are supposed to depict buildings, fields and paths, among other things. Scholars disagree , though, on whether the map was meant as a portrayal of an actual geographical area, or only as a symbolic statement - about the relationship between its creators and their environment, for example.

Australian Songlines

Some prehistoric cultures devised "maps" of a less conventional kind. Indigenous Australian peoples saw their world in terms of "songlines," which are essentially oral maps based on sacred features of the landscape. First and foremost they record traditional beliefs about the , a mythological period during which the ancestors of all living creatures shaped the world we see now. But the songlines also involve recognizable places and objects, meaning they can be used for navigation as well. "The mapping of these eternal patterns ... was more than a set of spiritual beliefs," Clark writes. "It was also a practical means by which all the Aboriginal tribes managed to survive."

The Peutinger Table

This granddaddy of all roadmaps stretches 22 feet to make room for all the thoroughfares of the ancient Roman Empire. The version in existence today is a 13th-century replica of the original, which some scholars believe was drafted in the first century B.C. at the behest of Roman general Marcus Agrippa. It extends as far west as Britain and Spain, as far east as India, and charts some 50,000 miles of stone-paved highway. Though not drawn to scale, the map lists mileage between towns, and offers prominent landmarks for the traveler to follow. (Even so, G0ogle Maps may give better results in the 21st century.)

Ptolemy's Geography

Of all the ancient maps, this one was surely the most influential. As Jerry Brotton writes in A History of the World in 12 Maps , Claudius Ptolemy's remarkably comprehensive Geography - completed around 150 A.D. - "would come to define mapmaking for the next two millennia." It wasn't a map in the standard format, but an eight-volume book that claimed to describe the entire known world according to mathematical principles, with longitudinal and latitudinal coordinates for various locations. It boasted an astonishing 8,000 place names, including regions as far flung as Iceland and China. As with the Peutinger Table, the originals are lost. Likewise, the oldest known version comes from 13th-century Byzantium, where scholars resurrected the map that would dominate and inform cartographic efforts for centuries to come.

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Humans have made maps for untold thousands of years. They're among the oldest modes of communication, predating written language. But, as cartographer Norman Thrower writes in Maps and Civilization: Cartography in Culture and Society, "Only a small fraction of the maps produced in earlier ages has survived."

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6.G.1 Understand the geographical factors that influence human migration and settlement.
6.G.1.1 Explain how human and physical characteristics impacted migration and settlement in various regions in Africa, Asia, Europe and the Americas.
6.G.1.2 Explain how movement and settlement patterns affected the development of civilizations, empires, and societies in Africa, Asia, Europe, and the Americas.