Early Human Evolution
The past five thousand years of human history are a small fraction of the millions of years of human development that came before the first civilizations. Four million year-old remains of hominids with human facial features and who stood erect have been found in East Africa. Archaeologists found a number of different hominids that lived millions of years ago, one of which may be the ancestor of modern humans. About 2 million years ago early hominids learned how to use stones as weapons and to crack nuts and bones. This period, called the Old Stone Age (or the Paleolithic period), is the longest period of human development. The early ancestors of humans chipped rocks to give them points or sharp edges to use as awls, knives, or arrowheads, learned to use fire for heat and cooking, and began wearing animal skins for warmth. Early humans were social animals who traveled in small bands that lived by hunting, scavenging, and gathering nuts, fruits, and grains. Survival of the species depended on cooperation because children needed nurturing for years before they could function independently. During this time, the earth was going through a series of ice ages when glaciers covered much of Europe, Asia, and North America. Early humans survived by using their larger brain capacity to adapt to changing climates and food sources. In the later years of the Old Stone Age early humans began painting the interiors of their caves, burying their dead, decorating their bodies with beads, and carving small figures that suggest a form of religious worship.
The Emergence and Spread of Modern Humans
Over a hundred thousand years ago, early Homo sapiens, the direct ancestor of modern humans, evolved in Africa and later began to migrate to other parts of the globe. Sea levels were lower when much of the earth was covered with ice, so bands of early humans could easily cross from Africa to the Middle East and from there to Europe, South Asia, and East Asia. In Europe Cro-Magnon people encountered the Neanderthals, a different species of hominids that had evolved parallel with Homo sapiens. Neanderthals had many features in common with modern humans; however, some anatomical differences placed them at a disadvantage when in competition with modern humans. The Neanderthals became extinct about the same time that Cro-Magnons spread across Europe. About 17,000 years ago, Homo sapiens crossed a land bridge from Asia to North America, rapidly spread across North America, and migrated to South America. By 10,000 B.C., Homo sapiens were living on all parts of the globe, except the islands in the Pacific Ocean. These early nomads were no different anatomically from people today. Humans are unusual in that Homo sapiens is the only species of hominids in the animal kingdom. All other species have become extinct. Skin color and some differences in body structure are minor variations that evolved among the races within the single species of humankind.
The Neolithic Period
The population of humans began to increase as the last glacial period ended around 11,000 years ago. Many bands of people had begun to live less nomadic lives, even though they depended on hunting and gathering. However, people had to find new food sources because global warming caused changes in the ecology. Some plants and animals could not adapt to the changes: grasslands became deserts, and forests became plains. The Neolithic period (or New Stone Age) began when groups in different parts of the world began to plant seeds, tend and harvest crops, and store a surplus in woven baskets or clay pots. The first crops planted were grains that could be kept for later use. People also began to domesticate animals to provide a steady food source. Independently of other cultures, farming began in the Middle East, Southeast Asia, China, Mexico, and Peru. Farming and herding spread rapidly from the Middle East to Europe and across Central Asia to India.
At first, early Neolithic farmers often did not do as well as nomadic hunters and food gatherers because their diet was limited to grains that did not supply all the nutrients necessary for good health. Also, the unsanitary conditions of their permanent settlements spread disease. However, populations had increased beyond the capacity of the environment to provide enough food through hunting and gathering. Neolithic farmers often altered the environment by cutting down trees and changing watercourses. Sometimes over-cutting of forests and over-grazing of pastures led to a deterioration of the environment that forced the people to abandon their communities and resettle elsewhere. People living in permanent settlements improved the size and quality of their dwellings and began to decorate them. Though their day's activities were mostly determined by dawn and dusk, they could provide some light at night by fires and torches made of bundled sticks and sometimes dipped in grease. Later Neolithic people used oil lamps with wicks; they also began to plant grains that were more productive and improved their farming techniques. They developed better plows, used draft animals to pull them, and planted seeds carefully instead of just casting the seeds on the ground.
The Neolithic period began for different groups in different parts of the world. Today, some hunting-gathering tribes in isolated parts of rain forests in South America, Africa, and Asia continue as Old Stone Age cultures. Historians commonly accept that the New Stone Age ended for a culture when it entered the Iron Age by learning to smelt iron ore and forge iron tools and weapons. That improvement became common first in Southwest Asia around 1200 B.C., long after civilizations had been established there.
Neolithic cultures had been farming and domesticating animals for thousands of years when some of them took the next step in human progress by developing more complex political, social, and economic cultures called civilizations. These evolved independently of each other in four river valleys: between the Tigris and Euphrates rivers in Mesopotamia, along the Nile River in Egypt, in the Indus River Valley in India, and along the Huang He (Yellow River) in China. Later, other Neolithic communities learned from these first civilizations through trade and cultural diffusion and adapted their characteristics to create their own civilizations.
