section_path: Prehistory
section_name: Prehistory
paragraph_text: Prehistory
  
  Prehistory is the period before written history. Most of our knowledge of that period comes from the work of archaeologists. Prehistory is often known as the Stone Age, and is divided into the Paleolithic (earliest), Mesolithic, and Neolithic.
  
  The early human migrations in the Lower Paleolithic saw Homo erectus spread across Eurasia 1.8 million years ago. Evidence for the use of fire has been dated as early as 1.8 million years ago, a date which is contested, with generally accepted evidence for the controlled use of fire dating to 780,000 years ago. Actual use of hearths first appears 400,000 years ago. Dates for the emergence of Homo sapiens (modern humans) range from 250,000 to 160,000 years ago, with the varying dates being based on DNA studies and fossils respectively. Some 50,000 years ago, Homo sapiens migrated out of Africa. They reached Australia about 45,000 years ago, southwestern Europe about the same time, southeastern Europe and Siberia around 40,000 years ago, and Japan about 30,000 years ago. Humans migrated to the Americas about 15,000 years ago.
  
  Evidence for agriculture emerges in about 9000 BC in what is now eastern Turkey and spread through the Fertile Crescent. Settlement at Göbekli Tepe began around 9500 BC and may have the world's oldest temple. The Nile River Valley has evidence of sorghum and millet cultivation starting around 8000 BC and agricultural use of yams in Western Africa perhaps dates to the same time period. Cultivation of millet, rice, and legumes began around 7000 BC in China. Taro cultivation in New Guinea dates to about 7000 BC also with squash cultivation in Mesoamerica perhaps sharing that date. Animal domestication began with the domestication of dogs, which dates to at least 15,000 years ago, and perhaps even earlier. Sheep and goats were domesticated around 9000 BC in the Fertile Crescent, alongside the first evidence for agriculture. Other animals, such as pigs and poultry, were later domesticated and used as food sources. Cattle and water buffalo were domesticated around 7000 BC and horses, donkeys, and camels were domesticated by about 4000 BC. All of these animals were used not only for food, but to carry and pull people and loads, greatly increasing human ability to do work. The invention of the simple plough by 6000 BC further increased agricultural efficiency.
  
  Metal use in the form of hammered copper items predates the discovery of smelting of copper ores, which happened around 6000 BC in western Asia and independently in eastern Asia before 2000 BC. Gold and silver use dates to between 6000 and 5000 BC. Alloy metallurgy began with bronze in about 3500 BC in Mesopotamia and was developed independently in China by 2000 BC. Pottery developed independently throughout the world, with fired pots appearing first among the Jomon of Japan and in West Africa at Mali. Sometime between 5000 and 4000 BC the potter's wheel was invented. By 3000 BC, the pottery wheel was adapted into wheeled vehicles which could be used to carry loads further and easier than with human or animal power alone.
  
  Writing developed separately in five different locations in human history: Mesopotamia, Egypt, India, China, and Mesoamerica. By 3400 BC, "proto-literate" cuneiform spread in the Middle East. Egypt developed its own system of hieroglyphs by about 3200 BC. By 2800 BC the Indus Valley civilization had developed its Indus script, which remains undeciphered. Chinese Characters were independently developed in China during the Shang dynasty in the form of the Oracle Bone Script dating to the period 1600 to 1100 BC. Writing in Mesoamerica dates to 600 BC with the Zapotec civilization.