The Paleolithic Period ended when the Neolithic Period began. However, this transition point is much debated, as different parts of the world achieved the Neolithic stage at different times. It is generally thought to have occurred sometime about 10,000 BCE. During that time, humans learned to raise crops and keep domestic livestock and were thus no longer dependent on hunting, fishing, and gathering of wild plants. These cultures made more useful stone tools by grinding and polishing harder rocks rather than merely chipping softer ones down to the desired shape. The cultivation of cereal grains enabled people to settle in one location, build permanent dwellings, and develop villages, and the release from nomadism and a hunting-and-gathering economy gave them the time to pursue specialized crafts.