Paleolithic, with dates ranging from 40,000 to 18,500 BP. In Prehistoric and Ancient Mesopotamia, the climate was cooler than in Egypt or the Indus Valley, meaning that the valleys of the Tigris and Euphrates rivers were very different from the deserts of today; in the highlands there were bands of forest interspersed with steppes and savannas rich in flora and abounding with goats, boars, deers, and fox. After the invention of agriculture, farmers worked in the valley, but the community lived in the more easily fortifiable hills. Unlike in China and the Indus Valley civilization, the villages had two economic orientations, downhill to the fields of grain and uphill into the mountains of Anatolia with their rich mines of gold and copper. Mesopotamian cultures were thus continually in a state of flux, which had its own advantages and difficulties. Art of the Pre-Pottery Neolithic period (circa 9000–7000 BC) Pre-Pottery Neolithic A Following the Epipalaeolithic period in the Near East, several Pre-Pottery Neolithic A sites are known from the areas of Upper Mesopotamia and the northern mountainous fringes of Mesopotamia, marked by the appearance around 9000 BC on the banks of the Upper Euphrates of the world's oldest known megaliths at Göbekli Tepe, and the first known use of agriculture around the same time at Tell Abu Hureyra, a site from the preceding Natufian culture. Numerous realistic reliefs and a few sculptures of animals, as well as fragments of reliefs of humans or deities, are known from Göbekli Tepe and dated to circa 9000 BC. The Urfa Man found in another site nearby is dated to the period of the Pre-Pottery Neolithic circa 9000 BC, and is considered as "the oldest naturalistic life-sized sculpture of a human". Slightly later, early human statuettes in stone and fired clay have been found in other Upper Mesopotamia sites such as Mureybet, dated to 8500–8000 BC. Pre-Pottery Neolithic B Around 8000 BC, during the following period of Pre-Pottery Neolithic B, still before the invention of pottery, several early settlements became experts in crafting beautiful and highly sophisticated containers from stone, using materials such as alabaster or granite, and employing sand to shape and polish. Artisans used the veins in the material to maximum visual effect. Such object have been found in abundance on the upper Euphrates river, in what is today eastern Syria, especially at the site of Bouqras. In northeastern Mesopotamia, the Jarmo culture