The Paleolithic (US spelling; also spelled Palaeolithic or Palæolithic) Age, Era or Period, is a prehistoric period of human history distinguished by the development of the most primitive stone tools discovered (Grahame Clark's Modes I and II), and covers roughly 99% of human technological prehistory. It extends from the earliest known use of stone tools, probably by hominins such as australopithecines, 2.6 million years ago, to the end of the Pleistocene around 10,000 BP. The Paleolithic era is followed by the Mesolithic. The date of the Paleolithic—Mesolithic boundary may vary by locality as much as several thousand years.
During the Paleolithic, humans grouped together in small societies such as bands, and subsisted by gathering plants and hunting or scavenging wild animals. The Paleolithic is characterized by the use of knapped stone tools, although at the time humans also used wood and bone tools. Other organic commodities were adapted for use as tools, including leather and vegetable fibers; however, due to their nature, these have not been preserved to any great degree. Surviving artifacts of the Paleolithic era are known as paleoliths. Humankind gradually evolved from early members of the genus Homo such as Homo habilis – who used simple stone tools – into fully behaviorally and anatomically modern humans (Homo sapiens sapiens) during the Paleolithic era. During the end of the Paleolithic, specifically the Middle and or Upper Paleolithic, humans began to produce the earliest works of art and engage in religious and spiritual behavior such as burial and ritual. The climate during the Paleolithic consisted of a set of glacial and interglacial periods in which the climate periodically fluctuated between warm and cool temperatures.