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 period, humans grouped together in small societies such as bands, and subsisted by gathering plants and fishing, 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.
About 50,000 years ago, there was a marked increase in the diversity of artifacts. In Africa, bone artifacts and the first art appear in the archaeological record. The first evidence of human fishing is also noted, from artifacts in places such as Blombos cave in South Africa. Archaeologists classify artifacts of the last 50,000 years into many different categories, such as projectile points, engraving tools, knife blades, and drilling and piercing tools.
Humankind gradually evolved from early members of the genus Homo—such as Homo habilis, who used simple stone tools—into anatomically modern humans as well as behaviorally modern humans by the Upper Paleolithic. During the end of the Paleolithic, specifically the Middle and or Upper Paleolithic, humans began to produce the earliest works of art and began to 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. Archaeological and genetic data suggest that the source populations of Paleolithic humans survived in sparsely wooded areas and dispersed through areas of high primary productivity while avoiding dense forest cover.
By c. 50,000 – c. 40,000 BP, the first humans set foot in Australia. By c. 45,000 BP, humans lived at 61°N latitude in Europe. By c. 30,000 BP, Japan was reached, and by c. 27,000 BP humans were present in Siberia, above the Arctic Circle. At the end of the Upper Paleolithic, a group of humans crossed Beringia and quickly expanded throughout the Americas.
The term "Palaeolithic" was coined by archaeologist John Lubbock in 1865. It derives from Greek: παλαιός, palaios, "old"; and λίθος, lithos, "stone", meaning "old age of the stone" or "Old Stone Age".