↓ Stone Age
The Lower Paleolithic (or Lower Palaeolithic) is the earliest subdivision of the Paleolithic or Old Stone Age. It spans the time from around 2.5 million years ago when the first evidence of craft and use of stone tools by hominids appears in the current archaeological record, until around 300,000 years ago, spanning the Oldowan ("mode 1") and Acheulean ("mode 2") lithics industries.
The Lower Paleolithic is followed by the Middle Paleolithic, which sees the appearance of the more advanced prepared-core tool-making technologies such as the Mousterian. Whether the earliest control of fire by hominids dates to the Lower or to the Middle Paleolithic remains an open question.
The Lower Paleolithic begins with the Gelasian (Lower Pleistocene), some 2.5 million years ago with the appearance of the Homo genus (Homo habilis), possibly developing out of australopithecine forebears (such as Australopithecus garhi). These early members of the Homo genus had primitive tools, summarized under the Oldowan horizon, which remained dominant for the best part of a million years, from about 2.5 to 1.7 million years ago. Homo habilis is assumed to have lived primarily on scavenging, using the tools to cleave meat off carrion or to break bones in order to extract the marrow.
The move from the mostly frugivorous or omnivorous diet of Australopithecus to the carnivorous scavenging lifestyle of early Homo has been explained by the climate changes in East Africa associated with the Quaternary glaciation. Decreasing oceanic evaporation resulted in a drier climate and an expansion of the savannah at the expense of forests. Reduced availability of fruits forced some Australopithecine to unlock new food sources found in the drier savannah climate. Derek Bickerton has placed to this period the move from simple animal communication systems as they are found in all great apes to the earliest form of symbolic communication systems capable of displacement (referring to items not currently within sensory perception), motivated for the need for "recruitment" of group members for scavenging large carcasses.
Homo erectus moved from scavenging to hunting, developing the hunting-gathering lifestyle that would remain dominant throughout the Paleolithic into the Mesolithic. The unlocking of the new niche of hunting-gathering subsistence drove a number of further changes, behavioral and physiological, leading to the appearance of Homo heidelbergensis by some 600,000 years ago.
Homo erectus migrated out of Africa and dispersed throughout Eurasia. Stone tools in Malaysia have been dated to be 1.83 million years old. The Peking Man fossil, discovered in 1929, is roughly 700,000 years old.
In Europe, the Olduwan tradition (known in Europe as Abbevillian) split into two parallel traditions, the Clactonian, a flake tradition, and the Acheulean, a hand-axe tradition. The Levallois technique for knapping flint developed during this time.
The carrier species from Africa to Europe undoubtedly was Homo erectus. This type of human is more clearly linked to the flake tradition, which spread across southern Europe through the Balkans to appear relatively densely in southeast Asia. Many Mousterian finds in the Middle Paleolithic have been knapped using a Levallois technique, suggesting that Neanderthals evolved from Homo erectus (but, perhaps, Homo heidelbergensis (see below)).
Middle Pleistocene 
The appearance of Homo heidelbergensis about 600,000 years ago heralds a number of other new varieties, such as Homo rhodesiensis and Homo cepranensis about 400,000 years ago. Homo heidelbergensis is a candidate for first developing an early form of symbolic language. Whether control of fire and earliest burials date to this period or only appear during the Middle Paleolithic is an open question.
Also in Europe, there appeared a type of human intermediate between Homo erectus and Homo sapiens, sometimes summarized under "archaic Homo sapiens, typified by such fossils as those found at Swanscombe, Steinheim, Tautavel, and Vertesszollos (Homo palaeohungaricus). The hand-axe tradition originates in the same period. The intermediate may have been Homo heidelbergensis, held responsible for the manufacture of improved Mode 2 Acheulean tool types, in Africa, after 600,000 years BP. Flakes and axes coexisted in Europe, sometimes at the same site. The axe tradition, however, spread to a different range in the east. It appears in Arabia and India, but more importantly, it does not appear in southeast Asia.
Transition to the Middle Paleolithic 
From about 300,000 years ago, technology, social structures and behaviour appear to grow more complex, with prepared-core technique lithics, earliest instances of burial and hunting-gathering subsistence. Homo sapiens first appears about 200,000 years ago.
See also 
- Derek Bickerton, Adam's Tongue: How Humans Made Language, How Language Made Humans, New York: Hill and Wang 2009.
- Malaysian scientists find stone tools 'oldest in Southeast Asia'
- The First People and Culture at Indiana University Bloomington