Fire was used by the Lower Paleolithic hominins "Homo erectus" and "Homo ergaster" as early as 300,000 to 1.5 million years ago and possibly even earlier by the early Lower Paleolithic (Oldowan) hominin "Homo habilis" or by robust "Australopithecines" such as "Paranthropus". However, the use of fire only became common in the societies of the following Middle Stone Age and Middle Paleolithic. Use of fire reduced mortality rates and provided protection against predators. Early hominins may have begun to cook their food as early as the Lower Paleolithic ( million years ago) or at the latest in the early Middle Paleolithic ( years ago). Some scientists have hypothesized that hominins began cooking food to defrost frozen meat, which would help ensure their survival in cold regions.