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Human evolution is the evolutionary process leading to the appearance of anatomically modern humans. The topic typically focuses on the evolutionary history of the primates—in particular the genus ''Homo'', and the emergence of ''Homo sapiens'' as a distinct species of the hominids (or "great apes")—rather than studying the earlier history that led to the primates. The study of human evolution involves many scientific disciplines, including physical anthropology, primatology, archaeology, paleontology, ethology, linguistics, evolutionary psychology, embryology and genetics. Genetic studies show that primates diverged from other mammals about , in the Late Cretaceous period, and the earliest fossils appear in the Paleocene, around . Within the Hominoidea (apes) superfamily, the Hominidae family diverged from the Hylobatidae (gibbon) family some 15–20 million years ago; African great apes (subfamily Homininae) diverged from orangutans (Ponginae) about ; the Hominini tribe (humans, ''Australopithecines'' and other extinct biped genera, and chimpanzees) parted from the Gorillini tribe (gorillas) about ; and, in turn, the subtribes Hominina (humans and biped ancestors) and Panina (chimps) separated about .〔 *(【引用サイトリンク】title=Find Time of Divergence: Hominidae versus Hylobatidae )〕 The basic adaptation of the hominin line is bipedalism. The earliest bipedal hominin is considered to be either ''Sahelanthropus'' or ''Orrorin''; alternatively, either ''Sahelanthropus'' or ''Orrorin'' may instead be the last shared ancestor between chimps and humans. ''Ardipithecus'', a full biped, arose somewhat later, and the early bipeds eventually evolved into the australopithecines, and later into the genus ''Homo''. The earliest documented representative of the genus ''Homo'' is ''Homo habilis'', which evolved around , and is arguably the earliest species for which there is positive evidence of the use of stone tools. The brains of these early hominins were about the same size as that of a chimpanzee, although it has been suggested that this was the time in which the human SRGAP2 gene doubled, producing a more rapid wiring of the frontal cortex. During the next million years a process of rapid encephalization occurred, and with the arrival of ''Homo erectus'' and ''Homo ergaster'' in the fossil record, cranial capacity had doubled to 850 cm3. (Such an increase in human brain size is equivalent to each generation having 125,000 more neurons than their parents.) It is believed that ''Homo erectus'' and ''Homo ergaster'' were the first to use fire and complex tools, and were the first of the hominin line to leave Africa, spreading throughout Africa, Asia, and Europe between . According to the recent African origin of modern humans theory, modern humans evolved in Africa possibly from ''Homo heidelbergensis'', ''Homo rhodesiensis'' or ''Homo antecessor'' and migrated out of the continent some 50,000 to 100,000 years ago, gradually replacing local populations of ''Homo erectus'', Denisova hominins, ''Homo floresiensis'' and ''Homo neanderthalensis''. Archaic ''Homo sapiens'', the forerunner of anatomically modern humans, evolved in the Middle Paleolithic between 400,000 and 250,000 years ago. Recent DNA evidence suggests that several haplotypes of Neanderthal origin are present among all non-African populations, and Neanderthals and other hominins, such as Denisovans, may have contributed up to 6% of their genome to present-day humans, suggestive of a limited inter-breeding between these species. The transition to behavioral modernity with the development of symbolic culture, language, and specialized lithic technology happened around 50,000 years ago according to many anthropologists although some suggest a gradual change in behavior over a longer time span. ==History of study== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「human evolution」の詳細全文を読む スポンサード リンク
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