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A number of varieties of ''Homo'' are grouped into the broad category of archaic humans in the period beginning 500,000 years ago (or 500ka). It typically includes ''Homo neanderthalensis'' (40ka-300ka), ''Homo rhodesiensis'' (125ka-300ka), ''Homo heidelbergensis'' (200ka-600ka), and may also include ''Homo antecessor'' (800ka-1200ka).〔 This category is contrasted with anatomically modern humans, which include ''Homo sapiens sapiens'' and ''Homo sapiens idaltu''. Modern humans are theorized to have evolved from archaic humans, who in turn evolved from ''Homo erectus''. Varieties of archaic humans are sometimes included under the binomial name "''Homo sapiens''" because their brain size is very similar to that of modern humans. Archaic humans had a brain size averaging 1200 to 1400 cubic centimeters, which overlaps with the range of modern humans. Archaics are distinguished from anatomically modern humans by having a thick skull, prominent brow ridges and the lack of a prominent chin.〔(Companion encyclopedia of archaeology )〕 Anatomically modern humans appear from about 200,000 years ago and after 70,000 years ago (see Toba catastrophe theory) gradually marginalize the "archaic" varieties. Non-modern varieties of ''Homo'' are certain to have survived until after 30,000 years ago, and perhaps until as recent as 10,000 years ago. Which of these, if any, are included under the term "archaic human" is a matter of definition and varies among authors. Nonetheless, according to recent genetic studies, modern humans may have bred with "at least two groups" of ancient humans: Neanderthals and Denisovans. Other studies have cast doubt on admixture being the source of the shared genetic markers between archaic and modern humans, pointing to an ancestral origin of the traits originating 500,000 to 800,000 years ago.〔()〕〔 http://www.theguardian.com/science/2013/feb/04/neanderthals-modern-humans-research〕〔 ()〕 New evidence suggests another group may also have been extant as recently as 11,500 years ago, the ''Red Deer Cave people'' of China. Chris Stringer of the Natural History Museum in London has suggested that these people could be a result of mating between Denisovans and modern humans. Other scientists remain skeptical, suggesting that the unique features are within the variations expected for human populations. ==Terminology and definition== The category archaic human lacks a single, agreed upon definition.〔 According to one definition, ''Homo sapiens'' is a single species comprising several subspecies that include the archaics and modern humans. Under this definition, modern humans are referred to as ''Homo sapiens sapiens'' and archaics are also designated with the prefix "''Homo'' ''sapiens''". For example, the Neanderthals are ''Homo sapiens neanderthalensis'', and ''Homo heidelbergensis'' is ''Homo sapiens heidelbergensis''. Other taxonomists prefer not to consider archaics and modern humans as a single species but as several different species. In this case the standard taxonomy is used, i.e. ''Homo rhodesiensis'', or ''Homo neanderthalensis''.〔 The dividing lines that separate modern humans from archaic ''Homo sapiens'' and archaics from ''Homo erectus'' are unclear. The earliest known fossils of anatomically modern humans such as the Omo remains from 195,000 years ago, ''Homo sapiens idaltu'' from 160,000 years ago, and Qafzeh remains from 90,000 years ago are recognizably modern humans. However, these early modern humans do exhibit a mix of some archaic traits, such as moderate, but not prominent, brow ridges. 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「Archaic humans」の詳細全文を読む スポンサード リンク
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