The Acheulo-Yabrudian Cultural Complex, sometimes referred to as simply the Acheulo-Yabrudian or AYCC, is the name archaeologists have given to the period of time in the Levant at the end of the Lower Paleolithic and the beginning of the Middle Paleolithic. The period begins ca 400,000 years ago, as established by thermoluminescence and electron spin resonance at the Levantine sites of Tabun Cave, Hayonim Cave, Yabrud Cave, Qesem Cave, Hummal Cave, and Zuttiyeh, among others.
Few dates are available in general for the AYCC, and those that have been published--especialy Tabun and Hummal--have been controversial. Thermoluminescence, electron spin resonance and Uranium/Thorium dates do seem to show a pattern between 420,000-225,000 years ago. Most recently, a sequence of 54 U/Th dates on speleotherms have been published for Qesem Cave, with the oldest directly associated with the archaeological sediments at 300,000 years ago, in the midpoint of the 8 meter-thick deposit.
Hominids and the AYCC
Human remains from AYCC contexts include eight teeth from Qesem and a partial face from Zuttiyeh, and not much else. Who made the artifacts from the AYCC is an interesting question, because the Lower Paleolithic Acheulian is believed to have been made by Homo erectus, while the Middle Paleolithic Mousterian is believed to have been the product of Neanderthals and Anatomically Modern Humans. Further, the AYCC currently predates all of the AMH sites in Africa, where it is currently believed, by most scientists, that AMH evolved.
Unfortunately, the data are pretty slim, and what exists is controversial. Zuttiyeh, a AYCC site in Israel, contained a fragment of the face of a hominid skull which some scholars identify as Neanderthal, some scholars arguing for anatomically modern humans (AMH), and others still that Zuttiyeh is transitional. Teeth recovered from Qesem cave have aspects of both archaic AMH and Neanderthals, although its excavators are convinced that Qesem's occupants were AMH.
At the moment (January 2011), most scholars agree that AMH evolved in Africa. The Levant is considered the main exit route for AMH out of Africa. The earliest dated Anatomically Modern Human sites are Bouri in Ethiopia, at 160,000 years ago, and possibly Omo Kibish, also in Ethiopia, at 195,000 years ago. Additional evidence, in the form of more complete fossils combined with tighter dating of AYCC, might change that.
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