The Initial Upper Paleolithic (also IUP, ) covers the first stage of the Upper Paleolithic, during which modern human populations expanded throughout Eurasia.

Genetics

Modern humans of the Initial Upper Paleolithic wave (IUP) are suggested to have expanded from a population hub through a star-like expansion pattern (>45kya), and are linked to "East-Eurasian" lineages, broadly ancestral to modern populations in Eastern Eurasia and Oceania, notably East Asian peoples, Aboriginal Australians, and Papuans. While ancient samples found in Central Asia and Europe, such as the Ust'-Ishim man, Bacho Kiro or Oase 2, used inland routes, the ancestors of Eastern Asians and Oceanians used a Southern dispersal route through South Asia, rapidly diverging there.

Initial Upper Paleolithic sites are considered as forming the earliest culture of modern humans in Europe. However, these people do not appear to have been the ancestors of later Europeans as the very few ancient DNA (aDNA) samples recovered from this period are not related to later samples. They ended in Bacho Kiro cave and Oase, but this wave of colonization did not go as far as Western Europe, and apparently was not successful.

These early Eurasian populations probably mated episodically with Neanderthals in the period between 50,000 and 60,000 years ago, probably during the initial phase of their expansion in the Middle East, and they carried ~2–9% Neanderthal ancestry in their genomes. It is also considered that the early modern human coexisted with Neanderthals in Europe for a period of about 3,000–5,000 years.

Among the earliest modern humans which have been directly dated to this period are:
 the individual from 46,000 to 43,000 years ago in the Bacho Kiro cave, located in present-day Bulgaria;
 the 45,000-year-old Ust’-Ishim man (no continuity with later Eurasians);
 the 43,000-year-old Zlatý kůň woman (no continuity with later Eurasians);
 the Tianyuan man, circa 40,000 BP, who is more closely related to modern Asians and Native Americans;
 Oase 1, Oase 2 (no shared ancestry with later Eurasians);
 Fumane 2, circa 40,000 BP.

These individuals (except Tianyuan) did not contribute substantially to modern humans, but from around 37,000 a new wave of modern humans emerged, creating a single founder population, which became ancestral to modern Europeans, exemplified by individuals such as Kostenki-14.

Technology and art
The Initial Upper Paleolithic corresponds to the spread of a particular techno-complex in Eurasia, to which possibly relates the European Châtelperronian. But the Aurignacian complex (Protoaurignacian and Early Aurignacian) with its famous Cave art  seems to correspond to another, later, human wave which spread through the Levant area. In effect Aurignacian (42,000-28,000 BP) layers generally postdate late Mousterian and Initial Upper Paleolithic assemblages. Aurignacian seems to have emerged out of the Initial Upper Paleolithic around 43,000 to 42,000 cal BP, in a process that is yet to be determined.

References

Sources
 
 

Upper Paleolithic