Initial Upper Paleolithic

The Initial Upper Paleolithic (also IUP, c. 50,000–40,000 BP) covers the first stage of the Upper Paleolithic, during which modern human populations expanded throughout Eurasia.

Main Initial Upper Paleolithic human remains ( ) and stone assemblage sites ( ).^[1]

Technology, art and distribution

The Initial Upper Paleolithic period is characterized by a broadly shared material culture and tools associated with an early modern human dispersal >45kya. These IUP tools are characterized by a combination of elements of the Levallois technique (faceted platforms, hard hammer percussion, flat-faced cores). There are broadly two major IUP-affilated types: 'microlithic blades' (or microblades) and 'core & flakes' (or CAF assemblages). While most archaeologists agree on the existence of a shared set of traits, it remains unclear how much those can be related to a single demic diffusion event, or be explained by cultural transmission or convergence.^[2][3][4]

Microblade and core & flake sites in Eastern Asia

The dispersal of IUP-affilated material culture into Europe, Central Asia and Siberia as well as Northwest China may stem from a distinct migration wave than the dispersal of IUP-affilated material culture into the South, Southeast and East Asian region as well as Oceania.^[2][5] While the IUP types in Europe, Central Asia and Siberia, such as the Bacho Kiro, Ust'-Ishim, and Kara-Bom sites, are primarily affilated with microblades, the IUP-types in South, Southeast, and East Asia, as well as Oceania, such as the Tianyuan site, are primarily affilated with core and flake tools. A distinct type of IUP-affilated technology has also been found in Nwya Devu, a Paleolithic site on the Tibetan plateau.^[6][5]

In Eastern Asia the Initial Upper Paleolithic corresponds to the spread of 'core & flakes'. Although there is a sharp border between core/flake-based tools in Northern China and nearby blade-based tools in Mongolia, the Shuidonggou site displays both types, pointing to an period of contact or adaption.^[6] The 'core & flake' tools may be associated with the major source of ancestry for modern Eastern Asians, having arrived in East Asia via a southern route through South Asia into Southeast Asia and subsequently rapidly expanding northwards.^[7][8][9]

In Europe and Central Asia, the Initial Upper Paleolithic corresponds to the spread of a particular techno-complex in Eurasia,^[10] to which possibly relates the European Châtelperronian.^[11] The European UP-affilated 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.^[10] In effect Aurignacian (42,000-28,000 BP) layers generally postdate late Mousterian and Initial Upper Paleolithic assemblages.^[12] 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.^[13]

• 
  Skeletal remains from the Zlatý kůň woman
• 
  Femur from the Ust'-Ishim man
• 
  Blades from Kara-Bom, a probable Initial Upper Paleolithic site

Archaeogenetics

Repetitive expansions into Eurasia from a population Hub OoA.

See also: Ancient East Eurasians

Modern humans of the Initial Upper Paleolithic (IUP) wave 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.^{[14][15][16][17]}

Initial Upper Paleolithic sites are considered as forming the earliest culture of modern humans in Europe.^[10][18] 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.^[19] 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.^[20]

Ancient East Eurasians and Ancient West Eurasians diverged around 46,000 years ago, with Ancient East Eurasians rapidly further diverging since 45,000 years ago, which aligns with the timeframe of the Initial Upper Paleolithic.^[17]

Forensic facial reconstruction of Oase 2

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.^[21] It is also considered that the early modern human coexisted with Neanderthals in Europe for a period of about 3,000–5,000 years.^[22]

Among the earliest modern humans which have been directly dated to this period are:^[23]

• the individual from 46,000 to 43,000 years ago in the Bacho Kiro cave, located in present-day Bulgaria;^[24]
• the 45,000-year-old Ust’-Ishim man (no continuity with later Eurasians);^[25]
• the 43,000-year-old Zlatý kůň woman (no continuity with later Eurasians);^[23]
• 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);^[25]
• Fumane 2, circa 40,000 BP.

These individuals (except Tianyuan)^[26] 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.^[27]