COMMENTARY The earliest modern human colonization of Europe Jean-Jacques Hublin1 Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany he expansion of modern humans over the planet is one of the most T spectacular events in the course of human evolution. During mil- lions of years, distinctive forms of homi- nins evolved in parallel and sometimes coexisted in the same regions. Between 60,000 and 40,000 y ago, one species ex- panded out of its African birthplace and replaced all others. The Neanderthals are the best-known archaic humans to go ex- tinct at this time. In PNAS, Lowe et al. (1) resolve pending issues surrounding the mechanism of this evolutionary drama. Their study also fuels an increasing num- ber of questions on the antiquity of the modern human colonization of Eurasia. Scenarios accounting for the demise of the Neanderthals are much debated. For some, their replacement resulted from intrinsic biological and behavioral differ- ences with our species (2). For others, external causes precipitated their decline at the time of modern human expansion. Fig. 1. The Bohunician and other initial Upper Paleolithic assemblages of Eurasia display the retention Of these, climatic disasters are most often of Levallois blank production (Middle) and a large use of various types of points (Top). This pattern is envisioned (3) but a mega-volcanic erup- reminiscent of North African assemblages predating the out-of-Africa exodus of modern humans. Upper tion (4), and even an inversion of the Paleolithic-style tools such as end-scrapers and burins (Bottom) complete this toolkit. Unfortunately, at magnetic field resulting in a brutal in- most Bohunician sites, sediments do not allow the preservation of human remains, bone tools or body crease of deleterious radiation (5), have ornaments. (Scale bar: 5 cm.) [Reprinted with permission from ref. 20 (Copyright 2008, Elsevier).] also been proposed. Epidemics devastat- ing Neanderthal populations represent an nature of these ash deposits allows this Rather, it suggests that the main threat intermediate category of explanations (6). event to be very accurately dated. It also to indigenous populations were the mod- Crucial to demonstrating any of these has a distinctive chemical signature that ern human invaders themselves and not scenarios is the establishment of accurate can be recognized, even when the ashes environmental hazards. chronologies for each region and their themselves are invisible to the naked eye Several recent studies based on 14C synchronization on a continental scale. in sediments. This has allowed Lowe et al. dating also support this conclusion. They For this time period, archeologists (1) to accurately synchronize the chronol- 14 assign diagnostically modern human re- mostly use the decay of the radioactive C ogies of deposits between very distant mains (11), as well as early Aurignacian isotopes in organic matter to assess the areas and to compare archeological se- assemblages (9), to a period predating ages of sites and human remains. Other quences in caves with more detailed geo- the CI and Heinrich event 4. This raises methods are less precise or are not easily logical sections in open air sites, lake, or the question of when exactly the first applied in archeological contexts. How- even sea deposits. This method provides modern humans reached Europe. A major ever, 14C isotopes virtually disappear from a precise chronological marker to relate difficulty in answering this question bones and charcoal more than 50,000 y cultural changes and human occupations comes from the extreme scarcity of hu- old, which makes the application of this to well-recorded environmental changes. man remains from this time period. The technique increasingly delicate beyond This large-scale study demonstrates that makers of most lithic assemblages dated 40,000 y. Only recently have some im- lithic assemblages of the Upper Paleolithic to between 50,000 and 40,000 y ago provements in the pretreatment of the associated with the spread of modern remain unknown. dating samples (7), and in the conversion humans predate the CI eruption in several Long have archeologists recognized the to calendar dates (8), started to produce European sites. This applies in particular 14 Aurignacian as a proxy for the first ex- reliable C dates for this crucial to some forms of the Aurignacian, a lithic time period. industry with sophisticated art objects pansion of modern humans into Europe. A dramatic volcanic eruption surpassing and musical instruments (9) and associ- Thus, discussions of a possible chronolog- anything known in the historical record ated with modern human remains (10). ical overlap between these modern invad- took place in central Italy 39,300 y ago. It This observation falsifies the hypothesis ers and late Neanderthal populations have is known as the Campanian Ignimbrite proposing that the CI eruption itself, (CI) eruption. Atmospheric circulation and/or the short but intense cooling epi- carried clouds of ash all over the eastern sode known as Heinrich event 4, which Author contributions: J.-J.H. wrote the paper. Mediterranean, and the products of the started 40,000 y ago, could have triggered The author declares no conflict of interest. eruption reached regions as distant as the cultural changes or population re- See companion article 10.1073/pnas.1204579109. southwestern Russia. The mineralogical placements witnessed around this time. 1E-mail: [email protected]. www.pnas.org/cgi/doi/10.1073/pnas.1211082109 PNAS Early Edition | 1of2 Downloaded by guest on September 29, 2021 mostly focused on the age of the first tions, either under the influence of the assemblages spread from the Levant Aurignacian (12). An early form of this modern newcomers (14) or independently (Emirian) to Bulgaria (Bacho-Kirian) and assemblage, the Protoaurignacian, spread (15). Indeed, in western Europe, one Moravia (Bohunician). This may well over southern Europe from Ukraine to of these transitional assemblages, the document an early episode of modern southwestern France. Among other nov- colonization of Europe as old as 50,000 y elties, Protoaurignacian people produced Lithic assemblages of (19, 20). flint bladelets that armed light projectile Such an early arrival of modern humans weapons. This assemblage is rooted in the Upper Paleolithic in western Eurasia better matches what a broader group of lithic industries known we know of the dispersal of modern all over central and western Eurasia and associated with the humans to the east, into Asia and toward characterized by an explosion in the use Australia. It also implies a patchy pattern of these artifacts. In the Levant, this group spread of modern of colonization. Modern humans would is represented by the early Ahmarian, have initially been unsuccessful in replac- beginning 47,000 y ago. Although virtually humans predate the CI ing the Neanderthals throughout the no human remains have been discovered entire extension of their geographical do- in the European Protoaurignacian, the eruption in several main. On a continental scale, there was Ahmarian yielded a fully modern imma- likely some overlap in time between the ture human skeleton at the site of Ksar European sites. two groups. Thus, any innovation observed Akil (Lebanon) (13). The limit between the Middle Paleo- in the Neandertal world around or after lithic, produced in Europe by Neander- Châtelperronian, has yielded Neandertal 50,000 y ago may have resulted from thals, and the genuine Upper Paleolithic, remains (14, 16), and a Neandertal origin cultural diffusion triggered by modern fl produced by modern humans, is not always is also suspected for others (17). population in uxes into western Eurasia clear-cut. So-called “transitional assem- However, modern humans might also (14, 21). blages” separate the Middle and Upper have produced transitional assemblages. Although modern human expansions Paleolithic in many sites. These assem- Before they left Africa, they indeed used out of their African cradle were irresist- blages display tools reminiscent of those technologies such as Levallois. Assem- ible, a full understanding of the complex found in the later Upper Paleolithic, and blages identified in southwestern Asia as processes that drove indigenous humans often technological features inherited “initial” Upper Paleolithic display this and portions of the local fauna to extinc- from the Middle Paleolithic, e.g., the combination of older methods to produce tion still stands ahead of us. Confirming Levallois technique of blank production blades alongside remarkable novelties. the biological identity of the makers (Fig. 1). This mix has suggested to many At the Üçag˘ızlı I cave (Turkey), these of the initial Upper Paleolithic in eastern that a local evolution of late Neanderthals include shell beads and bone artifacts and central Europe is crucial to this took place and resulted in these innova- (18). A series of initial Upper Paleolithic understanding. 1. Lowe J, et al. (2012) Volcanic ash layers illuminate the 8. Reimer PJ, et al. (2009) Intcal09 and marine09 radio- 15. d’Errico F (2003) The invisible frontier. A multiple spe- resilience of Neanderthals and early modern humans carbon age calibration curves, 0–50,000 years cal BP. cies model for the origin of behavioral modernity. Evol to natural hazards. Proc Natl Acad Sci USA, 10.1073/ Radiocarbon 51:1111–1150. Anthropol 12:188–202. pnas.1204579109. 9. Higham T, et al. (2012) Testing models for the begin- 16. Lévêque F, Vandermeersch B (1980) Découverte de 2. Klein RG (2009) The Human Career: Human Biological nings of the Aurignacian and the advent of figurative restes humains dans un niveau castelperronien à and Cultural Origins (Univ Chicago Press, Chicago), 3rd art and music: The radiocarbon chronology of Gei- Saint-Césaire (Charente-Maritime). C.R. Acad Sc Paris Ed. ßenklösterle. J Hum Evol 62:664–676. 291:187–189. 3. Tzedakis PC, Hughen KA, Cacho I, Harvati K (2007) Plac- 10. Wild EM, et al.