According to  gene flow from Neandertals to modern humans occurred between 47, and 65, years ago, and most likely happened at the time when Neandertals and modern humans encountered each other in Europe and the Middle East around 50, years ago. In sum, interbreeding and assimilation, the tenants of a model first proposed by Fred Smith  are now supported by genetic data  , .
It can be argued that the level of interbreeding may have been too limited to support an assimilation scenario. But the Mesolithic hunter-gatherers, who cannot be described as cognitively inferior, were not submerged by hordes of farmers. Farmers and foragers coexisted for thousands of years in NW Europe; in Central Europe local hunter-gatherers adopted farming but in southern Scandinavia local foragers retained the Mesolithic lifestyle for c. Cultural contact is suggested by clear continuities in flint technology between the Mesolithic and early Neolithic in the region.
It would take at least one millennium between the first arrival of immigrants and a notable increase in their population size. The original Neandertal contribution to modern human biology may have been larger 40, years ago - equivalent to generations with generation time at 20 years — than estimates based on genomic regions of present-day humans suggest  , . Interbreeding of Neandertals and modern humans may have helped modern humans to adapt to non-African environments but also introduced alleles that were not tolerated and contributed to male hybrid sterility thus reducing the proportion of Neandertal ancestry of the period of contact to that seen today .
The high coverage genome of the Altai Neandertal  also suggests low genetic diversity which could indicate small population sizes see Text S1 Hypothesis 8 for archaeological data. The Neandertal demise appears to have resulted from a complex and protracted process  including multiple dynamic factors such as low population density, interbreeding with some cultural contact, possible male hybrid sterility and contraction in geographic distribution  followed by genetic swamping and assimilation by the increasing numbers of modern immigrants.
In a review of the MSA and Middle Paleolithic archaeological record we have shown that inferred markers of modern human cognitive and behavioral capacities have a greater time depth in the Middle Palaeolithic record than commonly acknowledged. We have found no data in support of the supposed technological, social and cognitive inferiority of Neandertals compared to their AMH contemporaries.
Hypotheses 1— Data on the various competing models on the evolutionary disadvantages of Neandertals, presented as Hypotheses 1 to 11, systematically described listing each specific hypothesis and supporting as well as refuting evidence. We thank three reviewers for their constructive comments. Marie Soressi and Alexander Verpoorte gave valuable feedback on previous versions of the paper.
Conceived and designed the experiments: PV WR. Analyzed the data: PV WR. Wrote the paper: PV WR.
Performed research: PV WR. Browse Subject Areas? Click through the PLOS taxonomy to find articles in your field. Abstract Neandertals are the best-studied of all extinct hominins, with a rich fossil record sampling hundreds of individuals, roughly dating from between , and 40, years ago. Introduction The demise of Neandertals is one of the most debated issues in paleoanthropology.
Hypotheses for the Demise of Neandertals Virtually all explanations for the disappearance of the Neandertals from the Eurasian record point in one way or another to the arrival of Homo sapiens , anatomically modern humans AMH , in Europe and western Asia. Methods Our evaluation of the key archaeology-derived explanations for the demise of the Neandertals entails a comparative study of the archaeological record of Neandertals and contemporary modern humans, i. Download: PPT. However, the conflicting hypotheses of acculturation versus independent invention persist, as the dates appear to postdate or overlap in time with the arrival of early modern humans in Italy  and with dates for the Aurignacian in Germany [63; contra 2].
The Uluzzian, an Italian transitional industry also present in Greece and previously attributed to Neandertals  ,  , is now seen by some as a product of modern humans, on the basis of a study of two deciduous teeth from Grotta del Cavallo in southern Italy . AMS dates on shell beads from Grotta del Cavallo yielded If the dates and the taxonomic attribution are accepted, they would extend the period of Neandertal-modern human coexistence to some millennia.
Neandertals are thought to have persisted in southern Iberia until 37 ka, based on the dates for Middle Paleolithic assemblages there  and at other sites in Europe based on dates for Neandertal remains at Spy Belgium and Vindija Croatia. Elsewhere the dates for the Campanian Ignimbrite ash horizon, stratigraphically above several Proto-Aurignacian layers, situate the end of the Middle Paleolithic at about 40 ka see The date of the demise.
Language and Symbolism The archaeological record has been mined in various ways to produce evidence for symbolic aspects of human culture, with a strong focus on the emergence of language. Hunting Methods and Diet With the demise of the idea that Neandertals were scavengers and ineffective hunters  —  , the former interpretive framework has to some degree been reformulated in terms of Neandertals inferiority in subsistence strategies and hunting weaponry for which, again, there is no support from the archaeological record Text SI, Hypotheses 3—4.
Organized Use of Space The same applies to purported differences in the use of space at the level of camp sites by AMH and Neandertals, with organized use of space seen as typical for AMH. Capacity for Innovation Another prominent scenario suggests that the archaeological record of sub-Saharan modern humans, to wit of the two main technocomplexes of the South African late MSA, the Still Bay SB and the Howiesons Poort HP , indicates very dynamic and innovative phases which lasted less than 10, years each  , .
Table 2. Size of Social Networks Other workers have suggested that Neandertals and AMH differed significantly in the sizes of their social networks. Hafting Procedures, Heat Treatment and Cognition According to another hypothesis Neandertals hafting of tools was a simple procedure, only using naturally available glues. Interbreeding and Assimilation For some authors replacement and supposedly rapid extinction of Neandertals can be explained only in terms of substantial cognitive, technological and demographic differences between the Neandertals and AMH  , .
Conclusion In a review of the MSA and Middle Paleolithic archaeological record we have shown that inferred markers of modern human cognitive and behavioral capacities have a greater time depth in the Middle Palaeolithic record than commonly acknowledged. Supporting Information. Text S1. Text S2.
A single package of modern behavior? Text S3.
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