Neanderthal extinction hypotheses From Wikipedia, the free encyclopedia Jump to: navigation, search Reconstruction of a Neanderthal child from Gibraltar (Anthropological Institute, University of Zürich)Neanderthal extinction hypotheses refer to theories about how Neanderthals became extinct around 30,000 years ago.[1] Ever since their discovery, both the Neanderthals' place in the human family tree and their relation to modern Europeans have been hotly debated. At different times they have been classified as a separate species (Homo neanderthalensis) and as a subspecies of Homo sapiens (Homo sapiens neanderthalensis). Anthropologists advanced and still advance arguments favoring either an accelerated regional evolution of Neanderthal towards Homo sapiens,[clarification needed] or interbreeding with or replacement by anatomically modern humans. There is no agreement on the association of early Aurignacian culture to any specific physical human type, including figurative art found at Vogelherd.[2] The obvious anatomic differences between Neanderthal and anatomically modern humans inspired the general belief in two separate branches of the genus Homo, and favored the single-origin hypothesis in that modern humans are not directly descended from the Neanderthal branch. The nature of interaction and dividing lines between Neanderthal and archaic Homo Sapiens during the period 50,000 to 25,000 years ago remain largely unknown.[3] Though it has been suggested that the late Neanderthal populations survived in Southern Iberia, in general this area has been considered a "cul-de-sac", playing a passive role in human/biological evolution.[4][5] There is considerable debate about whether Cro-Magnon people accelerated the demise of the Neanderthals, and many hypotheses to that extent are currently available. Contents [hide] 1 Interaction with modern Homo Sapiens 2 Extinction scenarios 2.1 Rapid extinction 2.2 Gradual extinction 2.3 Interbreeding 2.4 Climate change 2.5 Division of labor 2.6 Anatomical differences and running ability 3 See also 4 References 5 Further reading 6 External links Interaction with modern Homo Sapiens Interaction may have occurred at any time along the fringes of the Neanderthal expanse, and ultimately anywhere they met with the Cro Magnon advance. As for now, the expansion of the first anatomically modern humans into Europe cannot be located by diagnostic and well-dated anatomically modern human fossils "west of the Iron Gates of the Danube" before 32 kya.[6] In Lagar Velho Neanderthal skeletons of younger dating have been found with mixed traits, in Southern Iberia.[7][8] The genetic variation at the microcephalin gene, a critical regulator of brain size whose loss-of-function by damaging mutations may also cause primary microcephaly, is claimed to be the most compelling evidence of admixture thus far. One type of the gene, dubbed haplogroup D having an exceptionally high worldwide frequency (~70%), was shown to have a remarkably young coalescence age to its most recent common ancestor ~37,000 years ago. The remaining types (non-D) coalesce to ~990,000 years ago, while the separation time between D and non-D was estimated at ~1,100,000 years ago. An evolutionary advance was assumed, even though positive selection was never as all-decisive as to wipe out the remaining 30% of non-D haplogroups (in which case no introgression could have been suggested) and as for now, a measurable genetic advance has not been attested.[9] Both the worldwide frequency distribution of the D allele, exceptionally high outside of Africa but low in sub-Saharan Africa (29%) that suggests involvement of an archaic Eurasian population, and current estimates of the divergence time between modern humans and Neanderthals based on mitochondrial DNA (mtDNA), are in favor of the Neanderthal lineage as the most likely archaic Homo population from which introgression into the modern human gene pool took place. [10][11] Extinction scenarios Rapid extinction Jared Diamond has suggested a scenario of violent conflict comparable to the genocides suffered by indigenous peoples in recent human history.[12] Another possibility raised by Diamond and others, paralleling colonialist history, would be a greater susceptibility on the part of the Neanderthals to pathogens introduced by Cro-Magnon man. Diamond argues that asymmetry in susceptibility to pathogens is a consequence of the difference in lifestyle. However, the analogy between Cro-Magnon diseases as a threat to Neanderthals, and more recent contacts between colonisers and indigenous peoples, may be misleading.[original research?] The distinction arises because Cro-Magnons and Neanderthals are both believed probably to have lived a nomadic lifestyle,[13][14] whereas in those genocides of the colonial era in which differential disease susceptibility was most significant, it resulted from the contact between colonists with a long history of agriculture and nomadic hunter-gatherer peoples.[original research?] On the other hand, many Native Americans before contact with Europeans were not nomadic, but agriculturalists (Mayans, Iroquois, Cherokee), and this still did not protect them from the disease epidemics brought by Europeans (especially smallpox). One theory is that because they usually lacked large domesticated animal agriculture, such as cows or pigs in close contact with people, they did not develop resistance to species-jumping diseases as Europeans had.[15] Gradual extinction These scenarios may be more drastic than is required to explain a decline of Neanderthal population over the course of 10,000-20,000 years[citation needed]: even a slight selective advantage on the part of modern humans could account for Neanderthals' replacement on such a timescale.[citation needed] Gradual climatic change as a cause of extinction is also a common hypothesis.[citation needed] Speech-related theories have been largely discredited.[citation needed] The problem with a gradual extinction scenario lies in the resolution of dating methods.[original research?] There have been claims for young Neanderthal sites, younger than 30,000 years old.[16] Even claims for interstratification of Neanderthal and modern human remains have been advanced.[17] So the fact that Neanderthals and modern humans coexisted at least for some time seems certain. However, because of difficulties in calibrating the C14 dates the duration of this period is uncertain.[18] Interbreeding Main article: Neanderthal Genome Project There is another hypothesis that the Neanderthals were absorbed into the Cro-Magnon population by interbreeding. This scenario would counter the Recent African Origin scenario in favour of a hybrid origin, since it would imply that at least a minor fraction of the genome of Europeans would descend from Neanderthals, who had left Africa at least 350,000 years ago. Thus far no evidence supporting this scenario has been found in mtDNA analysis of modern Europeans, suggesting at least that no direct maternal line originating with Neanderthals has survived into modern times.[19] The most vocal proponent of the hybridization hypothesis is Erik Trinkaus of Washington University.[20] Trinkaus claims various fossils as hybrid individuals, including the "child of Lagar Velho", a skeleton found at Lagar Velho in Portugal dated to about 24,000 years ago.[21] In a 2006 publication co-authored by Trinkaus, the fossils found in 1952 in the cave of Pestera Muierii, Romania, are likewise claimed as hybrids.[22] Based on an Oxford University 2001 study of the gene that results in red-headedness,[23] some commentators speculated that Neanderthals had red hair and that some red-headed and freckled humans today share some heritage with Neanderthals.[24][25] A 2007 study analysing Neanderthal DNA found that some Neanderthals were red-haired, but the mutation to the MC1R gene which caused red hair in Neanderthals is not found in modern humans.[26] Climate change Another hypothesis involves climate change. Although it is believed that Neanderthals had clothing[27], it has been proposed that failure to adapt their hunting methods caused their extinction when Europe changed into a sparsely vegetated steppe and half desert during the last Ice Age.[28] This article may contain original research or unverified claims. Please improve the article by adding references. See the talk page for details. (November 2007) Graph showing the pattern of temperature and ice volume changes associated with recent glacials and interglacialsEuropean populations of H. neanderthalensis have been traditionally thought to be adapted to a cold environment, and thus may have had problems adapting to a warming environment.[citation needed] This may or may not be the case, although it has been suggested that the difference in cold-adaptation between Neanderthals and H. sapiens may have been minor.[citation needed] Another possibility has to do with the loss of the Neanderthals' primary hunting territory - forests.[original research?] The Neanderthals hunted by stabbing their prey with spears (as opposed to throwing the spears at their prey).[citation needed] They were also far less mobile than modern humans.[citation needed] Thus when the forests were gradually replaced by flatlands, the Neanderthals would have had great difficulty hunting.[original research?] In the open they would not have been able to stalk their prey, their stabbing weapons would have been largely useless, and they - unlike modern humans - could not easily chase their prey. The heavily-set build of the Neanderthals also suggests that they may have had large energy requirements, so if their method of hunting became less efficient (as described above) the increased energy expenditure may have been too much to sustain.[original research?] Division of labor In 2006, anthropologists Steven L. Kuhn and Mary C. Stiner of the University of Arizona proposed a new explanation for the demise of the Neanderthals.[29] In an article titled "What's a Mother to Do? The Division of Labor among Neanderthals and Modern Humans in Eurasia",[30] they theorise that Neanderthals like Middle paleolithic Homo sapiens did not have a division of labor between the sexes. Both male and female Neanderthals participated in the single main occupation of hunting big game that flourished in Europe in the ice age like bison, deer, gazelles and wild horses. This contrasted with humans who were better able to use the resources of the environment because of a division of labor with the women going after small game and gathering plant foods. In addition because big game hunting was so dangerous this made humans, at least males, more resilient (see also Peter Frost's theory on the origins of European blond hair). Anatomical differences and running ability Researches including Karen L. Steudel of the University of Wisconsin have proposed that because Neanderthals had limbs that were shorter and stockier than those of modern humans, and because of other anatomical differences in their limbs, the primary reason the Neanderthals were not able to survive is related to the fact that they could not run as fast as modern humans, and they would require 30% more energy than modern humans would for running or walking.[31] This would have given modern humans a huge advantage in battle. Other researchers, like Yoel Rak, from Tel-Aviv University in Israel have noted that the fossil records show that Neanderthal pelvises in comparison to modern human pelvises would have made it much harder for Neanderthals to absorb shock and to bounce off from one step to the next, giving modern humans another advantage over Neanderthals in running and walking ability.[32] See also List of fossil sites (with link directory) List of hominina (hominid) fossils (with images) Neanderthal Neanderthal interaction with Cro-Magnons Neanderthal Genome Project Neanderthals in popular culture References ^ Last Neanderthals Were Smart, Discovery Channel ^ Conard, N.J. et al. (2004) Unexpectedly recent dates for human remains from Vogelherd. Nature 430, 198–201 [1]; [2] ^ [3] Rapid ecological turnover and its impact on Neanderthal and other human populations - Clive Finlayson and Jose´ S. Carrión, Trends in Ecology & Evolution, Volume 22, Issue 4 , April 2007, Pages 213-222 ^ Climate forcing and Neanderthal extinction in Southern Iberia: insights from a multiproxy marine record - Francisco J. Jiménez-Espejo, Quaternary Science Reviews, Volume 26, Issues 7-8, April 2007, Pages 836-852, Elsevier Ltd ^ European early modern humans and the fate of the Neandertals Erik Trinkaus; doi: 10.1073/pnas.0702214104 PNAS May 1, 2007 vol. 104 no. 18 7367-7372 ^ Trinkaus, E. (2005) Early modern humans. Annu. Rev. Anthropol. 34, 207–230 [4] ^ The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia - Cidália Duarte, João Maurício, Paul B. Pettitt, Pedro Souto, Erik Trinkaus, Hans van der Plicht, and João Zilhão, PNAS Vol. 96, Issue 13, 7604-7609, June 22, 1999 [5] ^ [6] ^ Mekel-Bobrov, N., et al. (2007). "The ongoing adaptive evolution of ASPM and Microcephalin is not explained by increased intelligence". Hum. Mol. Genet. 16: adv. access. doi:10.1093/hmg/ddl487. PMID 17220170. ^ Evans, Patrick D.; et al. (2006-11-07). "Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage". PNAS 10 (48): 18178–18183. doi:10.1073/pnas.0606966103. PMID 17090677. http://www.pnas.org/cgi/content/full/103/48/18178. Retrieved 2008-05-26. ^ Evans, Patrick D.; et al. (2005-09-09). "Microcephalin, a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans". Science 309 (5741): 1717–1720. doi:10.1126/science.1113722. PMID 16151009. http://www.sciencemag.org/cgi/content/abstract/309/5741/1717. ^ Diamond, Jared (1992), The Third Chimpanzee: The Evolution and Future of the Human Animal, Harper Perennial, ISBN 0060984031 ^ Prideaux, Tom (1979), Cro-Magnon Man, Time-Life Books, ISBN 0705400557 ^ Lewin, Roger (1999), Human Evolution: An Illustrated Introduction, Blackwell, ISBN 0632043091 ^ Diamond, Jared (1997), The Evolution of Germs in Guns, Germs, and Steel ^ Finlayson, C., F. G. Pacheco, J. Rodriguez-Vidal, D. A. Fa, J. M. G. Lopez, A. S. Perez, G. Finlayson, E. Allue, J. B. Preysler, I. Caceres, J. S. Carrion, Y. F. Jalvo, C. P. Gleed-Owen, F. J. J. Espejo, P. Lopez, J. A. L. Saez, J. A. R. Cantal, A. S. Marco, F. G. Guzman, K. Brown, N. Fuentes, C. A. Valarino, A. Villalpando, C. B. Stringer, F. M. Ruiz, and T. Sakamoto. 2006. Late survival of Neanderthals at the southernmost extreme of Europe. Nature advanced online publication. ^ Gravina, B., P. Mellars, and C. B. Ramsey. 2005. Radiocarbon dating of interstratified Neanderthal and early modern human occupations at the Chatelperronian type-site. Nature 438:51-56. ^ Mellars, P. 2006. A new radiocarbon revolution and the dispersal of modern humans in Eurasia. Nature' 439:931-935. ^ Krings et al., Neandertal DNA sequences and the origin of modern humans Cell. 1997 Jul 11;90(1):19-30. Deborah Hill, [7]; No Neandertals in the Gene Pool, Science (2004). ^ Dan Jones: The Neanderthal within., New Scientist 193.2007, H. 2593 (3 March), 28–32. Modern Humans, Neanderthals May Have Interbred; Humans and Neanderthals interbred ^ [8]; [9]; [10] ^ Andrei Soficaru u. a.: Early modern humans from Pestera Muierii, Baia de Fier, Romania. in: Proceedings of the National Academy of Sciences. Washington 2006. ^ Red hair a legacy of Neanderthal man ^ "Red-Heads and Neanderthals". May 2001. Archived from the original on 18 October 2005. http://web.archive.org/web/20051018130154/http://www.gktgazette.com/2001/may/news.asp. Retrieved 2005-10-28. ^ "Nicole's hair secrets". 2002-02-10. Archived from the original on 11 december 2005. http://web.archive.org/web/20051211173522/http://www.arts.telegraph.co.uk/connected/main.jhtml?xml=/connected/2002/10/04/ecfhair04.xml&sSheet=/connected/2002/10/04/ixconn.html. Retrieved 2005-11-02. ^ Paul Rincon, Neanderthals 'were flame-haired' BBC 25 October 2007. ^ Gilligan, I: "Neanderthal extinction and modern human behaviour: the role of climate change and clothing", World Archaeology, Vol. 39, No. 4. (2007), pp. 499-514. ^ Climate Change Killed Neandertals, Study Says, National Geographic News ^ Nicholas Wade, "Neanderthal Women Joined Men in the Hunt", from The New York Times, December 5, 2006 ^ Steven L. Kuhn and Mary C. Stiner, "What's a Mother to Do? The Division of Labor among Neandertals and Modern Humans in Eurasia", Current Anthropology, Volume 47, Number 6, December 2006 ^ http://www.zoology.wisc.edu/faculty/Ste/Ste.html ^ http://www.newscientist.com/article/mg13017664.500-science-neanderthals-puzzle-the-anthropologists-.html Further reading Serre et al. (2004). "No evidence of Neandertal mtDNA contribution to early modern humans". PLoS Biology 2 (3): 313–7. doi:10.1371/journal.pbio.0020057. PMID 15024415. External links Max Planck Institute for Evolutionary Anthropology Neanderthals & Humans may have interbred The Way We Are Retrieved from "http://en.wikipedia.org/wiki/Neanderthal_extinction_hypotheses" Categories: Neanderthals | Upper Paleolithic | European archaeology | Pleistocene extinctions | Recent single origin hypothesis Hidden categories: Wikipedia indefinitely semi-protected pages | All pages needing cleanup | Wikipedia articles needing clarification from April 2009 | All articles that may contain original research | Articles that may contain original research from December 2007 | All articles with unsourced statements | Articles with unsourced statements from December 2007 | Articles with unsourced statements from February 2007 | Articles that may contain original research from November 2007 | Articles with unsourced statements from July 2008ViewsArticle Discussion View source History Personal toolsTry Beta Log in / create account Navigation Main page Contents Featured content Current events Random article Search Interaction About Wikipedia Community portal Recent changes Contact Wikipedia Donate to Wikipedia Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page