In the last ten years, new fossil, archaeological, and genetic data have significantly altered our understanding of the peopling of the Old World in the Late Pleistocene. Scholars have long been challenged to define humanity’s place in evolution and to trace our phylogeny. Differences in the skeletal morphology of hominin fossils have often led to the naming of distinct new species, but recent genetic findings have challenged the traditional perspective by demonstrating that modern human DNA contains genes inherited from Neanderthals and Denisovans, thus questioning their status as separate species. The recent discovery of Homo floresiensis from Flores Island has also raised interesting queries about how much genetic and morphological diversity was present during the Late Pleistocene. This paper discusses the nature and implications of the evidence with respect to Homo floresiensis, Neanderthals, and Denisovans and briefly reviews major Late Pleistocene discoveries from the last ten years of research in the Old World and their significance to the study of human evolution. 1. Introduction In the literature of human evolution, recent years have been marked by new questions of what it means to be human. Scholars have long been challenged to define humans’ place in evolution and to trace our phylogeny. Differences in the skeletal morphology of hominin fossils have often led to the naming of distinct new species. Species are traditionally and most often defined as a population or group of populations capable of interbreeding and producing fertile offspring [1], although Mayden [2] more recently have identified at least 24 alternative species conceptualizations (see also de Queiroz [3] for a discussion of modern versus traditional species definitions). Recent genetic findings have challenged the traditional biological perspective by demonstrating that modern human DNA contains genes inherited from Neanderthals and Denisovans [4–6]. Not only do modern humans partially share their lineage but genetic evidences also indicate that these different hominins were capable of interbreeding and producing viable offspring, thus questioning their status as separate species. Genetic data to date indicate that at least Neanderthals, anatomically modern humans (AMH, i.e., humans with skeletons similar to those of present-day humans), and Denisovans were variants of a single breeding population of Homo, even though they present vast spatiotemporal differences in their skeletal morphology and artifactual productions. Despite these findings, however, in general the human
References
[1]
E. Mayr, Systematics and the Origin of Species from the Viewpoint of a Zoologist, Columbia University Press, New York, NY, USA, 1942.
[2]
R. L. Mayden, “A hierarchy of species concepts: the denouement in the saga of the species problem,” in Species: The Units of Biodiversity, M. F. Claridge, H. A. Dawah, and M. R. Wilson, Eds., pp. 381–424, Chapman & Hall, London, UK, 1997.
[3]
K. De Queiroz, “Ernst Mayr and the modern concept of species,” Proceedings of the National Academy of Sciences of the United States of America, vol. 102, no. 1, pp. 6600–6607, 2005.
[4]
R. E. Green, J. Krause, A. W. Briggs, et al., “A draft sequence of the Neandertal genome,” Science, vol. 328, pp. 710–722, 2010.
[5]
D. Reich, R. E. Green, M. Kircher et al., “Genetic history of an archaic hominin group from Denisova cave in Siberia,” Nature, vol. 468, no. 7327, pp. 1053–1060, 2010.
[6]
D. Reich, N. Patterson, M. Kircher et al., “Denisova admixture and the first modern human dispersals into Southeast Asia and Oceania,” The American Journal of Human Genetics, vol. 89, no. 4, pp. 516–528, 2011.
[7]
L. R. Berger, D. J. de Ruiter, S. E. Churchill et al., “Australopithecus sediba: a new species of homo-like australopith from South Africa,” Science, vol. 328, no. 5975, pp. 195–204, 2010.
[8]
P. Brown, T. Sutikna, M. J. Morwood, R. P. Soejono, E. W. Saptomo, and R. A. Due, “A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia,” Nature, vol. 431, no. 7012, pp. 1055–1061, 2004.
[9]
M. J. Morwood, R. P. Soejono, R. G. Roberts et al., “Archaeology and age of a new hominin from Flores in Eastern Indonesia,” Nature, vol. 431, no. 7012, pp. 1087–1091, 2004.
[10]
M. J. Morwood, P. Brown, T. Sutikna et al., “Further evidence for small-bodied hominins from the Late Pleistocene of Flores, Indonesia,” Nature, vol. 437, no. 7061, pp. 1012–1017, 2005.
[11]
D. Argue, M. J. Morwood, T. Sutikna, and E. W. Saptomo, “Homo floresiensis: a cladistic analysis,” Journal of Human Evolution, vol. 57, no. 5, pp. 623–639, 2009.
[12]
D. Argue, M. Morwood, T. Sutikna, and E. W. Saptomo, “A Reply to Trueman's “A new cladistic analysis of Homo floresiensis’,” Journal of Human Evolution, vol. 59, no. 2, pp. 227–230, 2010.
[13]
J. W. H. Trueman, “A new cladistic analysis of Homo floresiensis,” Journal of Human Evolution, vol. 59, no. 2, pp. 223–226, 2010.
[14]
Y. Kaifu, “Craniofacial morphology of Homo floresiensis: description, taxonomic affinities, and evolutionary implication,” Journal of Human Evolution, vol. 61, pp. 644–682, 2011.
[15]
P. Brown and T. Maeda, “Liang Bua Homo floresiensis mandibles and mandibular teeth: a contribution to the comparative morphology of a new hominin species,” Journal of Human Evolution, vol. 57, no. 5, pp. 571–596, 2009.
[16]
R. D. Martin, A. M. MacLarnon, J. L. Phillips, and W. B. Dobyns, “Flores hominid: new species or microcephalic dwarf?” Anatomical Record A: Discoveries in Molecular, Cellular, and Evolutionary Biology, vol. 288, no. 11, pp. 1123–1145, 2006.
[17]
R. C. Vannucci, T. F. Barron, and R. L. Holloway, “Craniometric ratios of microcephaly and LB1, Homo floresiensis, using MRI and endocasts,” Proceedings of the National Academy of Sciences of the United States of America, vol. 108, no. 34, pp. 14043–14048, 2011.
[18]
D. Argue, D. Donlon, C. Groves, and R. Wright, “Homo floresiensis: microcephalic, pygmoid, Australopithecus, or Homo?” Journal of Human Evolution, vol. 51, no. 4, pp. 360–374, 2006.
[19]
P. Brown, “LB1 and LB6 Homo floresiensis are not modern human (Homo sapiens) cretins,” Journal of Human Evolution, vol. 62, no. 2, pp. 201–224, 2012.
[20]
S. G. Larson, W. L. Jungers, M. J. Morwood et al., “Homo floresiensis and the evolution of the hominin shoulder,” Journal of Human Evolution, vol. 53, no. 6, pp. 718–731, 2007.
[21]
S. G. Larson, W. L. Jungers, M. W. Tocheri et al., “Descriptions of the upper limb skeleton of Homo floresiensis,” Journal of Human Evolution, vol. 57, no. 5, pp. 555–570, 2009.
[22]
S. H. Montgomery, “Primate brains, the “island rule” and the evolution of Homo floresiensis,” Journal of Human Evolution, vol. 65, no. 6, pp. 750–760, 2013.
[23]
M. J. Morwood, T. Sutikna, E. W. Saptomo, D. R. Hobbs, and K. E. Westaway, “Preface: research at Liang Bua, Flores, Indonesia,” Journal of Human Evolution, vol. 57, no. 5, pp. 437–449, 2009.
[24]
C. M. Orr, M. W. Tocheri, S. E. Burnett et al., “New wrist bones of Homo floresiensis from Liang Bua (Flores, Indonesia),” Journal of Human Evolution, vol. 64, no. 2, pp. 109–129, 2013.
[25]
E. M. Weston and A. M. Lister, “Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis,” Nature, vol. 459, no. 7243, pp. 85–88, 2009.
[26]
R. G. Roberts, K. E. Westaway, J.-X. Zhao et al., “Geochronology of cave deposits at Liang Bua and of adjacent river terraces in the Wae Racang valley, Western Flores, Indonesia: a synthesis of age estimates for the type locality of Homo floresiensis,” Journal of Human Evolution, vol. 57, no. 5, pp. 484–502, 2009.
[27]
A. Brumm, G. M. Jensen, G. D. van den Bergh et al., “Hominins on Flores, Indonesia, by one million years ago,” Nature, vol. 464, no. 7289, pp. 748–752, 2010.
[28]
Y. Zaim, R. L. Ciochon, J. M. Polanski et al., “New 1.5 million-year-old Homo erectus maxilla from Sangiran (Central Java, Indonesia),” Journal of Human Evolution, vol. 61, no. 4, pp. 363–376, 2011.
[29]
I. Jankovié, “Neandertals…150 years later,” Collegium Antropologicum, vol. 28, supplement 2, no. 2, pp. 379–401, 2004.
[30]
D. Stapert, “Neanderthal children and their flints,” PalArch Journal of Archaeology of Northwest Europe, vol. 1-2, pp. 16–39, 2007.
[31]
W. King, “The reputed fossil man of neanderthal,” Quarterly Journal of Science, vol. 1, pp. 88–97, 1864.
[32]
C. P. T. Baillie, “Neandertals: unique from humans, or uniquely human?” Kroeber Anthropological Society, vol. 103, no. 1, pp. 93–107, 2013.
[33]
C. Duarte, J. Maurício, P. B. Pettitt et al., “The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia,” Proceedings of the National Academy of Sciences of the United States of America, vol. 96, no. 13, pp. 7604–7609, 1999.
[34]
J. Zilh？o, “Fate of the Neandertals,” Archaeology, vol. 53, no. 4, pp. 24–29, 2000.
[35]
J. Zilh？o and E. Trinkaus, Eds., Portrait of the Artist as a Child: The Gravettian Human Skeleton from the Abrigo do Lagar Velho and Its Archeological Context, Trabalhos de Arqueologia 22, Instituto Português de Arqueologia, Lisboa, Portugal, 2002.
[36]
V. H. Estabrook, Sampling biases and new ways of addressing the significance of trauma in Neandertals [Ph.D. dissertation], The University of Michigan, Ann Arbor, Mich, USA, 2009.
[37]
J. Hawcroft and R. Dennell, “Neanderthal cognitive life history and its implications for material culture,” in Children and Material Culture, J. S. Derevenski, Ed., pp. 89–99, Routledge, London, UK, 2000.
[38]
F. V. R. Rozzi and J. M. B. de Castro, “Surpisingly rapid growth in Neanderthals,” Nature, vol. 428, no. 6986, pp. 936–939, 2004.
[39]
M. S. P. de León, L. Golovanova, V. Doronichev et al., “Neanderthal brain size at birth provides insights into the evolution of human life history,” Proceedings of the National Academy of Sciences of the United States of America, vol. 105, no. 37, pp. 13764–13768, 2008.
[40]
O. Kondo, H. Ishida, T. Hanihara, T. Wakebe, Y. Dodo, and T. Akazawa, “Cranial ontogeny in Neandertal children: evidence from neurocranium, face and mandible,” in Current Trends in Dental Morphology Research, E. Zadzinska, Ed., pp. 243–255, University of Lodz Press, Lodz, Poland, 2005.
[41]
R. H. Gargett, “Grave shortcomings: the evidence for Neandertal burial,” Current Anthropology, vol. 30, no. 2, pp. 157–190, 1989.
[42]
P. B. Pettitt, “The Neanderthal dead: exploring mortuary variability in middle paleolithic eurasia,” Before Farming, vol. 1, no. 4, pp. 1–19, 2002.
[43]
L. V. Golovanova, J. F. Hoffecker, V. M. Kharitov, and G. P. Romanova, “Mezmaiskaya cave: a Neanderthal occupation in the Northern Caucasus,” Current Anthropology, vol. 40, no. 1, pp. 77–86, 1999.
[44]
R. Davies and S. Underdown, “The Neanderthals: a social synthesis,” Cambridge Archaeological Journal, vol. 16, no. 2, pp. 145–164, 2006.
[45]
B. L. Hardy and M.-H. Moncel, “Neanderthal use of fish, mammals, birds, starchy plants and wood 125–250,000 years ago,” PLoS ONE, vol. 6, no. 8, Article ID e23768, 2011.
[46]
V. R. Paix？o-C？rtes, L. H. Viscardi, F. M. Salzano, M. Cátira bortolini, and T. Hünemeier, “The cognitive ability of extinct hominins: bringing down the hierarchy using genomic evidences,” American Journal of Human Biology, vol. 25, no. 5, pp. 702–705, 2013.
[47]
L. Abi-Rached, M. J. Jobin, S. Kulkarni et al., “The shaping of modern human immune systems by multiregional admixture with archaic humans,” Science, vol. 334, no. 6052, pp. 89–94, 2011.
[48]
J. Krause, Q. Fu, J. M. Good et al., “The complete mitochondrial DNA genome of an unknown hominin from southern Siberia,” Nature, vol. 464, no. 7290, pp. 894–897, 2010.
[49]
M. Meyer, M. Kircher, M.-T. Gansauge et al., “A high-coverage genome sequence from an archaic Denisovan individual,” Science, vol. 338, no. 6104, pp. 222–226, 2012.
[50]
A. Cooper and C. B. Stringer, “Did the denisovans cross Wallace’s line?” Science, vol. 342, pp. 321–323, 2013.
[51]
M. Rasmussen, X. Guo, Y. Wang, et al., “An aboriginal Australian genome reveals separate human dispersals into Asia,” Science, vol. 334, no. 6052, pp. 94–98, 2011.
[52]
M. Petraglia, R. Korisettar, N. Boivin et al., “Middle Paleolithic assemblages from the Indian subcontinent before and after the Toba super-eruption,” Science, vol. 317, no. 5834, pp. 114–116, 2007.
[53]
M. Martinon-Torres, R. Dennell, and J. M. Bermudez de Castro, “The Denisova hominin need not be an out of Africa story,” Journal of Human Evolution, vol. 60, no. 2, pp. 251–255, 2011.
[54]
M. Meyer, Q. Fu, A. Aximu-Petri, et al., “A mitochondrial genome sequence of a hominin from Sima de los Huesos,” Nature, vol. 505, pp. 403–406, 2014.
[55]
J. Dabney, M. Knapp, I. Glocke, et al., “Complete mitochondrial genome sequence of a Middle Pleistocene cave bear reconstructed from ultrashort DNA fragments,” Proceedings of the National Academy of Sciences of the United States of America, 2013.
[56]
K. Prüfer, F. Racimo, N. Patterson, et al., “The complete genome sequence of a Neanderthal from the Altai mountains,” Nature, vol. 505, no. 7481, pp. 43–49, 2014.
[57]
R. G. Klein, “Anatomy, behavior, and modern human origins,” Journal of World Prehistory, vol. 9, no. 2, pp. 167–198, 1995.
[58]
R. G. Klein, “Out of Africa and the evolution of human behavior,” Evolutionary Anthropology, vol. 17, no. 6, pp. 267–281, 2008.
[59]
R. G. Klein, The Human Career: Human Biological and Cultural Origins, The University of Chicago Press, Chicago, Ill, USA, 3rd edition, 2009.
[60]
J. M. B. de Castro and M. Martinón-Torres, “A new model for the evolution of the human Pleistocene populations of Europe,” Quaternary International, vol. 295, pp. 102–112, 2013.
[61]
M. H. Wolpoff, J. Hawks, and R. Caspari, “Multiregional, not multiple origins,” American Journal of Physical Anthropology, vol. 112, pp. 129–136, 2000.
[62]
F. H. Smith, I. Jankovi？, and I. Karavani？, “The assimilation model, modern human origins in Europe, and the extinction of Neandertals,” Quaternary International, vol. 137, no. 1, pp. 7–19, 2005.
[63]
L. Cowgill, “One year in biological anthropology: species, integration, and boundaries in 2010,” American Anthropologist, vol. 113, no. 2, pp. 213–221, 2011.
