Periods of decreased precipitation diminish the amount of vegetation and dependent biomass (including humans) and produce more dust. However, Spanish researchers prefer the older date, noting that the younger age is contradicted by fossil fauna from the same deposit as the hominins, including relatively primitive fossils of Ursus deningeri and the vole Clethrionomys acrorhiza (García and Arsuaga). The period of time between 250 and 35 ka witnessed the emergence of Neanderthals in western Eurasia, modern humans in Africa, and, at around 60 ka, the spread of modern humans into Eurasia, where they replaced archaic humans, albeit with a small amount of interbreeding. A similar approach is used with the Middle Pleistocene sample. Later populations display more derived features, and the skeletons from Qafzeh and Klasies River are near-modern in their morphology. In Europe, the Neanderthal lineage evolved a series of apomorphies, including midfacial prognathism, a posterior position of the mental foramen, a retromolar gap in the mandible, a broad suprainiac fossa that is oval in form, a large juxtamastoid process coupled with a small mastoid process, an occipital bun, double-arched browridges that are reduced in absolute volume and vertical thickness compared with those of Middle Pleistocene hominins, and a substantially larger brain than those of most Middle Pleistocene hominins (Hublin; Stringer). Toward the close of the Pleistocene, skulls appear increasingly similar to those of living humans. Large populations also tend to moderate, often to a great degree, the effects of drift. Noteworthy, it falls well within the range of variation of the Sima de los Huesos sample. The palaeobotanical record of early Palaeolithic sites from Western Europe indicates that hominins settled in different kinds of environments. We use cookies to help provide and enhance our service and tailor content and ads. Drift would have accelerated during periods of low population numbers, while selection operates best when populations are large and expanding. The origin of Homo sapiens remains a matter of debate. Some of the reconstructed lake levels (e.g., for Lake Malawi) do not closely follow the dust curves, suggesting yet another layer of complexity in the climatic record. In a review of 75 distinctive cranial, dental, and postcranial features of early modern humans and Neanderthals, Trinkaus) concluded that only one quarter were unique to Neanderthals while twice that many were unique to modern humans, a finding that means that Neanderthal morphology had remained fairly primitive while early moderns were much more derived. middle pleistocene hominins Canine enamel and dentine measures might allow sex estimation to a high accuracy Human Evolution. If this was the case, much of the genetic and morphological change may have been concentrated in bursts of drift that corresponded to major contractions in Neanderthal numbers during OIS 8, 6, and 4. The time is ripe for a reconsideration of scenarios for adaptive change because of the accumulation of a critical mass of new evidence from paleoecology, genetics, anatomy, and chronology. Trinkaus argued that many distinctive facial features of Neanderthals and their relatively large canines and incisors were adaptations for increased amounts of anterior biting. In contrast, periods of warmer but not yet heavily forested conditions would have supported a higher biomass of large herbivores and the humans who preyed on them (Roebroeks, Conard, and Van Kolfschoten), thus producing an increase in hominin population numbers and a decelerated rate of drift. Any test of these hypotheses faces practical limitations, including an incomplete fossil record, poor dating of some fossils, and inadequate resolution of current methods in pinpointing morphological or genetic changes to exact spots in the 100,000-year glacial and faster insolation cycles. The paleoclimate of Africa presents a more complicated picture but one that is ultimately related to orbital dynamics because of changes in air circulation and rainfall that arose as consequences of the amount of solar radiation (insolation) that reached the earth (Siddall et al; Trauth, Larrasoaña, and Mudelsee). Reviewing previous estimates of Neanderthal population numbers, Dennell, Martinón-Torres, and Bermúdez de Castro proposed the Neanderthal population of Europe totaled 3,000-5,000 during interstadials and 1,500-2,500 during the depths of glacial advances, when Neanderthal populations were confined to refugia in Iberia, Italy, and the Balkans. Neanderthal mtDNA sequences provide support for a late bottleneck in their population. Request full-text PDF. If selection was the crucial factor driving change in the lineages of Neanderthals or modern humans, then major changes in anatomy in each lineage should emerge during periods that favor large population numbers. The life-history pattern and brain ontogeny of extant humans emerged only recently in the course of human evolution. Weaver’s model, however, assumes a constant effective population. Here, both Periods of low dust flux indicate more precipitation, more vegetation, more animal biomass, and more people. The climate in Europe in the Middle-Upper Pleistocene was dominated by a high-amplitude 100,000-year cycle that appears to have been determined by the eccentricity cycle in the earth’s orbit around the sun (deMenocal). Excavations at the Middle Pleistocene Stone Age site. These patterns help to illuminate a particularly irksome issue in research on the origin of modern humans: the question of why modern humans only expanded out of Africa at 50-60 ka if “anatomically modern” morphology arose between 200 and 150 ka (e.g., Klein). Pleistocene Homo can thus be characterized by patterns in widespread dispersal, followed by gradual fragmentation into geographically distinct subpopulations. A short summary of this paper. OIS 6 has been likened to the hyperarid conditions of the Last Glacial Maximum in OIS 2 (Deacon and Lancaster), which featured greatly decreased archaeological visibility of human populations in much of Africa (Brooks and Robertshaw). Describe the differences between middle Pleistocene hominins and Neandertals. Search. Views of the origin of modern humans and our divergence from Neanderthals have been profoundly and perhaps decisively influenced by genetic data from living humans as well as ancient DNA (aDNA) from Neanderthals. Copyright © 2013 Elsevier Ltd. All rights reserved. This suite of Neanderthal features had become common in European hominins by OIS 5, including the specimens from Krapina and Saccopatore, and they became even more frequent in OIS 4-3. In addition, cores and seismology of several of the oldest East African great lakes, especially Lakes Malawi and Tanganyika, have shown that substantial portions of tropical Africa south of the equator experienced severe droughts over the last 200 kyr that would not have been inferred from the oxygen isotope curve (Burnett et al; Cohen et al; Scholz et al), although the effects of these droughts appear to have been mitigated or absent at the equator and cannot be generalized to the whole of Africa (Blome et al). Coon, for example, argued that the enormous nose of Neanderthals had evolved to warm glacial air. Evidence presented here supports arguments for speciation in the Middle Pleistocene. The picture that emerges is one of human population history that was highly (although almost certainly not exclusively) contingent on climatic changes. The biogeographic range reconstructions suggest the presence of a geographically widespread, mid-Pleistocene ancestor to humans, Neanderthals, H. heidelbergensis and H. rhodesiensis. Likewise, by applying a population genetics model to expectations for (neutral) change in cranial dimensions, Weaver showed that crania that had dimensions that differed by one standard deviation from modern crania could be expected by around 165 ka, which corresponds reasonably well to when most researchers agree that modern (or nearly modern) humans appear in the East African fossil record. On the other hand, if drift was the key force in driving the divergence of Neanderthals and early modern humans, then key evolutionary events and appearance of new morphologies should appear during or immediately after periods of low population numbers. In this basin the persistence of high edaphic humidity, even during the glacial phases, could have favoured the establishment of a refuge area for the arboreal flora and provided subsistence resources for the animal and hominin communities during the Middle Pleistocene. 2012; Kappelman 1996). Mellars and French have argued that Neanderthals in southwestern France had population numbers during the Würm Glaciation (OIS 4-3) that totaled approximately one-tenth (actually 1/9) as many individuals as the later Aurignacian occupation, although many of the assumptions that led to this conclusion have been challenged (Dogandηić and McPherron) and defended (Mellars and French). For the sake of argument, I assume in this paper that the record of dust flux from the Arabian Sea is the most relevant to the origin of modern humans, but this issue is certainly open to debate. Here we use a phylogenetic modelling method to predict possible morphologies of a last common ancestor of all modern humans, which we compare to LMP African … However, the available archaeological evidence Their results for East Africa are perhaps the most useful for inferences regarding the origin and dispersal of modern humans. Comparison of the time lines of paleoclimate, the fossil record, and genetic divergences and bottlenecks provide a rough check of whether key events occur in periods favorable for large population numbers or in periods unfavorable for large populations. Changes in population size have predictable consequences for the expected rate of neutral genetic change. As a result, population size emerges as a key variable in both selection and drift. Emphasized its potential importance ( e.g., Hublin ) variable in both continents useful for regarding. Pleistocene hominins Canine enamel and dentine measures might allow sex estimation to great! 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