Monday, May 29, 2017

Aegean Pleistocene Landscapes Above and Below Sea-Level: Palaeogeographic Reconstruction and Hominin Dispersals

Dimitris Sakellariou and Nena Galanidou
Chapter 22 in:
Volume 20 of the series Coastal Research Library 
pp. 335-359

Abstract

The Aegean Region has remained marginal to research into human origins despite its key position in the multiple movements of animals between Europe and Asia. A possible explanation for this is that the Palaeolithic remains are invisible because they lie beneath the sea, whilst research in the field was hitherto developed on the mainland. In this chapter we make the submerged land, the coastal zones and the islands a unified research focus to examine the main, long-term and short-term geological and geotectonic processes which have controlled the development of Pleistocene landscapes in the Aegean Region above and below the fluctuating sea-level. We integrate evidence on the geology, tectonics, morphology and hydrogeology of the shallow coastal and shelf areas in order to reconstruct the palaeogeography. Given the variable tectonic evolution and geomorphological configuration of the coastal and shelf areas, we divide the Aegean into nine geographical units. Each unit has its own geotectonic and morphological history and offers a frame of reference to assess land-routes and the natural resources available to hominins at different times of the Pleistocene. We link this palaeogeographic reconstruction to the discussion of the early occupation of Europe. This allows the NE Mediterranean to become part of the discussion about hominin dispersals into Europe through a south-eastern route and gives a more complete view of the variations in Palaeolithic settlement.


Thursday, May 25, 2017

Pre-Sapiens Man in Greece

View from above Petralona Cave, looking south toward the Aegean Sea 














Aris N. Poulianos
Current Anthropology
Volume 22, Number 3, June 1981
(Link)

Until only 15 years ago, the Palaeolithic was almost unknown in Greece.  Some important Middle and Upper Palaeolithic sites and materials were discovered in Epirus and Thessaly in the 1960s, but apart from a few handaxes Greece remained terra incognita for the Lower Palaeolithic and the pre-sapiens stages of human development.  In recent years, however, discoveries by members of the Anthropological Association of Greece have radically transformed the situation.

In 1959, at Petralona, a village in Khalkidiki province, south of Thessaloniki, some local men searching for a spring in the mountainside happened upon a hole through which they were able to enter a huge cave full of stalagmites and stalactites.  The following year a primitive human skull was found adhering to a rock in the cave and was removed.  An early examination of this skull and of animal bones from the cave floor led to an estimated age of ca. 70,000 years; a search for the rest of the skeleton involved breaking up of the stalagmite layer and led to the destruction of the human bones.  My systematic excavations in the cave since 1968 have established a detailed stratigraphy, salvaged some human fragments, and proved conclusively that the skeleton and the cave's occupation belong to the Lower and Middle Pleistocene.  No fewer than 27 layers, with thicknesses ranging from 2 cm to 2 m and a total depth of over 15m, have so far been differentiated in the cave's fill.  The original entrance is blocked by a huge cone of sediment.  The layers decrease in thickness as one moves from this entrance to the interior of the cave.  Almost all the layers show traces of human occupation.

The Petralona hominid, known as Archanthropus europaeus petraloniensis, was located in a sort of compartment formed by a large fallen rock which had become wedged against the cave wall, thus constituting a 2 meter squared natural "mausoleum."  The body was in a crouched position with the head slightly elevated and resting on a rock;  it was surrounded by bone awls, burnt animal bones, and stone implements.  All of these finds are from Layer 11, which is the thickest and contains the most tools and other traces of habitation.  It is not surprising that the use of the cave at this time was intensive, since the sediments and fauna indicate a cold, humid climate.  Subsequently it became more humid, and a stalagmitic breccia (Layer 10) covered the floor and walls of the "mausoleum" and made a bridge between the skull and the rock.  During a later, drier phase, the sediments shrank and dropped to 24 cm, but the skull remained suspended, fixed by the stalagmite and thus separated from the rest of the skeleton.

Fauna, sediments, and stratigraphy all point to a late stage of the Lower Pleistocene for Layer 11.  The new dating technique of electron spin resonance gave a figure of 670,000 years, probably the Günz-Mindel interglacial, for Layer 10 and dated the stalagmite of Layer 1 to between 250,000 and 350,000 years.  Before the formation of this top stalagmite, probably by the end of the Mindel glacial, the cave had been abandoned and had closed up.  The uranium/thorium method dated the stalagmite of Layer 10 to a minimum of 400,000 B.P. (the upper limit of this method) and suggested a true age of ca. 600,000.  Palaeomagnetic studies of the sediments have shown an inversion of the earth's magnetic field in layers below 11, but such studies are fraught with problems.  In short, the cave's stratigraphy spans at least half a million years, corresponding to the late Lower and early Middle Pleistocene, Archanthropus having died more than 700,000 years ago, is the most ancient European yet known.

The fragments of post cranial skeleton salvaged from the "mausoleum" suggest that this hominid was a short (about 157 cm), muscular, mature individual.  Thought it is classified as Homo erectus, many features of the skull and skeleton fall within the modern human range.  Fragments of up to 15 other individuals have so far been found in different parts of the cave.

The first ten layers contain bone tools, pebble tools, and handaxes;  this stone industry has been dubbed Petralonian.  A cruder industry, the Crenian, is found in Layer 11 and below.  The type of tool technology used here was not known in Europe until these finds; . . .

(read more)

Bone tools from Broken Hill (Kabwe) cave, Zambia, and their evolutionary significance

LS Barham, AC Pinto Llona, CB Stringer
Before Farming
Volume 2002, Issue 2
2002
(Link)

Abstract
Shaped bone tools are now recognised as part of the technological repertoire of some Middle Stone Age hunter-gatherers in southern Africa. Currently accepted dates for the earliest bone working technology in the region range from ~70-90 ka. This study re-examines three bone objects from the site of Broken Hill (Kabwe), Zambia, that were described in the 1940s as formal bone tools. Broken Hill is well known for its fossils of Homo heidelbergensis, a species not previously associated with bone working, and less well known for its small sample of early Middle Stone Age lithic artefacts. The claim for bone tools at Broken Hill takes on added significance in light of new dates from south-central Africa which place the development of stone tool technology (Mode 3) in the later Middle Pleistocene (~300 ka). If these bone objects are indeed tools and associated with the hominid use of the cave, they may be the oldest evidence of bone tool working in the archaeological record. The results are reported of scanning electron microscopy of the surfaces of each putative tool and implications are drawn for the behavioural evolution of H heidelbergensis.

Tuesday, May 23, 2017

Middle Pleistocene Homo Crania from Broken Hill and Petralona: Morphology, Metric Comparisons, and Evolutionary Relationships

G. Philip Rightmire
Human Paleontology and Prehistory
Part of the series Vertebrate Paleobiology and Paleoanthropology pp 145-159
25 January 2017
(Link)

 
















Abstract

A fossilized human cranium was discovered by miners quarrying at Broken Hill (now Kabwe ) in 1921. Broken Hill is one of the best preserved hominins ever recovered from a later Middle Pleistocene locality. Remarkably, no comprehensive descriptive or comparative account has been published since 1928. Overall, Broken Hill resembles Homo erectus . The frontal is flattened with midline keeling, the vault is low, and the massive face is “hafted” to the braincase in such a way as to accentuate facial projection. At the same time, there are apomorphic features shared with later humans. Brain size is 1280 cm3, the temporal squama is arch-shaped, and the upper scale of the occipital is expanded relative to its lower nuchal portion. Specialized characters of the temporomandibular joint region include a raised articular tubercle and a sphenoid spine. Reorientation of the nasal aperture and placement of the incisive canal suggest that the face may be more nearly vertical than in H. erectus. It is apparent that Broken Hill is similar to other African crania from Bodo, Ndutu, and Elandsfontein as well as European fossils including Arago and Petralona. However, the systematic position of these hominins remains controversial. The material has been grouped into a series of grades within a broad H. sapiens category. A very different reading of the record recognizes multiple, distinct taxa and suggests that speciation must have occurred repeatedly throughout the Pleistocene. Still another perspective holds that differences among the African and European specimens are minor and can be attributed to geography and intragroup variation. It is argued that many of the fossils belong together in one widely dispersed taxon. If the Mauer mandible is included within this hypodigm , then the appropriate name is H. heidelbergensis . Treated in a broad sense, H. heidelbergensis is ancestral to both H. neanderthalensis and H. sapiens . This study will provide a detailed account of the morphology of Broken Hill and its similarities to other Middle Pleistocene hominins from Africa. Comparisons will include Arago, Petralona, and assemblages such as Sima de los Huesos. My approach will address the taxonomic utility of characters of the vault, cranial base and face, species-level systematics, and evolutionary relationships.

from the chapter:

Introduction

The cranium from Broken Hill (now Kabwe) remains one of the treasures of prehistory. It was found in 1921, when miners quarrying for lead ore broke into the lower part of an extensive cavern containing quantities of mineralized bones and stone artifacts. Accounts of the circumstances surrounding this discovery are contradictory (Hrdlička 1930). Several additional human fossils, along with animal bones, were collected from the cave fill, but claims for the association of any of these elements with the original cranium remain incompletely documented. Comparative studies of the fauna have demonstrated similarities with the large assemblage from Elandsfontein in South Africa, indicating an early Middle Pleistocene age (Klein 1994; Klein et al. 2006). However, more recent efforts to date individual bones directly using Electron Spin Resonance (ESR) suggest that the Broken Hill material may be of late Middle Pleistocene antiquity (Stringer 2011).

The cranium was described initially by Woodward (1921), who saw resemblances to the Neanderthals then known from Europe but attributed the find to a new species (‘Homo rhodesiensis’). More comprehensive studies were published several years later by Pycraft (1928) and Mourant(1928). While pointing to differences in certain features, Mourant (1928) again argued for a close relationship between Broken Hill and Late Pleistocene Neanderthals. It is now recognized that this comparison was inappropriate.  Broken Hill lacks the specialized characters of Neanderthals but resembles other crania from Elandsfontein in South Africa and Bodo from the Middle Awash of Ethiopia. As a group, these African fossils are broadly similar to hominins from Middle Pleistocene localities in Europe including the Sima de los Huesos in Spain, Arago Cave in France, and Petralona in Greece.

Interpreting this record has been problematic. The number of taxa represented is disputed, and phylogenetic relationships remain to be clarified. In one view, African and European mid-Pleistocene populations can be grouped with later humans within a broad Homo sapiens category. Archaic and modern grades are defined by advances in brain size and skull form. Although changes to the vault and face accumulate in a mosaic pattern, early and late groups are said to follow one another seamlessly, as segments of a single evolving lineage (Bräuer 2007, 2008). A very different reading of the record recognizes multiple, distinct taxa as evidence for speciation occurring repeatedly throughout the Pleistocene (Tattersall and Schwartz 2008; Schwartz and Tattersall 2010). At least two lineages are identified, in addition to Homo erectus and recent humans. A European branch can be traced back via Petralona, Arago, and Sima de los Huesos, deeply into the Middle Pleistocene. Proponents of this view (Arsuaga et al. 1989, 1997; see also Hublin 2009) claim that even the oldest European hominins share apomorphies with Homo neanderthalensis and can reasonably be attributed to this species. A variation on this phylogenetic scheme has been proposed by Martinón-Torres et al. (2012), who find that the Sima de los Huesos teeth are “more Neanderthal” in form than the Mauer or Arago dentitions.

Given this result, Martinón-Torres et al. (2012) suggest that along with an ancient lineage linking the Sima hominins directly with Neanderthals, a second population including Mauer and Arago was present in Europe. This second species must be called Homo heidelbergensis.

A key question is how these European lineages are related to the hominins in Africa. If all of the European fossils are subsumed within Homo neanderthalensis, then the species represented by Broken Hill, Elandsfontein, and Bodo can be called Homo rhodesiensis, following the nomenclature proposed by Woodward (1921). Some (chronologically late) members of this group exhibit morphology that is archaic, coupled with characters suggestive of a link to anatomically modern humans. Still another perspective holds that morphological differences among the most ancient European and African specimens are minor and can be attributed to geography and intragroup variation (Stringer 1983, 1993; Rightmire 1990, 1996, 1998, 2008; Mounier et al. 2009). It can be argued that many of the fossils belong together in one geographically dispersed taxon. If the Mauer mandible is included within the hypodigm, then the appropriate name for this species is Homo heidelbergensis. Treated in this broad sense, Homo heidelbergensis must be ancestral to both Homo neanderthalensis and Homo sapiens.

While many of the Middle Pleistocene fossils are incomplete, Broken Hill is clearly one of the most informative specimens. Another is the cranium from Petralona. It is possible to document the extent to which these African and European fossils differ in their craniofacial morphology.

Over the course of nearly a century, Broken Hill has been treated in numerous comparisons involving modern humans, Neanderthals, and earlier Homo. Following Mourant (1928), many of these studies have been based on measurements or, more recently, cranial landmarks used in morphometric analysis (Friess 2010; Harvati et al. 2010, 2011). Another approach has emphasized anatomical description, with attention to the relevance of individual characters. Since it was discovered in 1959, the Petralona cranium has also been studied in detail (Stringer et al. 1979, 1983). This research has produced many useful data, but there is (still) no firm consensus as to the evolutionary significance of either specimen. In this review, I introduce further evidence from measurements and comparative anatomy. My goal is to clarify the relationship of Broken Hill to Petralona, with the goal of testing the null hypothesis that these individuals can be grouped together in one taxon.

Body of chapter omitted here.

Discussion and Conclusion of the paper below:

Discussion

Hominin fossils are known from numerous Middle Pleistocene localities. It is recognized that these individuals display traits that are derived in comparison to Homo erectus. At the same time, the skulls retain numerous primitive features that set them apart from modern humans. How these diverse mid-Pleistocene assemblages should be classified, and how they fit into the “tree” of human evolution, are important questions. The crania from Broken Hill and Petralona are key specimens, from which inferences concerning the morphology of larger African and European regional populations can be drawn. Of course, all biological populations display variation, and the extent of this variation cannot be gauged adequately from small samples. Particularly for Africa, few complete skulls are available. Nevertheless, the detailed anatomical and metric comparisons conducted here provide information that is useful in evaluating the null hypothesis that Broken Hill and Petralona represent paleodemes of one species.

The two crania are similar in many aspects of form. Both are long with relatively low vertices, and both display massive and projecting supraorbital tori, flattened frontals heavily invaded by complex air sinuses, postorbital narrowing, and occipitals that are flexed relative to those of modern humans. Petralona differs from Broken Hill in having a wider cranial base, a reduced vol/aub ratio, massive supramastoid crests, and a less prominent torus crossing the occipital bone. The well preserved Broken Hill basicranium presents derived (sapiens-like) features including an increased petrotympanic angle associated with (coronal) alignment of the petrous and tympanic axes, “erosion” of the pyramid apex leading to enlargement of the foramen lacerum, a projecting sphenoid spine, and clear definition of an articular tubercle at the anterior margin of the mandibular fossa (Rightmire 1990, 2001, 2008). Insofar as the (damaged and partly obscured) cranial base of Petralona can be evaluated, its morphology resembles that of Broken Hill.

In forward placement of the facial skeleton relative to the anterior cranial fossa, Broken Hill and Petralona are comparable to Homo erectus. At the same time, the lateral margin of the nose is vertical, rather than forward sloping as in Homo erectus. The lower terminus of this border is set back below the overhanging nasal saddle. This reorientation suggests that the facial profile is less prognathic than in Homo erectus. In facial forwardness at subspinale, Broken Hill and Petralona are similar, and the angle at subspinale is reduced in relation to that of the flat-faced Bodo cranium. Both Broken Hill and Petralona possess prominent anterior nasal spines, coupled with spinal crests separating the sill from the subnasal portion of the maxilla.

Elsewhere in the facial skeleton, there is more variation. The Petralona face is broader at the zygomatic arches and exhibits a more robust cheek region than does Broken Hill. The orbital cavities are low and relatively broad. The walls of the maxillae appear to be inflated. Infraorbital foramina are not associated with any grooves or furrows. Neither here nor elsewhere in the cheek region is there much indication of hollowing. Petralona thus stands in some contrast to Broken Hill, where there are localized depressions of the infraorbital surface, even if no canine fossa is developed. These observations have been taken to indicate that not only Petralona but also Arago and other European mid-Pleistocene hominins anticipate the distinctive midfacial morphology of later Neanderthals (Hublin 1998, 2009). As described by Arsuaga et al. (1997), the cheek region of SH 5 is not inflated in the extreme manner of Neanderthals, but it can be interpreted as intermediate in form. How such facial features are evaluated (whether any of them can be judged to be true Neanderthal apomorphies) is critical to determining how the Petralona, Arago, and Sima de los Huesos individuals are related to populations outside of Europe and how the fossils should be treated in phylogenetic schemes.

Information relevant to these questions is advanced by Harvati et al. (2010), who have carried out a geometric morphometric study designed to quantify craniofacial shape in Middle Pleistocene hominins, Neanderthals, and modern humans. This analysis is based (in part) on landmarks situated on the supraorbital torus, the orbits and nasal aperture, the zygomatic bone, and the maxilla. After superimposition with generalized Procrustes analysis (GPA), mean configurations of the groups are assessed visually. When viewed in the transverse plane, configurations confirm that “classic” Neanderthals have “a more convex maxilla” and a more receding infraorbital profile than do recent populations. Importantly, Petralona, Arago, and SH 5 are essentially indistinguishable from Broken Hill and Bodo. Both European and African groups are said to approach (but not match) the Neanderthal condition. Midfacial prognathism is explored by comparing orientation of midsagittal landmarks in relation to lateral portions of the face. The Middle Pleistocene crania appear to have “less anteriorly placed” faces than Neanderthals and to be “nearly identical” to one another in (mean) shape. These findings suggest that there is little basis for claiming that the European mid-Pleistocene hominins are more similar to Neanderthals than their African counterparts. Consequently, Harvati et al. (2010) hypothesize that some facial attributes of Petralona and Arago commonly regarded as “incipient” Neanderthal features may instead be plesiomorphic states.

 A different interpretation invokes the effects of scaling. Size has long been recognized as contributing to variation in craniofacial shape (Lahr and Wright 1996). Maddux and Franciscus (2009) have used a geometric morphometric approach to explore the influence of allometry on the infraorbital region in Middle Pleistocene, Late Pleistocene, and recent populations of Homo. The authors project a grid onto each specimen, fitting it to the boundaries of the infraorbital plate. Landmarks are digitized as the intersections of grid lines and are intended to capture the topography of the underlying curvilinear surface. GPA serves to superimpose the landmarks of all specimens, aligning them to the mean configuration and allowing quantification of size and shape. Principal components analysis suggests that Neanderthals share with European and African mid-Pleistocene crania (and some Upper Paleolithic anatomically modern individuals) a relatively flat infraorbital surface topography.  Most recent human skulls exhibit relatively depressed infraorbital plates. It can be established that the degree of infraorbital depression is clearly correlated with cheek size. There is thus “a growing body of evidence” that changes in facial shape are, at least in part, secondary allometric consequences of reduction in overall size during the evolution of Homo. Maddux and Franciscus (2009) caution against treating features such as an inflated maxilla or a canine fossa as discrete phylogenetic traits. A “puffy” maxilla may not be a Neanderthal apomorphy, and the “canine fossa” of later humans may be a result of decreasing facial size.

Conclusions

If the Broken Hill and Petralona midfacial contours are indeed nearly coincident, and if differences in orbit shape, nasal aperture size, and palatal proportions are taken as indications of the variation to be expected within (all) hominoid populations, then there is little basis in facial form for distinguishing these mid-Pleistocene individuals.

Both the African and the European crania seem to approach Neanderthals in flatness of the infraorbital profile and shape of the maxilla, but neither conforms fully to the Neanderthal condition. Harvati et al. (2010) are inclined to view the Middle Pleistocene morphology as plesiomorphic. But size and scaling must also be considered. It is probable that Broken Hill and Petralona share with Neanderthals (and some Upper Paleolithic humans) a relatively flat infraorbital topography because they have larger faces than recent Homo sapiens (Maddux and Franciscus 2009).

These findings can be read to show that Petralona does not evince true Neanderthal apomorphies in the midface.

Neither Petralona nor Arago can be linked more closely to later European populations than can the African mid-Pleistocene hominins. At the same time, Petralona and Broken Hill share many aspects of facial form, vault proportions, and discrete anatomy. The same conclusion can be drawn from studies of the skull base. It follows that the initial null hypothesis cannot be rejected. The fossils represent paleodemes of a single evolutionary lineage widely dispersed across Africa and Europe. Just how this lineage is related to the Neanderthals, and when the latter emerged as a distinct species, are key questions that remain unresolved.  But it is likely that European and African populations of Homo heidelbergensis did not separate until relatively late in the Middle Pleistocene.

Saturday, May 20, 2017

Questions for "Recent Out of Africa" Modelers

Marnie Dunsmore
5/20/2017

The most common variant of the Out of Africa Model is this:  Homo sapiens emerge in Africa approximately 200,000 years ago (based on the  Omo remains found in modern-day Ethiopia, which date to 195,000 years ago) and emerge from Africa approximately 100,000 years ago (1).

Under this model, Homo sapiens would be required to stay in Africa for 100,000 years, from 200,000 to 100,000 years ago, and then emerge from Africa 100,000 years ago and reach Arctic Siberia by 45,000 years ago (2).

This would require that for 100,000 years, advanced Homo would expand their range northward no more than 25 meters per year, and then would suddenly expand to Siberia between 100,000 and 45,000 years ago.  This is at a time when the Sahara was at times a grassland and not the desert that it has been for the last eight thousand years and most of the last 70,000 years.  Needless to say, this problematic scenario of complete stasis in the range of early Homo sapiens is almost never discussed by proponents of the Recent Out of Africa Model.

Even more curious is the sudden mobility of Homo sapiens 100,000 years ago.  Suddenly, from 100,000 years ago, to 45,000 years ago, Homo sapiens, under this model, expands at a rate of 250 meters per year, ten times their former dispersal rate, and reaches, as well as adapts to, Arctic Siberia 45,000 years ago.

Some argue that the reason for this is that prior to approximately 100,000 years ago, Eurasia was occupied by other hominins and therefore, that the possibility of range expansion for Homo sapiens was blocked.  It is possible that this is true, but many other scenarios, almost never explored or even considered, are plausible.

Neandertals Revised


"The modern human phenotype evolved in the Middle Pleistocene in Africa and from there expanded its range into Eurasia, reaching the Levant by around 100 ka and possibly surfacing in southern China already at 80 ka."

How China is rewriting the book on human origins

Jane Qiu
Nature News Feature
July 12, 2016
(Link)

From the article:

“Many Western scientists tend to see Asian fossils and artifacts through the prism of what was happening in Africa and Europe,” says Wu. Those other continents have historically drawn more attention in studies of human evolution because of the antiquity of fossil finds there, and because they are closer to major palaeoanthropology research institutions, he says. “But it's increasingly clear that many Asian materials cannot fit into the traditional narrative of human evolution.”

In its typical form, the story of Homo sapiens starts in Africa. The exact details vary from one telling to another, but the key characters and events generally remain the same. And the title is always 'Out of Africa'.

In this standard view of human evolution, H. erectus first evolved there more than 2 million years ago (see 'Two routes for human evolution'). Then, some time before 600,000 years ago, it gave rise to a new species: Homo heidelbergensis, the oldest remains of which have been found in Ethiopia. About 400,000 years ago, some members of H. heidelbergensis left Africa and split into two branches: one ventured into the Middle East and Europe, where it evolved into Neanderthals; the other went east, where members became Denisovans — a group first discovered in Siberia in 2010. The remaining population of H. heidelbergensis in Africa eventually evolved into our own species, H. sapiens, about 200,000 years ago. Then these early humans expanded their range to Eurasia 60,000 years ago, where they replaced local hominins with a minuscule amount of interbreeding.

A hallmark of H. heidelbergensis — the potential common ancestor of Neanderthals, Denisovans and modern humans — is that individuals have a mixture of primitive and modern features. Like more archaic lineages, H. heidelbergensis has a massive brow ridge and no chin. But it also resembles H. sapiens, with its smaller teeth and bigger braincase. Most researchers have viewed H. heidelbergensis — or something similar — as a transitional form between H. erectus and H. sapiens.

Unfortunately, fossil evidence from this period, the dawn of the human race, is scarce and often ambiguous. It is the least understood episode in human evolution, says Russell Ciochon, a palaeoanthropologist at the University of Iowa in Iowa City. “But it's central to our understanding of humanity's ultimate origin.”

The tale is further muddled by Chinese fossils analysed over the past four decades, which cast doubt over the linear progression from African H. erectus to modern humans. They show that, between roughly 900,000 and 125,000 years ago, east Asia was teeming with hominins endowed with features that would place them somewhere between H. erectus and H. sapiens, says Wu (see ‘Ancient human sites’).

“Those fossils are a big mystery,” says Ciochon. “They clearly represent more advanced species than H. erectus, but nobody knows what they are because they don't seem to fit into any categories we know.”

Thursday, May 18, 2017

Revising the archaeological record of the Upper Pleistocene Arctic Siberia: Human dispersal and adaptations in MIS 3 and 2

Vladimir Pitulko, Elena Pavlova, Pavel Nikolskiy
Quaternary Science Reviews
Volume 165, 1 June 2017, Pages 127–148
(Link)

Abstract

As the main external driver, environmental changes largely predetermine human population distribution, especially in the Arctic, where environmental conditions were often too extreme for human survival. Not that long ago the only evidence of human presence here was the Berelekh site in the lower reaches of the Indighirka River. This landmark dates to 13,000–12,000 years ago but it was widely accepted as documentation of the earliest stage of human dispersal in the Arctic. New research discussed here, shows that humans began colonizing the Siberian Arctic at least by the end of the early stage of MIS 3 at around 45,000 years ago. For now, this earliest known stage of human occupation in the arctic regions is documented by the evidence of human hunting. The archaeological record of continued human occupation is fragmentary; nevertheless, evidence exists for each significant phase including the Last Glacial Maximum (LGM). Siberian Arctic human populations were likely supported by the local mammoth population, which provided humans with food and raw material in the form of mammoth tusks. Processing of mammoth ivory is recognized widely as one of the most important peculiarities of the material culture of ancient humans. In fact, ivory tool manufacturing is one of the most important innovations of the Upper Palaeolithic in northern Eurasia. Technology that allowed manufacturing of long ivory shafts – long points and full-size spears – was critical in the tree-less open landscapes of Eurasian mammoth steppe belt. These technological skills reach their greatest extent and development shortly before the Last Glacial Maximum but are recognizable until the Pleistocene-Holocene boundary across Northern Eurasia in all areas populated by mammoths and humans. Loss of this stable source of raw material due to the late Pleistocene mammoth extinction may have provoked a shift in post-LGM Siberia to the Beringian microblade tradition. This paper reviews the most important archaeological findings made in arctic Siberia over the last twenty years.

The first archaic Homo from Taiwan

Tuesday, May 16, 2017

Early Pleistocene occurrence of Acheulian technology in North China

Figure 2. Characteristic in situ artefacts from the Shuigou-Huixinggou site in the Sanmenxia Basin. Artefacts include: (A) handaxe (P. 2768); (B) cleaver (P. 2769); (C) cleaver (P. 2752); (D) pick (P. 2770); (E) unifacial chopper (P. 2758); (F) bifacial chopper (P. 2763); and (G) spheroid (P. 2774). The line drawings of artefacts are after Huang (1964). (Scale bars: 5 cm).



















  
Early Pleistocene occurrence of Acheulian technology in North China
Xingwen Li, Hong Ao, Mark J. Dekkers, Andrew P. Roberts, Peng Zhang, Shan Lin, Weiwen Huang, Yamai Hou, Weihua Zhang, Zhisheng An
Quaternary Science Reviews 156 (2017) pp. 12-22
(Link)

From the paper:

1. Introduction
 
Acheulian technology is characterized by bifacially and unifacially shaped tool types, such as handaxes, cleavers, picks and other large cutting tools (LCTs) (Isaac, 1969; Bar-Yosef and Goren-Inbar, 1993; Goren-Inbar et al., 2000; Semaw et al., 2009; Lepre et al., 2011; Beyene et al., 2013 ;  Diez-Martín et al., 2015). Its appearance represents a technological advance over the preceding Oldowan technology, and is associated with innovative hominin cognitive and adaptive abilities (Goren-Inbar, 2011 ;  Stout, 2011). Current thinking is that Acheulian technology originated in East Africa (possibly West Turkana, Kenya) at least 1.76 million years ago (Ma) (Lepre et al., 2011), that it became distributed somewhat widely across Africa (e.g., Vaal River Valley and Gona) at ∼1.6 Ma (Gibbon et al., 2009 ;  Semaw et al., 2009), and then spread to the Levant at ∼1.4 Ma (Bar-Yosef and Goren-Inbar, 1993), South Asia at 1.5–1.1 Ma (Pappu et al., 2011), and Europe at 1.0–0.9 Ma (Scott and Gibert, 2009 ;  Vallverdú et al., 2014) (Fig. 1). The 0.8–0.9 Ma Acheulian stone stools from South and central China (Hou et al., 2000 ;  de Lumley and Li, 2008) (Fig. 1) suggest that Acheulian technology arose in China at least during the terminal Early Pleistocene. However, there are only a few sites with in situ Acheulian artefacts from North China with ages ranging from the late Mid-Pleistocene to the Late Pleistocene ( Wang et al., 2014 ;  Yang et al., 2014) (Fig. 1). Thus, it remains enigmatic as to how early Acheulian technology can be traced back in North China, compared with its Early Pleistocene occurrence in South and central China.

Sanmenxia Basin (also Sanmen area), which lies on the southeastern Loess Plateau, is a rich source of stone artefacts and is an important area for understanding the early human occupation of North China (Jia et al., 1961; Huang, 1964; Jia, 1985 ;  Li, 1990). The first Early Pleistocene Paleolithic site in China, that is the Xihoudu site dated at 1.4–1.27 Ma (Zhu et al., 2003 ;  Kong et al., 2013), was found in northwestern Sanmenxia Basin (Fig. 1) in 1961–1962 (Jia, 1985). In 1963, 128 stone artefacts were found from 6 localities in eastern Sanmenxia Basin (Huang, 1964). Among the 128 artefacts, 94 were from the Shuigou and Huixinggou sites (Huang, 1964). At that time the chronology of the Chinese loess-paleosol sequence was not yet established; a tentative Mid-Pleistocene age was suggested for the lithic assemblage based on lithostratigraphic arguments (Huang, 1964). Furthermore, when these artefacts were discovered, consensus was that Acheulian handaxes and cleavers were lacking in East Asia during the period when they flourished in Africa and western Eurasia (Movius, 1948). Therefore, the handaxe and cleavers from the Shuigou and Huixinggou sites (Fig. 2) were not recognized and reported as Acheulian artefacts; instead, they were considered to represent different kinds of choppers that are indicative of a chopper-chopping tool industry (Huang, 1964; Huang, 1987; Huang, 1993 ;  Lin, 1992).

In the present study, we reassess the previously excavated lithic assemblage from the Shuigou and Huixinggou sites. We establish a numerical age for the lithic assemblage using magneto-cyclostratigraphy. We provide definitive evidence of an Early Pleistocene date for Acheulian stone tools in North China, which offers an important new window into the distribution of Acheulian technology out of Africa during the late Early Pleistocene.

[See the original paper for sections 2, 3, and 4.]

5.2. Implications for the distribution of Acheulian technology outside of Africa
 
Current consensus in defining a lithic assemblage to represent typical Acheulian technology depends on the following characteristic attributes: the ability to produce large flake blanks and to recurrently shape these blanks into LCTs that are typologically qualified as Acheulian tool types (i.e., handaxes, cleavers, and picks) (Isaac, 1969; Semaw et al., 2009; Stout, 2011; Beyene et al., 2013; Diez-Martín et al., 2015 ;  Dennell, 2016). Accordingly, the technological traits (i.e., production of large flakes) and typological traits (i.e., readily attribution of LCTs as handaxes, cleavers, and picks), which are documented in the lithic assemblage from the Shuigou-Huixinggou site, point unambiguously to Acheulian technology.

Our newly established age of ∼0.9 Ma for these artifacts provides evidence for the emergence of Acheulian technology in North China as early as the late Early Pleistocene. The tools are slightly older than the Bose Acheulian stone tools, which are considered the oldest in South China and are dated at ∼0.8 Ma with 40Ar/39Ar dating of in situ tektites ( Hou et al., 2000). Combined with 0.9–0.8 Ma ages for Acheulian stone stools from Yunxian in central China (de Lumley and Li, 2008) and from Sangiran in Indonesia (Simanjuntak et al., 2010), the Acheulian appears to have extended across a large area in East Asia since the terminal Early Pleistocene. Apparently, the hominins with this advanced technology, most likely Homo erectus, were adapted to diverse habitats that ranged from tropical rainforests in Indonesia to subtropical evergreen broad-leaved forests in South China, and now to temperate grasslands in North China during the late Early Pleistocene. This supports the proposition that the Movius Line ( Movius, 1948) over which no Acheulian artefacts were argued to occur in East Asia is no longer an appropriate concept for the Early Paleolithic of East and Southeast Asia and should be disregarded ( Hou et al., 2000; Wang, 2005; Li et al., 2014 ;  Dennell, 2016). Although the presence of late Early Pleistocene Acheulian technology has been established firmly in East Asia, there is no consensus concerning its origin (Li et al., 2014). Some researchers interpret it to have been introduced into China with population movements from the west ( Hou et al., 2000; Wang, 2005 ;  Huang et al., 2009), while another possibility is that these Early Pleistocene Acheulian artefacts were manufactured by the descendants of hominins that left Africa earlier (Lycett and Norton, 2010).

Widespread distribution of Acheulian technology in East Asia, as documented here, is roughly coeval with their first emergence in Europe (e.g., Estrecho del Quípar and Barranc de la Boella, Spain) at ∼1.0–0.9 Ma (Scott and Gibert, 2009 ;  Vallverdú et al., 2014). By comparison, Acheulian technology appeared in the eastern Mediterranean (e.g., ‘Ubeidiya) and South India (e.g., Attirampakkam) as early as ∼1.4 Ma (Bar-Yosef and Goren-Inbar, 1993) and 1.5–1.1 Ma (Pappu et al., 2011), respectively. Combined with ∼0.8–0.7 Ma Acheulian stone tools from Gesher Benot Ya'aqov (Israel) (Goren-Inbar et al., 2000), a widespread Early Pleistocene distribution of Acheulian technology outside of Africa is suggested, with expansion by ∼0.9 Ma across the southern, western, and eastern portions of Eurasia, including temperate North China (Fig. 1).

5.3. Implications for early human occupation of North China
 
During the late Early Pleistocene, global climate variability shifted from lower-amplitude ∼40 kyr oscillations to higher-amplitude ∼100 kyr oscillations (Clark et al., 2006). This climate transition lasted from ∼1.2 Ma to ∼0.7 Ma (Clark et al., 2006), but occurred in North China (including the Loess Plateau) at 0.9–0.7 Ma (Heslop et al., 2002 ;  Ao et al., 2012). Pollen data indicate mainly savanna grassland conditions on the Loess Plateau during the late Early Pleistocene (Wang et al., 2002 ;  Wu et al., 2004). The occurrence of Acheulian tools in Sanmenxia Basin against such a global climatic and regional environmental background points to the role of climate in shaping the behavior of early humans, which is consistent with the climatic variability selection hypothesis of hominin evolution (Potts, 1998).

The southern Loess Plateau in the middle reaches of the Yellow River north of the Qinling Mountains, including Sanmenxia Basin, was an important habitat for early humans in North China. Many hominin and Paleolithic sites have been found in this region, such as the hominin sites of Gongwangling (1.63 Ma) (Zhu et al., 2015), Chenjiawo (0.65 Ma) (An and Ho, 1989), Dali (0.27 Ma) (Xiao et al., 2002) and Dingcun (0.21–0.16 Ma) (Chen et al., 1984), as well as the Paleolithic sites from Xihoudu (1.4–1.27 Ma) (Zhu et al., 2003 ;  Kong et al., 2013), Luonan Basin (0.8–0.7, 0.4–0.3, and 0.2–0.1 Ma) (Lu et al., 2011b), Lushi Basin (0.62–0.6 Ma) (Lu et al., 2011a), Beiyao (0.2–0.01 Ma) (Du and Liu, 2014), and the Lantian area (0.6–0.03 Ma) (Wang et al., 2014). Combined with the abundant Paleolithic sites in Nihewan Basin, North China (Ao et al., 2013a), including the oldest sites of Majuangou (1.66 Ma) (Zhu et al., 2004) and Shangshazui (1.7–1.6 Ma) (Ao et al., 2013b), there appears to have been a flourishing population of early humans in North China since the Early Pleistocene.
 
6.  Conclusions
 
An integrated stratigraphic analysis, involving lithostratigraphy, magnetic susceptibility stratigraphy and magnetostratigraphy, indicates that the Huixinggou section records the upper Matuyama and Brunhes chrons. The Acheulian-bearing layer occurs in a reversed polarity magnetozone below the Matuyama–Brunhes boundary and is probably equivalent to MIS 23, which yields an estimated age of ∼0.9 Ma. This discovery indicates that the emergence of Acheulian technology in North China can be dated back to the Early Pleistocene. Along with archeological evidence from South China and Southeast Asia, the Acheulian now appears to have been widespread in East Asia since the terminal Early Pleistocene. The East Asian occurrences of Acheulian technology are contemporaneous with the first emergence of Acheulian tools in Europe and support a wide geographic distribution of Acheulian technology outside of Africa during the Early Pleistocene. Our results have important implications for understanding early human occupation on the Chinese Loess Plateau and provide guidance for future archeological investigations in this region.

Monday, May 15, 2017

The Lithic Assemblages of Xiaochangliang, Nihewan Basin: Implications for Early Pleistocene Hominin Behaviour in North China

Fig 10. XCL retouched pieces. 1–2: Borers with short retouched points; 3–5, 7–9, 11: Scrapers with continuous retouch along an edge; 6, 10, 12–13: Denticulates showing uneven edges with more than three retouch scars.






Shi-Yia Yang, Ya-Mei Hou, Jian-Ping Yue, Michael D. Petraglia, Cheng-Long Deng, Ri-Xiang Zhu
PLOS One
May 20, 2016
(Link) open access

Abstract

Xiaochangliang (XCL), located in the Nihewan Basin of North China, is a key archaeological locality for understanding the behavioural evolution of early humans. XCL dates to ca. 1.36 Ma, making it one of the earliest sites in Northeast Asia. Although XCL represents the first excavation of an Early Pleistocene site in the Nihewan Basin, identified and excavated in the 1970’s, the lithic assemblages have never been published in full detail. Here we describe the lithic assemblages from XCL, providing information on stone tool reduction techniques and the influence of raw materials on artefact manufacture. The XCL hominins used both bipolar and freehand reduction techniques to manufacture small flakes, some of which show retouch. Bipolar reduction methods at XCL were used more frequently than previously recognized. Comparison of XCL with other Early Pleistocene sites in the Nihewan Basin indicates the variable use of bipolar and freehand reduction methods, thereby indicating a flexible approach in the utilization of raw materials. The stone tools from XCL and the Nihewan sites are classifiable as Mode I lithic assemblages, readily distinguished from bifacial industries manufactured by hominins in Eastern Asia by ca. 800 ka.

Sunday, May 14, 2017

Evolutionary Processes Shaping Diversity Across The Homo Lineage


Fig. 3. Principal component plots of PC1 and PC2 for a subset of Generalized Procrustes analyses (GPA). The remaining principal components plots are illustrated in SOM Fig. S2. A summary of all GPA results is given in Table 3. The percentage of variance explained by each principal component is displayed on each plot. (a) GPA 1 – mandible. Species convex hulls are separated along PC1. Most Pleistocene Homo specimens fall within the H. erectus convex hull, with the exception of H. rudolfensis specimens and KNM-ER 1802. KNM-ER 60000 is an outlier along PC2. (b) GPA 2 – mandible. There is a fair amount of overlap between species convex hulls. All Pleistocene Homo specimens are contained within the convex hull of H. erectus, with the exception of LD 350-1 which falls just outside of the range. D2600 is an outlier along PC2. (c) GPA 5 – upper face. Most specimens fall within the H. sapiens range, except for Ndutu, SK 847, D2700 and KNM-ER 3732. (d) GPA 6 – maxilla. Dmanisi H. erectus shows the most variability along PC1. A.L.666-1 is closely associated with D2282 and Stw 53 in shape space, and OH 65 along PC1. The H. habilis convex hull is enclosed within the H. sapiens range. (e) GPA 8 – temporal. Most specimens are contained within the H. sapiens convex hull, with the exception of OH 24, DH3, OH 9, KNM-BC 1, Tuinplaas 1 and KNMES 11693. (f) GPA 11 – neurocranium. H. erectus is most variable along PC2. DH2 falls just outside the convex hull of H. erectus along PC 1.







  

Evolutionary Processes Shaping Diversity Across The Homo Lineage
Lauren Schroeder, Rebecca Rogers Ackermann
This manuscript is currently under review in the Journal of Human Evolution
bioRxiv preprint first posted online May. 10, 2017
(Link)

From the paper:

Discussion

The results of our analyses indicate that morphological relationships among Homo taxa are complex, and suggest that diversification may be driven primarily (though not exclusively) by neutral evolution. Multivariate and geometric morphometric results were generally consistent and highlighted the large amount of morphological diversity within Homo, especially within H. erectus, a geographically and temporally widespread species. Other interesting patterns also emerged. First, the spatial relationships among specimens differed depending on the morphological region analyzed. For example, Mahalanobis’ distances between H. erectus specimen KNM-ER 3883 and other Pleistocene Homo are significantly different for the temporal region (Fig. 2c), but not for the face (Fig. 2a) and neurocranium (Fig. 2d). Second, the Dmanisi hominins and specimens of H. rudolfensis are consistently different from each other and from other taxa. Third, the oldest Homo specimen, LD 350-1, is significantly different from all other specimens for calculations of Mahalanobis’ distances, except for H. erectus specimen KNM-BK 8518 and H. sapiens specimen Tuinplaas 1. This specimen also falls within, or on the boundary of, the H. erectus convex hulls in principal component plots of Procrustes shape coordinates (Figs 3a-b), lending support to the initial diagnosis of this specimen as Homo (Villmoare et al., 2015). Finally, it is worth noting that there is a close association between H. naledi and H. erectus in both cranial and mandibular analyses (e.g. similar to what has been shown in Dembo et al., 2016; Laird et al., 2016; Schroeder et al., 2016), as well as between ~2.4 Ma early Homo specimen A.L.666-1, South African specimen Stw 53, and H. habilis specimen KNM-ER 1813. The results of these metric analyses confirm the complexity of the phenotypic variation within Homo and the difficulty faced when trying to identify potential evolutionary relationships, especially given the possibility multiple lineages within our genus.

What has produced this diversity? Our results indicate that for 95% of taxon comparisons (51% when a conservative estimate of statistical power is used), across the entire skull (face, maxilla, neurocranium, temporal, mandible), the null hypothesis of genetic drift cannot be rejected. This indicates that of the majority of the cranial and mandibular phenotypic diversity within Homo, from ~2.8 Ma-0.0117 Ma, is consistent with random genetic drift. This is particularly striking for the neurocranium where all three analyses comprising 39 different comparisons are shown to be consistent with drift, even when including very small-brained H. erectus (Dmanisi) and H. naledi(South Africa). What this indicates is that the relative size and shape variation that exists between taxa is proportional to that seen within taxa (here based on the Homo sapiens model). In other words, although morphological divergence is occurring among species, it happens consistently across the phenotype in a manner that does not change the relative relationships among parts. For the neurocranium, this is true despite considerable brain size differences between Homo taxa. In this light, recent suggestions that brain size and shape differences may poorly define Homo (Spoor et al., 2015) are intriguing, because they have arisen in the context of an increased understanding of comparable magnitudes and patterns of variation within taxa. It may be more difficult to delineate taxa under a model of drift, as opposed to a model of selection, which drives changes in the relative relationships among traits. However, it is important to remember that the neurocranial analyses in particular, due to a dearth of available homologous landmarks, did not capture all aspects of brain shape but rather gross shape/size. Nonetheless, based on these results it is necessary to re-consider the traditional view that selection was the main evolutionary process driving changes in the neurocranium, and most other cranial regions, within Homo, and consider the implications of that for our understanding of how and why our lineage evolved.

For the remaining cases, where drift was rejected, three primary patterns can be observed. First, adaptation played a role in driving the evolution of differences between the Dmanisi hominins and other early Homo specimens across both the face and mandible. Interestingly, even though the Dmanisi group itself is hugely diverse, we found that this rejection of drift is consistent across all of the Dmanisi specimens, regardless of the specimen or combination of specimens included in each analysis, confirming that this result was not just a product of intra-group variability. The Dmanisi hominins were the first of our lineage to leave Africa, and our results indicate that selection played an important role in that dispersal, resulting in significant morphological changes (and a different covariance structure) as these hominins adapted to new environmental contexts. Second, although drift was the primary force implicated in neurocranial change, selection repeatedly acted to shape maxillary and mandibular diversity among Homo groups. This result suggests that the evolution of Homo is characterized by adaptive diversification in masticatory systems among taxa, which may be related to dietary change, possibly as a result of environmental change (Vrba, 1985, 1995, 1996, 2007; Cerling, 1992; Stanley, 1992; deMenocal, 1995; Reed, 1997; Bobe and Behrensmeyer, 2004; Wynn, 2004), environment variability (Potts, 1998), and/or shifts to new foraging strategies (Stanley, 1992; Braun et al., 2010; Lepre et al., 2011; Potts, 2012; Ferraro et al., 2013). Third, the mandibular morphology of H. rudolfensis consistently emerges as being adaptively different from other Homo taxa, including the earliest Homo specimen, LD 350-1. This result implies a potentially divergent and distinct evolutionary trajectory for this taxon, possibly signifying a branching event, supporting the distinctiveness of this taxon, and providing an adaptive explanation for divergence in sympatry with other Homo taxa (i.e. H. habilis). However, despite these instances where drift was rejected, we reiterate that, for the majority, selection was not detected. For some cases, this lack of selection is surprising. For example, we do not see a massive adaptive change occurring between 2.7 and 2.5 Ma as per Vrba’s 1985 turnover-pulse hypothesis (Vrba, 1985), nor do we see the expected correspondence between most major cultural transitions and changes in skull morphology.

Interestingly, we also do not detect major selective pressure acting to differentiate Homo sapiens from Middle Pleistocene Homo. This result parallels the findings of Weaver et al. 2007 who show that genetic drift can account for the cranial differences between Neanderthals and modern humans. It also provides further evidence for a “lengthy process model” of modern human origins (Weaver, 2012), supporting the theory of morphological continuity from the later Middle Pleistocene, ~400 000 years ago, to the appearance of anatomically modern humans. While it is important to note that these analyses were only performed on crania and mandibles, these results are nonetheless significant given the emphasis placed on cranial and mandibular material for alpha taxonomy.

There is a fundamental disconnection between the realization that molecular change over evolutionary timeframes occurs predominantly through neutral processes (Kimura, 1968, 1991), and the dominant interpretation (explicitly or implicitly) that morphological change in human evolution is primarily adaptive and directional. The results of this study lend further support to the notion that random change has played a major role in human evolution (see also Ackermann and Cheverud, 2004; Weaver et al., 2007; Schroeder et al., 2014). The detection of widespread genetic drift acting on all aspects of skull morphology during the evolution of our genus is likely to be due, in part, to small population sizes of groups in isolation. This could also be correlated with a purported population bottleneck at ~2.0 Ma (Hawks et al., 2000). Because the emergence and evolution of Homo and the appearance and proliferation of stone tools roughly correspond, and continue to co-evolve, it is also possible that hominins were increasingly reliant on cultural adaptations – as opposed to biological adaptations – to manage environmental changes (Schroeder et al., 2014; Ackermann and Cheverud, 2004; Lynch, 1990). Continued investigation into evolutionary process is necessary – especially for anatomical regions such as the postcranium which remain largely unexplored (but see Grabowski and Roseman, 2015) – in order to provide further insight into how and why the human lineage evolved.

Friday, May 12, 2017

The age of the Paleolithic handaxes from the Imjine-Hantan River Basins, South Korea

























Kidong Bae, Christopher J. Bae, Kiryong Kim
Quaternary International
23 June, 2012
(Link) open access pdf

Abstract

Since the discovery of bifacially worked implements at the Chongokni site in the ImjineHantan River Basins (IHRB) area in Korea in 1978, the nature of the Movius Line has been strongly debated. One of the primary debates is the chronometric age of the IHRB handaxes with ages ranging between the middle Middle Pleistocene and the Late Pleistocene. Two primary basalts were identified in the IHRB: Chongok and Chatan (based on fission-track analyses the Chongok basalt dates tow0.5 Ma and the Chatan basalt tow0.15 Ma).  Using a combination of chronometric dating methods (e.g., tephra, TL, OSL, fission-track, 26Ale10Be), a conservative estimate for the age bracket of the IHRB deposits that overlie the Chongok basalt is the middle Middle Pleistocene (w350 ka) to the Late Pleistocene and any deposits in the IHRB that overly the Chatan basalt should date to the Late Pleistocene and be of more recent deposition. Sediment that is sandwiched between the Chongok and Chatan basalts should fall between 350 ka and 115 ka. It is possible the earliest hominin occupation of the IHRB may be slightly older than the 350 ka datapoint used here.

Thursday, May 11, 2017

Beringia, The Last 140,000 Years

Marnie Dunsmore
5/11/2017

Note:  The bison symbols below indicate when bison crossed Beringia into North America (according to the recent paper in PNAS "Fossil and genomic evidence constrains the timing of bison arrival in North America", Froese et al, referenced below.)

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Tolbaga, south of Lake Baikal, Siberia, probably about 35,000 years old.
(Link)

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Ust'-Ishim, 45,000 years ago in Siberia
(Link)

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References

Similar Meltwater Contributions to Glacial Sea Level Changes from Antarctic and Northern Ice Sheets
Eelco J. Rohling, Robert Marsh, Neil C. Wells, Mark Siddall & Neil R. Edwards
Nature 430, 1016-1021(26 August 2004)
(Link)

Sea Level and Global Ice Volumes From the Last Glacial Maximum to the Holocene
Kurt Lambeck, Hélène Rouby, Anthony Purcell, Yiying Sun, Malcolm Sambridge
PNAS
vol. 111 no. 43
October 28th, 2014
(Link)

A Chronology of Paleozoic Sea-Level Changes
Haq, B. U.; Schutter, SR
Science
322 (5898): 64-8
2008

Fossil and genomic evidence constrains the timing of bison arrival in North America
Froese et al
PNAS, February 3, 2017.