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.)

5,000 years ago


















10,000 years ago


















12,000 years ago


















15,000 Years Ago


















20,000 Years Ago


















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

40,000 Years Ago


















42,000 Years Ago


















45,000 Years Ago


















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

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52,500 Years Ago


















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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.

Thursday, May 4, 2017

Thoughts on the paper "Neandertal and Denisovan DNA from Pleistocene sediments"

Marnie Dunsmore
5/4/2017

Last week the paper "Neandertal and Denisovan DNA from Pleistocene sediments" was published in Science.  The paper describes DNA that was sampled and sequenced from four "Pleistocene" dated caves, including from Denisova Cave.

Many journalists writing about this paper, including Lizzie Wade writing for Science Magazine, and Kate Wong, writing for Scientific American, suggested that this method could be applied to investigate another archaeological announcement last week, that of the Cerutti San Diego mastodon site which was published in Nature.

It should be mentioned that Denisova Cave today has a mean annual temperature of about 1 degree C.  It is also a cave site, with relatively stable temperature compared to an exposed open environment.  Do I really need to say it?  The San Diego site is in, well, San Diego, California. It does not, and probably has not for the last 100,000 years, had a stable annual mean temperature close 0 degrees C.  So it is very unlikely that the DNA sampling method used at Denisova Cave could be used at the Cerutti mastodon site.

That is not to say that revelatory archaeology won't happen with this method.  There are at least twenty anthropologically significant cave sites in areas with cold mean annual temperatures outside the already highly sampled areas in Europe, Denisova Cave, Iran, Armenia, and Afghanistan.  Sampling at these sites could quickly advance our understanding of human origins.

Here's my wish list, in no particular order, for colder temperatures sites similar to Denisova Cave that I would like to see sampled:

On Your Knees Cave, Alaska
Dyuktai Cave, Aldan River, Siberia
Fugoppe Cave, Hokkaido, Japan
Temiya Cave, Hokkaido, Japan
Zhoukoudian Cave System, China
Bluefish Cave, Yukon
January Cave, Alberta
Eagle Cave, Alberta
Ma'anshan Cave, China
Chiquihuite Cave, Mexico
Tennessee Rock Art Caves, USA
Pictograph, Middle and Ghost Caves, Montana
Chertovy Vorota Cave, Primorsky Krai, Russia
Charlie Lake Cave, British Columbia
Kundodo Caves, Ethiopia
Caves of the Atlas Mountains, Morocco
Jeommal Cave, South Korea
Turubong Caves, South Korea
Cheongwon and the Chommal Cave, South Korea
Chongokni (Jeongokni) Acheulean type site, South Korea
Cave of Hearths, Makapansgat, Northern Transvaal, South Africa

It would be good to find some cold temperature sites in South East Asia as well.  Perhaps there are some sites in the highlands of New Guinea.

It remains to be seen as to whether there is the leadership, will, funding and objectivity on the part of ancient DNA researchers and paleoanthropologists to pursue detailed efforts to sample, sequence and study these sites into timeframes that would be meaningful to the study of recent human origins: that of the period between 200,000 and 20,000 years ago.

Having been to a few human origins, archaeology, paleoanthropology and physical anthropology conferences, I myself have become quite reticent about the leadership of the study of human origins.  A lot of the work seems to be motivated by personal pet theories.  Shall I name them:

The Recent Out of Africa (within the last 65,000 years) Eve Hypothesis

The Recent Out of South Africa Eve Hypothesis

The Multi-Regional Hypothesis

The Out of America Hypothesis

The Out of China Hypothesis

The Out of India Hypothesis

The Out of Australia Hypothesis

The Out of Italy Hypothesis

The Humans are Becoming Less Violent due to "Domestication" Hypothesis
         (we can thank Steven Pinker at Harvard for that one)

The Southern European Farmers out of the Levant Hypothesis

The Clovis First Hypothesis

The Beringia Standstill Hypothesis

The Mass Migration from the Steppe was the Source for Indo-European Languages Hypothesis

The Horse Riding Warriors on Chariots Rode in and Killed All the Men and Raped the Women Hypothesis

The Men Made All the Tools and Women Only Made Babies and Watched the Children Hypothesis (and therefore that Men are Smart and Women are Stupid Hypothesis)

Man the Hunter (Need I say more?)

The Only White Skinned People are Civilized and Modern Hypothesis

and its evil twin:  The Solutrean Hypothesis for the "Peopling" of the Americas

The Theory that Cultural Modernity Developed with Farming

The Mammals Suck Milk Hypothesis and therefore If You Don't Breast Feed Your Babies, They Will Be One Eyed and Impaired For Life Hypothesis

The Neandertals were Stupid Hypothesis

The Neandertals were Smart Hypothesis

The Neandertals Buried their Dead Hypothesis

The Neandertals Never Wore Eagle Claw Jewelry And If You Say So I Will Have a Temper Tantrum Hypothesis

And that's just the beginning.

It's quite the trick to come up with all this stuff, but hey, it's a pretty good gig if you can get it.  Five or six all expenses paid conferences a year in five star hotels, lots of press attention and all expenses paid extended vacations to places like South Africa.  Hey why not?  Why would you want to worry about whether or not your theories are inaccurate and even harm people?

Maybe we won't look back at this in the way we now look back at Aleš Hrdlička.  I do hope that there is soon a more objective effort to investigate human origins.  Perhaps we could start with an objective effort to test cave sediments.

Monday, May 1, 2017

Tom Deméré: Paleontologist at the San Diego Natural History Museum: "Bring it on."


National Geographic

Friday, April 28, 2017

Reaction to the Holen Paper (130,000 year old mastodon hunting site in California)

Marnie Dunsmore
4/28/2017

I noticed in the last few days that a number of scientists and journalists are dismissive of the Holen paper (Link) [130,000 year old mastodon hunting site in California].  Many of the criticisms can be traced back to a handful of extremely vocal Clovis First or Beringia Standstill promoters such as David Meltzer, Don Grayson and Michael Waters.  British Chris Stringer, a proponent of the recent African Origin Hypothesis, is highly cited and retweeted, even when he knows almost nothing about American archaeology.

In my view, this paper was carefully reviewed and has been published in the journal Nature.  It is at least worthy of consideration.  I doubt that in the two days since it has been published, that any of the journalists or scientists voicing deep skepticism about this paper have even had a chance to read it, let alone check into related source material.  I therefore find the deep rejection of this paper by journalists and scientists such as Marc Kissel, Chris Stringer, Lizzie Wade, Kate Wong, Jennifer Raff, Maria Avila-Arcos, and Tom Higham, to be premature.


Marc Kissel, protégé and graduate student of John Hawks, seems to think that non adherents of the now outdated Clovis First Theory belong to the "Preclovis Crowd".  Hmmm, sad to think that Marc is a newly minted professor and will be teaching and supporting the Clovis First Hypothesis at the University of Notre Dame likely for the next fifty years. 



More from Marc.



Says Chris Stringer, poster boy and talking head for British Paleoanthropology, who knows absolutely nothing about North or South American archaeology



Says Lizzie Wade.  Dating of even more Neanderthal and Denisovan ancient DNA is not going to entirely solve the question of the origin of anatomically modern humans.  And about her latest write up in Science Magazine:  it would be a cause for celebration if some of these journalists at Science Magazine could talk to a broader group of scientists.  I myself am a little sick of hearing about what Chris Stringer and Eske Willerslev think.



Yes, Kate Wong talked to 7 skeptical archaeologists, such as David Meltzer, who continues to relentlessly push the Clovis First/Beringia Standstill Theory, in the face of overwhelming evidence to the contrary.



Jennifer Raff, supposed skeptic and native American ancient DNA researcher, retweets Kate Wong.
  



Tom Higham, professor at Oxford, dismisses the Holen paper.  Yet Tom Higham, a dating specialist, is perfectly happy to be a frequent presenter at the ESHE Conference, which promotes experimental archaeology research similar to the use wear studies presented in the Holen paper.  OK if a site is dated to 100,000+ years in Siberia, but not in the Americas?  Why is that, Tom?  Somehow, in the long periods that Siberia and North America were connected by Beringia in the last 200,000 year, humans somehow read a signpost as they past into Beringia that read "Do not pass Beringia, do not collect $200, go back to jail, go back to Eurasia?"  Right.




Maria Avila-Arcos, recent Stanford graduate, and ancient DNA researcher, retweets Lizzie Wade (who knows nothing about American archaeology)



Maria Avila-Arcos retweets skeptical comment by Chris Stringer (who knows nothing about American archaeology).




Here's Maria Avila-Arcos explaining to a CARTA audience that humans arrived in the Americas 15,000 years ago.  She cites Monte Verde dating as the reason for the date of 15,000 years ago.  Oddly, the date for Monte Verde is 18,500 years ago, not 15,000 years ago, so the date Maria cites is off by 3,500 years.  She's quite emphatic about the 15,000 year old date for entry of humans into the Americas, and doesn't bother to even hint that there are some sites in the Americas that might be older than Monte Verde.