Amplitudes of orbitally induced climatic cycles and patterns of hominin speciation

Palaeoanthropologists and archaeologists have long invoked climate change to explain aspects of human evolution. Collection of new climatic and environmental data combined with new fossil discoveries and methodological improvements continue to make exploration of this link a vital endeavour in studying human evolution. The current study employs a global climatic dataset and a rigorously compiled catalogue of hominin first and last appearance dates to test the effects of changes in temperature on hominin speciation and extinction. Through the use of wavelet analysis and bandpass filters the eccentricity, obliquity, and precession components of the studied climatic record are extracted and tested independently for associations with patterns of speciation and extinction. Results suggest that all three components may play a role in speciation events, but that only the obliquity cycle shows a statistically significant relationship with extinction events. It is suggested that, whilst climatic factors could contribute to the appearance of new hominin species, subsequent competition between these species may lead to their extinction.     

Assessing the distribution of African Palaeolithic sites: a predictive model of collagen degradation

In order to assess the distribution of African Palaeolithic sites and hominin remains, we need an understanding of the factors that may affect the preservation of archaeological material in the fossil record. One of the main factors that is thought to affect seriously the global distribution of fossil remains is taphonomy, but it would seem that taphonomic processes may themselves be overprinted by collagen degradation.The rate of collagen loss is highly temperature dependent, and it has been shown that bone is more likely to be preserved in areas of lower temperature and so lower collagen loss. Hence, it would be expected that fossil fauna remains would be distributed in areas of low collagen loss, i.e. low temperature. Conversely, lithics will not be subject to a temperature bias in their preservation. We have tested this hypothesis through the use of archaeological material.Our results show that the distributions of both lithic and faunal assemblages are non-random across the African continent, with all archaeological sites being found in areas of relatively low collagen degradation. This implies that bone collagen degradation is not the only factor affecting the distribution of African Palaeolithic sites and hominin remains. We suggest that the site distribution is not a reflection of bias in excavation history, but is a real phenomenon reflecting hominin habitat choice.     

Direct radiocarbon (AMS) dating of split-based points from the (Proto)Aurignacian of Trou de la Mère Clochette,Northeastern France. Implications for the characterization of the Aurignacian and the timing of technical innovations in Europe

Radiocarbon (AMS) dates on two split-based point wings and a hominin molar from the site of Trou de la Mère Clochette in the French Jura are presented in this paper. Dating split-based points has very rarely been undertaken. This is unfortunate given that these artefacts are critical to our definition and characterization of Early Upper Palaeolithic technocomplexes, as they are considered to be the type fossil of the Classic Aurignacian.     

Change and variability in Plio-Pleistocene climates: modelling the hominin response

Research into the links between climatic change and hominin evolution has generated numerous hypotheses. In recent years, methodological refinement of, and increased research effort directed towards, reliable proxies for palaeoclimatic change have provided a growing body of data with which to test such hypotheses. Whilst many archaeologists are aware of these data, few are cognizant of the wealth of techniques developed by theoretical biologists over the last half-century to explicitly address the evolutionary consequences of adaptation to temporally heterogeneous environments. The current paper expands and adapts one such technique for use with empirical data, and applies it to a global palaeoclimatic record spanning the last five million years, in order to discern the potential impact of environmental heterogeneity on hominin evolution during this period. Of particular interest are the contributions of climatic change, associated with directional selection, and climatic variability, associated with selection for phenotypic plasticity. At this macro-scale, results suggest an early peak in selection for plasticity at approximately 2–2.7 mya, combined with three major shifts in directional selection at approximately 3.3–3.4, 1.4–1.5, and 0.5–0.6 mya. These results are employed to relate the fossil and archaeological records to a number of environmental hypotheses of human evolution. In particular, it is argued that the origins of the genus Homo and the spread of Oldowan technology are associated not with a major turnover pulse, but with a period of selection for phenotypic plasticity.     

Assessing the function of early hominin bone tools

Bone tools from early hominin sites in southern Africa continue to intrigue researchers interested in the development of early human technology and cognition. Sterkfontein, Swartkrans and Drimolen have all yielded bone tools dated to between 1 and 2 Mya associated with numerous Paranthropus robustus and few early Homo remains. The bone tools are described by different authors as implements used to excavate tubers from the ground and termites from their nests, work hides and strip bark from trees. The purpose of this research was to develop a more powerful analytical tool for the study and interpretation of bone surface modifications in general, and early hominin bone tool function(s) in particular. We used an optical interferometer to scan the worn areas of a sample of bone tools from Swartkrans and Drimolen, an ethnographic collection of implements used for defleshing marula fruits, and a set used experimentally to excavate in the ground and in termite mounds. The 3D rendering of archaeological and experimental wear patterns better highlights previously described differences between these patterns, and demonstrates the pertinence of this analytical tool to visually discriminating between different bone modifications. Analysis of selected 2D and 3D roughness variables indicates that the wear pattern on the early hominin bone tools from Drimolen is significantly different from that of tuber digging, very similar to termite foraging, and not unlike marula fruit processing. Marked differences are detected between the Swartkrans and Drimolen wear patterns, which suggests that the tools from these sites may have been used with different motions, in contact with abrasive particles of different size, or in different tasks. Principal component analyses conducted on 2D and 3D variables suggest that early hominin bone tools from southern Africa may have been used to forage for termites, extract tubers in a motion parallel to the tool main axis, process fruits and conduct other, as yet unidentified, tasks.     

Response to Nowell and Horstwood (2009)

Here we respond to the comment by Nowell and Horstwood (2009) written in response to our 2008 paper where we presented the first results of the application of laser ablation strontium isotope analysis to a fossil hominin. Although we are pleased that the paper has attracted so much interest, including from researchers outside the field such as Nowell and Horstwood, we completely disagree with the two main arguments of their comment. Namely, we reject the notion that they can recalibrate our data using different methods and (non matrix-matched) standards determined in a different laboratory, and that is simply irresponsible to advocate the further development of this method for rare and important hominin samples through drilling rather than the almost non-destructive method of laser ablation that we presented in our paper.     

Probable human hair found in a fossil hyaena coprolite from Gladysvale cave,South Africa

Until now, the oldest known human hair was from a 9000-year-old South American mummy. Here we report fossil hairs of probable human origin that exceed that age by about 200,000 years. The hairs have been discovered in a brown hyaena (Parahyaena brunnea) coprolite from Gladysvale cave in South Africa. The coprolite is part of a hyaena latrine preserved in calcified cave sediment dated between 195,000 and 257,000 years ago. This find supports the hypothesis that hyaenas accumulated some of the early hominin remains found in cave sites, and provides a new source of information on Pleistocene mammals in the Sterkfontein Valley.     

Experimental study of cut marks made with rocks unmodified by human flaking and its bearing on claims of ∼3.4-million-year-old butchery evidence from Dikika, Ethiopia

In order to assess further the recent claims of ∼3.4 Ma butchery marks on two fossil bones from the site of Dikika (Ethiopia), we broadened the actualistic-interpretive zooarchaeological framework by conducting butchery experiments that utilized naïve butchers and rocks unmodified by human flaking to deflesh chicken and sheep long limb bones. It is claimed that the purported Dikika cut marks present their unexpectedly atypical morphologies because they were produced by early hominins utilizing just such rocks. The composition of the cut mark sample produced in our experiments is quite dissimilar to the sample of linear bone surface modifications preserved on the Dikika fossils. This finding substantiates and expands our earlier conclusion that—considering the morphologies and patterns of the Dikika bone surface modifications and the inferred coarse-grained depositional context of the fossils on which they occur—the Dikika bone damage was caused incidentally by the movement of the fossils on and/or within their depositional substrate(s), and not by early hominin butchery. Thus, contrary to initial claims, the Dikika evidence does not warrant a major shift in our understanding of early hominin behavioral evolution with regard to carcass foraging and meat-eating.     

Fluvial transport of bovid long bones fragmented by the feeding activities of hominins and carnivores

This study explores the hydraulic transportability of bovid long bone fragments created through hominin and carnivore carcass consumption in order to determine the effect of fluvial transport on the incidences of hominin- and carnivore-induced bone surface modifications. Transportability was determined using an oval race track flume and 311 long bone fragments from modern control collections of hominin- and carnivore-modified bone. Results show that the fluvial transport of long bone fragments is predicted by animal size class and bone specimen size, as measured by maximum cortical thickness, maximum length, and maximum width. All of these variables can be measured on fossil specimens. Long bone portion (midshaft, near-epiphysis, and epiphysis) does not affect transport and hydraulic transport does not substantially modify the incidences of tooth, percussion, and cut marking in transported or lag assemblages in low energy fluvial environments. Implications of this study are: 1) animal size classes, and cortical thickness, length, and width of long bone fragments can be used to identify fluvial winnowing in fossil assemblages; 2) analyses concerning the relative timing of hominin and carnivore carcass consumption based on the proportions of long bone fragments bearing tooth, percussion, or cut marks can be meaningfully applied to fossil assemblages deposited in low-energy fluvial environments.     

Micro‐CT Imaging and Analysis of Enamel Defects on the Early Late Pleistocene Xujiayao Juvenile

Dental pathologies and enamel defects in East Asian hominins have rarely been reported. Here, we systematically document and describe a suite of enamel defects in the Xujiayao juvenile maxilla, an East Asian hominin from the early Late Pleistocene that may represent an unknown hominin lineage. In addition, we determine the chronology of growth disruptions represented by matched linear enamel hypoplasias, evaluate the long‐held hypothesis that the large brownish pit on the I¹ is evidence of dental fluorosis and assess the utility of micro‐computed tomography (micro‐CT) techniques in analyzing enamel defects. With the use of binocular microscopy, scanning electron microscopy (SEM) and micro‐CT imaging techniques, the Xujiayao teeth were found to exhibit a high number of pit‐form defects seldom seen in the fossil record. By matching the timing of linear enamel hyperplasia across multiple teeth, a minimum of five developmental disruptions were identified, indicating that the Xujiayao juvenile experienced several growth disturbances during its short lifespan. Our SEM and micro‐CT analyses suggest that the large pit on the I¹ is an enamel hypoplasia due to its morphology and pre‐eruptive enamel thinning. It is not a post‐eruptive fluorotic pit, and there is no evidence of chalkiness or opacity associated with dental fluorosis. The micro‐CT technique made it possible to verify the presence of enamel hypoplasia and to more precisely quantify defect dimensions, especially in unerupted teeth and shallow hypoplasias that are difficult to detect by binocular microscopy or SEM. Copyright © 2015 John Wiley & Sons, Ltd.     

Reappraisal of ‘chronospecies’ and the use of Arvicola (Rodentia,Mammalia) for biochronology

The water vole, genus Arvicola, is characterised by a broad geographic distribution throughout Europe and is widespread during the late Middle and Upper Pleistocene. This genus is used as a major biostratigraphic tool within the Quaternary. Specific determinations using the Schmelzband-Differenzierung-Quotient or SDQ have identified many chronospecies within the fossil species Arvicola cantiana (Hinton, 1910). As SDQ calculation remains limited, this study reappraises the Arvicola genus in terms of morphodiversity and morphospace using outline analysis which takes into account the tooth as a whole. Outline analysis suggests that one single species of Arvicola, A. cantiana, was present during the Pleistocene. This species shows great variability with no trends or patterns in morphospace. Thus, these results call into question the reliability of SDQ for specific determinations and throw doubt on the biochronological framework based on Arvicola.     

The Lower Paleolithic of the Arabian Peninsula: Occupations,Adaptations, and Dispersals

To understand major processes of human evolution during the Plio- Pleistocene, it is necessary to consider the available evidence from key regions of the Old World. The Arabian peninsula is often depicted as a key geographic route for hominin dispersals in Out of Africa models, although the available primary evidence is rarely cited. And yet, significant Lower Paleolithic assemblages have been identified in many parts of the peninsula, including in areas near the Strait of Bab al Mandab. The presence of Oldowan-like and Acheulean assemblages may reflect at least two major dispersals outside of Africa. Acheulean localities are particularly abundant on the Arabian peninsula, and variations in stone tool manufacturing techniques and tool-type frequencies may reflect temporal changes in assemblages. Although there is good potential to chronometrically date sites in the Arabian peninsula, absolute dating methods have not been adequately applied, most temporal reconstructions relying on typotechnological change. If the Arabian peninsula is to provide solid evidence for understanding hominin adaptation and dispersal patterns, future fieldwork in secure depositional contexts needs to be conducted to overcome current limits in dating and environmental reconstructions.     

The first fossil crow (Corvus sp. indet.) from the Early Pleistocene Nihewan Paleolithic sites in North China

We describe a three dimensional preserved right tarsometatarsus, representing the first fossil crow from the well-known Early Pleistocene Nihewan paleolithic sites in North China. The new specimen is distinguished from other known species of the genus Corvus by the combined morphological features, especially the peculiar hypotarsus. The phylogenetic significance of the arrangement of canals at the proximal hypotarsus in passerines is discussed. Although the fossil was too incomplete to warrant the erection of a new species of Corvus, it nonetheless increases the taxonomical diversity of the Nihewan fauna and improves our knowledge on Pleistocene birds in China. Finally the paleoenvironment of the Nihewan sites are discussed in terms of its faunal composition.     

Taxonomic reassignment of the Paleolithic human navicular from Cueva de los Torrejones (Guadalajara,Spain)

Evidence of human activity and hominin remains are very scarce inland on the Iberian Peninsula. This fact raises the issue of the scarcity of evidence that Paleolithic Homo sapiens occupied this area outside of the littoral margins (Atlantic, Cantabrian, and Mediterranean coasts). Here, we comparatively describe a human right adult navicular bone recovered in the Cueva de los Torrejones site, located in the village of Tamajón (Guadalajara, Spain). This fossil was preliminarily established as belonging to Homo cf. neanderthalensis, due to the late Pleistocene faunal association, mainly because of the presence of Crocuta crocuta and Panthera pardus. The metrical and morphological study of the navicular T93-S3.27 from Cueva de los Torrejones clearly differentiates it from Neandertals and their ancestors, the hominins from Sima de los Huesos, allowing for this fossil to be taxonomically assigned with confidence as H. sapiens. The navicular from the Cueva de los Torrejones is absolutely and relatively medio-laterally narrow with a low wedging index as those of fossil and modern H. sapiens, and clearly different of Neandertals. The increased discoveries and publications of new naviculars belonging to genus Homo, together with the findings of P. pardus and C. crocuta in more recent chronologies in the Iberian Peninsula, are compatible with this reevaluation. We propose a probable chronology for this fossil between 12 and 15 ka and ca. 25 ka, based on the biostratigraphy and the oldest presence of H. sapiens in the Iberian Peninsula. This work confirms the human presence within the Iberian Peninsula during the Upper Paleolithic and reopens the question of the peopling of the inner Peninsula during this period.     

Evidence of Stress Fracture in a Homo antecessor Metatarsal from Gran Dolina Site (Atapuerca,Spain)

We present the palaeopathological analysis of a right fourth metatarsal (ATD6‐124) recovered from the Atapuerca–Gran Dolina site (Spain). This fossil, ca. 1 Ma, belongs to Homo antecessor, the earliest known European hominin species. The metatarsal exhibits a proliferative lesion on its medial periosteal surface. Periosteal reaction can be the bone response to a wide number of injurious processes. We describe a lesion on the basis of macroscopic and microscopic analyses, including microtomography and scanning electron microscopy. Externally, the osteoblastic lesion presents a highly porotic and disorganised morphology. Internally, we observe a series of micro‐fractures on the compact bone that do not affect the medullary canal. We provide a differential diagnosis and suggest that the ATD6‐124 lesion could correspond to a pedal stress fracture, also known as fatigue or march fracture. Stress fractures have been related to a load increase and muscular fatigue. This type of fracture has been widely reported in the foot of soldiers and athletes, which are usually engaged in strenuous, excessive or prolonged locomotive activities. Despite its high frequency in these groups, stress fractures have not been reported as such in fossil collections, with the exception of a metatarsal belonging to the Sima de los Huesos site (Atapuerca). Copyright © 2013 John Wiley & Sons, Ltd.     

The phylogenetic significance of the Middle Pleistocene Narmada hominin cranium from central India

A parsimony analysis of the Narmada cranium from central India and a number of other demes and species of Homo concludes that the Narmada hominin shares a closer relationship with the European Steinheim specimen, than with Asian H. erectus or H. pekinensis. This suggests that the population represented by the Narmada cranium is likely to have had its origins in Europe rather than in Asia. Overall the available evidence supports an ‘Out of Africa’ scenario, as the early Asian hominins belong to a distinct clade which has no extant descendants and thus appear to represent an evolutionary ‘dead end’. The later African and European hominins are defined by a clade including early H. sapiens from Africa. The main difference between these two distinct clades is that the H. erectus lineage is defined by increasing degrees of neuro‐orbital disjunction associated with increased anterior cranial base extension, while the lineage leading to early H. sapiens is characterized by the opposite condition of reduced neuro‐orbital disjunction associated with increased anterior cranial base flexion. While there is also evidence of differential patterns of head and neck musculature between these two clades, they are of secondary importance. Preliminary dating of bovid remains found in association with the hominin cranium by the gamma spectrometric U‐series dating technique suggests a tentative minimum age of not less than 236,000 years. This is in agreement with evidence from biostratigraphical studies of the Boulder Conglomerate, which place these deposits in the Middle Pleistocene. Copyright © 2004 John Wiley & Sons, Ltd.     

The Middle Stone Age human remains from Diepkloof Rock Shelter (Western Cape,South Africa)

In the course of recent excavations at Diepkloof Rock Shelter (South Africa), three human remains were found in the Middle Stone Age layers. These human remains are two pedal phalanges (intermediate and distal) from a fifth ray, which belong to the same individual, and a deciduous first lower molar. The layers in which they were found represent the end of the Howiesons Poort and the beginning of post-Howiesons Poort occupation, and are radiometrically dated to MIS 3, between 45 and 65 kyr ago. They are thus very close in time to the assumed period of anatomically modern humans (AMH) dispersal out of Africa into Eurasia, a period for which very few remains are available in the African fossil record. Here, we describe these new remains and compare their morphology and dimensions to samples of African and Eurasian Pleistocene and Holocene humans. Our results show that the human remains from Diepkloof Rock Shelter fall well within the range of variation of AMH. The phalanges are of very small size and indistinguishable from those of recent humans. In addition, our analysis of the dm₁ underlines a large size variation at the end of the MIS 4/beginning of the MIS 3 in the Western Cape. The discovery of human remains at Diepkloof Rock Shelter, albeit limited to three small bones, enriches a poorly represented chronological period of the African hominin fossil record.     

Preliminary U-series and Thermoluminescence dating of excavated deposits in Liang Bua sub-chamber,Flores, Indonesia

We report the results of a test excavation of deposits in a limestone cave sub-chamber located beneath the main chamber of Liang Bua, Flores, Indonesia; the discovery site of the small hominin species, Homo floresiensis. Well-preserved remains of extinct Pleistocene fauna and stone artefacts have previously been identified on the surface of a sediment cone within the sub-chamber. Our excavation of the deposits, at the base of the sediment cone in the sub-chamber (to 130 cm depth) yielded only a few fragmentary bones of extant fauna. Uranium/Thorium (U-series or U/Th) dating of soda straw stalactites excavated from 20 to 130 cm in depth demonstrates that the excavated sediments were deposited during the Holocene. Red Thermoluminescence (TL) dating of the sediments at the base of the excavation (130 cm depth) indicates these sediments were last exposed to sunlight at 84 ± 15 ka (thousand years), similar to red TL ages of cave sediments from the main chamber. Together, these results indicate that the surface faunal remains, which are morphologically analogous to Pleistocene finds from the main chamber excavations, were transported to the sub-chamber relatively recently from the main chamber of Liang Bua and probably originated from conglomerate deposits at the rear of the cave and from deposits around the front entrance. There is no evidence for hominin occupation of the sub-chamber, instead it seems to have acted as a sink for cultural materials and fossil remains transported from the surface via sinkholes. Despite the small number of finds from the test excavation, it is possible that more extensive excavations may yield additional transported cultural and faunal evidence at greater depths.     

Fluvial dispersal potential of guanaco bones (Lama guanicoe) under controlled experimental conditions: the influence of age classes to the hydrodynamic behavior

Hydrodynamic sorting is a taphonomic process able to transport and scatter bones deposited in archaeological and paleontological sites. This study presents the results of experimentation performed in an artificial flume with guanaco (Lama guanicoe) bones of different ontogenetic development, dry and saturated in water, in hydric flows velocities of 15 and 30 cm/s. The obtained results show that bone global density, the age of the individual, the dry or wet bone state, and the hydric flow velocity influence significantly bone dispersion. In this way, bones from immature individuals with unfused secondary growth centers and relatively low bulk density have better possibility of being transported than fused bones from adult individuals. Taking into account the results obtained in this experimentation and the feasibility of discriminating age categories in fossil assemblages, two bone groups with differential potential transport are presented in this paper. These transport groups constitute a methodological tool to evaluate the role hydric current may had played in the formation of a fossil assemblage.     

Taphonomic resolution and hominin subsistence behaviour in the Lower Palaeolithic: differing data scales and interpretive frameworks at Boxgrove and Swanscombe (UK)

The identification of human butchery-signatures on fauna from Lower Palaeolithic sites is well documented and readily identifiable. Such bone surface modifications have the potential to provide not only information about past hominin meat-procurement behaviour but address the wider issue of competition for resources with other carnivore species. To understand and discuss these broader issues both hominin and natural bone surface modifications must be understood and contextualised within a site-specific spatial and temporal framework. This paper presents new results from faunal analysis at two key British Lower Palaeolithic localities: Boxgrove and Swanscombe. It illustrates that different depositional environments and excavation histories have resulted in different scales and resolutions of available data and hence in varying interpretive potentials. At Swanscombe the archaeological record has been disturbed by both fluvial activity and excavation history providing a coarser-grained record of anthropogenic behaviour than previously acknowledged. Conversely, at Boxgrove, a finer-grained, higher resolution record of human behaviours has been preserved; this, combined with both an extensive and intensive excavation strategy, has allowed for a broader discussion of hominin landscape use, resource competition and meat-procurement behaviour. This paper highlights that assessing the specific depositional environment at each site is crucial to understanding Palaeolithic faunal assemblage formation and, consequently, the available data-resolution and behavioural interpretation.