A cranium for the earliest Europeans: phylogenetic position of the hominid from Ceprano, Italy

Genomic inference of a severe human bottleneck during the Early to Middle Pleistocene transition

Population size history is essential for studying human evolution. However, ancient population size history during the Pleistocene is notoriously difficult to unravel. In this study, we developed a fast infinitesimal time coalescent process (FitCoal) to circumvent this difficulty and calculated the composite likelihood for present-day human genomic sequences of 3154 individuals. Results showed that human ancestors went through a severe population bottleneck with about 1280 breeding individuals between around 930,000 and 813,000 years ago. The bottleneck lasted for about 117,000 years and brought human ancestors close to extinction. This bottleneck is congruent with a substantial chronological gap in the available African and Eurasian fossil record. Our results provide new insights into our ancestry and suggest a coincident speciation event.

Reassessment of the human mandible from Banyoles (Girona, Spain)

Since the discovery of a human mandible in 1887 near the present-day city of Banyoles, northeastern Spain, researchers have generally emphasized its archaic features, including the lack of chin structures, and suggested affinities with the Neandertals or European Middle Pleistocene (Chibanian) specimens. Uranium-series and electron spin resonance dating suggest the mandible dates to the Late Pleistocene (Tarantian), approximately ca. 45-66 ka. In this study, we reassessed the taxonomic affinities of the Banyoles mandible by comparing it to samples of Middle Pleistocene fossils from Africa and Europe, Neandertals, Early and Upper Paleolithic modern humans, and recent modern humans. We evaluated the frequencies and expressions of morphological features and performed a three-dimensional geometric morphometric analysis on a virtual reconstruction of Banyoles to capture overall mandibular shape. Our results revealed no derived Neandertal morphological features in Banyoles. While a principal component analysis based on Euclidean distances from the first two principal components clearly grouped Banyoles with both fossil and recent Homo sapiens individuals, an analysis of the Procrustes residuals demonstrated that Banyoles did not fit into any of the comparative groups. The lack of Neandertal features in Banyoles is surprising considering its Late Pleistocene age. A consideration of the Middle Pleistocene fossil record in Europe and southwest Asia suggests that Banyoles is unlikely to represent a late-surviving Middle Pleistocene population. The lack of chin structures also complicates an assignment to H. sapiens, although early fossil H. sapiens do show somewhat variable development of the chin structures. Thus, Banyoles represents a non-Neandertal Late Pleistocene European individual and highlights the continuing signal of diversity in the hominin fossil record. The present situation makes Banyoles a prime candidate for ancient DNA or proteomic analyses, which may shed additional light on its taxonomic affinities.

Through 40,000 years of human presence in Southern Europe: the Italian case study

The Italian Peninsula, a natural pier across the Mediterranean Sea, witnessed intricate population events since the very beginning of the human occupation in Europe. In the last few years, an increasing number of modern and ancient genomes from the area have been published by the international research community. This genomic perspective started unveiling the relevance of Italy to understand the post-Last Glacial Maximum (LGM) re-peopling of Europe, the earlier phase of the Neolithic westward migrations, and its linking role between Eastern and Western Mediterranean areas after the Iron Age. However, many open questions are still waiting for more data to be addressed in full. With this review, we summarize the current knowledge emerging from the available ancient Italian individuals and, by re-analysing them all at once, we try to shed light on the avenues future research in the area should cover. In particular, open questions concern (1) the fate of pre-Villabruna Europeans and to what extent their genomic components were absorbed by the post-LGM hunter-gatherers; (2) the role of Sicily and Sardinia before LGM; (3) to what degree the documented genetic structure within the Early Neolithic settlers can be described as two separate migrations; (4) what are the population events behind the marked presence of an Iranian Neolithic-like component in Bronze Age and Iron Age Italian and Southern European samples.

Conceptual issues in hominin taxonomy: Homo heidelbergensis and an ethnobiological reframing of species

Efforts to name and classify Middle Pleistocene Homo, often referred to as "Homo heidelbergensis" are hampered by confusing patterns of morphology but also by conflicting paleoanthropological ideologies that are embedded in approaches to hominin taxonomy, nomenclature, and the species concept. We deconstruct these issues to show how the field's search for a "real" species relies on strict adherence to pre-Darwinian essentialist naming rules in a post-typological world. We then examine Middle Pleistocene Homo through the framework of ethnobiology, which examines on how Indigenous societies perceive, classify, and name biological organisms. This research reminds us that across human societies, taxonomies function to (1) identify and classify organisms based on consensus pattern recognition and (2) construct a stable nomenclature for effective storage, retrieval and communication of information. Naming Middle Pleistocene Homo as a "real" species cannot be verified with the current data; and separating regional groups into distinct evolutionary lineages creates taxa that are not defined by readily perceptible or universally salient differences. Based on ethnobiological studies of this kind of patterning, referring to these hominins above the level of the species according to their generic category with modifiers (e.g., "European Middle Pleistocene Homo") is consistent with observed human capabilities for cognitive differentiation, is both necessary and sufficient given the current data, and will allow for the most clear communication across ideologies going forward.

Environmental evolution, faunal and human occupation since 2 Ma in the Anagni basin, central Italy

We present the study of a composite, yet continuous sedimentary succession covering the time interval spanning 2.6–0.36 Ma in the intramontane basin of Anagni (central Italy) through a dedicated borecore, field surveys, and the review of previous data at the three palaeontological and archaeological sites of Colle Marino, Coste San Giacomo and Fontana Ranuccio. By combining the magneto- and chronostratigraphic data with sedimentologic and biostratigraphic analysis, we describe the palaeogeographic and tectonic evolution of this region during this entire interval. In this time frame, starting from 0.8 Ma, the progressive shallowing and temporary emersion of the large lacustrine basins and alluvial plains created favorable conditions for early hominin occupation of the area, as attested by abundant tool industry occurrences and fossils. This study provides new constraints to better interpret the hominin migratory dynamics and the factors that influenced the location and spatial distribution during the early occupation of this region.

Amplio, Ergo Sum

This article aims to explore the idea that enhancement technologies have been and will continue to be an essential element of what we might call the "human continuum," and are indeed key to our existence and evolution into persons. Whereas conservative commentators argue that enhancement is likely to cause us to lose our humanity and become something other, it is argued here that the very opposite is true: that enhancement is the core of what and who we are. Using evidence from paleoanthropology to examine the nature of our predecessor species, and their proclivities for tool use, we can see that there is good reason to assume that the development of Homo sapiens is a direct result of the use of enhancement technologies. A case is also made for broad understandings of the scope of enhancement, based on the significant evolutionary results of acts that are usually dismissed as "unremarkable." Furthermore, the use of enhancement by modern humans is no different than these prehistoric applications, and is likely to ultimately have similar results. There is no good reason to assume that whatever we may become will not also consider itself human.

A reassessment of the Montmaurin-La Niche mandible (Haute Garonne, France) in the context of European Pleistocene human evolution

We here present a comparative study of the Montmaurin-LN Middle Pleistocene mandible (Haute-Garonne, France). This mandible, of which its right and left molar series are preserved in situ, was found in La Niche cave (Montmaurin's karst system) in 1949, and was first attributed to the 'Mindel-Riss' interglacial (= MIS 9 to 11) based on its geological context. Later studies based on geological and faunal evidence have attributed the Montmaurin-LN mandible to MIS 7. Following a detailed morphological and metric comparative study of the mandible in the 1970s, it was interpreted in the light of a still limited fossil record and the prevailing paradigm back then. Waiting for geochronological studies in the forthcoming years, here we review the main morphological and metrical features of this mandible and its molars, which have been reassessed in the framework of a remarkably enlarged Pleistocene fossil record since the mandible was first described, and our current, more in-depth understanding of human evolution in Europe. Using a selection of mandibular features with potential taxonomic signal we have found that the Montmaurin-LN mandible shares only a few derived traits with Neandertals. Our analyses reveal that this mandible is more closely related to the ancient specimens from the African and Eurasian Early and Middle Pleistocene, particularly due to the presence of primitive features of the Homo clade. In contrast, the external morphology of the molars is clearly similar to that of Neandertals. The results are assessed in the light of the present competing hypotheses used to explain the European hominin fossil record.

Digital reconstruction of the Ceprano calvarium (Italy), and implications for its interpretation

The Ceprano calvarium was discovered in fragments on March 1994 near the town of Ceprano in southern Latium (Italy), embedded in Middle Pleistocene layers. After reconstruction, its morphological features suggests that the specimen belongs to an archaic variant of H. heidelbergensis, representing a proxy for the last common ancestor of the diverging clades that respectively led to H. neanderthalensis and H. sapiens. Unfortunately, the calvarium was taphonomically damaged. The postero-lateral vault, in particular, appears deformed and this postmortem damage may have influenced previous interpretations. Specifically, there is a depression on the fragmented left parietal, while the right cranial wall is warped and angulated. This deformation affected the shape of the occipital squama, producing an inclination of the transverse occipital torus. In this paper, after X-ray microtomography (μCT) of both the calvarium and several additional fragments, we analyze consistency and pattern of the taphonomic deformation that affected the specimen, before the computer-assisted retrodeformation has been performed; this has also provided the opportunity to reappraise early attempts at restoration. As a result, we offer a revised interpretation for the Ceprano calvarium’s original shape, now free from the previous uncertainties, along with insight for its complex depositional and taphonomic history.

Twentieth anniversary of Homo antecessor (1997-2017): a review

It has been twenty years since diagnosis and publication of the species Homo antecessor.¹ Since then, new human fossils recovered from the TD6 level of the Gran Dolina site (Sierra de Atapuerca, northern Spain) have helped to refine its taxonomic and phylogenetic position. In this paper, we present a synthesis of the most characteristic features of this species, as well as our interpretation derived from the latest investigations. We focus on the phylogenetic interpretation of Homo antecessor, taking into account the most recent paleogenetic analyses and a reassessment of the European Middle Pleistocene hominin record. We try to show that, twenty years after its publication, H. antecessor provides a good opportunity to address the morphology of the last common ancestor of Neandertals and modern humans.

New Middle Pleistocene hominin cranium from Gruta da Aroeira (Portugal)

The Middle Pleistocene is a crucial time period for studying human evolution in Europe, because it marks the appearance of both fossil hominins ancestral to the later Neandertals and the Acheulean technology. Nevertheless, European sites containing well-dated human remains associated with an Acheulean toolkit remain scarce. The earliest European hominin crania associated with Acheulean handaxes are at the sites of Arago, Atapuerca Sima de los Huesos (SH), and Swanscombe, dating to 400-500 ka (Marine Isotope Stage 11-12). The Atapuerca (SH) fossils and the Swanscombe cranium belong to the Neandertal clade, whereas the Arago hominins have been attributed to an incipient stage of Neandertal evolution, to Homo heidelbergensis, or to a subspecies of Homo erectus A recently discovered cranium (Aroeira 3) from the Gruta da Aroeira (Almonda karst system, Portugal) dating to 390-436 ka provides important evidence on the earliest European Acheulean-bearing hominins. This cranium is represented by most of the right half of a calvarium (with the exception of the missing occipital bone) and a fragmentary right maxilla preserving part of the nasal floor and two fragmentary molars. The combination of traits in the Aroeira 3 cranium augments the previously documented diversity in the European Middle Pleistocene fossil record.

Human Brain Expansion during Evolution Is Independent of Fire Control and Cooking

What makes humans unique? This question has fascinated scientists and philosophers for centuries and it is still a matter of intense debate. Nowadays, human brain expansion during evolution has been acknowledged to explain our empowered cognitive capabilities. The drivers for such accelerated expansion remain, however, largely unknown. In this sense, studies have suggested that the cooking of food could be a pre-requisite for the expansion of brain size in early hominins. However, this appealing hypothesis is only supported by a mathematical model suggesting that the increasing number of neurons in the brain would constrain body size among primates due to a limited amount of calories obtained from diets. Here, we show, by using a similar mathematical model, that a tradeoff between body mass and the number of brain neurons imposed by dietary constraints during hominin evolution is unlikely. Instead, the predictable number of neurons in the hominin brain varies much more in function of foraging efficiency than body mass. We also review archeological data to show that the expansion of the brain volume in the hominin lineage is described by a linear function independent of evidence of fire control, and therefore, thermal processing of food does not account for this phenomenon. Finally, we report experiments in mice showing that thermal processing of meat does not increase its caloric availability in mice. Altogether, our data indicate that cooking is neither sufficient nor necessary to explain hominin brain expansion.

Middle pleistocene human remains from Tourville-la-Rivière (Normandy, France) and their archaeological context

Despite numerous sites of great antiquity having been excavated since the end of the 19th century, Middle Pleistocene human fossils are still extremely rare in northwestern Europe. Apart from the two partial crania from Biache-Saint-Vaast in northern France, all known human fossils from this period have been found from ten sites in either Germany or England. Here we report the discovery of three long bones from the same left upper limb discovered at the open-air site of Tourville-la-Rivière in the Seine Valley of northern France. New U-series and combined US-ESR dating on animal teeth produced an age range for the site of 183 to 236 ka. In combination with paleoecological indicators, they indicate an age toward the end of MIS 7. The human remains from Tourville-la-Rivière are attributable to the Neandertal lineage based on morphological and metric analyses. An abnormal crest on the left humerus represents a deltoid muscle enthesis. Micro- and or macro-traumas connected to repetitive movements similar to those documented for professional throwing athletes could be origin of abnormality.

New radiometric ages for the BH-1 hominin from Balanica (Serbia): implications for understanding the role of the Balkans in Middle Pleistocene human evolution

Newly obtained ages, based on electron spin resonance combined with uranium series isotopic analysis, and infrared/post-infrared luminescence dating, provide a minimum age that lies between 397 and 525 ka for the hominin mandible BH-1 from Mala Balanica cave, Serbia. This confirms it as the easternmost hominin specimen in Europe dated to the Middle Pleistocene. Inferences drawn from the morphology of the mandible BH-1 place it outside currently observed variation of European Homo heidelbergensis. The lack of derived Neandertal traits in BH-1 and its contemporary specimens in Southeast Europe, such as Kocabaş, Vasogliano and Ceprano, coupled with Middle Pleistocene synapomorphies, suggests different evolutionary forces acting in the east of the continent where isolation did not play such an important role during glaciations.

Before the Emergence of Homo sapiens: Overview on the Early-to-Middle Pleistocene Fossil Record (with a Proposal about Homo heidelbergensis at the subspecific level)

The origin of H. sapiens has deep roots, which include two crucial nodes: (1) the emergence and diffusion of the last common ancestor of later Homo (in the Early Pleistocene) and (2) the tempo and mode of the appearance of distinct evolutionary lineages (in the Middle Pleistocene). The window between 1,000 and 500 thousand years before present appears of crucial importance, including the generation of a new and more encephalised kind of humanity, referred to by many authors as H. heidelbergensis. This species greatly diversified during the Middle Pleistocene up to the formation of new variants (i.e., incipient species) that, eventually, led to the allopatric speciation of H. neanderthalensis and H. sapiens. The special case furnished by the calvarium found near Ceprano (Italy), dated to 430–385 ka, offers the opportunity to investigate this matter from an original perspective. It is proposed to separate the hypodigm of a single, widespread, and polymorphic human taxon of the Middle Pleistocene into distinct subspecies (i.e., incipient species). The ancestral one should be H. heidelbergensis, including specimens such as Ceprano and the mandible from Mauer.

The stem species of our species: a place for the archaic human cranium from Ceprano, Italy

One of the present challenges in the study of human evolution is to recognize the hominin taxon that was ancestral to Homo sapiens. Some researchers regard H. heidelbergensis as the stem species involved in the evolutionary divergence leading to the emergence of H. sapiens in Africa, and to the evolution of the Neandertals in Europe. Nevertheless, the diagnosis and hypodigm of H. heidelbergensis still remain to be clarified. Here we evaluate the morphology of the incomplete cranium (calvarium) known as Ceprano whose age has been recently revised to the mid of the Middle Pleistocene, so as to test whether this specimen may be included in H. heidelbergensis. The analyses were performed according to a phenetic routine including geometric morphometrics and the evaluation of diagnostic discrete traits. The results strongly support the uniqueness of H. heidelbergensis on a wide geographical horizon, including both Eurasia and Africa. In this framework, the Ceprano calvarium – with its peculiar combination of archaic and derived traits – may represent, better than other penecontemporaneous specimens, an appropriate ancestral stock of this species, preceding the appearance of regional autapomorphic features.

The biology of the colonizing ape

Hominin evolutionary history is characterized by regular dispersals, cycles of colonization, and entry into novel environments. This article considers the relationship between such colonizing capacity and hominin biology. In general, colonizing strategy favors rapid rates of reproduction and generalized rather than specialized biology. Physiological viability across diverse environments favors a high degree of phenotypic plasticity, which buffers the genome from selective pressures. Colonizing also favors the capacity to access and process information about environmental variability. We propose that early hominin adaptive radiations were based upon the development of such capacities as adaptations to unstable Pliocene environments. These components came together, along with fundamental changes in morphology, behavior, and cognition in the genus Homo, who exploited them in subsequent wider dispersals. Middle Pleistocene hominins and modern humans also show development of further traits, which correspond with successful probing of, and dispersals into, stressful environments. These traits have their precursors in primate or ape biology, but have become more pronounced during hominin evolution. First, short interbirth intervals and slow childhood growth allow human females to provision several offspring simultaneously, increasing the rate of reproduction in favorable conditions. This allows rapid recovery from population crashes, or rapid population growth in new habitats. Second, despite high geographical phenotypic variability, humans have high genetic unity. This is achieved by a variety of levels of plasticity, including physiology, behavior, and technology, which reduce the need to commit to genetic adaptation. Hominin behavior may increasingly have shaped both the ecological niches occupied and the selective pressures acting back on the genome. Such selective pressures may have been exacerbated by population dynamics, predicted to both derive from, and favor, the colonizing strategy. Exposure to ecological variability is likely to have generated particular selective pressures on female biology, favoring increasing steering of offspring ontogeny by maternal phenotype. We propose that the concept of hominins as "colonizing apes" offers a novel unified model for interpreting the suite of traits characteristic of our genus.

Natural history of Homo erectus

Our view of H. erectus is vastly different today than when Pithecanthropus erectus was described in 1894. Since its synonimization into Homo, views of the species and its distribution have varied from a single, widely dispersed, polytypic species ultimately ancestral to all later Homo, to a derived, regional isolate ultimately marginal to later hominin evolution. A revised chronostratigraphic framework and recent work bearing either directly or indirectly on reconstructions of life-history patterns are reviewed here and, together with a review of the cranial and postcranial anatomy of H. erectus, are used to generate a natural history of the species. Here I argue that H. erectus is a hominin, notable for its increased body size, that originates in the latest Pliocene/earliest Pleistocene of Africa and quickly disperses into Western and Eastern Asia. It is also an increasingly derived hominin with several regional morphs sustained by intermittent isolation, particularly in Southeast Asia. This view differs from several current views, most especially that which recognizes only a single hominin species in the Pleistocene, H. sapiens, and those which would atomize H. erectus into a multiplicity of taxa. Following Jolly ([2001] Yrbk Phys Anthropol 44:177-204), the regional morphs of H. erectus may be productively viewed as geographically replacing allotaxa, rather than as the focus of unresolvable species debates. Such a view allows us to focus on the adaptations and biology of local groups, including questions of biogeographic isolation and local adaptation. A number of issues remain unresolved, including the significance of diversity in size and shape in the early African and Georgian records.

Landmark-based shape analysis of the archaicHomo calvarium from Ceprano (Italy)

The Ceprano calvarium represents one of the most important sources of information about both the dynamics of the earliest hominid dispersal toward Europe and the evolution of the genus Homo in the early-to-middle Pleistocene. In this paper, the midsagittal vault profile and the 3D frontal bone morphology of Ceprano are investigated comparatively, using landmark coordinates and Procrustes superimposition. In fact, despite the fact that the skull appears partially distorted by diagenetic pressures (thus precluding a comprehensive landmark-based analysis), some aspects of the overall morphology are suitable for consideration in terms of geometric morphometrics. The midsagittal profile shows an archaic shape, comparable with the H. ergaster/erectus range of variation because of the fronto-parietal flattening, the development of the supraorbital and nuchal structures, and the occurrence of a slightly larger occipital bone. By contrast, the frontal bone displays a derived 3D shape that, mostly because of the widening of the frontal squama, appears comparable with the Afro-European variation of the Middle Pleistocene (i.e., H. heidelbergensis/rhodesiensis). Taking into account the unique morphological pattern displayed by Ceprano, its role as a link between early Homo and the Middle Pleistocene populations of Europe and Africa is not falsified. Thus, when aspects of the Ceprano's morphology are described within the analytical framework provided by geometric morphometrics, the relationships between Ceprano and the subsequent Afro-European fossil record are emphasized, suggesting the occurrence of an ancestral stock of H. heidelbergensis/rhodesiensis that is properly represented by the Italian specimen.

Adaptive dimensions of health research among indigenous Siberians

Present evidence suggests that modern humans were the first hominid species to successfully colonize high-latitude environments (> or =55 degrees N). Given evidence for a recent (<200,000 years) lower latitude naissance of modern humans, the global dispersal and successful settlement of arctic and subarctic regions represent an unprecedented adaptive shift. This adaptive shift, which included cultural, behavioral, and biological dimensions, allowed human populations to cope with the myriad environmental stressors encountered in circumpolar regions. Although unique morphological and physiological adaptations among contemporary northern residents have been recognized for decades, human biologists are only now beginning to consider whether biological adaptations to regional environmental conditions influence health changes associated with economic modernization and lifestyle change. Recent studies have documented basal metabolic rates (BMRs) among indigenous Siberian populations that are systematically elevated compared to lower latitude groups; this metabolic elevation apparently is a physiological adaptation to cold stress experienced in the circumpolar environment. Important health implications of metabolic adaptation are suggested by research with the Yakut (Sakha), Evenki, and Buriat of Siberia. BMR is significantly positively correlated with blood pressure, independently of body size, body composition, and various potentially confounding variables (e.g., age and smoking). Further, this research has documented a significant negative association between BMR and LDL cholesterol, which remains after controlling for potential confounders; this suggests that high metabolic turnover among indigenous Siberians has a protective effect with regard to plasma lipid levels. These results underscore the importance of incorporating an evolutionary approach into health research among northern populations.

A critical review of the German Paleolithic hominin record

We review the hominin fossil record from western Central Europe in light of the recent major revisions of the geochronological context. The mandible from Mauer (Homo heidelbergensis), dated to circa 500,000 years ago, continues to represent the earliest German hominin and may coincide with the occupation of Europe north of the high alpine mountain chains. Only limited new evidence is available for the Middle Pleistocene, mostly in the form of skull fragments, a pattern that may relate to taphonomic processes. These finds and their ages suggest the gradual evolution of a suite of Neandertal features during this period. Despite new finds of classic Neandertals, there is no clear proof for Neandertal burial from Germany. Alternatively, cut marks on a skull fragment from the Neandertal type site suggest special treatment of that individual. New Accelerator Mass Spectrometry (AMS) radiocarbon dates of previous finds leave little reliably dated evidence for anatomically modern humans (AMH) in Europe before 30,000 BP; the remains from Hahnöfersand, Binshof-Speyer, Paderborn-Sande, and Vogelherd are now of Holocene age. Thus, a correlation of AMH with the Aurignacian remains to be proven, and the general idea of a long coexistence of Neandertals and AMH in Europe may be questioned. In western Central Europe, evidence of Gravettian human fossils is also very limited, although a new double grave from lower Austria may be relevant. The only dated burial from the German Upper Paleolithic (from Mittlere Klause) falls into a time period (circa 18,600 BP) represented by only a few occupation sites in western Central Europe. A number of human remains at Magdalenian sites appear to result from variable (secondary) burial practices. In contrast, the Final Paleolithic (circa 12,000-9600 cal. BC) yields an increase of hominin finds, including multiple burials (Bonn-Oberkassel, Neuwied-Irlich), similar to the situation in western and southern Europe.

CT-based description and phyletic evaluation of the archaic human calvarium from Ceprano, Italy

The discovery in 1994, of a fossilized human calvarium near Ceprano, Italy, dated about 800-900 thousand years before present, opened a new page for the study of human evolution in Europe. It extended the continental fossil record over the boundary between Early and Middle Pleistocene for the first time and revealed the cranial morphology of humans that where probably ancestral to both Neanderthals and modern Homo sapiens. A tomographic analysis of the Italian specimen is reported here in order to describe size and shape, vascular traces, and other features of the endocranium, as well as some relevant ectocranial traits (particularly of the frontal region). Our results show that the Ceprano calvarium displays plesiomorphies shared by early Homo taxa, involving a general archaic phenotype. At the same time, the presence of some derived features suggests a phylogenetic relationship with the populations referred to the subsequent polymorphic species H. heidelbergensis. The morphology of the supraorbital structures is different from the double-arched browridge of the African H. ergaster, while its superior shape shows similarities with African Middle Pleistocene specimens (Bodo, Kabwe). In contrast, the relationship between supraorbital torus and frontal squama points to an archaic pattern of the relationship between face and vault, associated to moderately narrow frontal lobes and limited development of the upper parietal areas. Despite a nonderived endocranial shape, the increase of cranial capacity (related to a general endocranial widening) and the probable absence of a clear occipital projection also suggest an evolutionary independence from the Asian H. erectus lineage. This analysis therefore supports the conclusion that the Ceprano calvarium represents the best available candidate for the ancestral phenotype of the cranial variation observed among Middle Pleistocene fossil samples in Africa and Europe. Nevertheless, a proper taxonomic interpretation of this crucial specimen remains puzzling.

An Early Pleistocene hominin mandible from Atapuerca-TD6, Spain

We present a mandible recovered in 2003 from the Aurora Stratum of the TD6 level of the Gran Dolina site (Sierra de Atapuerca, northern Spain). The specimen, catalogued as ATD6-96, adds to the hominin sample recovered from this site in 1994-1996, and assigned to Homo antecessor. ATD6-96 is the left half of a gracile mandible belonging to a probably female adult individual with premolars and molars in place. This mandible shows a primitive structural pattern shared with all African and Asian Homo species. However, it is small and exhibits a remarkable gracility, a trait shared only with the Early and Middle Pleistocene Chinese hominins. Furthermore, none of the mandibular features considered apomorphic in the European Middle and Early Upper Pleistocene hominin lineage are present in ATD6-96. This evidence reinforces the taxonomic identity of H. antecessor and is consistent with the hypothesis of a close relationship between this species and Homo sapiens.

Early-Middle Pleistocene transitions: an overview and recommendation for the defining boundary

The Early-Middle Pleistocene transition (c. 1.2–0.5 Ma), sometimes known as the ‘mid-Pleistocene revolution’, represents a major episode in Earth history. Low-amplitude 41-ka obliquity-forced climate cycles of the earlier Pleistocene were replaced progressively in the later Pleistocene by high-amplitude 100-ka cycles. These later cycles are indicative of slow ice build-up and subsequent rapid melting, and imply a transition to a strongly non-linear forced climate system. Changes were accompanied by substantially increased global ice volume at 940 ka. These climate transformations, particularly the increasing severity and duration of cold stages, have had a profound effect on the biota and the physical landscape, especially in the northern hemisphere. This review assesses and integrates the marine and terrestrial evidence for change across this transition, based on the literature and especially the following 17 chapters in the present volume. Orbital and non-orbital climate forcing, palaeoceanography, stable isotopes, organic geochemistry, marine micropalaeontology, glacial history, loess-palaeosol sequences, pollen analysis, large and small mammal palaeoecology and stratigraphy, and human evolution and dispersal are all considered, and a series of discrete events is identified from Marine Isotope Stage (MIS) 36 (c. 1.2 Ma) to MIS 13 (c. 540–460 Ma). Of these, the cold MIS 22 (c. 880–870 ka) is perhaps the most profound. However, we here endorse earlier views that on practical grounds the Matuyama-Brunhes palaeomagnetic Chron boundary (mid-point at 773 ka, with an estimated duration of 7 ka) would serve as the best overall guide for establishing the Early-Middle Pleistocene Subseries boundary.

Small Mid-Pleistocene Hominin Associated with East African Acheulean Technology

Hominin fossils from the African mid-Pleistocene are rare despite abundant Acheulean tools in Africa and apparently African-derived hominins in Eurasia between 1.0 and 0.5 million years ago (Ma). Here we describe an African fossil cranium constrained by 40Ar/39Ar analyses, magnetostratigraphy, and sedimentary features to 0.97 to 0.90 Ma, and stratigraphically associated with Acheulean handaxes. Although the cranium represents possibly the smallest adult or near-adult known between 1.7 and 0.5 Ma, it retains features observed in larger Homo erectus individuals, yet shows a distinct suite of traits indicative of wide population variation in the hominins of this period.

Brain size and encephalization in early to Mid-PleistoceneHomo

Important changes in the brain have occurred during the course of human evolution. Both absolute and relative size increases can be documented for species of Homo, culminating in the appearance of modern humans. One species that is particularly well-represented by fossil crania is Homo erectus. The mean capacity for 30 individuals is 973 cm(3). Within this group there is substantial variation, but brain size increases slightly in specimens from later time periods. Other Middle Pleistocene crania differ from those of Homo erectus. Characters of the facial skeleton, vault, and cranial base suggest that fossils from sites such as Arago Cave in France, the Sima de los Huesos in Spain, Bodo in Ethiopia, Broken Hill in Zambia, and perhaps Dali in China belong to the taxon Homo heidelbergensis. Ten of these mid-Quaternary hominins have brains averaging 1,206 cm(3) in volume, and many fall beyond the limits of size predicted for Homo erectus of equivalent age. When orbit height is used to construct an index of relative brain size, it is apparent that the (significant) increase in volume documented for the Middle Pleistocene individuals is not simply a consequence of larger body mass. Encephalization quotient values confirm this finding. These changes in absolute and relative brain size can be taken as further corroborative evidence for a speciation event, in which Homo erectus produced a daughter lineage. It is probable that Homo heidelbergensis originated in Africa or western Eurasia and then ranged widely across the Old World. Archaeological traces indicate that these populations differed in their technology and behavior from earlier hominins.

Modern human origins: progress and prospects

The question of the mode of origin of modern humans (Homo sapiens) has dominated palaeoanthropological debate over the last decade. This review discusses the main models proposed to explain modern human origins, and examines relevant fossil evidence from Eurasia, Africa and Australasia. Archaeological and genetic data are also discussed, as well as problems with the concept of 'modernity' itself. It is concluded that a recent African origin can be supported for H. sapiens, morphologically, behaviourally and genetically, but that more evidence will be needed, both from Africa and elsewhere, before an absolute African origin for our species and its behavioural characteristics can be established and explained.