Apes and Tricksters: The Evolution and Diversification of Humans’ Closest Relatives

The evolutionary history of humans comprises an important but small branch on the larger tree of ape evolution. Today’s hominoids—gibbons, orangutans, gorillas, chimpanzees, and humans—are a meager representation of the ape diversity that characterized the Old World from 23–5 million years ago. In this paper, I briefly review this evolutionary history focusing on features important for understanding modern ape and human origins. As the full complexity of ape evolution is beyond this review, I characterize major geographic, temporal, and phylogenetic groups using a few flagship taxa. Improving our knowledge of hominoid evolution both complicates and clarifies studies of human origins. On one hand, features thought to be unique to the human lineage find parallels in some fossil ape species, reducing their usefulness for identifying fossil humans. On the other hand, the Miocene record of fossil apes provides an important source for generating hypotheses about the ancestral human condition; this is particularly true given the dearth of fossils representing our closest living relatives: chimpanzees and gorillas.     

Lagoa Santa's contribution to the origins and life of early Americans

The region of Lagoa Santa, Central‐Eastern Brazil, provides an exceptional archeological record about Late Pleistocene/Early Holocene occupation of the Americas. Since the first interventions made by the Danish naturalist Peter Lund in the 19th century, hundreds of human skeletons have been exhumed in the region. These skeletons are complemented by a rich botanic, faunal, technological, and geomorphological archeological record. We explore here the contributions of Lagoa Santa material to the origins and lifestyle of early Americans, providing an historic background. Cranial morphology of Lagoa Santa skeletons allowed the proposition of a model of two biological components for the occupation of the Americas, in which early Americans are morphologically similar to people of African and Australo‐Melanesian origin. Furthermore, the archeological record in the region has revealed an intense use of plant resources, a restricted spatial distribution, and the symbolic elaboration of local hunter‐gatherers, unveiling a distinct lifestyle compared to early North American populations.     

From small holes to grand narratives: the impact of taphonomy and sample size on the modernity debate in Australia and New Guinea

Our knowledge of early Australasian societies has significantly expanded in recent decades with more than 220 Pleistocene sites reported from a range of environmental zones and depositional contexts. The uniqueness of this dataset has played an increasingly important role in global debates about the origins and expression of complex behaviour among early modern human populations. Nevertheless, discussions of Pleistocene behaviour and cultural innovation are yet to adequately consider the effects of taphonomy and archaeological sampling on the nature and representativeness of the record. Here, we investigate the effects of preservation and sampling on the archaeological record of Sahul, and explore the implications for understanding early cultural diversity and complexity. We find no evidence to support the view that Pleistocene populations of Sahul lacked cognitive modernity or cultural complexity. Instead, we argue that differences in the nature of early modern human populations across the globe were more likely the consequence of differences in population size and density, interaction and historical contingency.     

东亚现代人来源的考古学思考:证据与解释

现代人的起源与扩散是当今古人类学界极具争议的问题。目前,"多地区进化"假说和非洲起源为主的"同化"假说是该争议的两大阵营。在"多地区进化"假说的基础上,立足中国的化石材料,吴新智提出了中国乃至东亚古人类"连续演化、附带杂交"的假说,认为中国的现代人主要由本地古老类型人类演化而来。本文从现代人扩散关键时段的考古材料出发,讨论氧同位素5～3阶段(大约13～3万年)考古材料在研究中国现代人形成中的作用和存在的挑战。首先,概括介绍现代人起源的主要假说和现代人扩散的假定路线——南线和北线的多重证据;其次,在此背景下,通过对中国境内考古材料的概括,分析不同石器技术可能反映的现代人来源;最后,简要探讨立足考古材料研究现代人起源与扩散的挑战。总体而言,氧同位素5～3阶段的旧石器考古材料支持中国北方南部和中国南方古人类的连续演化,同时也指示了非洲扩散而出的现代人人群自西北地区和南方地区进入中国的可能性。该模式支持中国古人类"连续演化、附带杂交"假说,然而我们也认识到中国现代人起源研究的考古基础仍十分薄弱,使用考古学材料研究现代人扩散的理论基础也需探讨。目前,细化、完善基础考古数据仍是中国旧石器时代考古学和古人类学学者努力的主要方向之一。如此,我们才能够更加有效地将人类化石与考古学证据融合,进而结合分子生物学的研究,更为全面地理解现代人的起源与演化。     

The view from down under: a test of the multiregional hypothesis of modern human origins using the basicranial evidence from Australasia

Proponents of the Multiregional Hypothesis of modern human origins have consistently stated that Australasia provides one of the most compelling examples of regional continuity in the human fossil record. According to these workers, features found in the earliest Homo erectus fossils from Sangiran, Central Java, can be traced through more advanced hominids from Ngandong and are found in fossil and recent Australian Aborigines. In order to test the hypothesis that a close evolutionary relationship exists amongst the fossils from Australasia, this study will examine the cranial base. This region of the skull is considered to be evolutionarily conservative and has relatively good representation and preservation throughout much of the Australasian record. The results of this project highlight a number of features on the cranial base in the Ngandong sample that appear to be unique not only within the region, but in the human fossil sample as a whole. Several of these features, such as the morphology of the foramen ovale, the location of the squamotympanic fissure in the roof of the temporomandibular fossa, and the extreme expression of the postcondyloid tuberosities have been pointed out by workers such as Weidenreich and Jacob in their surveys of this material. The presence of these characters in the Ngandong population, and their apparent lack of expression outside of this group, provides strong evidence of discontinuity in the Australasian fossil record.     

The global evidence of early human symboling behaviour

A model of art origins based on the author’s first-hand studies is presented, which differs significantly from the dominant paradigm of these developments. The earliest known evidence for art, art-like or presumably non-utilitarian activities collectively provide the principal information about human symboling behaviour. These corpora are systematically considered from each continent, including rock art and various surviving forms of portable art. The immense age of some of this evidence is illuminated, and the record’s poor resolution with increasing age is presented as an essentially taphonomic phenomenon. It is shown, nevertheless, that the available record provides a considerably broader basis for hypotheses about symbolism, language and cognitive evolution than is often assumed, and that the evidence favours a model of comparatively early origins of the human capacity of concept-mediated thought and culture. These beginnings may be found in the endeavours of Lower Palaeolithic hominids to create taxonomic systems of physical reality. The available record renders it likely that such capacities existed several hundred thousand years ago.     

A new research strategy for integrating studies of paleoclimate,paleoenvironment, and paleoanthropology

Paleoanthropologists (scientists studying human origins) universally recognize the evolutionary significance of ancient climates and environments for understanding human origins. 1 - 6 Even those scientists working in recent phases of human evolution, when modern humans evolved, agree that hunter‐gatherer adaptations are tied to the way that climate and environment shape the food and technological resource base. 7 - 10 The result is a long tradition of paleoanthropologists engaging with climate and environmental scientists in an effort to understand if and how hominin bio‐behavioral evolution responded to climate and environmental change. Despite this unusual consonance, the anticipated rewards of this synergy are unrealized and, in our opinion, will not reach potential until there are some fundamental changes in the way the research model is constructed. Discovering the relation between climate and environmental change to human origins must be grounded in a theoretical framework and a causal understanding of the connection between climate, environment, resource patterning, behavior, and morphology, then move beyond the strict correlative research that continues to dominate the field.     

The origins and early elaboration of projectile technology

The ability of Homo sapiens to kill prey at a distance is arguably one of the catalysts for our current ecological dominance. Many researchers have suggested its origins lie in the African Middle Stone Age or the European Middle Palaeolithic (～300‐30 thousand years ago), but the perishable components of armatures rarely preserve. Most research on this subject therefore emphasises analysis of armature tip size, shape, and diagnostic impacts or residues. Other lines of evidence have included human skeletal anatomy or analyses of the species composition of faunal assemblages. Projectile Impact Marks (PIMs) on archaeofaunal remains offer an ideal complement to this work, but their potential has been restricted mainly to the later Eurasian zooarchaeological record. A review of current evidence and approaches shows that systematic PIM research could add much to our understanding of early projectile technology, especially in Africa.     

朝向人类起源与演化研究的共业:古人类学、考古学与遗传学的交叉与整合

对于方兴未艾的现代人类起源与演化问题的研究,目前主要在遗传学、古人类学和旧石器时代考古学三个领域内进行。学者们提出了"多地区进化说"、"连续进化附带杂交说"、"出自非洲说"、"融合说"等观点与假说,有的学说针锋相对,南辕北辙。究其原因,除了相关研究还处于盲人摸象的阶段,只是在局部问题与材料上做分析和解释,尚无法得出全面、能被普遍接受的结论外,由于不同学科存在研究对象、方法和思路的不同,学科间缺少了解、沟通与协作,出现一些学术语言和研究结论不被彼此理解和接受的情况,存在一定的误解与无谓的争论,影响了相互之间的借鉴、互动和成果的共享,进而妨碍了跨学科的整合研究并达成学术共识。其实,每个学科都有自己的特点和不可替代的优势,每个学科也有难以克服的弱点,在解决人类起源与演化这样重大的学术问题上,任何一个学科都不可能包打天下,独享其成。因而,开展相关领域的交流合作,尤其是传统的古人类学、考古学与新兴的分子生物学之间的交叉与协作,明确彼此的关注点、需求和专长,凝练共同的学术问题和目标,整合现有的研究问题、资源与成果并向着共同的学术方向一道前行,是推动相关研究走向深入并破译现代人起源这一重大命题的必要举措。     

Multiregional, not multiple origins

Multiregional evolution is a model to account for the pattern of human evolution in the Pleistocene. The underlying hypothesis is that a worldwide network of genic exchanges, between evolving human populations that continually divide and reticulate, provides a frame of population interconnections that allows both species-wide evolutionary change and local distinctions and differentiation. "Multiregional" does not mean independent multiple origins, ancient divergence of modern populations, simultaneous appearance of adaptive characters in different regions, or parallel evolution. A valid understanding of multiregional evolution would go a long way toward reducing the modern human origins controversy.     

Early sponge evolution: A review and phylogenetic framework

Sponges are one of the critical groups in understanding the early evolution of animals. Traditional views of these relationships are currently being challenged by molecular data, but the debate has so far made little use of recent palaeontological advances that provide an independent perspective on deep sponge evolution. This review summarises the available information, particularly where the fossil record reveals extinct character combinations that directly impinge on our understanding of high-level relationships and evolutionary origins. An evolutionary outline is proposed that includes the major early fossil groups, combining the fossil record with molecular phylogenetics. The key points are as follows. (1) Crown-group sponge classes are difficult to recognise in the fossil record, with the exception of demosponges, the origins of which are now becoming clear. (2) Hexactine spicules were present in the stem lineages of Hexactinellida, Demospongiae, Silicea and probably also Calcarea and Porifera; this spicule type is not diagnostic of hexactinellids in the fossil record. (3) Reticulosans form the stem lineage of Silicea, and probably also Porifera. (4) At least some early-branching groups possessed biminerallic spicules of silica (with axial filament) combined with an outer layer of calcite secreted within an organic sheath. (5) Spicules are homologous within Silicea, but also between Silicea and Calcarea, and perhaps with Homoscleromorpha. (6) The last common ancestor of extant sponges was probably a thin-walled, hexactine-bearing sponge with biminerallic spicules. (7) The stem group of sponges included tetraradially-symmetric taxa that grade morphologically into Cambrian fossils described as ctenophores. (8) The protomonaxonid sponges are an early-branching group, probably derived from the poriferan stem lineage, and include the problematic chancelloriids as derived members of the piraniid lineage. (9) There are no definite records of Precambrian sponges: isolated hexactine-like spicules may instead be derived from radiolarians. Early sponges had mineralised skeletons and thus should have a good preservation potential: the lack of sponge fossils in Precambrian strata may be due to genuine absence of sponges. (10) In contrast to molecular clock and biomarker evidence, the fossil record indicates a basal Cambrian diversification of the main sponge lineages, and a clear relationship to ctenophore-like ancestors. Overall, the early sponge fossil record reveals a diverse suite of extinct and surprising character combinations that illustrate the origins of the major lineages; however, there are still unanswered questions that require further detailed studies of the morphology, mineralogy and structure of early sponges.     

The origins of stone tool technology in Africa: a historical perspective

The search for the earliest stone tools is a topic that has received much attention in studies on the archaeology of human origins. New evidence could position the oldest traces of stone tool-use before 3.39 Myr, substantially earlier than previously documented. Nonetheless, the first unmistakable evidence of tool-making dates to 2.6 Ma, the period in which Oldowan assemblages first appear in the East African record. However, this is not an unchangeable time boundary, and considerations about the tempo and modo of tool-making emergence have varied through time. This paper summarizes the history of research on the origins of stone knapping in Africa and places the current evidence in a historical perspective.     

Skeletal biology,functional asymmetry and the origins of "Handedness"

The past decade has witnessed the (re)emergence of a debate as to whether handedness is apomorphic within hominins. There are both qualitative and quantitative arguments, some which draw non-human primates into the handed sphere and others which exclude them. Ultimate questions concern origins of structural asymmetry of both brain and body and lateralized behaviours with implications for tool use and language. Lateralization is thus an important realm of phylogenetic study, and archaeologists and psychologists alike have sought to identify handedness within material culture. However, hand preference for tool manufacture and use among extant non-human primates, such as Cebus and Pan, suggests that the archaeological record may well be mute regarding the origins of laterality. In this paper, an argument is put forward positioning skeletal biology as a viable approach to the handedness origins issue. Behaviour is a mediator of the complementary processes of geometric modelling (change in size and shape) and histological remodelling (disuse osteopenia; microfracture repair); therefore, directional asymmetry in the pattern of skeletal modelling and remodelling is a putative signal of lateralized activity.     

A stem-group caecilian (Lissamphibia: Gymnophiona) from the Lower Cretaceous of North Africa

Of living amphibian groups, the limbless burrowing caecilians are amongst the most highly specialised, but are the least known. Their fossil record is extremely poor, leaving unresolved questions as to their origins, relationships and early distribution. We describe here caecilian remains from a Lower Cretaceous (Berriasian) microfossil locality near Anoual, Morocco. This material represents the second oldest record for the group, after the Jurassic Eocaecilia of North America, and the earliest caecilian record for Gondwana. It forms the basis of a new genus, Rubricacaecilia , which appears slightly more derived than Eocaecilia , but lacks major features of crown-group taxa. We support the use of Apoda Oppel, 1811 for the crown-group alone, and Gymnophiona Rafinesque 1814 for the clade comprising stem-group taxa + Apoda.     

Did a discrete event 200,000-100,000 years ago produce modern humans?

Scenarios for modern human origins are often predicated on the assumption that modern humans arose 200,000-100,000 years ago in Africa. This assumption implies that something ‘special’ happened at this point in time in Africa, such as the speciation that produced Homo sapiens, a severe bottleneck in human population size, or a combination of the two. The common thread is that after the divergence of the modern human and Neandertal evolutionary lineages ∼400,000 years ago, there was another discrete event near in time to the Middle-Late Pleistocene boundary that produced modern humans. Alternatively, modern human origins could have been a lengthy process that lasted from the divergence of the modern human and Neandertal evolutionary lineages to the expansion of modern humans out of Africa, and nothing out of the ordinary happened 200,000-100,000 years ago in Africa.Three pieces of biological (fossil morphology and DNA sequences) evidence are typically cited in support of discrete event models. First, living human mitochondrial DNA haplotypes coalesce ∼200,000 years ago. Second, fossil specimens that are usually classified as ‘anatomically modern’ seem to appear shortly afterward in the African fossil record. Third, it is argued that these anatomically modern fossils are morphologically quite different from the fossils that preceded them.Here I use theory from population and quantitative genetics to show that lengthy process models are also consistent with current biological evidence. That this class of models is a viable option has implications for how modern human origins is conceptualized.     

Zooarcheological evidence for the faunal exploitation behavior of Neandertals and early modern humans

The study of the origins of modern humans continues to be a dynamic, quickly changing field, as shown by the recent extraction and analysis of DNA from the Neander Valley fossils.¹ The dynamic nature of the field partly arises from the clearly defined opposing models for the origins of modern humans,² and the spirited defense of the opposing models by the main protagonists in the debate. Although the “Out-of-Africa” and “Multiregional Continuity Models” are typically argued from the perspective of biological evolution, with the debates centering on anatomical and molecular evidence, the behavioral side of the question is of equal significance. Even though the anatomical record will always be a productive avenue for behavioral reconstruction,^3,4 archeology remains the major contributor to our understanding of the behavioral side of this debate.     

Into Eurasia: A geometric morphometric re-assessment of the Upper Cave (Zhoukoudian) specimens

Since the discovery of the human remains from the Upper Cave of Zhoukoudian in the 1930s there has been speculation over their affinities. In particular, the degree to which the three adult crania exhibit recent East Asian morphology, as well as their degree of within-group variability, has long been debated. Several early researchers described a resemblance to East Asian populations, but these findings have been for the most part rejected by more recent metric and non-metric analyses. Nevertheless, the Upper Cave specimens have not been classified conclusively into any recent modern human population to which they have been compared, and classification results differ for each cranium. Here, the question of the affinities of Upper Cave 101 and 103, the two better-preserved crania, is examined from the perspective of the Late Pleistocene human fossil record using the methodology of 3-D geometric morphometrics. The degree of morphological variation between the two specimens is also evaluated within the context of recent population variability. Neurocranial and facial morphology are analyzed separately so as to maximize comparative samples. Results show a morphological resemblance of the Upper Cave material to Upper Paleolithic Europeans. It is proposed that the Upper Cave specimens retain important aspects of modern human ancestral morphology, and possibly share a recent common ancestral population with Upper Paleolithic Europeans, in accordance with the Single Origin model of modern human origins.     

Identification of new human origins of DNA replication by an origin-trapping assay

Metazoan genomes contain thousands of replication origins, but only a limited number have been characterized so far. We developed a two-step origin-trapping assay in which human chromatin fragments associated with origin recognition complex (ORC) in vivo were first enriched by chromatin immunoprecipitation. In a second step, these fragments were screened for transient replication competence in a plasmid-based assay utilizing the Epstein-Barr virus latent origin oriP. oriP contains two elements, an origin (dyad symmetry element [DS]) and the family of repeats, that when associated with the viral protein EBNA1 facilitate extrachromosomal stability. Insertion of the ORC-binding human DNA fragments in oriP plasmids in place of DS enabled us to screen functionally for their abilities to restore replication. Using the origin-trapping assay, we isolated and characterized five previously unknown human origins. The assay was validated with nascent strand abundance assays that confirm these origins as active initiation sites in their native chromosomal contexts. Furthermore, ORC and MCM2-7 components localized at these origins during G(1) phase of the cell cycle but were not detected during mitosis. This finding extends the current understanding of origin-ORC dynamics by suggesting that replication origins must be reestablished during the early stages of each cell division cycle and that ORC itself participates in this process.     

Models and realities in modern human origins: the African fossil evidence.

The recent application of such chronometric techniques as electron spin resonance (ESR), thermoluminescence (TL), and uranium series dating has had a significant impact on perceptions of modern human origins. Claims for the presence of anatomically modern humans in Africa prior to 100 ka and for the transition leading to modern Africans at an even earlier date have been made, partly based on results of these techniques. However, a careful examination of the pertinent record shows that these claims are not unequivocally supported by the available fossil and chronological evidence.