Zeresenay Alemseged

California Academy of Sciences · Department of Anthropology

The phylogenetic position of Homo habilis is central to debates over the origin and early evolution of the genus Homo. A large portion of the species hypodigm consists of dental remains, but they have only been studied at the often worn enamel surface. We investigate the morphology of the H. habilis enamel-dentine junction (EDJ), which is preserved...

The Miocene was a key time in the evolution of African ecosystems witnessing the origin of the African apes and the isolation of eastern coastal forests through an expanding arid corridor. Until recently, however, Miocene sites from the southeastern regions of the continent were unknown. Here, we report the first Miocene fossil teeth from the shoul...

The naming of Australopithecus africanus in 1925, based on the Taung Child, heralded a new era in human evolutionary studies and turned the attention of the then Eurasian-centric palaeoanthropologists to Africa, albeit with reluctance. Almost one hundred years later, Africa is recognized as the cradle of humanity, where the entire evolutionary hist...

Models are mathematical representations of systems, processes or phenomena. In biomechanics, finite-element modelling (FEM) can be a powerful tool, allowing biologists to test form–function relationships in silico , replacing or extending results of in vivo experimentation. Although modelling simplifications and assumptions are necessary, as a mini...

Humans evolved in the dynamic landscapes of Africa under conditions of pronounced climatic, geological and environmental change during the past 7 million years. This book brings together detailed records of the paleontological and archaeological sites in Africa that provide the basic evidence for understanding the environments in which we evolved....

Humans evolved in the dynamic landscapes of Africa under conditions of pronounced climatic, geological and environmental change during the past 7 million years. This book brings together detailed records of the paleontological and archaeological sites in Africa that provide the basic evidence for understanding the environments in which we evolved....

The Miocene is a key time in the evolution of African mammals and their ecosystems witnessing the origin of the African apes and the isolation of eastern coastal forests through an expanding biogeographic arid corridor. Until recently, however, Miocene sites from the southeastern regions of the continent were unknown. Here we report discovery of th...

The mechanical behaviour of the mandibles of Pan and Macaca during mastication was compared using finite element modelling. Muscle forces were calculated using species-specific measures of physiological cross-sectional area and scaled using electromyographic estimates of muscle recruitment in Macaca . Loading regimes were compared using moments act...

We describe the non-primate mammalian fauna from the late Pliocene to earliest Pleistocene deposits of Mille-Logya in the Lower Awash Valley, Ethiopia, dated to c. 2.9–2.4 Ma, and divided into three successive units: Gafura, Seraitu, and Uraitele. We identify 41 mammalian taxa (including rodents), the most diverse group being the Bovidae, with 17 t...

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The Old World fossil record of the family Camelidae is patchy, but a new partial cranium and some other remains of Camelus grattardi from the Mille-Logya Project area in the Afar, Ethiopia, greatly increase the fossil record of the genus in Africa. These new data – together with analysis of unpublished and recently published material from other sit...

Studies of hominin dental morphology frequently consider accessory cusps on the lower molars, in particular those on the distal margin of the tooth (C6 or distal accessory cusp) and the lingual margin of the tooth (C7 or lingual accessory cusp). They are often utilized in studies of hominin systematics, where their presence or absence is assessed a...

Significance Reconstructing the dietary adaptations of our earliest ancestors is critical to understanding the evolution of our relationship with our environment. Here, we present carbon isotope data from hominins of the Shungura and Usno Formations, both part of the Pliocene to Pleistocene Omo Group, Ethiopia, a key sequence for the study of homin...

Significance Studying the diet of fossil herbivores is a critical aspect of understanding past ecology. Here, we present carbon isotope data from the collective herbivore fauna in the Shungura Formation, Ethiopia, a key sequence for the study of mammalian evolution in eastern Africa. We document temporal patterns in the diet of nine mammalian herbi...

Several hypotheses posit a link between the origin of Homo and climatic and environmental shifts between 3 and 2.5 Ma. Here we report on new results that shed light on the interplay between tectonics, basin migration and faunal change on the one hand and the fate of Australopithecus afarensis and the evolution of Homo on the other. Fieldwork at the...

Enamel thickness remains an important morphological character in hominin systematics and is regularly incorporated into dietary reconstructions in hominin species. We expand upon a previous study of enamel thickness in mandibular molars by examining a large maxillary molar sample of Plio-Pleistocene hominins (n = 62) and a comparative sample of ext...

Human brains are three times larger, are organized differently, and mature for a longer period of time than those of our closest living relatives, the chimpanzees. Together, these characteristics are important for human cognition and social behavior, but their evolutionary origins remain unclear. To study brain growth and organization in the homini...

Since it was named in 1978, analyses of Australopithecus afarensis have culminated in several dominant theories on how humans acquired many of their unique adaptations. Because bipedal locomotion is one of the earliest characteristics of human functional anatomy to appear in the fossil record, its associated anatomy in early hominins has significan...

Reliable estimates of when hominin taxa originated and went extinct are central to addressing many paleoanthropological questions, including those relating to macroevolutionary patterns. The timing of hominin temporal ranges can be used to test chronological predictions generated from phylogenetic hypotheses. For example, hypotheses of phyletic anc...

Variation among extant hominoid taxa in the anatomy of the thoracolumbar vertebral transition is well-established and constitutes an important framework for making inferences about posture and locomotion in fossil hominins. However, little is known about the developmental bases of these differences, posing a challenge when interpreting the morpholo...

Understanding the emergence of the genus Homo is a pressing problem in the study of human origins. Australopithecus sediba has recently been proposed as the ancestral species of Homo, although it postdates earliest Homo by 800,000 years. Here, we use probability models to demonstrate that observing an ancestor's fossil horizon that is at least 800,...

Raw craniofacial landmark data comprising papio specimens from Gorongosa National Park and the comparative dataset from Dunn et al. 2013. 3D Mesh at: http://www.morphosource.org/Detail/MediaDetail/Show/media_id/40022

Most authors recognize six baboon species: hamadryas (Papio hamadryas), Guinea (Papio papio), olive (Papio anubis), yellow (Papio cynocephalus), chacma (Papio ursinus), and Kinda (Papio kindae). However, there is still debate regarding the taxonomic status, phylogenetic relationships, and the amount of gene flow occurring between species. Here, we...

The habitual consumption of large-animal resources (e.g., similar sized or larger than the consumer) separates human and nonhuman primate behavior. Flaked stone tool use, another important hominin behavior, is often portrayed as being functionally related to this by the necessity of a sharp edge for cutting animal tissue. However, most research on...

Since its inception, the East African Association for Palaeoanthropology and Palaeontology has brought together scholars and researchers who conduct research in palaeoanthropology, archaeology and palaeontology, creating a balanced forum for the study of human heritage in Africa.

The East African Rift System (EARS) has played a central role in our understanding of human origins and vertebrate evolution in the late Cenozoic of Africa. However, the distribution of fossil sites along the rift is highly biased towards its northern extent, and the types of paleoenvironments are primarily restricted to fluvial and lacustrine sett...

Knowing how the diversity of large mammal communities changes across space and time provides an important ecological framework for studying hominin evolution. However, diversity studies that apply methods currently used by neoecologists are rare in paleoanthropology and are also challenging due to diversity's unusual statistical properties. Here, w...

The functional and evolutionary implications of primitive retentions in early hominin feet have been under debate since the discovery of Australopithecus afarensis. Ontogeny can provide insight into adult phenotypes, but juvenile early hominin foot fossils are exceptionally rare. We analyze a nearly complete, 3.32-million-year-old juvenile foot of...

One approach to understanding the context of changes in hominin paleodiets is to examine the paleodiets and paleohabitats of contemporaneous mammalian taxa. Recent carbon isotopic studies suggest that the middle Pliocene was marked by a major shift in hominin diets, characterized by a significant increase in C4 foods in Australopithecus-grade speci...

Poster

We welcome Almecija’s critique (1), but his claims of “bias” in our conclusions are unfounded. All available evidence continues to support an African ape-like shoulder and pattern of forelimb use in our last common ancestor (LCA) with chimpanzees and bonobos (Pan). First, controlling for within-group size variation is uncontroversial (2), and neith...

Understanding patterns of human evolution across space and time requires synthesizing data collected by independent research teams, and this effort is part of a larger trend to develop cyber infrastructure and e-science initiatives.[1] At present, paleoanthropology cannot easily answer basic questions about the total number of fossils and artifacts...

Modern African great apes, even the so-called “savanna chimpanzees,” have relatively restricted diets consisting largely of leaves and fruits from C3 plants (1). In contrast, fossil members of the genus Homo, like their modern descendants, are believed to have had a rather eclectic diet, consuming foods from C3, C4, and crassulacean acid metabolism...

Significance Knowing the direction and pace of evolutionary change is critical to understanding what selective forces shaped our ancestors. Unfortunately, the human fossil record is sparse, and little is known about the earliest members of our lineage. This unresolved ancestor complicates reconstructions of what behavioral shifts drove major specia...

Enamel thickness continues to be an important morphological character in hominin systematics and is frequently invoked in dietary reconstructions of Plio-Pleistocene hominin taxa. However, to date, the majority of published data on molar enamel thickness of Pliocene and early Pleistocene hominins derive from naturally fractured random surfaces of a...

Fontes-Villalba et al. (1) correctly observe that carbon isotope ratios in tooth enamel do not speak directly to plant versus animal food ingestion. Carbon isotope ratio data are useful for quantifying the consumption of C3- or C4-derived carbon, whether it comes directly from C3 or C4 plants or indirectly through consumption of animals that eat th...

Carbon isotope studies of early hominins from southern Africa showed that their diets differed markedly from the diets of extant apes. Only recently, however, has a major influx of isotopic data from eastern Africa allowed for broad taxonomic, temporal, and regional comparisons among hominins. Before 4 Ma, hominins had diets that were dominated by...

The enhanced dietary flexibility of early hominins to include consumption of C4/crassulacean acid metabolism (CAM) foods (i.e., foods derived from grasses, sedges, and succulents common in tropical savannas and deserts) likely represents a significant ecological and behavioral distinction from both extant great apes and the last common ancestor tha...

Australopithecus in Ethiopia is currently represented by three species: Australopithecus anamensis, Australopithecus afarensis and Australopithecus garhi ranging in age from about 4.2 to 2.5 Ma. The genus is encountered from Hadar and environs in the North to Fejej in the southernmost part of the country. The relationship among the three species ap...

Climbing Like an Ape Recently, studies of several early human leg and foot fossils have implied that in some early species—even after humans became bipedal—climbing may have still been important. Shoulder bones, which would provide i mportant complementary information, are scarce, however. One of the few examples is from Australopithecus afarensis...

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We describe here a new species of gigantic otter, Enhydriodon dikikae, sp. nov., from the Pliocene of Dikika, in the lower Awash valley of Ethiopia. The holotype consists of an associated snout and mandible, and is the most complete fossil specimen of a large bunodont otter. In some features, such as its very large size, the loss of anterior premol...

Understanding patterns of Pliocene environmental and climate change using data from terrestrial deposits helps to identify factors which govern the climate, and to unravel potential links between regional and global climate conditions. We use the stable carbon (C) and oxygen (O) isotopic composition of bioapatite from fossil tooth enamel to reconst...

The oldest direct evidence of stone tool manufacture comes from Gona (Ethiopia) and dates to between 2.6 and 2.5 million years (Myr) ago 1 . At the nearby Bouri site several cut-marked bones also show stone tool use approximately 2.5 Myr ago 2 . Here we report stone-tool-inflicted marks on bones found during recent survey work in Dikika, Ethiopia,...

The Middle Pleistocene environmental and climatic conditions at Asbole, lower Awash Valley, Ethiopia were reconstructed using stable carbon and oxygen isotopic composition (13C, 18O) of fossil tooth enamel coupled with faunal abundance data.We analyzed the isotopic composition of a total of 80 herbivorous tooth enamel samples from 15 mammalian taxa...

Unraveling the dietary adaptations of early hominin species has become a very important question in the paleobio-logical studies of extinct taxa. For long, dentognathic morphological studies have been used to infer diet. More recently, new systematic and quantitative approaches have been developed to explore this issue. In the present study, a pale...

Sediments exposed in the Dikika Research Project area form a nearly continuous sequence spanning the period from older than 3.8 Ma to younger than 0.15 Ma. By developing a stratigraphic framework of sedimentary basins, we are able to reconstruct a regional geological history that illuminates environmental changes resulting from tectonic events in t...

A sample of 117 fossil cercopithecids has been collected from the Middle Pleistocene site of Asbole, Afar Region, Ethiopia. A minimum of five species is present. There are two species of Cercopithecini, here recognized as cf. Chlorocebus aff. aethiops, and cf. Chlorocebus cf. patas. There are also two species of Papionini: Papio hamadryas ssp. inde...

Unraveling the context in which the evolution and diversification of early hominins occurred has become one of the core and highly debated subjects in paleoanthropology. Over the past three decades substantial progress has been made due to the proliferation of fieldwork and a consequently expanding fossil record, and development of new methods of a...

This volume grew out of two workshops (Tempe, Ariz., in 2003, and Washington, D. C., in 2004) that brought together scientists who have explored the East African environmental context during the millions of years in which hominins-including our ancestors-evolved. The community of people doing this kind of work is relatively small, in part because i...

The East African Plio-Pleistocene fossil record is important both for understanding diversification, extinction, and ancestor–descendent relationships among extinct and living African mammals and for investigating the interaction of environmental change and evolution. The 2004 Workshop on Faunal Evidence for Hominin Paleoecology at the Smithsonian...

Vertebrate faunas provide important evidence for the ecological context of evolving hominins over a wide range of scales, from site