The brow ridge, or supraorbital ridge known as superciliary arch in medicine, refers to a bony ridge located above the eye sockets of all primates. In Homo sapiens sapiens the eyebrows are located on their lower margin; the brow ridge is a crest of bone situated on the frontal bone of the skull. It forms the roof of the eye sockets. In humans, the ridges arch over each eye, offering mechanical protection. In other primates, the ridge is continuous and straight rather than arched; the ridges are separated from the frontal eminences by a shallow groove. The ridges are most prominent medially, are joined to one another by a smooth elevation named the glabella; the arches are more prominent in men than in women, vary between different ethnic groups. Behind the ridges, deeper in the bone, are the frontal sinuses; the brow ridges, being a prominent part of the face in some ethnic groups and a trait linked to both atavism and sexual dimorphism, have a number of names in different disciplines. In vernacular English, the terms eyebrow bone or eyebrow ridge are common.
The more technical terms frontal or supraorbital arch, ridge or torus are found in anthropological or archaeological studies. In medicine, the term arcus the English translation superciliary arch; this feature is different from the margin of the orbit. Some paleoanthropologists distinguish between supraorbital ridge. In anatomy, a torus is a projecting shelf of bone that unlike a ridge is rectilinear and goes through glabella; some fossil hominins, in this use of the word, have the frontal torus, but all modern humans only have the ridge. The Spatial model proposes that supraorbital torus development can be best explained in terms of the disparity between the anterior position of the orbital component relative the neurocranium. Much of the groundwork for the spatial model was laid down by Schultz, he was the first to document that at stages of development the growth of the orbit would outpace that of the eye. He proposed that facial size is the most influential factor in orbital development, with orbital growth being only secondarily affected by size and ocular position.
Weindenreich and Biegert argued that the supraorbital region can best be understood as a product of the orientation of its two components, the face and the neurocranium. The most composed articulation of the spatial model was presented by Moss and Young, who stated that "the presence… of supraorbital ridges is only the reflection of the spatial relationship between two functionally unrelated cephalic components, the orbit and the brain", they proposed that during infancy the neurocranium extensively overlaps the orbit, a condition that prohibits brow ridge development. As the splanchocranium grows, the orbits begin to advance, thus causing the anterior displacement of the face relative to the brain. Brow ridges form as a result of this separation; the bio-mechanical model predicts that morphological variation in torus size is the direct product of differential tension caused by mastication, as indicated by an increase in load/lever ratio and broad craniofacial angle. Research done on this model has been based on earlier work of Endo.
By applying pressure similar to the type associated with chewing, he carried out an analysis of the structural function of the supraorbital region on dry human and gorilla skulls. His findings indicated that the face acts as a pillar that carries and disperses tension caused by the forces produced during mastication. Russell and Oyen et al. elaborated on this idea, suggesting that amplified facial projection necessitates the application of enhanced force to the anterior dentition in order to generate the same bite power that individuals with a dorsal deflection of the facial skull exert. In more prognathic individuals, this increased pressure triggers bone deposition to reinforce the brow ridges, until equilibrium is reached. Oyen et al. conducted a cross-section study of Papio anubis in order to ascertain the relationship between palate length, incisor load and Masseter lever efficiency, relative to torus enlargement. Indications found of osteoblastic deposition in the glabella were used as evidence for supraorbital enlargement.
Oyen et al.’s data suggested that more prognathic individuals experienced a decrease in load/lever efficiency. This transmits tension via the frontal process of the maxilla to the supraorbital region, resulting in a contemporary reinforcement of this structure; this was correlated to periods of tooth eruption. In a series of papers, Russell developed aspects of this mode further. Employing an adult Australian sample, she tested the association between brow ridge formation and anterior dental loading, via the craniofacial angle, maxilla breadth, discontinuities in food preparation such as those observed between different age groups. Finding strong support for the first two criteria, she concluded that the supraorbital complex is formed as a result of increased tension due to the widening of the maxilla, thought to be positively correlated with the size of the masseter muscle, as well as with the improper orientation of bone in the superior orbital region; the brow ridge functions to reinforce the weaker bones of the face in much the same way that the chin of modern humans reinforces their comparatively thin mandibles.
This was necessary in pongids and early hominids because of the t
Orrorin tugenensis is a postulated early species of Homininae, estimated at 6.1 to 5.7 million years and discovered in 2000. It is not confirmed, its discovery was an argument against the hypothesis that australopithecines are human ancestors, as much as it still remains the most prevalent hypothesis of human evolution as of 2012. The name of genus Orrorin means "original man" in Tugen, the name of the only classified species, O. tugenensis, derives from Tugen Hills in Kenya, where the first fossil was found in 2000. As of 2007, 20 fossils of the species have been found; the 20 specimens found as of 2007 include: the posterior part of a mandible in two pieces. Orrorin had small teeth relative to its body size, its dentition differs from that found in Australopithecus in that its cheek teeth are smaller and less elongated mesiodistally and from Ardipithecus in that its enamel is thicker. The dentition differs from both these species in the presence of a mesial groove on the upper canines; the canines reduced, like those found in Miocene apes and female chimpanzees.
Orrorin had small post-canines and was microdont, like modern humans, whereas robust australopithecines were megadont. In the femur, the head rotated anteriorly. While these suggest that Orrorin was bipedal, the rest of the postcranium indicates it climbed trees. While the proximal phalanx is curved, the distal pollical phalanx is of human proportions and has thus been associated with toolmaking, but should be associated with grasping abilities useful for tree-climbing in this context. After the fossils were found in 2000, they were held at the Kipsaraman village community museum, but the museum was subsequently closed. Since according to the Community Museums of Kenya chairman Eustace Kitonga, the fossils are stored at a secret bank vault in Nairobi. If Orrorin proves to be a direct human ancestor australopithecines such as Australopithecus afarensis may be considered a side branch of the hominid family tree: Orrorin is both earlier, by 3 million years, more similar to modern humans than is A. afarensis.
The main similarity is that the Orrorin femur is morphologically closer to that of H. sapiens than is Lucy's. Other fossils found in the Lukeino Formation show that Orrorin lived in a dry evergreen forest environment, not the savanna assumed by many theories of human evolution; the team that found these fossils in 2000 was led by Brigitte Senut and Martin Pickford from the Muséum national d'histoire naturelle. The 20 fossils have been found at four sites in the Lukeino Formation, located in Kenya: of these, the fossils at Cheboit and Aragai are the oldest, while those in Kapsomin and Kapcheberek are found in the upper levels of the formation. Orrorin tugenensis - The Smithsonian Institution's Human Origins Program Human Timeline – Smithsonian, National Museum of Natural History
Ardipithecus is a genus of an extinct hominine that lived during the Late Miocene and Early Pliocene epochs in the Afar Depression, Ethiopia. Described as one of the earliest ancestors of humans after they diverged from the chimpanzees, the relation of this genus to human ancestors and whether it is a hominin is now a matter of debate. Two fossil species are described in the literature: A. ramidus, which lived about 4.4 million years ago during the early Pliocene, A. kadabba, dated to 5.6 million years ago. Behavioral analysis showed that Ardipithecus could be similar to chimpanzees, indicating that the early human ancestors were chimpanzee-like in behavior. A. ramidus was named in September 1994. The first fossil found was dated to 4.4 million years ago on the basis of its stratigraphic position between two volcanic strata: the basal Gaala Tuff Complex and the Daam Aatu Basaltic Tuff. The name Ardipithecus ramidus stems from the Afar language, in which Ardi means "ground/floor" and ramid means "root".
The pithecus portion of the name is from the Greek word for "ape". Like most hominids, but unlike all recognized hominins, it had a grasping hallux or big toe adapted for locomotion in the trees, it is not confirmed how much other features of its skeleton reflect adaptation to bipedalism on the ground as well. Like hominins, Ardipithecus had reduced canine teeth. In 1992–1993 a research team headed by Tim White discovered the first A. ramidus fossils—seventeen fragments including skull, mandible and arm bones—from the Afar Depression in the Middle Awash river valley of Ethiopia. More fragments were recovered in 1994; this fossil was described as a species of Australopithecus, but White and his colleagues published a note in the same journal renaming the fossil under a new genus, Ardipithecus. Between 1999 and 2003, a multidisciplinary team led by Sileshi Semaw discovered bones and teeth of nine A. ramidus individuals at As Duma in the Gona Western Margin of Ethiopia's Afar Region. The fossils were dated to between 4.35 and 4.45 million years old.
Ardipithecus ramidus had a small brain, measuring between 300 and 350 cm3. This is smaller than a modern bonobo or female common chimpanzee brain, but much smaller than the brain of australopithecines like Lucy and 20% the size of the modern Homo sapiens brain. Like common chimpanzees, A. ramidus was much more prognathic than modern humans. The teeth of A. ramidus lacked the specialization of other apes, suggest that it was a generalized omnivore and frugivore with a diet that did not depend on foliage, fibrous plant material, or hard and or abrasive food. The size of the upper canine tooth in A. ramidus males was not distinctly different from that of females. Their upper canines were less sharp than those of modern common chimpanzees in part because of this decreased upper canine size, as larger upper canines can be honed through wear against teeth in the lower mouth; the features of the upper canine in A. ramidus contrast with the sexual dimorphism observed in common chimpanzees, where males have larger and sharper upper canine teeth than females.
The less pronounced nature of the upper canine teeth in A. ramidus has been used to infer aspects of the social behavior of the species and more ancestral hominids. In particular, it has been used to suggest that the last common ancestor of hominids and African apes was characterized by little aggression between males and between groups; this is markedly different from social patterns in common chimpanzees, among which intermale and intergroup aggression are high. Researchers in a 2009 study said that this condition "compromises the living chimpanzee as a behavioral model for the ancestral hominid condition."A. ramidus existed more than the most recent common ancestor of humans and chimpanzees and thus is not representative of that common ancestor. It is in some ways unlike chimpanzees, suggesting that the common ancestor differs from the modern chimpanzee. After the chimpanzee and human lineages diverged, both underwent substantial evolutionary change. Chimp feet are specialized for grasping trees.
The canine teeth of A. ramidus are smaller, equal in size between males and females, which suggests reduced male-to-male conflict, increased pair-bonding, increased parental investment. "Thus, fundamental reproductive and social behavioral changes occurred in hominids long before they had enlarged brains and began to use stone tools," the research team concluded. On October 1, 2009, paleontologists formally announced the discovery of the complete A. ramidus fossil skeleton first unearthed in 1994. The fossil is the remains of a small-brained 50-kilogram female, nicknamed "Ardi", includes most of the skull and teeth, as well as the pelvis and feet, it was discovered in Ethiopia's harsh Afar desert at a site called Aramis in the Middle Awash region. Radiometric dating of the layers of volcanic ash encasing the deposits suggest that Ardi lived about 4.3-4.5 million years ago. This date, has been questioned by others. Fleagle and Kappelman suggest that the region in which Ardi was found is difficult to date radiometrically, they argue that Ardi should be dated at 3.9 million years.
The fossil is regarded by its describers as shedding light on a stage of human evolution about which little was known, more than a million years before Lucy, the iconic early human ancestor candidate who lived 3.2 million years ago, was discovered in 1974 just 74 km (46
Human taxonomy is the classification of the human species within zoological taxonomy. The systematic genus, Homo, is designed to include both anatomically modern humans and extinct varieties of archaic humans. Current humans have been designated as subspecies Homo sapiens sapiens, differentiated from the direct ancestor, Homo sapiens idaltu. Since the introduction of systematic names in the 18th century, knowledge of human evolution has increased drastically, a number of intermediate taxa have been proposed in the 20th to early 21st century; the most accepted taxonomy groups takes the genus Homo as originating between two and three million years ago, divided into at least two species, archaic Homo erectus and modern Homo sapiens, with about a dozen further suggestions for species without universal recognition. The genus Homo is placed in the tribe Hominini alongside Pan; the two genera are estimated to have diverged over an extended time of hybridization spanning 10 to 6 million years ago, with possible admixture as late as 4 million years ago.
A subtribe of uncertain validity, grouping archaic "pre-human" or "para-human" species younger than the Homo-Pan split is Australopithecina. A proposal by Wood and Richmond would introduce Hominina as a subtribe alongside Australopithecina, with Homo the only known genus within Hominina. Alternatively, following Cela-Conde and Ayala, the "pre-human" or "proto-human" genera of Australopithecus, Ardipithecus and Sahelanthropus may be placed on equal footing alongside the genus Homo. An more radical view rejects the division of Pan and Homo as separate genera, which based on the Principle of Priority would imply the re-classification of chimpanzees as Homo paniscus. Prior to the current scientific classification of humans and scientists have made various attempts to classify humans, they offered definitions of schemes for classifying types of humans. Biologists once classified races as subspecies, but today anthropologists reject the concept of race and view humanity as an interrelated genetic continuum.
Taxonomy of the hominins continues to evolve. Human taxonomy on one hand involves the placement of humans within the Taxonomy of the hominids, on the other the division of archaic and modern humans into species and, if applicable, subspecies. Modern zoological taxonomy was developed by Carl Linnaeus during the 1730s to 1750s, he named the human species as Homo sapiens in 1758, as the only member species of the genus Homo, divided into several subspecies corresponding to the great races. The Latin noun homō means "human being"; the systematic name Hominidae for the family of the great apes was introduced by John Edward Gray. Gray supplied Hominini as the name of the tribe including both chimpanzees and humans; the discovery of the first extinct archaic human species from the fossil record dates to the mid 19th century, Homo neanderthalensis, classified in 1864. Since a number of other archaic species have been named, but there is no universal consensus as to their exact number. After the discovery of H. neanderthalensis, which if "archaic" is recognizable as human, late 19th to early 20th century anthropology for a time was occupied with finding the "missing link" between Homo and Pan.
The "Piltdown Man" hoax of 1912 was the presentation of such a transitional species. Since the mid-20th century, knowledge of the development of Hominini has become much more detailed, taxonomical terminology has been altered a number of times to reflect this; the introduction of Australopithecus as a third genus, alongside Homo and Pan, in the Hominini tribe is due to Raymond Dart. Australopithecina as a subtribe containing Australopithecus as well as Paranthropus is a proposal by Gregory & Hellman. More proposed additions to the Australopithecina subtribe include Ardipithecus and Kenyanthropus; the position of Sahelanthropus relative to Australopithecina within Hominini is unclear. Cela-Conde and Ayala propose the recognition of Australopithecus, Ardipithecus and Sahelanthropus as separate genera. Other proposed genera, now considered part of Homo, include: Pithecanthropus, Sinanthropus, Cyphanthropus Africanthropus,Telanthropus, Tchadanthropus; the genus Homo has been taken to originate some two million years ago since the discovery of stone tools in Olduvai Gorge, Tanzania, in the 1960s.
Homo habilis would be the first "human" species by definition, its type specimen being the OH 7 fossils. However, the discovery of more fossils of this type has opened up the debate on the delineation of H. habilis from Australopithecus. The LD 350-1 jawbone fossil discovered in 2013, dated to 2.8 Mya, has been argued as being transitional between the two. It is disputed whether H. habilis was the first hominin to use stone tools, as Australopithecus garhi, dated to c. 2.5 Mya, has been found along with stone tool implements. Fossil KNM-ER 1470 is now seen as either a third early species of Homo at about 2 million years ago, or alternatively as transitional between Australopithecus and Homo. Wood and Richmond proposed that Gray's tribe Hominini be designated as comprising all species after the chimpan
The Pliocene Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58 million years BP. It is the youngest epoch of the Neogene Period in the Cenozoic Era; the Pliocene is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations within the Pleistocene, the Pliocene included the Gelasian stage, which lasted from 2.588 to 1.806 million years ago, is now included in the Pleistocene. As with other older geologic periods, the geological strata that define the start and end are well identified but the exact dates of the start and end of the epoch are uncertain; the boundaries defining the Pliocene are not set at an identified worldwide event but rather at regional boundaries between the warmer Miocene and the cooler Pliocene. The upper boundary was set at the start of the Pleistocene glaciations. Charles Lyell gave the Pliocene its name in Principles of Geology; the word pliocene comes from the Greek words πλεῖον and καινός and means "continuation of the recent", referring to the modern marine mollusc fauna.
H. W. Fowler called the term Pliocene a "regrettable barbarism" and an indication that "a good classical scholar" such as Lyell should have requested a philologist's help when coining words. To summarize the usage of these "regrettable barbarisms" in the labelling of the Cenozoic era: with the understanding that these are all new relative to the Mesozoic and Paleozoic eras. In the official timescale of the ICS, the Pliocene is subdivided into two stages. From youngest to oldest they are: Piacenzian Zanclean The Piacenzian is sometimes referred to as the Late Pliocene, whereas the Zanclean is referred to as the Early Pliocene. In the system of North American Land Mammal Ages include Hemphillian, Blancan; the Blancan extends forward into the Pleistocene. South American Land Mammal Ages include Montehermosan and Uquian. In the Paratethys area the Pliocene contains the Romanian stages; as usual in stratigraphy, there are many other local subdivisions in use. In Britain the Pliocene is divided into the following stages: Gedgravian, Pre-Ludhamian, Thurnian, Bramertonian or Antian, Pre-Pastonian or Baventian and Beestonian.
In the Netherlands the Pliocene is divided into these stages: Brunssumian C, Reuverian A, Reuverian B, Reuverian C, Tiglian A, Tiglian B, Tiglian C1-4b, Tiglian C4c, Tiglian C5, Tiglian C6 and Eburonian. The exact correlations between these local stages and the ICS stages is still a matter of detail; the global average temperature in the mid-Pliocene was 2–3 °C higher than today, carbon dioxide levels were the same as today, global sea level was 25 m higher. The northern hemisphere ice sheet was ephemeral before the onset of extensive glaciation over Greenland that occurred in the late Pliocene around 3 Ma; the formation of an Arctic ice cap is signaled by an abrupt shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic and North Pacific ocean beds. Mid-latitude glaciation was underway before the end of the epoch; the global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas. Continents continued to drift, moving from positions as far as 250 km from their present locations to positions only 70 km from their current locations.
South America became linked to North America through the Isthmus of Panama during the Pliocene, making possible the Great American Interchange and bringing a nearly complete end to South America's distinctive large marsupial predator and native ungulate faunas. The formation of the Isthmus had major consequences on global temperatures, since warm equatorial ocean currents were cut off and an Atlantic cooling cycle began, with cold Arctic and Antarctic waters dropping temperatures in the now-isolated Atlantic Ocean. Africa's collision with Europe formed the Mediterranean Sea, cutting off the remnants of the Tethys Ocean; the border between the Miocene and the Pliocene is the time of the Messinian salinity crisis. Sea level changes exposed the land bridge between Asia. Pliocene marine rocks are well exposed in the Mediterranean and China. Elsewhere, they are exposed near shores. During the Pliocene parts of southern Norway and southern Sweden, near sea level rose. In Norway this rise elevated the Hardangervidda plateau to 1200 m in the Early Pliocene.
In Southern Sweden similar movements elevated the South Swedish highlands leading to a deflection of the ancient Eridanos river from its original path across south-central Sweden into a course south of Sweden. The change to a cooler, seasonal climate had considerable impacts on Pliocene vegetation, reducing tropical species worldwide. Deciduous forests proliferated, coniferous forests and tundra covered much of the north, grasslands spread on all continents. Tropical forests were limited to a tight band around the equator, in addition to dry savannahs, deserts appeared in Asia and Africa. Both marine and co
Neanderthals are an extinct species or subspecies of archaic humans in the genus Homo, who lived within Eurasia from circa 400,000 until 40,000 years ago. The earliest fossils of Neanderthals in Europe are dated between 450,000 and 430,000 years ago, thereafter Neanderthals expanded into Southwest and Central Asia, they are known from numerous fossils, as well as stone tool assemblages. All assemblages younger than 160,000 years are of the so-called Mousterian techno-complex, characterised by tools made out of stone flakes; the type specimen is Neanderthal 1, found in Neander Valley in the German Rhineland, in 1856. Compared to modern humans, Neanderthals were stockier, with bigger bodies. In conformance with Bergmann's rule, as well as Allen's rule, this was was an adaptation to preserve heat in cold climates. Male and female Neanderthals had cranial capacities averaging 1,600 cm3 and 1,300 cm3 within the range of the values for anatomically modern humans. Average males stood around females 152 to 156 cm tall.
There has been growing evidence for admixture between Neanderthals and anatomically modern humans, reflected in the genomes of all modern non-African populations but not in the genomes of most sub-Saharan Africans. This suggests that interbreeding between Neanderthals and anatomically modern humans took place after the recent "out of Africa" migration, around 70,000 years ago. Recent admixture analyses have added to the complexity, finding that Eastern Neanderthals derived up to 2% of their ancestry from anatomically modern humans who left Africa some 100,000 years ago. Neanderthals are named after one of the first sites where their fossils were discovered in the mid-19th century in the Neander Valley, just east of Düsseldorf, at the time in the Rhine Province of the Kingdom of Prussia; the valley itself was named for Joachim Neander, Neander being the graecicized form of the surname Neumann. The German spelling of Thal "Valley" was current in the 19th century. Neanderthal 1 was known as the "Neanderthal cranium" or "Neanderthal skull" in anthropological literature, the individual reconstructed on the basis of the skull was called "the Neanderthal man".
The binomial name Homo neanderthalensis—extending the name "Neanderthal man" from the individual type specimen to the entire group—was first proposed by the Anglo-Irish geologist William King in a paper read to the British Association in 1863, although in the following year he stated that the specimen was not human and rejected the name. King's name had priority over the proposal put forward in 1866 by Homo stupidus. Popular English usage of "Neanderthal" as shorthand for "Neanderthal man", as in "the Neanderthals" or "a Neanderthal", emerged in the popular literature of the 1920s. Since the historical spelling -th- in German represents the phoneme /t/ or /tʰ/, not the fricative /θ/, standard British pronunciation of "Neanderthal" is with /t/; because of the usual sound represented by digraph ⟨th⟩ in English, "Neanderthal" is pronounced with the voiceless fricative /θ/, at least in "layman's American English". The spelling Neandertal is seen in English in scientific publications. Since "Neanderthal", or "Neandertal", is a common name, there is no authoritative prescription on its spelling, unlike the spelling of the binominal name H. neanderthalensis, predicated by King 1864.
The common name in German is always invariably Neandertaler, not Neandertal, but the spelling of the name of the Neander Valley itself has been affected by the species name, the names of the Neanderthal Museum and of Neanderthal station persisting with pre-1900 orthography. Since the discovery of the Neanderthal fossils, expert opinion has been divided as to whether Neanderthals should be considered a separate species or a subspecies relative to modern humans. Pääbo described such "taxonomic wars" as unresolveable in principle, "since there is no definition of species describing the case." The question depends on the definition of Homo sapiens as a chronospecies, in flux throughout the 20th century. Authorities preferring classification of Neanderthals as subspecies have introduced the subspecies name Homo sapiens sapiens for the anatomically modern Cro-Magnon population which lived in Europe at the same time as Neanderthals, while authorities preferring classification as separate species use Homo sapiens as equivalent to "anatomically modern humans".
During the early 20th century, a prevailing view of Neanderthals as "simian", influenced by Arthur Keith and Marcellin Boule, tended to exaggerate the anatomical differences between Neanderthals and Cro Magnon. Beginning in the 1930s, revised reconstructions of Neanderthals emphasized the similarity rather than differences from modern humans. From the 1940s throughout the 1970s, it was common to use the subspecies classification of Homo sapiens neanderthalensis vs. Homo sapiens sapiens; the hypothesis of "multiregional origin" of modern man was formulated in the 1980s on such grounds, arguing for the presence of an unbroken succession of fossil sites in both Europe and Asia. Hybridization between Neanderthals and Cro Magnon had been suggested on skeletal and craniological grounds since the early 20th century, found increasing support in the 20th century, until Neanderthal admixture was found to be present in modern populations genet
Homo sapiens idaltu
Homo sapiens idaltu called Herto Man, is the name given to a number of early modern human fossils found in 1997 in Herto Bouri, Ethiopia. They date to around 160,000 years ago. Paleoanthropologists determined that the skeletal finds belong to an extinct subspecies of Homo sapiens who lived in Pleistocene Africa. In the narrow definition of H. sapiens, the subspecies H. s. idaltu falls under the umbrella of Anatomically modern humans. The recognition of H. s. idaltu as a valid subspecies of the anatomically modern human lineage would justify the description of contemporary humans with the subspecies name H. s. sapiens. Because of their early dating and unique physical characteristics, they represent the immediate ancestors of anatomically modern humans, as suggested by the Out-of-Africa theory; the fossilized remains of Homo sapiens idaltu were discovered at Herto Bouri near the Middle Awash site of Ethiopia's Afar Triangle in 1997 by Tim White, Giday WoldeGabriel and Berhane Asfaw, but were first unveiled in 2003.
Herto Bouri is a region of Ethiopia under volcanic layers. According to radioisotope dating, the layers are between 160,000 years old. Three well preserved crania are accounted for, the best preserved being from an adult male having a brain capacity of 1,450 cm3; the other crania include a six-year-old child. The Omo fossils differ from those of chronologically forms of early Homo sapiens, their morphology has features that show resemblances to African fossils, such as huge and robust skulls, yet have a globular shape of the brain-case and the facial features typical of H. sapiens. Anthropologist Chris Stringer argued in a 2003 article in the journal Nature that "the skulls might not be distinctive enough to warrant a new subspecies name"; these specimens represent the direct ancestors of modern Homo sapiens sapiens which, according to the "recent African origin" or "out of Africa" model, developed shortly after this period in Eastern Africa. "The many morphological features shared by the Herto crania and AMHS, to the exclusion of penecontemporaneous Neanderthals, provide additional fossil data excluding Neanderthals from a significant contribution to the ancestry of modern humans."A 2005 potassium-argon dating of volcanic tuff associated with the Omo remains showed them to date from around 195,000 years ago.
At the time of the dating, this made these fossils the earliest known remains of anatomically modern humans, older than the idaltu specimens. In 2013, comparative craniometric analysis of the Herto Homo idaltu skull with ancient and recent crania from other parts of Africa found that the specimen was morphologically closest to the Pleistocene Rabat fossil and Early Holocene Kef Oum Touiza skeleton. A study found that Herto man and his contemporaries were cranially similar to Oceanians, with Northern Melenesians being the closest. 160,000-year-old fossilized skulls uncovered in Ethiopia are oldest anatomically modern humans, Robert Sanders, UC Berkeley, 11 June 2003. Missing link in human evolution found in Africa BBC report and image of the reconstructed skull discovered at Herto Homo sapiens idaltu - Nature Journal Article Fossil Hominids - Middle Awash Research Project Origins - Discovery of Earliest Homo Sapien Skulls backs'Out of Africa' Theory - Homo sapiens idaltu Bradshaw Foundation