The Iwo Eleru skull is an archaeological find that was discovered in an excavation site called Iwo Eleru in Isarun, Ondo State, Yorubaland in present day

Nigeria Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...

. The Iwo Eleru fossil that dates to approximately 13,000 years old may be evidence of modern humans possessing possible archaic human admixture or of a late-persisting

early modern human Early modern human (EMH) or anatomically modern human (AMH) are terms used to distinguish ''Homo sapiens'' (the only extant Hominina species) that are anatomically consistent with the range of phenotypes seen in contemporary humans from extin ...

Discovery

The Iwo Eleru site is a large rock shelter in western Nigeria. The skull was found in 1965 by

Thurstan Shaw Chief Charles Thurstan Shaw CBE FBA FSA (27 June 1914 – 8 March 2013) Later Stone Age The Later Stone Age (LSA) is a period in African prehistory that follows the Middle Stone Age. The Later Stone Age is associated with the advent of modern human behavior in Africa, although definitions of this concept and means of studying it ar ...

artefacts at the site.Brothwell and Shaw, 'A Late Upper Pleistocene Proto-West African Negro from Nigeria', p. 221. It was found as part of a skeleton that was buried with a thin covering of soil. The skeleton was excavated and encased in plaster, and the skull was separated from the rest of the body.

Name of archaeological site

The correct name for the archaeological site is not Iwo Eleru, but Ihò Eleru.

Date

On the basis of charcoal remains that were found surrounding the skeleton, it was initially dated 9250 BC ± 200. However, in a 2011 study conducted by

Katerina Harvati Katerina Harvati ( el, Κατερίνα Χαρβάτη; born 1970 in Athens) is a Greek paleoanthropologist and expert in early human evolution. She specializes in the broad application of 3-D geometric morphometric and virtual anthropology method ...

Chris Stringer Christopher Brian Stringer (born 1947) is a British physical anthropologist noted for his work on human evolution. Biography Growing up in a working-class family in the East End of London, Stringer's interest in anthropology began in primar ...

and others, the dating of the remains was revised: with the help of uranium–thorium dating, a time span of 11.7–16.3 ka was suggested.

Description

The

cranial vault The cranial vault is the space in the skull within the neurocranium, occupied by the brain. Development In humans, the cranial vault is imperfectly composed in newborns, to allow the large human head to pass through the birth canal. During bir ...

is relatively long and low, and the

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.''Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, par ...

shows moderate recession. The brow ridges are moderately developed for a male and there is no pronounced

nasal root The human nose is the most protruding part of the face. It bears the nostrils and is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones a ...

. What remains of the nasal area suggest that the nasal bridge was relatively flat, and the evidence from X-rays points to little frontal sinus development.Brothwell and Shaw, 'A Late Upper Pleistocene Proto-West African Negro from Nigeria', p. 222. The upper face is missing except for a small collection of fragments. Parts of the maxillary-molar region have been identified (including the infraorbital foramen) and, based on what survives, it is unlikely that the upper face was large.Brothwell and Shaw, 'A Late Upper Pleistocene Proto-West African Negro from Nigeria', p. 223. The

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

is well developed and has a masculine appearance, although there is no pronounced chin. Apart from two lower premolars, the teeth are not attached to the jaws and it is uncertain where the surviving teeth were originally placed. All the

anterior teeth In dentistry, the term anterior teeth usually refers as a group to the incisors and canine teeth as distinguished from the posterior teeth, which are the premolars and molars. The distinction is one of anterior (front of the body) versus posterio ...

show noticeable

attrition Attrition may refer to *Attrition warfare, the military strategy of wearing down the enemy by continual losses in personnel and material **War of Attrition, fought between Egypt and Israel from 1968 to 1970 **War of attrition (game), a model of agg ...

and most of the crown has been eroded by wear. Based on the evidence of tooth wear, the age of Iwo Eleru man has been estimated as over 30 years.Brothwell and Shaw, 'A Late Upper Pleistocene Proto-West African Negro from Nigeria', p. 224. What remains of the rest of the skeleton are generally crushed fragments of large bones. The shafts of the

humeri The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a round ...

appear robust and the cortical bone is moderately thick. The shafts of the

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

and

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

are also robust.Brothwell and Shaw, 'A Late Upper Pleistocene Proto-West African Negro from Nigeria', p. 225. The existing remains suggest he was of medium height and build, and was no taller than approximately 165cm.Brothwell and Shaw, 'A Late Upper Pleistocene Proto-West African Negro from Nigeria', p. 226.

Analysis

Don Brothwell and Thurstan Shaw said in 1971 that the sloping frontal vault was more pronounced in Iwo Eleru man than in both later Neolithic and recent sub-Saharan skull samples. However, they also found that the

occipital The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...

structure, nasal root and the frontal bone of the skull "would qualify for identification as that of a proto-West African negro".Brothwell and Shaw, 'A Late Upper Pleistocene Proto-West African Negro from Nigeria', p. 227. In 1974 Chris Stringer said that there were surprising similarities between the crania of the much older

Solo Man Solo Man (''Homo erectus soloensis'') is a subspecies of ''H. erectus'' that lived along the Solo River in Java, Indonesia, about 117,000 to 108,000 years ago in the Late Pleistocene. This population is the last known record of the species. ...

and Omo II with that of Iwo Eleru. The 2011 study found that "Iwo Eleru possesses neurocranial morphology intermediate in shape between archaic hominins (

Neanderthal Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While th ...

s and ''

Homo erectus ''Homo erectus'' (; meaning "upright man") is an extinct species of archaic human from the Pleistocene, with its earliest occurrence about 2 million years ago. Several human species, such as '' H. heidelbergensis'' and '' H. antecessor' ...

'') and modern humans".Harvati et al, 'The Later Stone Age Calvaria from Iwo Eleru, Nigeria: Morphology and Chronology', p. 6. The authors of the study asserted that the dating of Iwo Eleru man to the late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

"implies that the transition to anatomical modernity in Africa was more complicated than previously thought, with late survival of “archaic” features and possibly deep population substructure in Africa during this time". It has been argued that Iwo Eleru man was an archaic hybrid or part of a relict archaic ''Homo'' population. In 2014 Christopher Stojanowski of

Arizona State University Arizona State University (Arizona State or ASU) is a public research university in the Phoenix metropolitan area. Founded in 1885 by the 13th Arizona Territorial Legislature, ASU is one of the largest public universities by enrollment in the ...

summarised the three dominant explanations for Iwo Eleru man's atypical cranial shape: the first, that Iwo Eleru was a hybrid with archaic African populations; the second, that Iwo Eleru man was a member of a relict archaic population that was replaced by more modern humans upon the onset of the

Holocene era The Holocene calendar, also known as the Holocene Era or Human Era (HE), is a Calendar era, year numbering system that adds exactly 10,000 years to the currently dominant (Anno Domini, AD/Before Christ, BC or Common Era, CE/Before Common Era, BC ...

; and the third, that Iwo Eleru man was part of a population that diverged from the rest of North Africa's populations during a time of acute aridness in the

Sahara , photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , ...

desert that made it impassable until the arrival of the African humid period. In 2014 Peter J. Waddell of

Massey University Massey University ( mi, Te Kunenga ki Pūrehuroa) is a university based in Palmerston North, New Zealand, with significant campuses in Albany and Wellington. Massey University has approximately 30,883 students, 13,796 of whom are extramural or ...

argued that Iwo Eleru man descended from a lineage 200–400

kya Kya, kya or KYA may also refer to: People or fictional characters * Kya Lau, chef and contestant on ''MasterChef Junior'', season 4 * Kya, mother of Katara and Sokka, in ''Avatar: The Last Airbender'' * Kya, daughter of Aang and Katara in ''The ...

and whose extinction may have been caused by humans. Waddell also said: "Such a long apparently distinct lineage that terminated in West Africa perhaps 12kya, with no obvious sign of living descendants, suggests that the Iwo Eleru lineage quite probably represents a distinct species of near modern human. As such, the species name ''Homo iwoelerueensis'' suggests itself". However, the

University of Washington The University of Washington (UW, simply Washington, or informally U-Dub) is a public research university in Seattle, Washington. Founded in 1861, Washington is one of the oldest universities on the West Coast; it was established in Seattle a ...

's Fred L. Bookstein cautions against naming Iwo Eleru man as a new species until more confirmatory evidence is discovered.Fred L. Bookstein, '“Like Fixing an Airpline in Flight”: On Paleoanthropology as an Evolutionary Discipline, or, Paleoanthropology for What?', in Schwartz (ed.), ''Rethinking Human Evolution'', p. 198.

Notes

External links

*Daniel Boettcher,
Skull points to a more complex human evolution in Africa
, BBC News.co.uk (16 September 2011). Homo fossils 1965 archaeological discoveries {{DEFAULTSORT:Iwo Eleru skull Archaeology of Nigeria