HOME

TheInfoList



OR:

Jebel Irhoud or Adrar n Ighoud ( zgh, ⴰⴷⵔⴰⵔ ⵏ ⵉⵖⵓⴷ, Adrar n Iɣud; ar, جبل إيغود, žbəl iġud), is an
archaeological site An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or historic or contemporary), and which has been, or may be, investigated using the discipline of archaeology and ...
located just north of the locality known as Tlet Ighoud, approximately south-east of the city of Safi in Morocco. It is noted for the
hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The ...
fossils that have been found there since the discovery of the site in 1960. Originally thought to be Neanderthals, the specimens have since been assigned to '' Homo sapiens'' and, as reported in 2017, have been dated to roughly 300,000 years ago ( for the Irhoud 3 mandible, based on other fossils and the flint artefacts found nearby). * *"Here we report the ages, determined by thermoluminescence dating, of fire-heated flint artefacts obtained from new excavations at the Middle Stone Age site of Jebel Irhoud, Morocco, which are directly associated with newly discovered remains of H. sapiens8. A weighted average age places these Middle Stone Age artefacts and fossils at 315 ± 34 thousand years ago. Support is obtained through the recalculated uranium series with electron spin resonance date of 286 ± 32 thousand years ago for a tooth from the Irhoud 3 hominin mandible."; *


Site

The site is the remnant of a
solutional cave A solutional cave, solution cave, or karst cave is a cave usually formed in the soluble rock limestone. It is the most frequently occurring type of cave. It can also form in other rocks, including chalk, dolomite, marble, salt beds, and gypsum. ...
filled with of deposits from the Pleistocene era, located on the eastern side of a
karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ...
ic outcrop of limestone at an elevation of . It was discovered in 1961 when the area was being mined for the mineral
baryte Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate ( Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), a ...
. A miner discovered a skull in the wall of the cave, extracted it, and gave it to an engineer, who kept it as a souvenir for a time. Eventually, it was handed over to the University of Rabat, which organized a joint French-Moroccan expedition to the site that was headed by anthropologist Émile Ennouchi. Ennouchi's team identified the remains of approximately 30 species of mammals, some of which are associated with the
Middle Pleistocene The Chibanian, widely known by its previous designation of Middle Pleistocene, is an age in the international geologic timescale or a stage in chronostratigraphy, being a division of the Pleistocene Epoch within the ongoing Quaternary Period. Th ...
, but the
stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers ( strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...
provenance is unknown. Another excavation was carried out by
Jacques Tixier 250px, Jacques Tixier Jacques Tixier (1 January 1925 – 3 April 2018) was a French archaeologist and prehistorian notable for his work on prehistory in Qatar, Lebanon, and North Africa North Africa, or Northern Africa is a region encompassin ...
and
Roger de Bayle des Hermens Roger is a given name, usually masculine, and a surname. The given name is derived from the Old French personal names ' and '. These names are of Germanic origin, derived from the elements ', ''χrōþi'' ("fame", "renown", "honour") and ', ' ...
in 1967 and 1969, during which 22 layers were identified in the cave. The lower 13 layers were found to contain signs of human habitation including a tool industry classified as Levallois Mousterian.


Human remains

The site is particularly noted for the
hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The ...
fossils found there. Ennouchi discovered a skull that he termed Irhoud 1. It is now on display in the
Rabat Archaeological Museum The Museum of History and Civilizations (, french: Musée de l'histoire et des civilisations) is an archaeological museum in Rabat, Morocco. Opened in 1932, it contains the most extensive collection of archaeological artifacts found in the country. ...
. He discovered part of another skull, designated Irhoud 2, the following year and subsequently uncovered the lower
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 ...
of a child, designated Irhoud 3. Tixier's excavation found 1,267 recorded objects including skulls, a
humerus 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 ...
designated Irhoud 4, and a
hip bone The hip bone (os coxae, innominate bone, pelvic bone or coxal bone) is a large flat bone, constricted in the center and expanded above and below. In some vertebrates (including humans before puberty) it is composed of three parts: the ilium, ischi ...
recorded as Irhoud 5. Further excavations were carried out by American researchers during the 1990s as well as by a team led by
Jean-Jacques Hublin Jean-Jacques Hublin (born 30 November 1953) is a French paleoanthropologist. He is a professor at the Max Planck Society, Leiden University and the University of Leipzig and the founder and director of the Department of Human Evolution at the ...
from 2004. Animal remains found at the site have enabled the ancient ecology of the area to be reconstructed. It was quite different to the present and probably represented a dry, open, and perhaps, steppe-like environment roamed by equids,
bovid The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes cattle, bison, buffalo, antelopes, and caprines. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, t ...
s, gazelles, rhinoceros, and various predators.


Dating

Initially, the finds were interpreted as Neanderthal, as the stone tools found with them were believed to be associated exclusively with Neanderthals. They also had archaic phenotypical features believed to be representative of the Neanderthals, rather than '' Homo sapiens''. They were thought to be approximately 40,000 years old, but this was thrown into doubt by faunal evidence suggesting a Middle Pleistocene date, approximately 160,000 years ago. Because of that, the fossils were reappraised as representing an archaic form of ''Homo sapiens'' or perhaps a population of ''Homo sapiens'' that had interbred with Neanderthals. * * This was consistent with the concept that the then-oldest-known remains of a ''Homo sapiens'', dated to approximately 195,000 years ago and found in Omo Kibish, Ethiopia, indicated an eastern African origin for humans at approximately 200,000 years ago. The Ethiopian Omo remains were more recently dated to about 233,000 years old. However, dating carried out by the Max Planck Institute for Evolutionary Anthropology in Leipzig revealed that the Jebel Irhoud site was far older than first thought. Fresh excavations carried out in 2004 by the Hublin team revealed more than 20 new bones from the remains of at least five people, and a number of stone tools. The finds included part of a skull, a jawbone, teeth, and limb bones that had come from three adults, a juvenile, and a child aged about seven-and-a-half years old. The facial bones resembled those of humans today, but had much larger lower jaws and more elongated posterior braincases. They have similar features to the
Florisbad Skull The Florisbad Skull is an important human fossil of the early Middle Stone Age, representing either late ''Homo heidelbergensis'' or early ''Homo sapiens''. It was discovered in 1932 by T. F. Dreyer at the Florisbad site, Free State Province, ...
dating to 260,000 years ago found at the other end of the continent, in
Florisbad Florisbad is a health resort 45 km northwest of Bloemfontein Bloemfontein, ( ; , "fountain of flowers") also known as Bloem, is one of South Africa's three capital cities and the capital of the Free State province. It serves as the ...
, South Africa, which now has been attributed to ''Homo sapiens'' on the basis of the Jebel Irhoud finds. The tools discovered were found alongside gazelle bones and lumps of charcoal, indicating the presence of fire and, probably, of cooking in the cave. The gazelle bones showed characteristic signs of butchery and cooking, such as cut marks, notches consistent with marrow extraction, and charring. Some of the tools had been burned due to fires being lit on top of them, presumably after they had been discarded. This enabled the researchers to use
thermoluminescence dating Thermoluminescence dating (TL) is the determination, by means of measuring the accumulated radiation dose, of the time elapsed since material containing crystalline minerals was either heated ( lava, ceramics) or exposed to sunlight ( sed ...
to ascertain when the burning occurred, and by proxy, the age of the fossil bones that were found in the same deposit layer. In 2017, the burnt tools were dated to approximately 315,000 years ago, indicating that the fossils are of approximately the same age. This conclusion was confirmed by recalculating the age of the Irhoud 3 mandible, which produced an age range compatible with that of the tools, at roughly 280,000 to 350,000 years old. If they hold up, these dates would make the remains by far the earliest known examples of ''Homo sapiens''. This suggests that, rather than arising in East Africa approximately 200,000 years ago, modern humans may have been present across the length of Africa 100,000 years earlier. According to study author Jean-Jacques Hublin, "The idea is that early ''Homo sapiens'' dispersed around the continent and elements of human modernity appeared in different places, and so different parts of Africa contributed to the emergence of what we call modern humans today." Early humans may have comprised a large, interbreeding population dispersed across Africa approximately 330,000 to 300,000 years ago. Thus, the rise of modern humans may have taken place on a continental scale rather than being confined to a particular corner of Africa. Hublin and his team also attempted to obtain DNA samples from these fossils, but these attempts were unsuccessful. Genomic analysis would have provided necessary evidence supporting the conclusion that these fossils are representative of the main lineage leading up to modern humanity, and that ''Homo sapiens'' had dispersed and developed all across Africa. Because of the unclear boundaries between different species of the genus ''Homo'', and the lack of genomic evidence from these fossils, some doubt the classification of these fossils as ''Homo sapiens''. Questions remain over the classification of these fossils.


Morphology

When comparing these fossils with those of modern humans, the main difference is the elongated shape of the fossil
braincase In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calvaria or sku ...
. According to the researchers, this indicates that brain shape, and possibly brain functions, evolved within the ''Homo sapiens'' lineage and relatively recently. Evolutionary changes in brain shape are likely to be associated with genetic changes of brain organization, interconnection, and development, and may reflect adaptive changes in the way the brain functions. Such changes may have caused the human brain to become rounder and two regions in the posterior of the brain to become enlarged during thousands of years of evolution. The Jebel Irhoud individuals also had very thick
brow ridge The brow ridge, or supraorbital ridge known as superciliary arch in medicine, is a bony ridge located above the eye sockets of all primates. In humans, the eyebrows are located on their lower margin. Structure The brow ridge is a nodule or crest ...
s and lacked prognathism. The degree of tooth development found is similar to modern European children of the same age, but teeth roots develop faster than for modern humans (and slower than for apes and for some other fossil hominids).
Tooth crowns In dentistry, crown refers to the anatomical area of teeth, usually covered by enamel. The crown is usually visible in the mouth after developing below the gingiva The gums or gingiva (plural: ''gingivae'') consist of the mucosal tissue ...
took a longer time to form than in modern humans. While the Jebel Irhoud specimens originally were noted to have been similar to later
Aterian The Aterian is a Middle Stone Age (or Middle Palaeolithic) stone tool industry centered in North Africa, from Mauritania to Egypt, but also possibly found in Oman and the Thar Desert. The earliest Aterian dates to c. 150,000 years ago, at the sit ...
and
Iberomaurusian The Iberomaurusian is a backed bladelet lithic industry found near the coasts of Morocco, Algeria, and Tunisia. It is also known from a single major site in Libya, the Haua Fteah, where the industry is locally known as the Eastern Oranian.The ...
specimens, further examinations revealed that the Jebel Irhoud specimens differ from them in that they have a continuous supraorbital torus while the Aterian and Iberomaurasian specimens have a discontinuous supraorbital torus or, in some cases, none at all, and from this, it was concluded that the Jebel Irhoud specimens represent archaic ''Homo sapiens'' while the Aterian and Iberomaurasian specimens represent anatomically modern ''Homo sapiens''. Despite this, it was noted that the Jebel Irhoud specimen whose cranium was complete enough to assess, showed "hints of 'modern' basicranial flexion in the relationship of the face and vault", and the teeth of another Jebel Irhoud specimen were subjected to synchrotron analysis that suggested "a modern developmental pattern."


See also

* Fossil * List of fossil sites ''(with link directory)'' *
List of human evolution fossils The following tables give an overview of notable finds of hominin fossils and remains relating to human evolution, beginning with the formation of the tribe Hominini (the divergence of the human and chimpanzee lineages) in the late Miocene, rou ...
''(with images)'' * List of transitional fossils


References


External links


Article at PhysOrg.com


* ttps://www.nytimes.com/2017/06/07/science/human-fossils-morocco.html ''The New York Times'': Oldest Fossil of ''Homo sapiens'' Found in Morocco, Altering History of Our Species
''National Geographic'': These Early Humans Lived 300,000 Years Ago—But Had Modern Faces
{{Human Evolution 1960 archaeological discoveries 2017 in Morocco 2017 in paleontology Archaeological sites in Morocco Caves of Morocco Human evolution Paleoanthropological sites Pleistocene paleontological sites of Africa Mousterian