Its nickname is η Συμπρωτεύουσα, literally the co-capital, a reference to its historical status as the Συμβασιλεύουσα or co-reigning city of the Eastern Roman Empire, alongside Constantinople. The city is renowned for its festivals and vibrant cultural life in general, Thessaloniki was the 2014 European Youth Capital. The city of Thessaloniki was founded in 315 BC by Cassander of Macedon, an important metropolis by the Roman period, Thessaloniki was the second largest and wealthiest city of the Byzantine Empire. It was conquered by the Ottomans in 1430, and passed from the Ottoman Empire to modern Greece on November 8,1912, the citys main university, Aristotle University, is the largest in Greece and the Balkans. Thessaloniki is a popular tourist destination in Greece, among street photographers, the center of Thessaloniki is considered the most popular destination for street photography in Greece. All variations of the name derive from the original appellation in Ancient Greek, i. e. Θεσσαλονίκη.
The alternative name Salonica derives from the variant form Σαλονίκη in colloquial Greek speech, in local speech, the citys name is typically pronounced with a dark and deep L characteristic of Macedonian Greek accent. The name often appears in writing in the abbreviated form Θεσ/νίκη, the city was founded around 315 BC by the King Cassander of Macedon, on or near the site of the ancient town of Therma and 26 other local villages. He named it after his wife Thessalonike, a half-sister of Alexander the Great, under the kingdom of Macedon the city retained its own autonomy and parliament and evolved to become the most important city in Macedon. After the fall of the kingdom of Macedon in 168 BC, the city became the capital of one of the four Roman districts of Macedonia. Later it became the capital of all the Greek provinces of the Roman Empire because of the importance in the Balkan peninsula. At the time of the Roman Empire, about 50 A. D. Later, Paul wrote two letters to the new church at Thessaloniki, preserved in the Biblical canon as First and Second Thessalonians.
Some scholars hold that the First Epistle to the Thessalonians is the first written book of the New Testament, in 306 AD, Thessaloniki acquired a patron saint, St. Demetrius, a native of Thessalonica whom Galerius put to death. A basilical church was first built in the 5th century AD dedicated to St. Demetrius, in 379, when the Roman Prefecture of Illyricum was divided between the East and West Roman Empires, Thessaloniki became the capital of the new Prefecture of Illyricum. In 390, Gothic troops under the Roman Emperor Theodosius I, led a massacre against the inhabitants of Thessalonica, by the time of the Fall of Rome in 476, Thessaloniki was the second-largest city of the Eastern Roman Empire. From the first years of the Byzantine Empire, Thessaloniki was considered the city in the Empire after Constantinople. With a population of 150,000 in the mid-12th century, the city held this status until its transfer to Venetian control in 1423. In the 14th century, the population exceeded 100,000 to 150,000
Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can be subsequently turned into a metamorphic rock due to heat and pressure and is weathered, eroded and lithified, ultimately becoming a sedimentary rock.
Sedimentary rock may be re-eroded and redeposited, and metamorphic rock may undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart.
Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics provided a mechanism for Alfred Wegeners theory of continental drift and they provided a driving force for crustal deformation, and a new setting for the observations of structural geology
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate. The Mohs scale of hardness, based on scratch hardness comparison. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite, aragonite will change to calcite at 380–470 °C, and vaterite is even less stable. Calcite is derived from the German Calcit, a term coined in the 19th century from the Latin word for lime and it is thus etymologically related to chalk. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, prisms, or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms and it may occur as fibrous, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form and its fracture is conchoidal, but difficult to obtain. It has a defining Mohs hardness of 3, a gravity of 2.71.
Color is white or none, though shades of gray, orange, green, violet, calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence. A transparent variety called Iceland spar is used for optical purposes, acute scalenohedral crystals are sometimes referred to as dogtooth spar while the rhombohedral form is sometimes referred to as nailhead spar. Single calcite crystals display an optical property called birefringence and this strong birefringence causes objects viewed through a clear piece of calcite to appear doubled. The birefringent effect was first described by the Danish scientist Rasmus Bartholin in 1669, at a wavelength of ~590 nm calcite has ordinary and extraordinary refractive indices of 1.658 and 1.486, respectively. Between 190 and 1700 nm, the refractive index varies roughly between 1.9 and 1.5, while the extraordinary refractive index varies between 1.6 and 1.4. Calcite, like most carbonates, will dissolve with most forms of acid, calcite can be either dissolved by groundwater or precipitated by groundwater, depending on several factors including the water temperature, pH, and dissolved ion concentrations.
Although calcite is fairly insoluble in water, acidity can cause dissolution of calcite. Ambient carbon dioxide, due to its acidity, has a slight solubilizing effect on calcite, calcite exhibits an unusual characteristic called retrograde solubility in which it becomes less soluble in water as the temperature increases. When conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together or it can fill fractures. On a landscape scale, continued dissolution of calcium carbonate-rich rocks can lead to the expansion and eventual collapse of cave systems, high-grade optical calcite was used in World War II for gun sights, specifically in bomb sights and anti-aircraft weaponry
The site came to public attention when in 1960 a fossilized hominid skull was found. The cave had been discovered only a year earlier after erosion had left clefts in the rock. Bejeweled with impressive stalactite and stalagmite formations and holding an abundance of fossils the cave soon attracted geologists and paleontologists, after decades of excavations the cave is open to the public and scientific work is documented and presented in an adjacent Archaeological Museum. He considers it the oldest European hominid ever found and assessed it to be 800.000 years old, yet there was the constant problem that the skull was an isolated find as other scientists strongly disagree and the find has been a continuing cause of controversy since. The Anthropological Associations conclusions and results are in conflict with accepted speciation models of the genus Homo. The on-site Anthropological Museum of Petralona displays a selection of the caves findings, the cave was discovered accidentally in 1959 by Fillipos Chatzaridis, a local shepherd who was looking for a spring.
In his effort to find a source he found a small cleft on the slopes of Mount Katsika. Two men were lowered down and described a number of chambers and corridors, totaling 8 to 10 meters high with rich. The cave developed during the Mesozoic limestone, its sediments are divided into several stratigraphic levels, the rock formations resemble giant cactus, pink pearls, sturdy columns or delicate curtains, and in several places water ponds are fed by stalactite material. Covering an area of 10,400 m2, the length of the corridors is about 2,000 m, the first research of 1959 was undertaken by the Greek speleologist Ioannis Petrocheilos. He found numerous bones of animals, many of them covered with cave coral, the skull of the Archanthropus was according to Aris Poulianos found by another villager, Christos Sariannidis in 1960, hanging at the wall about 30 cm above ground, where it was held by sinter. Aris N. Poulianos states, that estimates at the time placed the age of the hominid remains to around 70,000 years.
He announced that the date was based on analyses of the cave’s stratigraphy, in 1981, the age of the Petralona skull deduced by Poulianos was investigated and the protocol published in the Nature journal. The scientists involved used electron spin resonance measurements of the calcite encrustation and of bone fragments, Poulianos states that his excavations in the cave since 1968 provide evidence of human occupation from the Pleistocene era. The Petralona hominid, was located in a layer containing the highest amount of tools. Poulianos claims that the age of the layer is approximately 670,000 years old. Other researchers point out, that contextual animal fossils found with it are elsewhere from approximately 350,000 years ago. In 1987 researchers announced that the cranium cant be older than 620.000 years after palaeo-magnetic, the results confirm earlier findings that the whole of layer 10 represents a long time span, from about 160 ka to more than 350 ka
Greece, officially the Hellenic Republic, historically known as Hellas, is a country in southeastern Europe, with a population of approximately 11 million as of 2015. Athens is the capital and largest city, followed by Thessaloniki. Greece is strategically located at the crossroads of Europe, situated on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, the Republic of Macedonia and Bulgaria to the north, and Turkey to the northeast. Greece consists of nine regions, Central Greece, the Peloponnese, Epirus, the Aegean Islands, Crete. The Aegean Sea lies to the east of the mainland, the Ionian Sea to the west, the Cretan Sea and the Mediterranean Sea to the south. Greece has the longest coastline on the Mediterranean Basin and the 11th longest coastline in the world at 13,676 km in length, featuring a vast number of islands, eighty percent of Greece is mountainous, with Mount Olympus being the highest peak at 2,918 metres. From the eighth century BC, the Greeks were organised into various independent city-states, known as polis, which spanned the entire Mediterranean region and the Black Sea.
Greece was annexed by Rome in the second century BC, becoming a part of the Roman Empire and its successor. The Greek Orthodox Church shaped modern Greek identity and transmitted Greek traditions to the wider Orthodox World, falling under Ottoman dominion in the mid-15th century, the modern nation state of Greece emerged in 1830 following a war of independence. Greeces rich historical legacy is reflected by its 18 UNESCO World Heritage Sites, among the most in Europe, Greece is a democratic and developed country with an advanced high-income economy, a high quality of life, and a very high standard of living. A founding member of the United Nations, Greece was the member to join the European Communities and has been part of the Eurozone since 2001. Greeces unique cultural heritage, large industry, prominent shipping sector. It is the largest economy in the Balkans, where it is an important regional investor, the names for the nation of Greece and the Greek people differ from the names used in other languages and cultures.
The earliest evidence of the presence of human ancestors in the southern Balkans, dated to 270,000 BC, is to be found in the Petralona cave, all three stages of the stone age are represented in Greece, for example in the Franchthi Cave. Neolithic settlements in Greece, dating from the 7th millennium BC, are the oldest in Europe by several centuries and these civilizations possessed writing, the Minoans writing in an undeciphered script known as Linear A, and the Mycenaeans in Linear B, an early form of Greek. The Mycenaeans gradually absorbed the Minoans, but collapsed violently around 1200 BC and this ushered in a period known as the Greek Dark Ages, from which written records are absent. The end of the Dark Ages is traditionally dated to 776 BC, the Iliad and the Odyssey, the foundational texts of Western literature, are believed to have been composed by Homer in the 7th or 8th centuries BC. With the end of the Dark Ages, there emerged various kingdoms and city-states across the Greek peninsula, in 508 BC, Cleisthenes instituted the worlds first democratic system of government in Athens
The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago. This Era is called from a paleobotanist view the Age of Conifers, Mesozoic means middle life, deriving from the Greek prefix meso-/μεσο- for between and zōon/ζῷον meaning animal or living being. It is one of three eras of the Phanerozoic Eon, preceded by the Paleozoic and succeeded by the Cenozoic. The era is subdivided into three periods, the Triassic and Cretaceous, which are further subdivided into a number of epochs. The Mesozoic was a time of significant tectonic and evolutionary activity, the era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would eventually move into their current positions. The climate of the Mesozoic was varied, alternating between warming and cooling periods, however, the Earth was hotter than it is today. Birds first appeared in the Jurassic, having evolved from a branch of theropod dinosaurs, the first mammals appeared during the Mesozoic, but would remain small—less than 15 kg —until the Cenozoic.
Following the Paleozoic, the Mesozoic extended roughly 186 million years and this time frame is separated into three geologic periods. It is known as the Great Dying because it is considered the largest mass extinction in the Earths history, the upper boundary of the Mesozoic is set at the Cretaceous–Paleogene extinction event, which may have been caused by the impactor that created Chicxulub Crater on the Yucatán Peninsula. Towards the Late Cretaceous large volcanic eruptions are believed to have contributed to the Cretaceous–Paleogene extinction event. Approximately 50% of all genera became extinct, including all of the non-avian dinosaurs, the Triassic ranges roughly from 252 million to 201 million years ago. The Triassic is a time in Earths history bracketed between the Permian Extinction and the Triassic–Jurassic extinction event, two of the big five, and precedes the Jurassic Period and it has three major epochs, the Early Triassic, the Middle Triassic and the Late Triassic. The Early Triassic was between about 252 million to 247 million years ago and was dominated by deserts as Pangaea had not yet broken up, thus the interior was nothing, the Earth had just witnessed a massive die-off in which 95% of all life became extinct.
The most common life on earth were Lystrosaurus, labyrinthodonts. Temnospondyls evolved during this time and would be the dominant predator for much of the Triassic, the Middle Triassic spans roughly from 247 million to 237 million years ago. The Middle Triassic featured the beginnings of the breakup of Pangaea, the ecosystem had recovered from the devastation that was the Great Dying. Algae, sponge and crustaceans all had recovered, new aquatic reptiles evolved, such as ichthyosaurs and nothosaurs. Meanwhile, on land, pine forests flourished, as did groups of insects like mosquitoes, the first ancient crocodilians evolved, which sparked competition with the large amphibians that had since ruled the freshwater world
Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. They inhabit a variety of habitats, with most species living within terrestrial, arboreal or freshwater aquatic ecosystems. Thus amphibians typically start out as larvae living in water, the young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs. Amphibians use their skin as a respiratory surface and some small terrestrial salamanders and frogs lack lungs. They are superficially similar to lizards but, along with mammals and birds, reptiles are amniotes, the earliest amphibians evolved in the Devonian period from sarcopterygian fish with lungs and bony-limbed fins, features that were helpful in adapting to dry land. They diversified and became dominant during the Carboniferous and Permian periods, over time, amphibians shrank in size and decreased in diversity, leaving only the modern subclass Lissamphibia. The three modern orders of amphibians are Anura and Apoda, the number of known amphibian species is approximately 7,000, of which nearly 90% are frogs.
The smallest amphibian in the world is a frog from New Guinea with a length of just 7.7 mm. The largest living amphibian is the 1.8 m Chinese giant salamander, the study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology. The word amphibian is derived from the Ancient Greek term ἀμφίβιος, the term was initially used as a general adjective for animals that could live on land or in water, including seals and otters. Traditionally, the class Amphibia includes all tetrapod vertebrates that are not amniotes, the numbers of species cited above follows Frost and the total number of known amphibian species is over 7,000, of which nearly 90% are frogs. With the phylogenetic classification, the taxon Labyrinthodontia has been discarded as it is a group without unique defining features apart from shared primitive characteristics. Classification varies according to the phylogeny of the author and whether they use a stem-based or a node-based classification.
The phylogeny of Paleozoic amphibians is uncertain, and Lissamphibia may possibly fall within groups, like the Temnospondyli or the Lepospondyli. If the common ancestor of amphibians and amniotes is included in Amphibia, all modern amphibians are included in the subclass Lissamphibia, which is usually considered a clade, a group of species that have evolved from a common ancestor. The three modern orders are Anura and Gymnophiona, although the fossils of several older proto-frogs with primitive characteristics are known, the oldest true frog is Prosalirus bitis, from the Early Jurassic Kayenta Formation of Arizona. It is anatomically similar to modern frogs. The oldest known caecilian is another Early Jurassic species, Eocaecilia micropodia, the earliest salamander is Beiyanerpeton jianpingensis from the Late Jurassic of northeastern China
Stratigraphy is a branch of geology which studies rock layers and layering. It is primarily used in the study of sedimentary and layered volcanic rocks, stratigraphy has two related subfields, lithologic stratigraphy or lithostratigraphy, and biologic stratigraphy or biostratigraphy. The first practical application of stratigraphy was by William Smith in the 1790s. Another influential application of stratigraphy in the early 19th century was a study by Georges Cuvier, variation in rock units, most obviously displayed as visible layering, is due to physical contrasts in rock type. This variation can occur vertically as layering, or laterally, and these variations provide a lithostratigraphy or lithologic stratigraphy of the rock unit. Key concepts in stratigraphy involve understanding how certain geometric relationships between rock layers arise and what these geometries imply about their original depositional environment. The basic concept in stratigraphy, called the law of superposition, states, in a stratigraphic sequence.
Chemostratigraphy studies the changes in the proportions of trace elements and isotopes within. Carbon and oxygen isotope ratios vary with time, and researchers can use those to map subtle changes that occurred in the paleoenvironment and this has led to the specialized field of isotopic stratigraphy. Biostratigraphy or paleontologic stratigraphy is based on evidence in the rock layers. Strata from widespread locations containing the fossil fauna and flora are said to be correlatable in time. Biologic stratigraphy was based on William Smiths principle of succession, which predated. It provides strong evidence for the formation and extinction of species, the geologic time scale was developed during the 19th century, based on the evidence of biologic stratigraphy and faunal succession. One important development is the Vail curve, which attempts to define a global historical sea-level curve according to inferences from worldwide stratigraphic patterns, stratigraphy is commonly used to delineate the nature and extent of hydrocarbon-bearing reservoir rocks and traps of petroleum geology.
Chronostratigraphy is the branch of stratigraphy that places an absolute age, a gap or missing strata in the geological record of an area is called a stratigraphic hiatus. This may be the result of a halt in the deposition of sediment, the gap may be due to removal by erosion, in which case it may be called a stratigraphic vacuity. It is called a hiatus because deposition was on hold for a period of time, a physical gap may represent both a period of non-deposition and a period of erosion. A geologic fault may cause the appearance of a hiatus, magnetostratigraphy is a chronostratigraphic technique used to date sedimentary and volcanic sequences
The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, known as the Age of Reptiles, the start of the period is marked by the major Triassic–Jurassic extinction event. The Jurassic is named after the Jura Mountains within the European Alps, by the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, on land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds appeared during the Jurassic, having evolved from a branch of theropod dinosaurs, other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals.
Crocodilians made the transition from a terrestrial to a mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, the chronostratigraphic term Jurassic is directly linked to the Jura Mountains. The name Jura is derived from the Celtic root jor, which was Latinised into juria, the Jurassic period is divided into the Early Jurassic and Late Jurassic epochs. The Jurassic System, in stratigraphy, is divided into the Lower Jurassic, the separation of the term Jurassic into three sections goes back to Leopold von Buch. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, the Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation, as in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed. In contrast, the North American Jurassic record is the poorest of the Mesozoic, the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate.
Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, South America, Australasia. As the Jurassic proceeded and more groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are well represented nor well studied in Africa. Late Jurassic strata are poorly represented apart from the spectacular Tendaguru fauna in Tanzania, the Late Jurassic life of Tendaguru is very similar to that found in western North Americas Morrison Formation. During the Jurassic period, the primary living in the sea were fish
Electron paramagnetic resonance
Electron paramagnetic resonance or electron spin resonance spectroscopy is a method for studying materials with unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance, EPR spectroscopy is particularly useful for studying metal complexes or organic radicals. EPR was first observed in Kazan State University by Soviet physicist Yevgeny Zavoisky in 1944, and was developed independently at the same time by Brebis Bleaney at the University of Oxford. Every electron has a moment and spin quantum number s =12, with magnetic components m s = +12 and m s = −12.0023 for the free electron. Therefore, the separation between the lower and the state is Δ E = g e μ B B0 for unpaired free electrons. This equation implies that the splitting of the levels is directly proportional to the magnetic fields strength. An unpaired electron can move between the two levels by either absorbing or emitting a photon of energy h ν such that the resonance condition. This leads to the equation of EPR spectroscopy, h ν = g e μ B B0.
Furthermore, EPR spectra can be generated by varying the photon frequency incident on a sample while holding the magnetic field constant or doing the reverse. In practice, it is usually the frequency that is kept fixed, a collection of paramagnetic centers, such as free radicals, is exposed to microwaves at a fixed frequency. At this point the electrons can move between their two spin states. The upper spectrum below is the absorption for a system of free electrons in a varying magnetic field. The lower spectrum is the first derivative of the absorption spectrum, the latter is the most common way to record and publish EPR spectra. For the microwave frequency of 9388.2 MHz, the predicted resonance occurs at a field of about B0 = h ν / g e μ B =0.3350 teslas =3350 gausses. For example, for the field of 3350 G shown at the right, in practice, EPR samples consist of collections of many paramagnetic species, and not single isolated paramagnetic centers. At 298 K, X-band microwave frequencies give n upper / n lower ≈0.998, transitions from the lower to the higher level are more probable than the reverse, which is why there is a net absorption of energy.
With k f and P being constants, N min ~ −1, i. e. N min ~ ν − α, in practice, α can change varying from 0.5 to 4.5 depending on spectrometer characteristics, resonance conditions, and sample size. A great sensitivity is obtained with a low detection limit N min
Homo sapiens is the binomial nomenclature for the only extant human species. Homo is the genus, which includes Neanderthals and many other extinct species of hominid. Modern humans are the subspecies Homo sapiens sapiens, which differentiates them from what has been argued to be their direct ancestor, the binomial name Homo sapiens was coined by Carl Linnaeus. The Latin noun homō means man, human being, subspecies of H. sapiens include Homo sapiens idaltu and the only extant subspecies, Homo sapiens sapiens. Some sources show Neanderthals as a subspecies, the discovered specimens of the Homo rhodesiensis species have been classified by some as a subspecies, but these last two subspecies classifications are not widely accepted by scientists. Traditionally, there are two competing views in paleoanthropology about the origin of H. sapiens, the recent African origin, since 2010, genetic research has led to the emergence of an intermediate position, characterised by mostly recent African origin plus limited admixture with archaic humans.
The recent African origin of humans is the mainstream model that describes the origin. The theory is called the Out-of-Africa model in the press, and academically the recent single-origin hypothesis, Replacement Hypothesis. The hypothesis that humans have a single origin was published in Charles Darwins Descent of Man, the concept was speculative until the 1980s, when it was corroborated by a study of present-day mitochondrial DNA, combined with evidence based on physical anthropology of archaic specimens. The recent single origin of humans in East Africa is the near-consensus position held within the scientific community. However, recent sequencing of the full Neanderthal genome suggests Neanderthals, the authors of the study suggest that their findings are consistent with Neanderthal admixture of up to 4% in some populations. But the study suggests that there may be other reasons why humans. That study however does not explain why only a fraction of humans have Neanderthal DNA. The multiregional origin model provides an explanation for the pattern of evolution proposed by Milford H.
Wolpoff in 1988. Scientific study of evolution is concerned, with the development of the genus Homo. Modern humans are defined as the Homo sapiens species, of which the extant subspecies is known as Homo sapiens sapiens. Homo sapiens idaltu, the known subspecies, is now extinct. Similarly, the specimens of the Homo rhodesiensis species have been classified by some as a subspecies