Haplorhini
Haplorhini is a suborder of primates containing the tarsiers and the simians, as sister of the Strepsirrhini. The name is sometimes spelled Haplorrhini; the simians include catarrhines, the platyrrhines. The extinct omomyids, which are considered to be the most basal haplorhines, are believed to be more related to the tarsiers than to other haplorhines; the exact relationship is not yet established – Williams and Kirk prefer the view that tarsiers and simians share a common ancestor, that common ancestor shares a common ancestor with the omomyids, citing evidence from analysis by Bajpal et al. in 2008. Haplorhines share a number of derived features that distinguish them from the strepsirrhine "wet-nosed" primates, the other suborder of primates from which they diverged some 63 million years ago; the haplorhines, including tarsiers, have all lost the function of the terminal enzyme that manufactures Vitamin C, while the strepsirrhines, like most other orders of mammals, have retained this enzyme.
Genetically, five short interspersed nuclear elements are common to all haplorhines whilst absent in strepsirrhines. The haplorhine upper lip, which has replaced the ancestral rhinarium found in strepsirrhines, is not directly connected to their nose or gum, allowing a large range of facial expressions, their brain-to-body mass ratio is greater than the strepsirrhines, their primary sense is vision. Haplorhines have a postorbital plate, unlike the postorbital bar found in strepsirrhines. Most species are diurnal. All anthropoids have a single-chambered uterus. Most species have single births, although twins and triplets are common for marmosets and tamarins. Despite similar gestation periods, haplorhine newborns are much larger than strepsirrhine newborns, but have a longer dependence period on their mother; this difference in size and dependence is credited to the increased complexity of their behavior and natural history. The taxonomic name Haplorhini rhinos, it refers to the lack of a rhinarium or "wet nose", found in many mammals, including strepsirrhine primates.
Haplorhini and its sister clade, diverged about 65 million years ago. 5 million years only a short time afterward from an evolutionary perspective, the infraorder Tarsiiformes, whose only remaining family is that of the tarsier, branched off from the other haplorhines. The fossil Archicebus may be similar to the most recent common ancestor at this time; the other major clade within Haplorhini, the simians, is divided into two parvorders: Platyrrhini and Catarrhini. The New World monkeys split from catarrhines about 40 mya, while the apes diverged from Old World monkeys about 25 mya; the available fossil evidence indicates that both the hominoid and cercopithecoid clades originated in Africa. The following is the listing of the living haplorhine families, their placement in the Order Primates: ORDER PRIMATES Suborder Strepsirrhini: lemurs, galagos etc. Suborder Haplorhini: tarsiers + monkeys, including apes Infraorder Tarsiiformes Family Tarsiidae: tarsiers Infraorder Simiiformes: monkeys, apes Parvorder Platyrrhini: New World monkeys Family Callitrichidae: marmosets, tamarins Family Cebidae: capuchins, squirrel monkeys Family Aotidae: night or owl monkeys Family Pitheciidae: titis, uakaris Family Atelidae: howler and woolly monkeys Parvorder Catarrhini Old World anthropoids Superfamily Cercopithecoidea Family Cercopithecidae Superfamily Hominoidea: apes Family Hylobatidae: lesser apes Family Hominidae: great apes and humans The exact placement of early haplorhine families is uncertain owing to limited evidence.
The following sets out a possible order put together by Williams and Kirk in 2010, based on cladograms put together by Seiffert et al, Marivaux and Bajpai et al, should not be seen as definitive. They do not include Propliopithecoidea. Included are Archicebidae, the discovery of, announced by Ni et al in 2013.. ORDER PRIMATES Suborder Strepsirrhini: lemurs, lorises and their ancestors stem Haplorhini †Omomyiformes Omomyids and their ancestors crown Haplorhini Tarsiiformes Tarsiers and their ancestors †Archicebidae Tarsiidae †Altiatlasius †Eosimiidae early anthropoids †Amphipithecidae †Parapithecoidea †Proteopithecoidea †Oligopithecidae Catarrhini Old World anthropoids Platyrrhini New World monkeysSigé et al describe Altiatlasius as an Omomyiform, but state that it could be an early anthropoid, with the latter view being supported by Godinot and Bajpai et al. Kay et al point out that a case can be made for Amphipithecidae being placed either as adapiformes or as early anthropoids, noting in particular that they had a long evolution separate from other groups, that key parts of their anatomy are missing from the fossil record.
They conclude that either possibility is e
Taichung
Taichung known as Taichung City, is a special municipality located in central Taiwan. Taichung has a population of 2.81 million people and is Taiwan's second most populous city, overtaking Kaohsiung in July 2017. It serves as the core of the Taichung–Changhua metropolitan area, the second largest metropolitan area in Taiwan; the current city was formed when Taichung County merged with the original provincial Taichung City to form the special municipality on 25 December 2010. Located in the Taichung Basin, the city was named under Japanese rule, became a major economic and cultural hub. Composed of several scattered hamlets, the city of Taichung was planned and developed by the Japanese, it was called "the Kyoto of Formosa" in Japanese era because of its beauty. The city is home to the National Museum of Natural Science, the National Taiwan Museum of Fine Arts, the National Taichung Theater, the National Library of Public Information, the National Taiwan Symphony Orchestra, as well as many cultural sites, including the historic Taichung Park, the Lin Family Gardens, many temples.
The Atayal Taiwanese aborigines as well as several Taiwanese Plains Aboriginal tribes populated the plains that make up modern Taichung. They were hunter gatherers who lived by cultivating millet and taro. In the 17th century, the Papora, Babuza and Hoanya established the Kingdom of Middag, occupying the western part of present-day Taichung. In 1682, the Qing dynasty wrested control of western Taiwan from the Cheng family. In 1684, Zhuluo County was established, encompassing the underdeveloped northern two-thirds of Taiwan. Modern-day Taichung traces its beginnings to a settlement named Toatun in 1705. To strengthen Qing control, a garrison was established in 1721 near the site of present-day Taichung Park by Lan Ting-chen. North of the city, on the Dajia River, an aboriginal revolt broke out in 1731 after Chinese officials moved in and compelled them to provide labor; the revolt spread through the city as far south as Changhua County in May 1732 before the rebels were chased into the mountains by Qing forces.
In 1786, another rebellion against the Qing, known as the Lin Shuangwen rebellion, began as an attempt to overthrow the government and restore the Ming dynasty. As the rebels moved northward, they turned to slaughter and looting, they were defeated by a coalition of Qing forces, Quanzhou Fujianese descendants, aboriginal volunteers. When Taiwan Province was declared an independent province in 1887, the government intended to construct its capital city at the centrally located Toatun, designated as the seat of Taiwan Prefecture, thus the city took the title of "Taiwan-fu", meaning "capital city of Taiwan", from modern-day Tainan, which had held the title for more than 200 years. Qing official Liu Ming-chuan received permission to oversee development of the area, which included constructing a railway through the city. However, the provincial capital was moved to Taipei. After China lost the Sino-Japanese War in 1895, Taiwan was ceded to Japan by the Treaty of Shimonoseki, the name of the city was changed to Taichū.
The Japanese sought to develop the city to make it the first “modern” area of Taiwan and invested in roads and levees. In 1901, Taichū Chō was established as one of twenty local administrative districts on the island. In 1904, the town of Taichū had a population of 6,423, Taichū District had more than 207,000. Taichū Park was completed in 1903. A tower marking the old north gate was moved to the new park; the first market in Taichū was built in 1908, along Jiguang Road between the Zhongzheng and Chenggong Roads and it is still in use today. The Japanese undertook a north-south island railway project. Taichū Train Station was completed and began operation in 1917, still operates today. Taichū City was declared by Japanese Imperial authorities in 1920, Taichū City Hall was completed in 1924 after eleven years of construction. Kōkan Airport, now known as Taichung Airport, was constructed during Japanese rule. Taichū Middle School was founded in 1915 by elite members of local gentry, including Lin Hsien-tang and his brother Lin Lieh-tang, two wealthy Taiwanese intellectuals of the era.
This was in an effort to teach children the culture of Taiwan and to foster the spirit of the Taiwanese localization movement. The Taiwanese Cultural Association, founded in 1921 in Taipei by Lin Hsien-tang, was moved to Taichū in 1927. Most of the members of this association were from Taichū and the surrounding area; the city became a center of Taiwanese nationalism. From 1926 to 1945, Taichū Prefecture covered modern-day Taichung as well as Changhua County and Nantou County. At the end of the war, Japan handed over control of Taiwan. In 1947 the first Mayor of Taichung County was Lai Tien Shen; the position was appointed by the government to rule during the interim period. Both Taichung areas were declared a provincial city and county in 1949. Since the city has grown as a center of higher education and culture, where 70% of employees worked in service industries; the surrounding county developed manufacturing, which employed 48% of the workforce, focused so on precision machinery, from machine tools to bicycles, that it was nicknamed the “Mechanical Kingdom.”
On 25 December 20
Neogene
The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago to the beginning of the present Quaternary Period 2.58 Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the Pliocene; some geologists assert that the Neogene cannot be delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes. During this period and birds continued to evolve into modern forms, while other groups of life remained unchanged. Early hominids, the ancestors of humans, appeared in Africa near the end of the period; some continental movement took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to the Atlantic Ocean, leaving only the Gulf Stream to transfer heat to the Arctic Ocean; the global climate cooled over the course of the Neogene, culminating in a series of continental glaciations in the Quaternary Period that follows.
In ICS terminology, from upper to lower: The Pliocene Epoch is subdivided into 2 ages: Piacenzian Age, preceded by Zanclean AgeThe Miocene Epoch is subdivided into 6 ages: Messinian Age, preceded by Tortonian Age Serravallian Age Langhian Age Burdigalian Age Aquitanian AgeIn different geophysical regions of the world, other regional names are used for the same or overlapping ages and other timeline subdivisions. The terms Neogene System and upper Tertiary System describe the rocks deposited during the Neogene Period; the continents in the Neogene were close to their current positions. The Isthmus of Panama formed, connecting South America; the Indian subcontinent continued forming the Himalayas. Sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America; the global climate became seasonal and continued an overall drying and cooling trend which began at the start of the Paleogene. The ice caps on both poles began to grow and thicken, by the end of the period the first of a series of glaciations of the current Ice Age began.
Marine and continental flora and fauna have a modern appearance. The reptile group Choristodera became extinct in the early part of the period, while the amphibians known as Allocaudata disappeared at the end. Mammals and birds continued to be the dominant terrestrial vertebrates, took many forms as they adapted to various habitats; the first hominins, the ancestors of humans, may have appeared in southern Europe and migrated into Africa. In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones and grasslands replaced many forests. Grasses therefore diversified, herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses and bison. Eucalyptus fossil leaves occur in the Miocene of New Zealand, where the genus is not native today, but have been introduced from Australia; the Neogene traditionally ended at the end of the Pliocene Epoch, just before the older definition of the beginning of the Quaternary Period. However, there was a movement amongst geologists to include ongoing geological time in the Neogene, while others insist the Quaternary to be a separate period of distinctly different record.
The somewhat confusing terminology and disagreement amongst geologists on where to draw what hierarchical boundaries is due to the comparatively fine divisibility of time units as time approaches the present, due to geological preservation that causes the youngest sedimentary geological record to be preserved over a much larger area and to reflect many more environments than the older geological record. By dividing the Cenozoic Era into three periods instead of seven epochs, the periods are more comparable to the duration of periods in the Mesozoic and Paleozoic eras; the International Commission on Stratigraphy once proposed that the Quaternary be considered a sub-era of the Neogene, with a beginning date of 2.58 Ma, namely the start of the Gelasian Stage. In the 2004 proposal of the ICS, the Neogene would have consisted of the Miocene and Pliocene epochs; the International Union for Quaternary Research counterproposed that the Neogene and the Pliocene end at 2.58 Ma, that the Gelasian be transferred to the Pleistocene, the Quaternary be recognized as the third period in the Cenozoic, citing key changes in Earth's climate and biota that occurred 2.58 Ma and its correspondence to the Gauss-Matuyama magnetostratigraphic boundary.
In 2006 ICS and INQUA reached a compromise that made Quaternary a subera, subdividing Cenozoic into the old classical Tertiary and Quaternary, a compromise, rejected by International Union of Geological Sciences because it split both Neogene and Pliocene in two. Following formal discussions at the 2008 International Geological Congress in Oslo, the ICS decided in May 2009 to make the Quaternary the youngest period of the Cenozoic Era with its base at 2.58 Mya and including the Gelasian age, considered part of the Neogene Period and Pliocene Epoch. Thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya. "Digital Atlas of Neogene Life for the Southeastern United States". San Jose State University. Archived from the original on 2013-04-23. Retrieved 21 September 2018
National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D. C. United States, it is open 364 days a year. In 2016, with 7.1 million visitors, it was the fourth most visited museum in the world and the most visited natural-history museum in the world. Opened in 1910, the museum on the National Mall was one of the first Smithsonian buildings constructed to hold the national collections and research facilities; the main building has an overall area of 1,500,000 square feet with 325,000 square feet of exhibition and public space and houses over 1,000 employees. The museum's collections contain over 126 million specimens of plants, fossils, rocks, human remains, human cultural artifacts, it is home to about 185 professional natural-history scientists—the largest group of scientists dedicated to the study of natural and cultural history in the world. The United States National Museum was founded in 1846 as part of the Smithsonian Institution.
The museum was housed in the Smithsonian Institution Building, better known today as the Smithsonian Castle. A formal exhibit hall opened in 1858; the growing collection led to the construction of the National Museum Building. Covering a then-enormous 2.25 acres, it was built in just 15 months at a cost of $310,000. It opened in March 1881. Congress authorized construction of a new building on June 28, 1902. On January 29, 1903, a special committee composed of members of Congress and representatives from the Smithsonian's board of regents published a report asking Congress to fund a much larger structure than planned; the regents began considering sites for the new building in March, by April 12 settled on a site on the north side of B Street NW between 9th and 12th Streets. The D. C. architectural firm of Hornblower & Marshall was chosen to design the structure. Testing of the soil for the foundations was set for July 1903, with construction expected to take three years; the Natural History Building opened its doors to the public on March 17, 1910, in order to provide the Smithsonian Institution with more space for collections and research.
The building was not completed until June 1911. The structure cost $3.5 million dollars. The Neoclassical style building was the first structure constructed on the north side of the National Mall as part of the 1901 McMillan Commission plan. In addition to the Smithsonian's natural history collection, it housed the American history and cultural collections. Between 1981 and 2003, the National Museum of Natural History had 11 acting directors. There were six directors alone between 1990 and 2002. Turnover was high as the museum's directors were disenchanted by low levels of funding and the Smithsonian's inability to define the museum's mission. Robert W. Fri was named the museum's director in 1996. One of the largest donations in Smithsonian history was made during Fri's tenure. Kenneth E. Behring donated $20 million in 1997 to modernize the museum. Fri resigned in 2001 after disagreeing with Smithsonian leadership over the reorganization of the museum's scientific research programs. J. Dennis O'Connor, Provost of the Smithsonian Institution was named acting director of the museum on July 25, 2001.
Eight months O'Conner resigned to become the vice president of research and dean of the graduate school at the University of Maryland. Douglas Erwin, a paleontologist at the National Museum of Natural History, was appointed interim director in June 2002. In January 2003, the Smithsonian announced that Cristián Samper, a Colombian with an M. Sc. and Ph. D. from Harvard University, would become the museum's permanent director on March 31, 2003. Samper founded the Alexander von Humboldt Biological Resources Research Institute and ran the Smithsonian Tropical Research Institute after 2001. Smithsonian officials said. Under Samper's direction, the museum opened the $100 million Behring Hall of Mammals in November 2003, received $60 million in 2004 for the Sant Hall of Oceans, received a $1 million gift from Tiffany & Co. for the purchase of precious gems for the National Gem Collection. On March 25, 2007, Lawrence M. Small, Secretary of the Smithsonian Institution and the organization's highest-ranking appointed official, resigned abruptly after public reports of lavish spending.
On March 27, 2007 Samper was appointed Acting Secretary of the Smithsonian. Paul G. Risser, former chancellor of the University of Oklahoma, was named Acting Director of the Museum of Natural History on March 29. Samper's tenure at the museum was not without controversy. In May 2007, Robert Sullivan, the former associate director in charge of exhibitions at the National Museum of Natural History, charged that Samper and Smithsonian Undersecretary for Science David Evans ordered "last minute" changes in the exhibit "Arctic: A Friend Acting Strangely" to tone down the role of human beings in the discussion of global warming, to make global warming seem more uncertain than depicted. Samper denied that he knew of any scientific objections to the changes, said that no political pressure had been applied to the Smithsonian to make the changes. In November 2007, The Washington Post reported that an interagency group of scientists from the Department of the Interior, NASA, Nati
Human evolution
Human evolution is the evolutionary process that led to the emergence of anatomically modern humans, beginning with the evolutionary history of primates—in particular genus Homo—and leading to the emergence of Homo sapiens as a distinct species of the hominid family, the great apes. This process involved the gradual development of traits such as human bipedalism and language, as well as interbreeding with other hominins, which indicate that human evolution was not linear but a web; the study of human evolution involves several scientific disciplines, including physical anthropology, archaeology, neurobiology, linguistics, evolutionary psychology and genetics. Genetic studies show that primates diverged from other mammals about 85 million years ago, in the Late Cretaceous period, the earliest fossils appear in the Paleocene, around 55 million years ago. Within the Hominoidea superfamily, the Hominidae family diverged from the Hylobatidae family some 15–20 million years ago. Human evolution from its first separation from the last common ancestor of humans and chimpanzees is characterized by a number of morphological, developmental and behavioral changes.
The most significant of these adaptations are bipedalism, increased brain size, lengthened ontogeny, decreased sexual dimorphism. The relationship between these changes is the subject of ongoing debate. Other significant morphological changes included the evolution of a power and precision grip, a change first occurring in H. erectus. Bipedalism is the basic adaptation of the hominid and is considered the main cause behind a suite of skeletal changes shared by all bipedal hominids; the earliest hominin, of primitive bipedalism, is considered to be either Sahelanthropus or Orrorin, both of which arose some 6 to 7 million years ago. The non-bipedal knuckle-walkers, the gorilla and chimpanzee, diverged from the hominin line over a period covering the same time, so either of Sahelanthropus or Orrorin may be our last shared ancestor. Ardipithecus, a full biped, arose 5.6 million years ago. The early bipeds evolved into the australopithecines and still into the genus Homo. There are several theories of the adaptation value of bipedalism.
It is possible that bipedalism was favored because it freed the hands for reaching and carrying food, saved energy during locomotion, enabled long distance running and hunting, provided an enhanced field of vision, helped avoid hyperthermia by reducing the surface area exposed to direct sun. A new study provides support for the hypothesis that walking on two legs, or bipedalism, evolved because it used less energy than quadrupedal knuckle-walking. However, recent studies suggest that bipedality without the ability to use fire would not have allowed global dispersal; this change in gait saw a lengthening of the legs proportionately when compared to the length of the arms, which were shortened through the removal of the need for brachiation. Another change is the shape of the big toe. Recent studies suggest that Australopithecines still lived part of the time in trees as a result of maintaining a grasping big toe; this was progressively lost in Habilines. Anatomically, the evolution of bipedalism has been accompanied by a large number of skeletal changes, not just to the legs and pelvis, but to the vertebral column and ankles, skull.
The femur evolved into a more angular position to move the center of gravity toward the geometric center of the body. The knee and ankle joints became robust to better support increased weight. To support the increased weight on each vertebra in the upright position, the human vertebral column became S-shaped and the lumbar vertebrae became shorter and wider. In the feet the big toe moved into alignment with the other toes to help in forward locomotion; the arms and forearms shortened relative to the legs making it easier to run. The foramen magnum migrated under more anterior; the most significant changes occurred in the pelvic region, where the long downward facing iliac blade was shortened and widened as a requirement for keeping the center of gravity stable while walking. A drawback is that the birth canal of bipedal apes is smaller than in knuckle-walking apes, though there has been a widening of it in comparison to that of australopithecine and modern humans, permitting the passage of newborns due to the increase in cranial size but this is limited to the upper portion, since further increase can hinder normal bipedal movement.
The shortening of the pelvis and smaller birth canal evolved as a requirement for bipedalism and had significant effects on the process of human birth, much more difficult in modern humans than in other primates. During human birth, because of the variation in size of the pelvic region, the fetal head must be in a transverse position during entry into the birth canal and rotate about 90 degrees upon exit; the smaller birth canal became a limiting factor to brain size increases in early humans and prompted a shorter gestation period leading to the relative immaturity of human
Denisovan
The Denisovans or Denisova hominins are an extinct species or subspecies of archaic humans in the genus Homo. Pending its taxonomic status, it carries temporary species or subspecies names Homo denisova, Homo altaiensis, Homo sapiens denisova, or Homo sp. Altai. In 2010, scientists announced the discovery of an undated finger bone fragment of a juvenile female found in the Denisova Cave in the Altai Mountains in Siberia, a cave, inhabited by Neanderthals and modern humans; the mitochondrial DNA of the finger bone showed it to be genetically distinct from Neanderthals and modern humans. The nuclear genome from this specimen suggested that Denisovans shared a common origin with Neanderthals, that they ranged from Siberia to Southeast Asia, that they lived among and interbred with the ancestors of some modern humans, with about 3% to 5% of the DNA of Melanesians and Aboriginal Australians and around 6% in Papuans deriving from Denisovans. Several additional specimens were subsequently characterized.
A comparison with the genome of another Neanderthal from the Denisova cave revealed local interbreeding with local Neanderthal DNA representing 17% of the Denisovan genome, evidence of interbreeding with an as yet unidentified ancient human lineage, while an unexpected degree of mtDNA divergence among Denisovans was detected. The lineage that developed into Denisovans and Neanderthals is estimated to have separated from the lineage that developed into "anatomically modern" Homo sapiens 600,000 to 744,000 years ago. Denisovans and Neanderthals significantly diverged from each other genetically a mere 300 generations after that. Several types of humans, including Denisovans and related hybrids, may have each dwelt in the Denisova Cave in Siberia over thousands of years, but it is unclear whether they co-habitated in the cave; the Denisova Cave is in south-western Siberia, Russia in the Altai Mountains near the border with Kazakhstan and Mongolia. It is named after a Russian hermit who lived there in the 18th century.
The cave was explored in the 1970s by Russian paleontologist Nikolai Ovodov, looking for remains of canids. In 2008, Michael Shunkov from the Russian Academy of Sciences and other Russian archaeologists from the Institute of Archaeology and Ethnology of Novosibirsk investigated the cave, they found the finger bone of a juvenile hominin referred to as the "X woman", or the Denisova hominin. Artifacts excavated in the cave at the same level were dated using radiocarbon and oxygen isotopes to around 40,000 BP. Excavations have since revealed human artifacts showing an intermittent presence going back 125,000 years. A team of scientists led by Johannes Krause and Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology in Leipzig, sequenced mtDNA extracted from the fragment; the cool climate of the Denisova Cave preserved the DNA. The average annual temperature of the cave is 0 °C, which has contributed to the preservation of archaic DNA among the remains discovered; the analysis indicated that the Denisova hominin "diverged from a common ancestor well before Neanderthals and modern humans did"—around 1 million years ago.
The mtDNA analysis further suggested that this new hominin species was the result of an earlier migration out of Africa, distinct from the out-of-Africa migrations associated with modern humans, but distinct from the earlier African exodus of Homo erectus. Pääbo noted that the existence of this distant branch creates a much more complex picture of humankind during the Late Pleistocene; this work shows that the Denisovans were a sister group to the Neanderthals, branching off from the human lineage 550,000 years ago, diverging from Neanderthals in the Middle East, 300,000 years ago. A second paper from the Svante Pääbo group reported the prior discovery of a third upper molar from a young adult, dating from about the same time; the tooth differed in several aspects from those of Neanderthals, while having archaic characteristics similar to the teeth of Homo erectus. They performed mtDNA analysis on the tooth and found it to have a sequence somewhat similar to that of the finger bone, indicating a divergence time about 7,500 years before, suggesting that it belonged to a different individual from the same population.
So far, the fossils of four distinct Denisovans from Denisova Cave have been identified through their DNA: Denisova 2, Denisova 3, Denisova 4, Denisova 8. Analysis of a fifth specimen, Denisova 11, proved it to have belonged to an F1 Denisovan-Neanderthal hybrid. Denisova 2 and Denisova 3 are prepubescent or adolescent females, while Denisova 4 and Denisova 8 are adult males. MtDNA analysis of the Denisovan individuals suggests the Denisova 2 fossil is the oldest, followed by Denisova 8, while Denisova 3 and Denisova 4 are contemporaneous. During DNA sequencing, a low proportion of the Denisova 2, Denisova 4 and Denisova 8 genomes were found to have survived, but a high proportion of the Denisova 3 genome had survived. Little is known of the precise anatomical features of the Denisovans, since the only physical remains discovered thus far are the finger bone, two teeth from which genetic material has been gathered, a toe bone; the single finger bone is unusually broad and robust, well outside the variation seen in modern people.
It belonged to a female, indicating that the Denisovans were robust similar in build to the Neanderthals. The tooth does not share the derived morphological features seen in Neanderthal or modern human teeth. An initial morphological
Australopithecus
Australopithecus ( OS-trə-lo-PITH-i-kəs. From paleontological and archaeological evidence, the genus Australopithecus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and becoming extinct two million years ago. Australopithecus is not extinct as the Kenyanthropus and Homo genera emerged as sister of a late Australopithecus species such as A. Africanus and/or A. Sediba. During that time, a number of australopithecine species emerged, including Australopithecus afarensis, A. africanus, A. anamensis, A. bahrelghazali, A. deyiremeda, A. garhi, A. sediba. For some hominid species of this time – A. robustus, A. boisei and A. aethiopicus – some debate exists whether they constitute members of the genus Australopithecus. If so, they would be considered'robust australopiths', while the others would be'gracile australopiths'. However, if these more robust species do constitute their own genus, they would be under the genus name Paranthropus, a genus described by Robert Broom when the first discovery was made in 1938, which makes these species P. robustus, P. boisei and P. aethiopicus.
Australopithecus species played a significant part in human evolution, the genus Homo being derived from Australopithecus at some time after three million years ago. In addition, they were the first hominids to possess certain genes, known as the duplicated SRGAP2, which increased the length and ability of neurons in the brain. One of the australopith species evolved into the genus Homo in Africa around two million years ago, modern humans, H. sapiens sapiens. In January 2019, scientists reported that Australopithecus sediba is distinct from, but shares anatomical similarities to, both the older Australopithecus africanus, the younger Homo habilis. Gracile australopiths shared several traits with modern apes and humans, were widespread throughout Eastern and Northern Africa around 3.5 million years ago. The earliest evidence of fundamentally bipedal hominids can be observed at the site of Laetoli in Tanzania; this site contains hominid footprints that are remarkably similar to those of modern humans and have been dated to as old as 3.6 million years.
The footprints have been classified as australopith, as they are the only form of prehuman hominins known to have existed in that region at that time. Australopithecus anamensis, A. afarensis, A. africanus are among the most famous of the extinct hominins. A. africanus was once considered to be ancestral to the genus Homo. However, fossils assigned to the genus Homo have been found. Thus, the genus Homo either split off from the genus Australopithecus at an earlier date, or both developed from a yet unknown common ancestor independently. According to the Chimpanzee Genome Project, the human and chimpanzee lineages diverged from a common ancestor about five to six million years ago, assuming a constant rate of evolution, it is theoretically more for evolution to happen more as opposed to more from the date suggested by a gene clock However, hominins discovered more are somewhat older than the presumed rate of evolution would suggest. Sahelanthropus tchadensis called "Toumai", is about seven million years old and Orrorin tugenensis lived at least six million years ago.
Since little is known of them, they remain controversial among scientists since the molecular clock in humans has determined that humans and chimpanzees had a genetic split at least a million years later. One theory suggests that the human and chimpanzee lineages diverged somewhat at first some populations interbred around one million years after diverging; the brains of most species of Australopithecus were 35% of the size of a modern human brain. Most species of Australopithecus were diminutive and gracile standing 1.2 to 1.4 m tall. In several variations is a considerable degree of sexual dimorphism, males being larger than females. According to one scholar, A. Zihlman, Australopithecus body proportions resemble those of bonobos, leading evolutionary biologists such as Jeremy Griffith to suggest that bonobos may be phenotypically similar to Australopithecus. Furthermore, thermoregulatory models suggest that Australopithecus species were hair covered, more like chimpanzees and bonobos, unlike humans.
Modern humans do not display the same degree of sexual dimorphism as Australopithecus appears to have. In modern populations, males are on average a mere 15% larger than females, while in Australopithecus, males could be up to 50% larger than females. New research suggests, that australopithecines exhibited a lesser degree of sexual dimorphism than these figures suggest, but the issue is not settled. Opinions differ as to whether the species A. aethiopicus, A. boisei, A. robustus should be included within the genus Australopithecus, no current consensus exists as to whether they should be placed in a distinct genus, Paranthropus
