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Savannah Hypothesis
The savannah hypothesis (or savanna hypothesis) is a hypothesis that human bipedalism evolved as a direct result of human ancestors' transition from an arboreal lifestyle to one on the savannas. According to the hypothesis, hominins left the woodlands that had previously been their natural habitat millions of years ago and adapted to their new habitat by walking upright. The idea that a climate-driven retraction of tropical forests forced early hominini into bipedalism has been around for a long time, often implicitly. Some early authors saw savannahs as open grasslands, while others saw a mosaic of environments from woodlands to grasslands. The hypothesis has seen rising criticism since at least the late 1960s. The open grasslands version is mostly dismissed; in contrast, the mosaic version still has relatively wide support. However, the transition from forest to savanna probably was more gradual than previously thought. History The fundamental ideas behind it date back to Lama ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothesis
A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess or thought. If a hypothesis is repeatedly independently demonstrated by experiment to be true, it becomes a scientific theory. In colloquial usage, the words "hypothesis" and "theory" are often used interchangeably, but this is incorrect in the context of science. A working hypothesis is a provisionally-accepted hypothesis used for the purpose of pursuing further progress in research. Working hypotheses are frequently discarded, and often proposed with knowledge (and warning) that they are incomplete and thus false, with the intent of moving research in at least somewhat the right direction, especially when scientists are stuck on an issue and brainstorming ideas. A different meaning of the term ''hypothesis'' is used in formal l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Weinert
Hans may refer to: __NOTOC__ People * Hans (name), a masculine given name * Hans Raj Hans, Indian singer and politician ** Navraj Hans, Indian singer, actor, entrepreneur, cricket player and performer, son of Hans Raj Hans ** Yuvraj Hans, Punjabi actor and singer, son of Hans Raj Hans * Hans clan, a tribal clan in Punjab, Pakistan Places * Hans, Marne, a commune in France * Hans Island, administrated by Greenland and Canada Arts and entertainment * ''Hans'' (film) a 2006 Italian film directed by Louis Nero * Hans (Frozen), the main antagonist of the 2013 Disney animated film ''Frozen'' * ''Hans'' (magazine), an Indian Hindi literary monthly * ''Hans'', a comic book drawn by Grzegorz Rosiński and later by Zbigniew Kasprzak Other uses * Clever Hans, the "wonder horse" * ''The Hans India'', an English language newspaper in India * HANS device, a racing car safety device * Hans, the ISO 15924 code for Simplified Chinese characters See also *Han (other) Han may refer t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Talbot Robinson
John Talbot Robinson FRSSAf (10 January 1923 – 12 October 2001) was a distinguished South African hominin paleontologist. His most famous discovery (with Robert Broom) was the nearly complete fossil skull of the hominin species ''Australopithecus africanus'', known as Mrs. Ples. Education and career Robinson was born in Elliot, South Africa to Theodore Clement Robinson and Florence Harriett Robinson (née Selby), both descendants of the British 1820 Settlers. He attended the University of Cape Town where he obtained a BSc in zoology and bacteriology in 1943 and an MSc (zoology) in 1944, with a thesis on the giant girdled lizard ('' Cordylus giganteus''). He contributed to two dissection manuals, one on the clawed frog (''Xenopus'') and the other on the spiney dogfish shark ( ''Squalus''). He started his doctorate in marine biology in Cape Town and even went so far as to publish descriptions of new diatoms and copepods but he interrupted it by moving to the Transvaal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elizabeth Vrba
Elisabeth S. Vrba (May 27, 1942 – February 5, 2025) was an American paleontologist at Yale University who developed the turnover-pulse hypothesis. Background Vrba was born in Hamburg, Germany. In 1944, following the death of her father, she moved with her family to a sheep farm in Namibia. She earned her Ph.D. in Zoology and Palaeontology at the University of Cape Town, in 1974. Vrba studied zoology and mathematical statistics at the University of Cape Town to earn her undergraduate degree. She remained there for doctoral study in zoology and paleontology to earn her Ph.D. After receiving her doctorate, Vrba conducted her early research on African fossil records over the last several million years, tracking the sequence of fossils from analyzing the geological strata and analyzing the morphology of the fossils. She was the chief assistant to Charles Kimberlin Brain during his directorship of the Transvaal Museum. Vrba died in New Haven, Connecticut, on February 5, 2025, at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turnover-pulse Hypothesis
The turnover-pulse hypothesis, formulated by paleontologist Elisabeth Vrba, suggests that major changes to the climate or ecosystem often result in a period of rapid extinction and high turnover of new species (a "pulse") across multiple different lineages. Changes may include climate change, tectonic plate shifting, and catastrophes, among other things. It can be seen as an extension of the concept of evolutionary radiation from a single to a multi-clade context. Theory Ecosystems periodically experience significant disruptions which cause mass extinctions and speciation. Vrba proposes that changes in the climate, through their effect on the physical environment, result in the "division of nimalpopulations into geographically and genetically isolated groups", which subsequently evolve into separate species. She also predicts that within an ecosystem this should occur for different groups of animals at roughly the same time, creating a "synchronous pulse" across multiple lineage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homo (genus)
''Homo'' () is a genus of great ape (family Hominidae) that emerged from the genus ''Australopithecus'' and encompasses only a single extant species, ''Homo sapiens'' (modern humans), along with a number of extinct species (collectively called archaic humans) classified as either ancestral or closely related to modern humans; these include '' Homo erectus'' and '' Homo neanderthalensis''. The oldest member of the genus is '' Homo habilis'', with records of just over 2 million years ago. ''Homo'', together with the genus ''Paranthropus'', is probably most closely related to the species ''Australopithecus africanus'' within ''Australopithecus''.'''' The closest living relatives of ''Homo'' are of the genus '' Pan'' ( chimpanzees and bonobos), with the ancestors of ''Pan'' and ''Homo'' estimated to have diverged around 5.7–11 million years ago during the Late Miocene. ''H. erectus'' appeared about 2 million years ago and spread throughout Africa (debatably ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gorilla
Gorillas are primarily herbivorous, terrestrial great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or five subspecies. The DNA of gorillas is highly similar to that of humans, from 96 to 99% depending on what is included, and they are the next closest living relatives to humans after the chimpanzees. Gorillas are the largest living primates, reaching heights between , weights between , and arm spans up to , depending on species and sex. They tend to live in troops, with the leader being called a silverback. The eastern gorilla is distinguished from the western by darker fur colour and some other minor morphological differences. Gorillas tend to live 35–40 years in the wild. Gorillas' natural habitats cover tropical or subtropical forest in Sub-Saharan Africa. Although their range covers a small percentage of Sub-Saharan Africa, gorillas c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pan (genus)
The genus ''Pan'' consists of two extant species: the chimpanzee and the bonobo. Taxonomically, these two ape species are collectively termed panins; however, both species are more commonly referred to collectively using the generalized term chimpanzees, or chimps. Together with humans, gorillas, and orangutans, they are part of the family Hominidae (the great apes, or ''hominids''). Native to sub-Saharan Africa, chimpanzees and bonobos are currently both found in the Congo jungle, while only the chimpanzee is also found further north in West Africa. Both species are listed as endangered species, endangered on the IUCN Red List of Threatened Species, and in 2017 the Convention on Migratory Species selected the chimpanzee for special protection. Chimpanzee and bonobo: comparison The chimpanzee (''P. troglodytes''), which lives north of the Congo River, and the bonobo (''P. paniscus''), which lives south of it, were once considered to be the same species, but since 1928 they h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is Cladogram#Homoplasies, homoplasy. The recurrent evolution of flight is a classic example, as flying pterygota, insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homology (biology), homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australopithecus Afarensis
''Australopithecus afarensis'' is an extinct species of australopithecine which lived from about 3.9–2.9 million years ago (mya) in the Pliocene of East Africa. The first fossils were discovered in the 1930s, but major fossil finds would not take place until the 1970s. From 1972 to 1977, the International Afar Research Expedition—led by anthropologists Maurice Taieb, Donald Johanson and Yves Coppens—unearthed several hundreds of hominin specimens in Hadar, Ethiopia, Hadar, Ethiopia, the most significant being the exceedingly well-preserved skeleton AL 288-1 ("Lucy (Australopithecus), Lucy") and the site AL 333 ("the First Family"). Beginning in 1974, Mary Leakey led an expedition into Laetoli, Tanzania, and notably recovered fossil trackways. In 1978, the species was first species description, described, but this was followed by arguments for splitting the wealth of specimens into different species given the wide range of variation which had been attributed to sexual dimorphi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australopithecus Anamensis
''Australopithecus anamensis'' is a hominin species that lived roughly between 4.3 and 3.8 million years ago, and is the oldest known ''Australopithecus'' species, Nearly 100 fossil specimens of ''A. anamensis'' are known from Kenya and Ethiopia, representing over 20 individuals. The first fossils of ''A. anamensis'' discovered are dated to around 3.8 and 4.2 million years ago and were found in Kanapoi and Allia Bay in northern Kenya. '' A. afarensis'' is normally accepted to have emerged within this lineage. However, ''A. anamensis'' and ''A. afarensis'' appear to have lived side-by-side for at least some period of time, and whether the lineage that led to extant humans emerged in ''A. afarensis'', or directly in ''A. anamensis'' is not fully settled. Fossil evidence determines that ''Australopithecus anamensis'' is the earliest hominin species in the Turkana Basin, but likely co-existed with ''afarensis'' towards the end of its existence. ''A. anamensis'' and ''A. afarensis'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Knuckle-walking
Knuckle-walking is a form of quadrupedal walking in which the forelimbs hold the fingers in a partially flexed posture that allows body weight to press down on the ground through the knuckles. Gorillas and chimpanzees use this style of locomotion, as do anteaters and platypuses. Knuckle-walking helps with actions other than locomotion on the ground. Gorillas use fingers for the manipulation of food, whereas chimpanzees use fingers for the manipulation of food and climbing. In anteaters and pangolins, the fingers have large claws for opening the mounds of social insects. Platypus fingers have webbing that extend past the fingers to aid in swimming, thus knuckle-walking is used to prevent stumbling. Gorillas move around by knuckle-walking, although they sometimes walk bipedally for short distances while carrying food or in defensive situations. Mountain gorillas use knuckle-walking plus other parts of their hand—fist-walking does not use the knuckles, using the backs of their h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
