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Ardipithecus is a genus of an extinct hominine that lived during the Late Miocene and Early Pliocene epochs in the Afar Depression, Ethiopia. Originally described as one of the earliest ancestors of humans after they diverged from the chimpanzees, the relation of this genus to human ancestors and whether it is a hominin is now a matter of debate. Two fossil species are described in the literature: A. ramidus, which lived about 4.4 million years ago during the early Pliocene, and A. kadabba, dated to approximately 5.6 million years ago. Initial behavioral analysis indicated that Ardipithecus could be very similar to chimpanzees, however more recent analysis based on canine size and lack of canine sexual dimorphism indicates that Ardipithecus was characterised by reduced aggression, and that they more closely resemble bonobos.
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped, meaning 'two feet'. Types of bipedal movement include walking, running, and hopping.
Human evolution is the evolutionary process within the history of primates that led to the emergence of Homo sapiens as a distinct species of the hominid family, which includes 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.
Homininae, also called "African hominids" or "African apes", is a subfamily of Hominidae. It includes two tribes, with their extant as well as extinct species: 1) the tribe Hominini ―and 2) the tribe Gorillini (gorillas). Alternatively, the genus Pan is sometimes considered to belong to its own third tribe, Panini. Homininae comprises all hominids that arose after orangutans split from the line of great apes. The Homininae cladogram has three main branches, which lead to gorillas, and to humans and chimpanzees via the tribe Hominini and subtribes Hominina and Panina. There are two living species of Panina and two living species of gorillas, but only one extant human species. Traces of extinct Homo species, including Homo floresiensis have been found with dates as recent as 40,000 years ago. Organisms in this subfamily are described as hominine or hominines.
Paranthropus is a genus of extinct hominin which contains two widely accepted species: P. robustus and P. boisei. However, the validity of Paranthropus is contested, and it is sometimes considered to be synonymous with Australopithecus. They are also referred to as the robust australopithecines. They lived between approximately 2.6 and 0.6 million years ago (mya) from the end of the Pliocene to the Middle Pleistocene.
Australopithecus is a genus of early hominins that existed in Africa during the Late Pliocene and Early Pleistocene. The genera Homo emerged within Australopithecus, as sister to e.g. Australipitecus sediba. Also the genera Paranthropus, and Kenyanthropus emerged within the Australopithecus. Australopithecus is a member of the subtribe Australopithecina, which also includes Ardipithecus, though the term "australopithecine" is sometimes used to refer only to members of Australopithecus. Species include A. garhi, A. africanus, A. sediba, A. afarensis, A. anamensis, A. bahrelghazali and A. deyiremeda. Debate exists as to whether some Australopithecus species should be reclassified into new genera, or if Paranthropus and Kenyanthropus are synonymous with Australopithecus, in part because of the taxonomic inconsistency.
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, the most significant being the exceedingly well-preserved skeleton AL 288-1 ("Lucy") and the site AL 333. Beginning in 1974, Mary Leakey led an expedition into Laetoli, Tanzania, and notably recovered fossil trackways. In 1978, the species was first 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 dimorphism. A. afarensis probably descended from A. anamensis and is hypothesised to have given rise to Homo, though the latter is debated.
Turkana Boy, also called Nariokotome Boy, is the name given to fossil KNM-WT 15000, a nearly complete skeleton of a Homo ergaster youth who lived 1.5 to 1.6 million years ago. This specimen is the most complete early hominin skeleton ever found. It was discovered in 1984 by Kamoya Kimeu on the bank of the Nariokotome River near Lake Turkana in Kenya.
Brachiation, or arm swinging, is a form of arboreal locomotion in which primates swing from tree limb to tree limb using only their arms. During brachiation, the body is alternately supported under each forelimb. This form of locomotion is the primary means of locomotion for the small gibbons and siamangs of southeast Asia. Gibbons in particular use brachiation for as much as 80% of their locomotor activities. Some New World monkeys, such as spider monkeys and muriquis, were initially classified as semibrachiators and move through the trees with a combination of leaping and brachiation. Some New World species also practice suspensory behaviors by using their prehensile tail, which acts as a fifth grasping hand. Evidence has shown that the extinct ape Proconsul from the Milocene of East Africa developed an early form of suspensory behaviour, and was therefore referred to as a probrachiator.
Australopithecus africanus is an extinct species of australopithecine which lived from 3.67 to 2 million years ago in the Middle Pliocene to Early Pleistocene of South Africa. The species has been recovered from Taung and the Cradle of Humankind at Sterkfontein, Makapansgat, and Gladysvale. The first specimen, the Taung child, was described by anatomist Raymond Dart in 1924, and was the first early hominin found. However, its closer relations to humans than to other apes would not become widely accepted until the middle of the century because most had believed humans evolved outside of Africa principally due to the hoax transitional fossil Piltdown Man from Britain. It is unclear how A. africanus relates to other hominins, being variously placed as ancestral to Homo and Paranthropus, to just Paranthropus, or to just P. robustus. The specimen "Little Foot" is the most completely preserved early hominin, with 90% of the skeleton intact, and the oldest South African australopith. However, it is controversially suggested that it and similar specimens be split off into "A. prometheus".
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.
Paranthropus robustus is a species of robust australopithecine from the Early and possibly Middle Pleistocene of the Cradle of Humankind, South Africa, about 2.27 to 0.87 million years ago. It has been identified in Kromdraai, Swartkrans, Sterkfontein, Gondolin, Cooper's, and Drimolen Caves. Discovered in 1938, it was among the first early hominins described, and became the type species for the genus Paranthropus. However, it has been argued by some that Paranthropus is an invalid grouping and synonymous with Australopithecus, so the species is also often classified as Australopithecus robustus.
Orthograde is a term derived from Greek ὀρθός, orthos + Latin gradi that describes a manner of walking which is upright, with the independent motion of limbs. Both New and Old World monkeys are primarily arboreal, and they have a tendency to walk with their limbs swinging in parallel to one another. This differs from the manner of walking demonstrated by the apes.
A facultative biped is an animal that is capable of walking or running on two legs (bipedal), as a response to exceptional circumstances (facultative), while normally walking or running on four limbs or more. In contrast, obligate bipedalism is where walking or running on two legs is the primary method of locomotion. Facultative bipedalism has been observed in several families of lizards and multiple species of primates, including sifakas, capuchin monkeys, baboons, gibbons, gorillas, bonobos and chimpanzees. Different facultatively bipedal species employ different types of bipedalism corresponding to the varying reasons they have for engaging in facultative bipedalism. In primates, bipedalism is often associated with food gathering and transport. In lizards, it has been debated whether bipedal locomotion is an advantage for speed and energy conservation or whether it is governed solely by the mechanics of the acceleration and lizard's center of mass. Facultative bipedalism is often divided into high-speed (lizards) and low-speed (gibbons), but some species cannot be easily categorized into one of these two. Facultative bipedalism has also been observed in cockroaches and some desert rodents.
The evolution of human bipedalism, which began in primates approximately four million years ago, or as early as seven million years ago with Sahelanthropus, or approximately twelve million years ago with Danuvius guggenmosi, has led to morphological alterations to the human skeleton including changes to the arrangement and size of the bones of the foot, hip size and shape, knee size, leg length, and the shape and orientation of the vertebral column. The evolutionary factors that produced these changes have been the subject of several theories.
Claude Owen Lovejoy is an evolutionary anthropologist and anatomist at Kent State University Ohio. He is best known for his work on Australopithecine locomotion and the origins of bipedalism. "The origin of man", which he published in Science in January 1981, is cited as among his best-known articles. The 'C' of his name stands for Claude, but he never uses the name and is known only as Owen.
John Hawks is an associate professor of anthropology at the University of Wisconsin–Madison. He also maintains a paleoanthropology blog. Contrary to the common view that cultural evolution has made human biological evolution insignificant, Hawks believes that biological evolution has sped up in recent history.
The Bodo cranium is a fossil of an extinct type of hominin species. It was found by members of an expedition led by Jon Kalb in 1976. The Rift Valley Research Mission conducted a number of surveys that led to the findings of Acheulean tools and animal fossils, as well as the Bodo Cranium. The initial discovery was by Alemayhew Asfaw and Charles Smart, who found a lower face. Two weeks later, Paul Whitehead and Craig Wood found the upper portion of the face. Pieces of the cranium were discovered along the surface of one of the dry branches of the Awash River in Ethiopia. The cranium, artifacts, and other animal fossils were found over a relatively large area of medium sand, and only a few of the tools were found near the cranium. The skull is 600,000 years old and is now the type specimen of Homo bodoensis. (formerly Homo heidelbergensis / Homo rhodesiensis).
Nina G. Jablonski is an American anthropologist and palaeobiologist, known for her research into the evolution of skin color in humans. She is engaged in public education about human evolution, human diversity, and racism. In 2021, she was elected to the U.S. National Academy of Sciences and in 2009, she was elected to the American Philosophical Society. She is an Evan Pugh University Professor at The Pennsylvania State University, and the author of the books Skin: A Natural History, Living Color: The Biological and Social Meaning of Skin Color, and the co-author of Skin We Are In.
References
- ↑ Vaughan, Christopher L (2003), "Theories of bipedal walking: an odyssey" (PDF), Journal of Biomechanics, 36 (4): 513–523, CiteSeerX 10.1.1.468.2414 , doi:10.1016/S0021-9290(02)00419-0, PMID 12600342, archived from the original (PDF) on 2009-11-22
- ↑ Wood, Trina (9 February 1996), "The Singing Anthropologist", Back from his latest African visit, Henry McHenry has a bone to pick with an old theory about human evolution, UC Davis Dateline, archived from the original on 3 June 2006