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Obstetrical Dilemma
The obstetrical dilemma is a hypothesis to explain why humans often require assistance from other humans during childbirth to avoid Complications of pregnancy, complications, whereas most non-human primates give birth unassisted with relatively little difficulty. This occurs due to the tight fit of the fetal head to the maternal birth canal, which is additionally convoluted, meaning the head and therefore body of the infant must rotate during childbirth in order to fit, unlike in other, non-upright walking mammals. Consequently, there is an unusually high incidence of cephalopelvic disproportion and obstructed labor in humans. The obstetrical dilemma claims that this difference is due to the biological trade-off imposed by two opposing evolutionary pressures in the development of the human pelvis: smaller birth canals in the mothers, and larger brains, and therefore Human skull, skulls in the babies. Proponents believe Bipedalism, bipedal locomotion (the ability to walk upright) d ... [...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] |
Sacrum
The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It forms joints with four other bones. The two projections at the sides of the sacrum are called the alae (wings), and articulate with the ilium at the L-shaped sacroiliac joints. The upper part of the sacrum connects with the last lumbar vertebra (L5), and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua. The sacrum has three different surfaces which are shaped to accommodate surrounding pelvic structures. Overall, it is concave (curved upon itself). The base of the sacrum, the broadest and uppermost part, is tilted forward as the sacral promontory internally. The central part is curved outward toward the posterior, allowing greater room for the pelvic cavity. In a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Evolution
''Homo sapiens'' is a distinct species of the hominid family of primates, which also includes all the great apes. Over their evolutionary history, humans gradually developed traits such as Human skeletal changes due to bipedalism, bipedalism, dexterity, and complex language, as well as interbreeding with other hominins (a tribe of the Homininae, African hominid subfamily), indicating that human evolution was not linear but weblike. The study of the origins of humans involves Interdisciplinary, several scientific disciplines, including Biological anthropology, physical and evolutionary anthropology, paleontology, and genetics; the field is also known by the terms anthropogeny, anthropogenesis, and anthropogony—with the latter two sometimes used to refer to the related subject of hominization. Primate evolution, Primates diverged from other mammals about (Myr, mya), in the Late Cretaceous period, with their earliest fossils appearing over 55 mya, during the Paleocene. Prima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obstetrics
Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a surgical field. Main areas Prenatal care Prenatal care is important in screening for various complications of pregnancy. This includes routine office visits with physical exams and routine lab tests along with telehealth care for women with low-risk pregnancies: Image:Ultrasound_image_of_a_fetus.jpg, 3D ultrasound of fetus (about 14 weeks gestational age) Image:Sucking his thumb and waving.jpg, Fetus at 17 weeks Image:3dultrasound 20 weeks.jpg, Fetus at 20 weeks First trimester Routine tests in the first trimester of pregnancy generally include: * Complete blood count * Blood type ** Rh-negative antenatal patients should receive RhoGAM at 28 weeks to prevent Rh disease. * Indirect Coombs test (AGT) to assess risk of hem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solitary Birth
Solitary birth is the relatively unusual circumstance of human women delivering babies alone. Solitary birth is typically unplanned and thus is distinct from the unassisted birth movement. Carla Emery provided guidelines for solitary delivery of "wilderness babies" in her ''Encyclopedia of Country Living''. Key directives from the section "Giving Birth by Yourself" included don't yank on the umbilical cord and do clear mucus from the baby's nose and mouth. Many inadvertent born before arrival (BBA) outside-of-hospital deliveries in automobiles are de facto solitary births. These deliveries tend to be second or third or higher-order births. Solitary birth is a cultural practice of the !Kung people; solitary birth amongst the !Kung demonstrates female bravery. In practice, primigravidas are usually assisted by female relatives but multigravidas typically manage the entire birth process alone (and silently) in the bush. Bariba women in Benin have also traditionally practiced s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States asserts sovereignty over five Territories of the United States, major island territories and United States Minor Outlying Islands, various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's List of countries and dependencies by area, third-largest land area and List of countries and dependencies by population, third-largest population, exceeding 340 million. Its three Metropolitan statistical areas by population, largest metropolitan areas are New York metropolitan area, New York, Greater Los Angeles, Los Angel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Western Europe
Western Europe is the western region of Europe. The region's extent varies depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the Western half of the ancient Mediterranean world, the Latin West of the Roman Empire, and "Western Christendom". Beginning with the Renaissance and the Age of Discovery, roughly from the 15th century, the concept of ''Europe'' as "the Western world, West" slowly became distinguished from and eventually replaced the dominant use of "Christendom" as the preferred endonym within the area. By the Age of Enlightenment and the Industrial Revolution, the concepts of "Eastern Europe" and "Western Europe" were more regularly used. The distinctiveness of Western Europe became most apparent during the Cold War, when Europe was divided for 40 years by the Iron Curtain into the Western Bloc and Eastern Bloc, each characterised by distinct political and economical systems. Historical divisions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ontogeny
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the ovum, egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan. Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cooperative Breeding
Cooperative breeding is a social system characterized by alloparental care: offspring receive care not only from their parents, but also from additional group members, often called helpers. Cooperative breeding encompasses a wide variety of group structures, from a breeding pair with helpers that are offspring from a previous season, to groups with multiple breeding males and females ( polygynandry) and helpers that are the adult offspring of some but not all of the breeders in the group, to groups in which helpers sometimes achieve co-breeding status by producing their own offspring as part of the group's brood. Cooperative breeding occurs across taxonomic groups including birds, mammals, fish, and insects. Costs for helpers include a fitness reduction, increased territory defense, offspring guarding and an increased cost of growth. Benefits for helpers include a reduced chance of predation, increased foraging time, territory inheritance, increased environmental conditions and an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
How The Female Body Drove 200 Million Years Of Human Evolution
How may refer to: * How (greeting), a word used in some misrepresentations of Native American/First Nations speech * How, an interrogative word in English grammar Art and entertainment Literature * ''How'' (book), a 2007 book by Dov Seidman * ''HOW'' (magazine), a magazine for graphic designers * H.O.W. Journal, an American art and literary journal Music * ''How?'' (EP), by BoyNextDoor, 2024 * "How?" (song), by John Lennon, 1971 * "How", a song by Clairo from ''Diary 001'', 2018 * "How", a song by the Cranberries from ''Everybody Else Is Doing It, So Why Can't We?'', 1993 * "How", a song by Daughter from '' Not to Disappear'', 2016 * "How", a song by Lil Baby from '' My Turn'', 2020 * "How", a song by Maroon 5 from '' Hands All Over'', 2010 * "How", a song by Regina Spektor from '' What We Saw from the Cheap Seats'', 2012 * "How", a song by Robyn from ''Robyn Is Here'', 1995 Other media * HOW (graffiti artist), Raoul Perre, New York graffiti muralist * ''How'' (TV seri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altricial
Precocial species in birds and mammals are those in which the young are relatively mature and mobile from the moment of birth or hatching. They are normally nidifugous, meaning that they leave the nest shortly after birth or hatching. Altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. These categories form a continuum, without distinct gaps between them. In fish, this often refers to the presence or absence of a stomach: precocial larvae have one at the onset of first feeding whereas altricial fish do not. Depending on the species, the larvae may develop a functional stomach during metamorphosis (gastric) or remain stomachless (agastric). Precociality Precocial young have open eyes, hair or down, large brains, and are immediately mobile and somewhat able to flee from or defend themselves against predators. For example, with ground-nesting birds such as ducks or turkeys, the young are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ischial Spine
The ischial spine is part of the posterior border of the body of the ischium bone of the pelvis. It is a thin and pointed triangular eminence, more or less elongated in different subjects. Structure The pudendal nerve travels close to the ischial spine. Clinical significance The ischial spine can serve as a landmark in pudendal anesthesia, as the pudendal nerve The pudendal nerve is the main nerve of the perineum. It is a Mixed nerve, mixed (motor and sensory) nerve and also conveys Sympathetic nervous system, sympathetic Autonomic nervous system, autonomic fibers. It carries sensation from the exter ... lies close to the ischial spine. Additional images File:Sciatic notches.png, Right hip bone, external surface, showing the greater and lesser sciatic notches, separated by the ischial spine File:Gray319.png, Articulations of pelvis. Anterior view. File:Slide3ADA.JPG, Pelvis. Anterior view. File:Ischial spine - animation02-1.gif, Animation showing the ischial spine (highl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
