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Neuroscience | Define Neuroscience at Dictionary.com

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition William Collins Sons & Co. Ltd. 1979, 1986 HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cite This Source

neuroscience neuroscience (nur'-s'ns, nyur'-) n. Any of the sciences, such as neuroanatomy and neurobiology, that deal with the nervous system.

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Immunology – Wikipedia, the free encyclopedia

Immunology is a branch of biomedical science that covers the study of all aspects of the immune system in all organisms.[1] It deals with the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders (autoimmune diseases, hypersensitivities, immune deficiency, transplant rejection); the physical, chemical and physiological characteristics of the components of the immune system in vitro, in situ and in vivo. Immunology has applications in several disciplines of science, and as such is further divided.

Even before the concept of immunity (from immunis, Latin for "exempt") was developed, numerous early physicians characterized organs that would later prove to be part of the immune system. The key primary lymphoid organs of the immune system are the thymus and bone marrow, and secondary lymphatic tissues such as spleen, tonsils, lymph vessels, lymph nodes, adenoids, and skin and liver. When health conditions warrant, immune system organs including the thymus, spleen, portions of bone marrow, lymph nodes and secondary lymphatic tissues can be surgically excised for examination while patients are still alive.

Many components of the immune system are actually cellular in nature and not associated with any specific organ but rather are embedded or circulating in various tissues located throughout the body.

Classical immunology ties in with the fields of epidemiology and medicine. It studies the relationship between the body systems, pathogens, and immunity. The earliest written mention of immunity can be traced back to the plague of Athens in 430 BCE. Thucydides noted that people who had recovered from a previous bout of the disease could nurse the sick without contracting the illness a second time. Many other ancient societies have references to this phenomenon, but it was not until the 19th and 20th centuries before the concept developed into scientific theory.

The study of the molecular and cellular components that comprise the immune system, including their function and interaction, is the central science of immunology. The immune system has been divided into a more primitive innate immune system and, in vertebrates, an acquired or adaptive immune system. The latter is further divided into humoral (or antibody) and cell-mediated components.

The humoral (antibody) response is defined as the interaction between antibodies and antigens. Antibodies are specific proteins released from a certain class of immune cells known as Blymphocytes, while antigens are defined as anything that elicits the generation of antibodies ("anti"body "gen"erators). Immunology rests on an understanding of the properties of these two biological entities and the cellular response to both.

Immunological research continues to become more specialized, pursuing non-classical models of immunity and functions of cells, organs and systems not previously associated with the immune system (Yemeserach 2010).

Clinical immunology is the study of diseases caused by disorders of the immune system (failure, aberrant action, and malignant growth of the cellular elements of the system). It also involves diseases of other systems, where immune reactions play a part in the pathology and clinical features.

The diseases caused by disorders of the immune system fall into two broad categories:

Other immune system disorders include various hypersensitivities (such as in asthma and other allergies) that respond inappropriately to otherwise harmless compounds.

The most well-known disease that affects the immune system itself is AIDS, an immunodeficiency characterized by the suppression of CD4+ ("helper") T cells, dendritic cells and macrophages by the Human Immunodeficiency Virus (HIV).

Clinical immunologists also study ways to prevent the immune system's attempts to destroy allografts (transplant rejection).

The bodys capability to react to antigen depends on a person's age, antigen type, maternal factors and the area where the antigen is presented.[2]Neonates are said to be in a state of physiological immunodeficiency, because both their innate and adaptive immunological responses are greatly suppressed. Once born, a childs immune system responds favorably to protein antigens while not as well to glycoproteins and polysaccharides. In fact, many of the infections acquired by neonates are caused by low virulence organisms like Staphylococcus and Pseudomonas. In neonates, opsonic activity and the ability to activate the complement cascade is very limited. For example, the mean level of C3 in a newborn is approximately 65% of that found in the adult. Phagocytic activity is also greatly impaired in newborns. This is due to lower opsonic activity, as well as diminished up-regulation of integrin and selectin receptors, which limit the ability of neutrophils to interact with adhesion molecules in the endothelium. Their monocytes are slow and have a reduced ATP production, which also limits the newborn's phagocytic activity. Although, the number of total lymphocytes is significantly higher than in adults, the cellular and humoral immunity is also impaired. Antigen-presenting cells in newborns have a reduced capability to activate Tcells. Also, Tcells of a newborn proliferate poorly and produce very small amounts of cytokines like IL-2, IL-4, IL-5, IL-12, and IFN-g which limits their capacity to activate the humoral response as well as the phagocitic activity of macrophage. Bcells develop early during gestation but are not fully active.[3]

Maternal factors also play a role in the bodys immune response. At birth, most of the immunoglobulin present is maternal IgG. Because IgM, IgD, IgE and IgA dont cross the placenta, they are almost undetectable at birth. Some IgA is provided by breast milk. These passively-acquired antibodies can protect the newborn for up to 18 months, but their response is usually short-lived and of low affinity.[3] These antibodies can also produce a negative response. If a child is exposed to the antibody for a particular antigen before being exposed to the antigen itself then the child will produce a dampened response. Passively acquired maternal antibodies can suppress the antibody response to active immunization. Similarly the response of T-cells to vaccination differs in children compared to adults, and vaccines that induce Th1 responses in adults do not readily elicit these same responses in neonates.[3] Between six to nine months after birth, a childs immune system begins to respond more strongly to glycoproteins, but there is usually no marked improvement in their response to polysaccharides until they are at least one year old. This can be the reason for distinct time frames found in vaccination schedules.[4][5]

During adolescence, the human body undergoes various physical, physiological and immunological changes triggered and mediated by hormones, of which the most significant in females is 17--oestradiol (an oestrogen) and, in males, is testosterone. Oestradiol usually begins to act around the age of 10 and testosterone some months later.[6] There is evidence that these steroids act directly not only on the primary and secondary sexual characteristics but also have an effect on the development and regulation of the immune system,[7] including an increased risk in developing pubescent and post-pubescent autoimmunity.[8] There is also some evidence that cell surface receptors on B cells and macrophages may detect sex hormones in the system.[9]

The female sex hormone 17--oestradiol has been shown to regulate the level of immunological response,[10] while some male androgens such as testosterone seem to suppress the stress response to infection. Other androgens, however, such as DHEA, increase immune response.[11] As in females, the male sex hormones seem to have more control of the immune system during puberty and post-puberty than during the rest of a male's adult life.

Physical changes during puberty such as thymic involution also affect immunological response.[12]

The use of immune system components to treat a disease or disorder is known as immunotherapy. Immunotherapy is most commonly used in the context of the treatment of cancers together with chemotherapy (drugs) and radiotherapy (radiation). However, immunotherapy is also often used in the immunosuppressed (such as HIV patients) and people suffering from other immune deficiencies or autoimmune diseases. Like IL2,IL10,GM-CSF B,INF a .

The specificity of the bond between antibody and antigen has made it an excellent tool in the detection of substances in a variety of diagnostic techniques. Antibodies specific for a desired antigen can be conjugated with an isotopic (radio) or fluorescent label or with a color-forming enzyme in order to detect it. However, the similarity between some antigens can lead to false positives and other errors in such tests by antibodies cross-reacting with antigens that aren't exact matches.[13]

The study of the interaction of the immune system with cancer cells can lead to diagnostic tests and therapies with which to find and fight cancer.

This area of the immunology is devoted to the study of immunological aspects of the reproductive process including fetus acceptance. The term has also been used by fertility clinics to address fertility problems, recurrent miscarriages, premature deliveries and dangerous complications such as pre-eclampsia.

Immunology is strongly experimental in everyday practice but is also characterized by an ongoing theoretical attitude. Many theories have been suggested in immunology from the end of the nineteenth century up to the present time. The end of the 19th century and the beginning of the 20th century saw a battle between "cellular" and "humoral" theories of immunity. According to the cellular theory of immunity, represented in particular by Elie Metchnikoff, it was cells more precisely, phagocytes that were responsible for immune responses. In contrast, the humoral theory of immunity, held, among others, by Robert Koch and Emil von Behring, stated that the active immune agents were soluble components (molecules) found in the organisms humors rather than its cells.[14][15][16]

In the mid-1950s, Frank Burnet, inspired by a suggestion made by Niels Jerne,[17] formulated the clonal selection theory (CST) of immunity.[18] On the basis of CST, Burnet developed a theory of how an immune response is triggered according to the self/nonself distinction: "self" constituents (constituents of the body) do not trigger destructive immune responses, while "nonself" entities (pathogens, an allograft) trigger a destructive immune response.[19] The theory was later modified to reflect new discoveries regarding histocompatibility or the complex "two-signal" activation of T cells.[20] The self/nonself theory of immunity and the self/nonself vocabulary have been criticized,[16][21][22] but remain very influential.[23][24]

More recently, several theoretical frameworks have been suggested in immunology, including "autopoietic" views,[25] "cognitive immune" views,[26] the "danger model" (or "danger theory",[21] and the "discontinuity" theory.[27][28] The danger model, suggested by Polly Matzinger and colleagues, has been very influential, arousing many comments and discussions.[29][30][31][32]

According to the American Academy of Allergy, Asthma, and Immunology (AAAAI), "an immunologist is a research scientist who investigates the immune system of vertebrates (including the human immune system). Immunologists include research scientists (PhDs) who work in laboratories. Immunologists also include physicians who, for example, treat patients with immune system disorders. Some immunologists are physician-scientists who combine laboratory research with patient care."[33]

Bioscience is the overall major in which undergraduate students who are interested in general well-being take in college. Immunology is a branch of bioscience for undergraduate programs but the major gets specified as students move on for graduate program in immunology. The aim of immunology is to study the health of humans and animals through effective yet consistent research, (AAAAI, 2013).[34] The most important thing about being immunologists is the research because it is the biggest portion of their jobs.[35]

Most graduate immunology schools follow the AAI courses immunology which are offered throughout numerous schools in the United States.[36] For example, in New York State, there are several universities that offer the AAI courses immunology: Albany Medical College, Cornell University, Icahn School of Medicine at Mount Sinai, New York University Langone Medical Center, University at Albany (SUNY), University at Buffalo (SUNY), University of Rochester Medical Center and Upstate Medical University (SUNY). The AAI immunology courses include an Introductory Course and an Advance Course.[37]The Introductory Course is a course that gives students an overview of the basics of immunology.

In addition, this Introductory Course gives students more information to complement general biology or science training. It also has two different parts: Part I is an introduction to the basic principles of immunology and Part II is a clinically-oriented lecture series. On the other hand, the Advanced Course is another course for those who are willing to expand or update their understanding of immunology. It is advised for students who want to attend the Advanced Course to have a background of the principles of immunology.[38] Most schools require students to take electives in other to complete their degrees. A Masters degree requires two years of study following the attainment of a bachelor's degree. For a doctoral programme it is required to take two additional years of study.[39]

The expectation of occupational growth in immunology is an increase of 36 percent from 2010 to 2020.[40] The median annual wage was $76,700 in May 2010. However, the lowest 10 percent of immunologists earned less than $41,560, and the top 10 percent earned more than $142,800, (Bureau of Labor Statistics, 2013). The practice of immunology itself is not specified by the U.S. Department of Labor but it belongs to the practice of life science in general.[41]

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Immunology - Wikipedia, the free encyclopedia

The American Academy of Allergy Asthma and Immunology | AAAAI

Your Trusted Resource

Patients and healthcare professionals depend on authoritative, expert resources to make decisions about allergies, asthma and immune deficiency disorders.

Welcome to the AAAAI's website, a membership organization of more than 6,800 allergist / immunologists and related professionals world-wide with advanced training and experience dedicated to allergy, asthma, immune deficiencies & immunologic diseases.

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Trinity Allergy, Asthma, and Immunology Care

Trinity Allergy, Asthma and Immunology Care, P.C. is a professional corporation devoted to helping patients with allergy, asthma and primary immunodeficiency diseases. Trinity is located in Kingman, Arizona about 100 miles south of Las Vegas on the campus of Kingman Regional Medical Center. Trinity hopes to fulfill the healthcare needs of both adults and children residing in Mohave county. Trinity has two-satellite offices- one in Bullhead City to serve local residents and residents of Laughlin, Nevada and Needles, California and another one in Lake Havasu City to serve local residents and residents of Parker, Arizona and Needles, California. Dr. Natarajan Asokan, the founder and president of the corporation is a Board Certified Allergist & Immunologist and with excellent qualifications and extensive training. At Trinity, we believe in delivering high quality, state-of-the-art, compassionate and technologically sound healthcare services. If you, or your loved one, are suffering from allergy, asthma, or primary immunodeficiency diseases, we are confident that we can improve the quality of your life and health. On behalf of Dr. Asokan & his staff at Trinity, We thank you for your time and patience! Hope to serve your needs soon!!

Download what you need to know about Influenza and Swine Flu

3/5/2010: To accommodate the growing needs of residents of Bullhead City, Trinity moved its location in Bullhead City from 1975 Highway 95 to a bigger and better location next-door at 1971 Highway 95. The newer facility has a larger waiting area, more number of examination rooms and separate testing and injection areas. Our staff and patients just love our new location.

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Human nature – Wikipedia, the free encyclopedia

Human nature refers to the distinguishing characteristicsincluding ways of thinking, feeling and actingwhich humans tend to have naturally, independently of the influence of culture. The questions of what these characteristics are, how fixed they are, and what causes them are amongst the oldest and most important questions in western philosophy. These questions have particularly important implications in ethics, politics, and theology. This is partly because human nature can be regarded as both a source of norms of conduct or ways of life, as well as presenting obstacles or constraints on living a good life. The complex implications of such questions are also dealt with in art and literature, while the multiple branches of the humanities together form an important domain of inquiry into human nature and into the question of what it is to be human.

The branches of contemporary science associated with the study of human nature include anthropology, sociology, sociobiology, and psychology, particularly evolutionary psychology, which studies sexual selection in human evolution, and developmental psychology. The "nature versus nurture" debate is a broadly inclusive and well-known instance of a discussion about human nature in the natural sciences.

The concept of nature as a standard by which to make judgments was a basic presupposition in Greek philosophy. Specifically, "almost all" classical philosophers accepted that a good human life is a life in accordance with nature.[1]

(Notions and concepts of human nature from China, Japan, or India are not taken up in the present discussion.)

On this subject, the approach of Socratessometimes considered to be a teleological approachcame to be dominant by late classical and medieval times. This approach understands human nature in terms of final and formal causes. Such understandings of human nature see this nature as an "idea", or "form" of a human.[2] By this account, human nature really causes humans to become what they become, and so it exists somehow independently of individual humans. This in turn has sometimes been understood as also showing a special connection between human nature and divinity.

However, the existence of this invariable human nature is a subject of much historical debate, continuing into modern times. Against this idea of a fixed human nature, the relative malleability of man has been argued especially strongly in recent centuriesfirstly by early modernists such as Thomas Hobbes and Jean-Jacques Rousseau. In Rousseau's Emile, or On Education, Rousseau wrote: "We do not know what our nature permits us to be."[citation needed] Since the early 19th century, thinkers such as Hegel, Marx, Kierkegaard, Nietzsche, Sartre, structuralists, and postmodernists have also sometimes argued against a fixed or innate human nature.

Still more recent scientific perspectivessuch as behaviorism, determinism, and the chemical model within modern psychiatry and psychologyclaim to be neutral regarding human nature. (As in all modern science, they seek to explain without recourse to metaphysical causation.) They can be offered to explain human nature's origins and underlying mechanisms, or to demonstrate capacities for change and diversity which would arguably violate the concept of a fixed human nature.

Philosophy in classical Greece is the ultimate origin of the western conception of the nature of a thing. According to Aristotle, the philosophical study of human nature itself originated with Socrates, who turned philosophy from study of the heavens to study of the human things.[3] Socrates is said to have studied the question of how a person should best live, but he left no written works. It is clear from the works of his students Plato and Xenophon, and also by what was said about him by Aristotle (Plato's student), that Socrates was a rationalist and believed that the best life and the life most suited to human nature involved reasoning. The Socratic school was the dominant surviving influence in philosophical discussion in the Middle Ages, amongst Islamic, Christian, and Jewish philosophers.

The human soul in the works of Plato and Aristotle has a divided nature, divided in a specifically human way. One part is specifically human and rational, and divided into a part which is rational on its own, and a spirited part which can understand reason. Other parts of the soul are home to desires or passions similar to those found in animals. In both Aristotle and Plato, spiritedness (thumos) is distinguished from the other passions (epithumiai).[4] The proper function of the "rational" was to rule the other parts of the soul, helped by spiritedness. By this account, using one's reason is the best way to live, and philosophers are the highest types of humans.

AristotlePlato's most famous studentmade some of the most famous and influential statements about human nature. In his works, apart from using a similar scheme of a divided human soul, some clear statements about human nature are made:

For Aristotle, reason is not only what is most special about humanity compared to other animals, but it is also what we were meant to achieve at our best. Much of Aristotle's description of human nature is still influential today. However, the particular teleological idea that humans are "meant" or intended to be something has become much less popular in modern times.[8]

For the Socratics, human nature, and all natures, are metaphysical concepts. Aristotle developed the standard presentation of this approach with his theory of four causes. Human nature is an example of a formal cause, according to Aristotle. Their teleological concept of nature is associated with humans having a divine component in their psyches, which is most properly exercised in the lifestyle of the philosopher, which is thereby also the happiest and least painful life.

One of the defining changes that occurred at the end of the Middle Ages was the end of the dominance of Aristotelian philosophy, and its replacement by a new approach to the study of nature, including human nature. In this approach, all attempts at conjecture about formal and final causes were rejected as useless speculation. Also, the term "law of nature" now applied to any regular and predictable pattern in nature, not literally a law made by a divine law-maker, and, in the same way, "human nature" became not a special metaphysical cause, but simply whatever can be said to be typical tendencies of humans.

Although this new realism applied to the study of human life from the beginningfor example, in Machiavelli's worksthe definitive argument for the final rejection of Aristotle was associated especially with Francis Bacon, and then Ren Descartes, whose new approach returned philosophy or science to its pre-Socratic focus upon non-human things. Thomas Hobbes, then Giambattista Vico, and David Hume all claimed to be the first to properly use a modern Baconian scientific approach to human things.

Hobbes famously followed Descartes in describing humanity as matter in motion, just like machines. He also very influentially described man's natural state (without science and artifice) as one where life would be "solitary, poor, nasty, brutish and short."[9] Following him, John Locke's philosophy of empiricism also saw human nature as a tabula rasa. In this view, the mind is at birth a "blank slate" without rules, so data are added, and rules for processing them are formed solely by our sensory experiences.[10]

Jean-Jacques Rousseau pushed the approach of Hobbes to an extreme and criticized it at the same time. He was a contemporary and acquaintance of Hume, writing before the French Revolution and long before Darwin and Freud. He shocked Western civilization with his Second Discourse by proposing that humans had once been solitary animals, without reason or language or communities, and had developed these things due to accidents of pre-history. (This proposal was also less famously made by Giambattista Vico.) In other words, Rousseau argued that human nature was not only not fixed, but not even approximately fixed compared to what had been assumed before him. Humans are political, and rational, and have language now, but originally they had none of these things.[11] This in turn implied that living under the management of human reason might not be a happy way to live at all, and perhaps there is no ideal way to live. Rousseau is also unusual in the extent to which he took the approach of Hobbes, asserting that primitive humans were not even naturally social. A civilized human is therefore not only imbalanced and unhappy because of the mismatch between civilized life and human nature, but unlike Hobbes, Rousseau also became well known for the suggestion that primitive humans had been happier, "noble savages".[12]

Rousseau's conception of human nature has been seen as the origin of many intellectual and political developments of the 19th and 20th centuries.[13] He was an important influence upon Kant, Hegel, and Marx, and the development of German idealism, historicism, and romanticism.

What human nature did entail, according to Rousseau and the other modernists of the 17th and 18th centuries, were animal-like passions that led humanity to develop language and reasoning, and more complex communities (or communities of any kind, according to Rousseau).

In contrast to Rousseau, David Hume was a critic of the oversimplifying and systematic approach of Hobbes, Rousseau, and some others whereby, for example, all human nature is assumed to be driven by variations of selfishness. Influenced by Hutcheson and Shaftesbury, he argued against oversimplification. On the one hand, he accepted that, for many political and economic subjects, people could be assumed to be driven by such simple selfishness, and he also wrote of some of the more social aspects of "human nature" as something which could be destroyed, for example if people did not associate in just societies. On the other hand, he rejected what he called the "paradox of the sceptics", saying that no politician could have invented words like "'honourable' and 'shameful,' 'lovely' and 'odious,' 'noble' and 'despicable,'" unless there was not some natural "original constitution of the mind."[14]

Humelike Rousseauwas controversial in his own time for his modernist approach, following the example of Bacon and Hobbes, of avoiding consideration of metaphysical explanations for any type of cause and effect. He was accused of being an atheist. He wrote:

We needn't push our researches so far as to ask "Why do we have humanity, i.e. a fellow-feeling with others?" It's enough that we experience this as a force in human nature. Our examination of causes must stop somewhere.[14]

After Rousseau and Hume, the nature of philosophy and science changed, branching into different disciplines and approaches, and the study of human nature changed accordingly. Rousseau's proposal that human nature is malleable became a major influence upon international revolutionary movements of various kinds, while Hume's approach has been more typical in Anglo-Saxon countries, including the United States.

As the sciences the concerned with humanity split up into more specialized branches, many of the key figures of this evolution expressed influential understandings about human nature.

Charles Darwin gave a widely accepted scientific argument for what Rousseau had already argued from a different direction, that humans and other animal species have no truly fixed nature, at least in the very long term. However, he also gave modern biology a new way of understanding how human nature does exist in a normal human time-frame, and how it is caused.

Sigmund Freud, the founder of psychoanalysis, famously referred to the hidden pathological character of typical human behavior. He believed that the Marxists were right to focus on what he called "the decisive influence which the economic circumstances of men have upon their intellectual, ethical and artistic attitudes." But he thought that the Marxist view of the class struggle was too shallow, assigning to recent centuries conflicts that were actually primordial. Behind the class struggle, according to Freud, there stands the struggle between father and son, between established clan leader and rebellious challenger. Freud also popularized his notions of the id and the desires associated with each supposed aspect of personality.

E. O. Wilson's sociobiology and closely related theory of evolutionary psychology give scientific arguments against the "tabula rasa" hypotheses of Hobbes, Locke, and Rousseau. In his book Consilience: The Unity of Knowledge (1998), Wilson claimed that it was time for a cooperation of all the sciences to explore human nature. He defined human nature as a collection of epigenetic rules: the genetic patterns of mental development. Cultural phenomena, rituals, etc. are products, not part of human nature. For example, artworks are not part of human nature, but our appreciation of art is. This art appreciation, or our fear for snakes, or incest taboo (Westermarck effect) can be studied by the methods of reductionism. Until now, these phenomena were only part of psychological, sociological, and anthropological studies. Wilson proposes that they can be part of interdisciplinary research.

An example of this fear is discussed in the book An Instinct for Dragons,[15] where anthropologist David E. Jones suggests a hypothesis that humans, just like other primates, have inherited instinctive reactions to snakes, large cats, and birds of prey. Folklore dragons have features that are combinations of these three, which would explain why dragons with similar features occur in stories from independent cultures on all continents. Other authors have suggested that, especially under the influence of drugs or in children's dreams, this instinct may give rise to fantasies and nightmares about dragons, snakes, spiders, etc., which makes these symbols popular in drug culture and in fairy tales for children. However, the traditional mainstream explanation to the folklore dragons does not rely on human instinct, but on the assumption that fossils of, for example, dinosaurs gave rise to similar fantasies all over the world.

In Christian theology, there are two ways of "conceiving human nature": (1) "spiritual, Biblical, and theistic" or (2) "natural, cosmical, and anti-theistic."[16] The focus in this section is on the first way. As William James put it in his study of human nature from a religious perspective, "religion" has a "department of human nature."[17]

Various views of human nature have been held by theologians. However, there are some "basic assertions" in all "biblical anthropology." (1) "Humankind has its origin in God, its creator." (2) "Humans bear the 'image of God'." (3) Humans are "to rule the rest of creation." (4) Humans have the "ability to transcend" themselves.[18]

The Bible contains no single "doctrine of human nature." Rather, it provides material for more philosophical descriptions of human nature.[19] For example, Creation as found in the Book of Genesis provides a theory on human nature.[20]

Created human nature As originally created, the Bible describes "two elements" in human nature: "the body and the breath or spirit of life breathed into it by God." By this was created a "living soul," that is, a "living person."[21] According to Genesis 1:27, this living person was made in the "image of God."[22] From the biblical perspective, "to be human is to bear the image of God."[23]

"Two main modes of conceiving human naturethe one of which is spiritual, Biblical, and theistic," and the other "natural, cosmical, and anti-theistic." John Tulloch[24]

Genesis does not elaborate the meaning of "the image of God," but scholars find suggestions. One is that being created in the image of God distinguishes human nature from that of the beasts.[25] Another is that as God is "able to make decisions and rule" so humans made in God's image are "able to make decisions and rule." A third is that mankind possesses an inherent ability to "to set goals" and move toward them.[26] That God denoted creation as "good" suggests that Adam was "created in the image of God, in righteousness."[27]

Adam was created with ability to make "right choices," but also with the ability to choose sin, by which he fell from righteousness into a state of "sin and depravity."[28] Thus, according to the Bible, "humankind is not as God created it."[29]

Fallen human nature By Adam's fall into sin, "human nature" became "corrupt." although it still bears [God's] image." The Bible, both the Old Testament and the New Testament, teaches that "sin is universal."[30] For example, "I was sinful at birth," says Psalm 51:5.[31] Jesus taught that everyone is a "sinner naturally" because it is mankind's "nature and disposition to sin."[32] Paul, in Romans 7:18, speaks of his "sinful nature."[33]

Such a "recognition that there is something wrong with the moral nature of man is found in all religions"[34]Augustine of Hippo coined a term for the assessment that all humans are born sinful: "original sin."[35] "Original sin" means "the tendency to sin innate in all human beings."[36]

"The corruption of original sin extends to every aspect of human nature": to "reason and will" as well as to "appetites and impulses." This condition is sometimes called "total depravity."[37] Total depravity does not mean that humanity is as "thoroughly depraved" as it could become.[38] Commenting on Romans 2:14, John Calvin writes that all people have "some notions of justice and rectitude . . . which are implanted by nature" all people.[39]

Adam embodied the "whole of human nature" so when Adam sinned "all of human nature sinned"[40] The Old Testament does not explicitly link the "corruption of human nature" to Adam's sin. However, the "universality of sin" implies a link to Adam. In the New Testament, Paul concurs with the "universality of sin." He also makes explicit what the Old Testament implied: the link between humanity's "sinful nature" and Adam's sin[41] In Romans 5:19, Paul writes, "through [Adam's] disobedience humanity became sinful."[42] Paul also applied humanity's sinful nature to himself: "there is nothing good in my sinful nature."[43]

The theological "doctrine of original sin" as an inherent element of human nature is not based only on the Bible. It is in part a "generalization from obvious facts" open to empirical observation.[44]

Empirical facts A number of experts on human nature have described the manifestations of original (i.e., the innate tendency to) sin as empirical facts.

Realistic view Liberal theologians in the early 20th century described "human nature" as "basically good" needing only "proper training and education." But the above examples document the return to a "more realistic view" of human nature "as basically sinful and self-centered." Human nature needs "to be regenerated . . . to be able to live the unselfish life."[51]

Regenerated human nature According to the Bible, "Adam's disobedience corrupted human nature" but God mercifully "regenerates."[52] "Regeneration is a radical change" that involves a "renewal of our [human] nature."[53] Thus, to counter original sin, Christianity purposes "a complete transformation of individuals" by Christ.[54]

The goal of Christ's coming is that fallen humanity might be "conformed to or transformed into the image of Christ who is the perfect image of God," as in 2 Corinthians 4:4.[55] The New Testament makes clear the "universal need" for regeneration.[56] A sampling of biblical portrayals of regenerating human nature and the behavioral results follow.

Total transformation The goal is to raise transform human nature to a "higher level" than "before the Fall," a level in which people will no longer sin.[61] Theology holds that this goal is not reached in this life where always "human nature is deficient." Thus, the goal cannot be reached until after one dies.[62]

There are two portrayals of reaching the goal in an intermediate state between earth and heaven: one Protestant, the other Roman Catholic.

A Protestant portrayal Randy Alcorn says that "In heaven there will be no evil desires or corruption." Thus, because everyone's "human nature is deficient," no one can go to heaven immediately after death. Between death and the "final destination" (a sinless "New Earth"), there is an intermediate state: a temporary "intermediate Heaven." In the resurrection from this temporary state, "human nature" will be restored to "the state of its ultimate perfection." The resurrected inhabitants of the final Heaven will be "so constituted or reconstituted" that they cannot sin because they do not want to.[63]

A Roman Catholic portrayal Jerry L. Walls agrees with the Protestant view that sinful human nature requires a "complete transformation" before admission into heaven. Earthly "regeneration begins this transformation" but does not complete it. Thus, as with the Protestant perspective, an intermediate state between earth and heaven is required. In Catholic doctrine, the intermediate state is called Purgatory. Purgatory is a "process of transformation" to fit its residents for heaven.[64]

Goal met In both views, the Christian goal of the transformation of sinful human nature will be met. The goal is that people will be "conformed to or transformed into the image of Christ who is the perfect image of God."[65]

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Human nature - Wikipedia, the free encyclopedia

Human sexual activity – Wikipedia, the free encyclopedia

This article is about sexual practices and related social aspects. For broader aspects of sexual behaviour, see Human sexuality. "Sexual activity" and "sexual behavior" redirect here. For sexual activity among other animals, see Animal sexual behaviour.

Human sexual activity, human sexual practice or human sexual behavior is the manner in which humans experience and express their sexuality. People engage in a variety of sexual acts from time to time, for a wide variety of reasons. Sexual activity normally results in sexual arousal and physiological changes in the aroused person, some of which are pronounced while others are more subtle. Sexual activity may also include conduct and activities which are intended to arouse the sexual interest of another, such as strategies to find or attract partners (courtship and display behavior), or personal interactions between individuals (for instance, foreplay). Sexual activity may follow sexual arousal.

Human sexual activity has sociological, cognitive, emotional, behavioral and biological aspects; these include personal bonding, sharing emotions and the physiology of the reproductive system, sex drive, sexual intercourse and sexual behavior in all its forms.

In some cultures, sexual activity is considered acceptable only within marriage, while premarital and extramarital sex are taboo. Some sexual activities are illegal either universally or in some countries, while some are considered contrary to the norms of a society. Two examples that are criminal offenses in most jurisdictions are sexual assault and sexual activity with a person below the local age of consent.

Sexual activity can be classified in a number of ways. It can be divided into acts which involve one person, also called autoeroticism, such as masturbation, or two or more people such as vaginal sex, anal sex, oral sex or mutual masturbation. If there are more than two participants in the sex act, it may be referred to as group sex. Autoerotic sexual activity can involve use of dildos, vibrators, anal beads, and other sex toys, though these devices can also be used with a partner.

Sexual activity can be classified into the gender and sexual orientation of the participants, as well as by the relationship of the participants. For example, the relationships can be ones of marriage, intimate partners, casual sex partners or anonymous. Sexual activity can be regarded as conventional or as alternative, involving, for example, fetishism, paraphilia, or BDSM activities.[1][2] Fetishism can take many forms ranging from the desire for certain body parts, for example large breasts, armpits or foot worship. The object of desire can often be shoes, boots, lingerie, clothing, leather or rubber items. Some non-conventional autoerotic practices can be dangerous. These include erotic asphyxiation and self-bondage. The potential for injury or even death that exists while engaging in the partnered versions of these fetishes (choking and bondage, respectively) becomes drastically increased in the autoerotic case due to the isolation and lack of assistance in the event of a problem.

Sexual activity can be consensual or take place under force or duress, or lawful/illegal or otherwise contrary to social norms or generally accepted sexual morals.

The physiological responses during sexual stimulation are fairly similar for both men and women and there are four phases.[3]

Sexual dysfunction is the inability to react emotionally or physically to sexual stimulation in a way projected of the average healthy person; it can affect different stages in the sexual response cycles, which are desire, excitement and orgasm.[7] In the media, sexual dysfunction is often associated with men, but in actuality, it is more commonly observed in females (43 percent) than males (31 percent).[8]

People engage in sexual activity for any of a multitude of possible reasons. Although the primary evolutionary purpose of sexual activity is reproduction, research on college students suggested that people have sex for four general reasons: physical attraction, as a means to an end, to increase emotional connection, and to alleviate insecurity.[9]

Most people engage in sexual activity because of pleasure they derive from the arousal of their sexuality, especially if they can achieve orgasm. Sexual arousal can also be experienced from foreplay and flirting, and from fetish or BDSM activities,[1][10] or other erotic activities. Most commonly, people engage in sexual activity because of the sexual desire generated by a person to whom they feel sexual attraction; but they may engage in sexual activity for the physical satisfaction they achieve in the absence of attraction for another, as in the case of casual or social sex.[11] At times, a person may engage in a sexual activity solely for the sexual pleasure of their partner, such as because of an obligation they may have to the partner or because of love, sympathy or pity they may feel for the partner.

Also, a person may engage in sexual activity for purely monetary considerations, or to obtain some advantage from either the partner or the activity. A man and woman may engage in sexual intercourse with the objective of conception. Some people engage in hate sex, which occurs between two people who strongly dislike or annoy each other. It is related to the idea that opposition between two people can heighten sexual tension, attraction and interest.[12]

It has been shown that sexual activity plays a large part in the interaction of social species. Joan Roughgarden, in her book Diversity, Gender, and Sexuality in Nature and People, postulates that this applies equally to humans as it does to other social species. She explores the purpose of sexual activity and demonstrates that there are many functions facilitated by such activity including pair bonding, group bonding, dispute resolution and reproduction.[13]

Research has found that people also engage in sexual activity for reasons associated with self-determination theory. The self-determination theory can be applied to a sexual relationship when the participants have positive feelings associated with the relationship. These participants do not feel guilty or coerced into the partnership.[14] Researchers have proposed the model of self-determined sexual motivation. The purpose of this model is to connect self-determination and sexual motivation.[15] This model has helped to explain how people are sexually motivated when involved in self-determined dating relationships. This model also links the positive outcomes, (satisfying the need for autonomy, competence, and relatedness) gained from sexual motivations.[15] According to the completed research associated with this model, it was found that people of both sexes who engaged in sexual activity for self-determined motivation had more positive psychological well-being.[15] While engaging in sexual activity for self-determined reasons, the participants also had a higher need for fulfillment. When this need was satisfied, they felt better about themselves. This was correlated with greater closeness to their partner and higher overall satisfaction in their relationship.[16] Though both sexes engaged in sexual activity for self-determined reasons, there were some differences found between males and females. It was concluded that females had more motivation than males to engage in sexual activity for self-determined reasons.[15] Females also had higher satisfaction and relationship quality than males did from the sexual activity.[15] Overall, research concluded that psychological well-being, sexual motivation, and sexual satisfaction were all positively correlated when dating couples partook in sexual activity for self-determined reasons.[15]

The frequency of sexual activity might range from zero (sexual abstinence) to 15 or 20 times a week.[17] In the United States, the average frequency of sexual intercourse for married couples is 2 to 3 times a week.[18] It is generally recognized that postmenopausal women experience declines in frequency of sexual intercourse[19] and that average frequency of intercourse declines with age. According to the Kinsey Institute, the average frequency of sexual intercourse in the US is 112 times per year (age 1829), 86 times per year (age 3039), and 69 times per year (age 4049).[20]

The age at which adolescents tend to become sexually active varies considerably between different cultures and from time to time. (See Prevalence of virginity.) The first sexual act of a child or adolescent is sometimes referred to as the sexualization of the child, and may be considered as a milestone or a change of status, as the loss of virginity or innocence.

A 1999 survey of students indicated that approximately 40% of ninth graders across the United States report having had sexual intercourse. This figure rises with each grade. Males are more sexually active than females at each of the grade levels surveyed. Sexual activity of young adolescents differs in ethnicity as well. A higher percent of African American and Hispanic adolescents are sexually active than White adolescents.[21]

Research on sexual frequency has also been conducted solely on female adolescents who engage in sexual activity. Female adolescents tended to engage in more sexual activity due to positive mood. In female teenagers, engaging in sexual activity was directly positively correlated with being older, greater sexual activity in the previous week or prior day, and more positive mood the previous day or the same day as the sexual activity occurred.[22] Decreased sexual activity was associated with prior or current day negative mood or vaginal bleeding.[23]

Although opinions differ, others suggest that sexual activity is an essential part of humans, and that teenagers need to experience sex. Sexual experiences help teenagers understand pleasure and satisfaction.[24] In relation to hedonic and eudaimonic well-being, teenagers can positively benefit from sexual activity according to one particular research study. In the United States of America, a cross-sectional study of teenagers was completed. Teenagers who had their first sexual experience at age 16 revealed a higher well-being than those who were sexually inexperienced or who were first sexually active at a later age of 17.[24] Furthermore, teenagers who had their first sexual experience at age 15 or younger, or who had many sexual partners were not negatively affected and did not have associated lower well-being.[24]

Sexual activity is a normal physiological function,[25] but like other physical activity, it comes with risks. There are four main types of risks that may arise from sexual activity: unwanted pregnancy, contracting a sexually transmitted infection (STI/STD), physical injury, and psychological injury.

Any sexual activity that involves the introduction of semen into a woman's vagina, such as during sexual intercourse, or even contact of semen with her vulva, may result in a pregnancy. To reduce the risk of unintended pregnancies, some people who engage in penile-vaginal sex may use contraception, such as birth control pills, a condom, diaphragms, spermicides, hormonal contraception or sterilization.[26] The effectiveness of the various contraceptive methods in avoiding pregnancy varies considerably.

Sexual activity that involves skin-to-skin contact, exposure to an infected person's bodily fluids or mucosal membranes[27] carries the risk of contracting a sexually transmitted infection. People may not be able to detect that their sexual partner has one or more STIs, for example if they are asymptomatic (show no symptoms).[28][29] The risk of STIs can be reduced by safe sex practices, such as using condoms. Both partners may opt be tested for STIs before engaging in sex.[30] There may also be an increased risk of contracting a STI when having sex with multiple partners.

Some STIs can also be contracted by using IV drug needles after their use by an infected person, as well as through childbirth or breastfeeding.

Typically, older men and women maintaining interest in sexual interest and activity could be therapeutic; it is a source of expressing their love and care for one another. Factors such as biological and psychological factors, diseases, mental conditions, boredom with the relationship, and widowhood have been found to contribute with the common decrease in sexual interest and activity in old age. National sex surveys given in Finland in the 1990s revealed aging men, as a result a female widowhood, had a higher incidence of sexual intercourse compared to aging women and that women were more likely to report a lack of sexual desire compared to men. Regression analysis, factors considered important to female sexual activity included: sexual desire, valuing sexuality, and a healthy partner, while high sexual self-esteem, good health, and active sexual history were important to male sexual activity. Both aging genders agreed they needed good health, good sexual functioning, positive sexual self-esteem, and a sexually skilful partner to maintain sexual desire.[31]

Heterosexuality is the romantic or sexual attraction to the opposite sex. Heterosexual sexual practices are subject to laws in many places. In some countries, mostly those where religion has a strong influence on social policy, marriage laws serve the purpose of encouraging people to have sex only within marriage. Sodomy laws were seen as discouraging same-sex sexual practices, but may affect opposite-sex sexual practices. Laws also ban adults from committing sexual abuse, committing sexual acts with anyone under an age of consent, performing sexual activities in public, and engaging in sexual activities for money (prostitution). Though these laws cover both same-sex and opposite-sex sexual activities, they may differ in regard to punishment, and may be more frequently (or exclusively) enforced on those who engage in same-sex sexual activities.[32]

Different-sex sexual practices may be monogamous, serially monogamous, or polyamorous, and, depending on the definition of sexual practice, abstinent or autoerotic (including masturbation). Additionally, different religious and political movements have tried to influence or control changes in sexual practices including courting and marriage, though in most countries changes occur at a slow rate.

Homosexuality is the romantic or sexual attraction to the same sex. People with a homosexual orientation can express their sexuality in a variety of ways, and may or may not express it in their behaviors.[33] Research indicates that many gay men and lesbians want, and succeed in having, committed and durable relationships. For example, survey data indicate that between 40% and 60% of gay men and between 45% and 80% of lesbians are currently involved in a romantic relationship.[34]

It is possible for a person whose sexual identity is mainly heterosexual to engage in sexual acts with people of the same sex. For example, mutual masturbation in the context of what may be considered normal heterosexual teen development. Gay and lesbian people who pretend to be heterosexual are often referred to as being closeted (hiding their sexuality in "the closet"). "Closet case" is a derogatory term used to refer to people who hide their sexuality. Making that orientation public can be called "coming out of the closet" in the case of voluntary disclosure or "outing" in the case of disclosure by others against the subject's wishes (or without their knowledge). Among some communities (called "men on the DL" or "down-low"), same-sex sexual behavior is sometimes viewed as solely for physical pleasure. Men who have sex with men, as well as women who have sex with women, or men on the "down-low" may engage in sex acts with members of the same sex while continuing sexual and romantic relationships with the opposite sex.

People who engage exclusively in same-sex sexual practices may not identify themselves as gay or lesbian. In sex-segregated environments, individuals may seek relationships with others of their own gender (known as situational homosexuality). In other cases, some people may experiment or explore their sexuality with same (and/or different) sex sexual activity before defining their sexual identity. Despite stereotypes and common misconceptions, there are no forms of sexual acts exclusive to same-sex sexual behavior that cannot also be found in opposite-sex sexual behavior, except those involving the meeting of the genitalia between same-sex partners tribadism (generally vulva-to-vulva rubbing, commonly known by its "scissoring" position) and frot (generally penis-to-penis rubbing).

People who have a romantic or sexual attraction to both sexes are referred to as bisexual.[35][36] People who have a distinct but not exclusive preference for one sex/gender over the other may also identify themselves as bisexual.[37] Like gay and lesbian individuals, bisexual people who pretend to be heterosexual are often referred to as being closeted.

Pansexuality (also referred to as omnisexuality)[38] may or may not be subsumed under bisexuality, with some sources stating that bisexuality encompasses sexual or romantic attraction to all gender identities.[39][40] Pansexuality is characterized by the potential for aesthetic attraction, romantic love, or sexual desire towards people without regard for their gender identity or biological sex.[41] Some pansexuals suggest that they are gender-blind; that gender and sex are insignificant or irrelevant in determining whether they will be sexually attracted to others.[42] As defined in the Oxford English Dictionary, pansexuality "encompasses all kinds of sexuality; not limited or inhibited in sexual choice with regards to gender or practice".[43]

Most people experiment with a range of sexual activities during their lives, although they tend to engage in only a few of these regularly. Some people enjoy many different sexual activities, while others avoid sexual activities altogether for religious or other reasons (see chastity, sexual abstinence, asexuality). Some prefer monogamous relationships for sex, while others may prefer many different partners throughout their lives.

Alex Comfort and others propose three potential social aspects of intercourse in humans, which are not mutually exclusive: reproductive, relational, and recreational.[44] The development of the contraceptive pill and other highly effective forms of contraception in the mid- and late 20th century has increased people's ability to segregate these three functions, which still overlap a great deal and in complex patterns. For example: A fertile couple may have intercourse while using contraception to experience sexual pleasure (recreational) and also as a means of emotional intimacy (relational), thus deepening their bonding, making their relationship more stable and more capable of sustaining children in the future (deferred reproductive). This same couple may emphasize different aspects of intercourse on different occasions, being playful during one episode of intercourse (recreational), experiencing deep emotional connection on another occasion (relational), and later, after discontinuing contraception, seeking to achieve pregnancy (reproductive, or more likely reproductive and relational).

Most world religions have sought to address the moral issues that arise from people's sexuality in society and in human interactions. Each major religion has developed moral codes covering issues of sexuality, morality, ethics etc. Though these moral codes do not address issues of sexuality directly, they seek to regulate the situations which can give rise to sexual interest and to influence people's sexual activities and practices. However, the impact of religious teaching has at times been limited. For example, though most religions disapprove of extramarital sexual relations, it has always been widely practiced. Nevertheless, these religious codes have always had a strong influence on peoples' attitudes to issues of modesty in dress, behavior, speech etc.

On the other hand, some people adopt the view that pleasure is its own justification for sexual activity. Hedonism is a school of thought which argues that pleasure is the only intrinsic good.[45]

Human sexual activity, like many other kinds of activity engaged in by humans, is generally influenced by social rules that are culturally specific and vary widely. These social rules are referred to as sexual morality (what can and can not be done by society's rules) and sexual norms (what is and is not expected).

Sexual ethics, morals, and norms relate to issues including deception/honesty, legality, fidelity and consent. Some activities, known as sex crimes in some locations, are illegal in some jurisdictions, including those conducted between (or among) consenting and competent adults (examples include sodomy law and adult-adult incest).

Some people who are in a relationship but want to hide polygamous activity (possibly of opposite sexual orientation) from their partner, may solicit consensual sexual activity with others through personal contacts, online chat rooms, or, advertising in select media.

Swinging, on the other hand, involves singles or partners in a committed relationship engaging in sexual activities with others as a recreational or social activity.[46] The increasing popularity of swinging is regarded by some as arising from the upsurge in sexual activity during the sexual revolution of the 1960s. Swinging sexual activity can take place in a sex club, also known as a swinger club (not to be confused with a strip club).[47]

Some people engage in various sexual activities as a business transaction. When this involves having sex with, or performing certain actual sexual acts for another person in exchange for money or something of value, it is called prostitution. Other aspects of the adult industry include phone sex operators, strip clubs, and pornography.

Social gender roles can influence sexual behavior as well as the reaction of individuals and communities to certain incidents; the World Health Organization states that, "Sexual violence is also more likely to occur where beliefs in male sexual entitlement are strong, where gender roles are more rigid, and in countries experiencing high rates of other types of violence."[48] Some societies, such as those where the concepts of family honor and female chastity are very strong, may practice violent control of female sexuality, through practices such as honor killings and female genital mutilation.[49][50]

The relation between gender equality and sexual expression is recognized, and promotion of equity between men and women is crucial for attaining sexual and reproductive health, as stated by the UN International Conference on Population and Development Program of Action:[51]

B/D, a form of BDSM, is bondage and discipline. Bondage includes the restraint of the body or mind.[52] D/S means "dominant and submissive." A dominant is someone who takes control of someone who wishes to give up control. A submissive is someone who gives up the control to a person who wishes to take control.[52] S/M (sadism and masochism) means an individual who takes pleasure in the humiliation or pain of others. Masochism means an individual who takes pleasure from their own pain and/or humiliation.[52]

In a 2013 study, the researchers suggest that BDSM is a sexual act(s) where they play role games, use restraint, use power exchange, use suppression and pain is sometimes involved depending on individual(s)[53] The study indicates that, in the past, BDSM has been seen as maladaptive to one's psychological health, but that this may be incorrect. According to the study, one who participates in BDSM can have greater strength socially, mentally and have greater independence than those who do not practice BDSM.[53] It states that people who participate in BDSM play actually have higher subjective well-being, and that this might be due to the fact that BDSM play requires extensive communication. Before any sexual act occurs, the partners must discuss their agreement of their relationship. They discuss how long the play will last, the intensity, their actions, what each participant needs and/or desires. The sexual acts are all consensual and pleasurable to both parties.[53]

In a 2015 study, BDSM relationships were suggested to have a higher level of connection, intimacy, trust and communication compared to individuals who do not practice BDSM.[52] The study suggests that dominants and submissives exchange control for each other's pleasure and to satisfy a need. They mention that both parties enjoys pleasing their partner in any way they can. Submissive and Dominants who participated in their research, felt that this is one of the best things about BDSM. It gives a submissive pleasure to do things in general for their dominant. Where Dominant enjoys making their encounters all about the submissive. They enjoy doing things that makes their submissive happy. Their findings suggest that submissives and dominants found BDSM play more pleasurable and fun. BDSM was also suggested to improve personal growth, romantic relationships, their sense of community, their sense of self, the dominants confidence, and help an individual cope with everyday things by giving them a psychological release.[52]

There are many laws and social customs which prohibit, or in some way have an impact on sexual activities. These laws and customs vary from country to country, and have varied over time. They cover, for example, a prohibition to non-consensual sex, to sex outside of marriage, to sexual activity in public, besides many others. Many of these restrictions are non-controversial, but some have been the subject of public debate.

Most societies consider it a serious crime to force someone to engage in sexual acts or to engage in sexual activity with someone who does not consent. This is called sexual assault, and if sexual penetration occurs it is called rape, the most serious kind of sexual assault. The details of this distinction may vary among different legal jurisdictions. Also, what constitutes effective consent in sexual matters varies from culture to culture and is frequently debated. Laws regulating the minimum age at which a person can consent to have sex (age of consent) are frequently the subject of debate, as is adolescent sexual behavior in general. Some societies have forced marriage, where consent may not be required.

Many locales have laws that limit or prohibit same-sex sexual activity.

In the West, sex before marriage is not illegal. There are social taboos and many religions condemn pre-marital sex. In many Muslim countries, such as Saudi Arabia, Pakistan,[54] Afghanistan,[55][56][57] Iran,[57] Kuwait,[58] Maldives,[59] Morocco,[60] Oman,[61] Mauritania,[62] United Arab Emirates,[63][64] Sudan,[65] Yemen,[66] any form of sexual activity outside marriage is illegal. Those found guilty, especially women, may be forced to wed the sexual partner, publicly beaten, or stoned to death.[67] In many African and native tribes, sexual activity is not viewed as a privilege or right of a married couple, but rather as the unification of bodies and is thus not frowned upon.[68]

Other studies have analyzed the changing attitudes about sex that American adolescents have outside of marriage. Adolescents were asked how they felt about oral and vaginal sex in relation to their health, social, and emotional well-being. Overall, teenagers felt that oral sex was viewed as more socially positive amongst their demographic.[69] Results stated that teenagers believed that oral sex for dating and non-dating adolescents was less threatening to their overall values and beliefs than vaginal sex was.[69] When asked, teenagers who participated in the research viewed oral sex as more acceptable to their peers, and their personal values than vaginal sex.[69]

The laws of each jurisdiction set the minimum age at which a young person is allowed to engage in sexual activity.[70] This age of consent is typically between 14 and 18 years, but laws vary. In many jurisdictions, age of consent is a person's mental or functional age.[71][71][72][73] As a result, those above the set age of consent may still be considered unable to legally consent due to mental immaturity.[71][72][73][74][75] Many jurisdictions regard any sexual activity by an adult involving a child as child sexual abuse.

Age of consent may vary by the type of sexual act, the sex of the actors, or other restrictions such as abuse of a position of trust. Some jurisdictions also make allowances for young people engaged in sexual acts with each other.[76]

Most jurisdictions prohibit sexual activity between certain close relatives. These laws vary to some extent; such acts are called incestuous.

Non-consensual sexual activity or subjecting an unwilling person to witnessing a sexual activity are forms of sexual abuse, as well as (in many countries) certain non-consensual paraphilias such as frotteurism, telephone scatophilia (indecent phonecalls), and non-consensual exhibitionism and voyeurism (known as "indecent exposure" and "peeping tom" respectively).[77]

People sometimes exchange sex for money or access to other resources. This practice, called prostitution, takes place under many varied circumstances. The person who receives payment for sexual services is called a prostitute and the person who receives such services is known by a multitude of terms, including (and most commonly) "john." Prostitution is one of the branches of the sex industry. The legal status of prostitution varies from country to country, from being a punishable crime to a regulated profession. Estimates place the annual revenue generated from the global prostitution industry to be over $100 billion.[78] Prostitution is sometimes referred to as "the world's oldest profession".[79] Prostitution may be a voluntary individual activity or facilitated or forced by pimps.

Survival sex is a form of prostitution engaged in by people in extreme need, usually when homeless or otherwise disadvantaged people trade sex for food, a place to sleep, or other basic needs, or for drugs.[80] The term is used by sex trade and poverty researchers and aid workers.[81][82]

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Human sexual activity - Wikipedia, the free encyclopedia