Neville Longbottom x Severus snape smut

First part

Disgust (Middle French: desgouster, from Latin gustus, 'taste') is an emotional response of rejection or revulsion to something potentially contagious[1] or something considered offensive, distasteful or unpleasant. In The Expression of the Emotions in Man and Animals, Charles Darwin wrote that disgust is a sensation that refers to something revolting. Disgust is experienced primarily in relation to the sense of taste (either perceived or imagined), and secondarily to anything which causes a similar feeling by sense of smell, touch, or vision. Musically sensitive people may even be disgusted by the cacophony of inharmonious sounds. Research has continually proven a relationship between disgust and anxiety disorders such as arachnophobia, blood-injection-injury type phobias, and contamination fear related obsessive–compulsive disorder (also known as OCD).[2][3] Disgust is one of the basic emotions of Robert Plutchik's theory of emotions, and has been studied extensively by Paul Rozin.[4] It invokes a characteristic facial expression, one of Paul Ekman's six universal facial expressions of emotion. Unlike the emotions of fear, anger, and sadness, disgust is associated with a decrease in heart rate.[5] It is believed that the emotion of disgust has evolved as a response to offensive foods that may cause harm to the organism.[6] A common example of this is found in human beings who show disgust reactions to mouldy milk or contaminated meat. Disgust appears to be triggered by objects or people who possess attributes that signify disease.[7]

Self-report and behavioural studies found that disgust elicitors include:

body products (feces, urine, vomit, sexual fluids, saliva, and mucus);
foods (spoiled foods);
animals (rats, fleas, ticks, lice, snakes, cockroaches, worms, flies, spiders, pigeons and frogs);
hygiene (visible dirt and "inappropriate" acts [e.g., using an unsterilized surgical instrument]);
body envelope violations (blood, gore, and mutilation);
death (dead bodies and organic decay), hard diseases and disasters;
visible signs of infection[8]
"When I turned the corner down there and started coming toward the house, I could smell it down there," said Citrus County Sheriff Mike Pendergast about a house overrun with rats. The owner searched for her house after being released from jail, but it had been razed.[9] The above-mentioned main disgust stimuli are similar to one another in the sense that they can all potentially transmit infections, and are the most common referenced elicitors of disgust cross-culturally.[10] Because of this, disgust is believed to have evolved as a component of a behavioral immune system in which the body attempts to avoid disease-carrying pathogens in preference to fighting them after they have entered the body. This behavioral immune system has been found to make sweeping generalizations because "it is more costly to perceive a sick person as healthy than to perceive a healthy person as sickly".[11] Researchers have found that sensitivity to disgust is negatively correlated to aggression because feelings of disgust typically bring about a need to withdraw[clarification needed] while aggression results in a need to approach.[12] This can be explained in terms of each of the types of disgust. For those especially sensitive to moral disgust, they would want to be less aggressive because they want to avoid hurting others. Those especially sensitive to pathogen disgust might be motivated by a desire to avoid the possibility of an open wound on the victim of the aggression. Those sensitive to sexual disgust must have some sexual object present to be especially avoidant of aggression.[12] Based on these findings, disgust may be used as an emotional tool to decrease aggression in individuals. Disgust may produce specific autonomic responses, such as reduced blood pressure, lowered heart-rate and decreased skin conductance along with changes in respiratory behaviour.[13]

Research has also found that people who are more sensitive to disgust tend to find their own in-group more attractive and tend to have more negative attitudes toward other groups.[14] This may be explained by assuming that people begin to associate outsiders and foreigners with disease and danger while simultaneously associating health, freedom from disease, and safety with people similar to themselves.

Taking a further look into hygiene, disgust was the strongest predictor of negative attitudes toward obese individuals. A disgust reaction to obese individuals was also connected with views of moral values.[15] Domains of disgust
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See also: Evolution of morality
Tybur, et al., outlines three domains of disgust: pathogen disgust, which "motivates the avoidance of infectious microorganisms"; sexual disgust, "which motivates the avoidance of [dangerous] sexual partners and behaviors"; and moral disgust, which motivates people to avoid breaking social norms. Disgust may have an important role in certain forms of morality.[16]

Pathogen disgust arises from a desire to survive and, ultimately, a fear of death. He compares it to a "behavioral immune system" that is the 'first line of defense' against potentially deadly agents such as dead bodies, rotting food, and vomit.[17]

Sexual disgust arises from a desire to avoid "biologically costly mates" and a consideration of the consequences of certain reproductive choices. The two primary considerations are intrinsic quality (e.g., body symmetry, facial attractiveness, etc.) and genetic compatibility (e.g., avoidance of inbreeding such as the incest taboo).[18]

Moral disgust "pertains to social transgressions" and may include behaviors such as lying, theft, murder, and rape. Unlike the other two domains, moral disgust "motivates avoidance of social relationships with norm-violating individuals" because those relationships threaten group cohesion.[19] Gender differences
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Women generally report greater disgust than men, especially regarding sexual disgust or general repulsiveness which have been argued to be consistent with women being more selective regarding sex for evolutionary reasons.[20]

Sensitivity to disgust rises during pregnancy, along with levels of the hormone progesterone.[21] Scientists have conjectured that pregnancy requires the mother to "dial down" her immune system so that the developing embryo won't be attacked. To protect the mother, this lowered immune system is then compensated by a heightened sense of disgust.[22]

Because disgust is an emotion with physical responses to undesirable or dirty situations, studies have proven there are cardiovascular and respiratory changes while experiencing the emotion of disgust.[23]

As mentioned earlier, women experience disgust more prominently than men. This is reflected in a study about dental phobia. A dental phobia comes from experiencing disgust when thinking about the dentist and all that entails. 4.6 percent of women compared to 2.7 percent of men find the dentist disgusting.[24]