The odor of , odor or fragrance is caused by one or more evaporated chemical compounds, generally at very low concentrations, perceived by humans or other animals. by the sense of smell. The smell is also commonly called aroma , which can refer to a pleasant and unpleasant odor. The terms aroma and aroma are used primarily by the food and cosmetics industry to describe pleasant odors, and are sometimes used to refer to perfumes, and to describe floral scents. In contrast, malodor , odor , reek , pong and smell are used specifically for describes an unpleasant odor. The term smell (in the form of noun) is used for both pleasant and unpleasant odors.
In the UK, smell refers to the scent in general. In the United States and for many non-native English speakers around the world, smell generally has a negative connotation, as a synonym for smell ; on the other hand, the scent or the scent is used by those people to show "a pleasant smell".
Video Odor
Basics
The sense of smell leads to odor perception, mediated by the olfactory nerve. The olfactory receptor cells (ORs) are neurons present in the olfactory epithelium, a small patch of tissue behind the nasal cavity. There are millions of olfactory receptor neurons that act as sensory signaling cells. Each neuron has a cilia that is in direct contact with air. The olfactory nerve is considered an olfactory mediator, the axon connecting the brain to the external air. The foul-smelling molecule acts as a chemical stimulus. The molecule binds an extended receptor protein from the cilia, initiating an electrical signal.
The main sequence of thousands of olfactory receptors is known from the genome of more than a dozen organisms: they are a seven-helix transmembrane protein, but there is (in July 2011) no known structure of the olfactory receptor (OR). There is a very sustainable sequence in about three quarters of all ORs that is a tripod metal binding site, and Suslick has proposed that OR is in fact a metalloprotein (most likely with zinc, copper and possibly manganese ions) that serves as Lewis Acid sites for binding of many odor molecules. Crabtree, in 1978, has previously suggested that Cu (I) is "the most likely candidate for odor-receptor sites in smell" for strong volatiles which are also good metal coordinating ligands, such as thiols. Zhuang, Matsunami and Blocks, in 2012, confirmed Crabtree/Suslick's proposal for the mouse-specific case OR, MOR244-3, indicating that copper is essential for detecting certain thiols and other sulfur-containing compounds. Thus, by using chemicals that bind copper in the rat's nose, so copper is not available for receptors, the authors suggest that mice can not detect thiols. However, this author also found that MOR244-3 does not have a specific metal ionic bonding site suggested by Suslick, instead showing different motifs in EC2 domains.
When the signal reaches the threshold, the neuron lights up, sending signals that run along the axon into the olfactory bulb, part of the limbic system of the brain. The odor interpretation begins, relates the smell to the past experience and in relation to the substance it emits. Balls olfactory acts as a relay station that connects the nose to the olfactory cortex in the brain. The olfactory information is further processed and projected via a pathway to the central nervous system (CNS), which controls emotions and behavior as well as basic thought processes.
The odor sensation usually depends on the concentration (number of molecules) available for the olfactory receptor. One type of odorant stimulus is usually recognized by several receptors, and different odors are recognized by the combination of receptors, the signaling pattern of neurons helping to identify the odor. The olfactory system does not interpret a single compound, but an odorous whole mixture, does not necessarily correspond to the concentration or intensity of any single constituent.
The largest odor consists of organic compounds, although some simple non-carbon-containing compounds, such as hydrogen sulfide and ammonia, are also odorous. The perception of the odor effect is a two-step process. First, there is a physiological part; detection of stimulation by receptors in the nose. Stimuli are processed by areas of the human brain responsible for smell. Therefore, the objective and analytical measure of the odor is not possible. While the feeling of smell is a very personal perception, individual reactions are related to gender, age, state of health, and personal history.
The common smell people use, such as their own body odor, is less visible to the individual than outside or unusual smells. This is because habituation ; after a continuous odor exposure, the sense of smell is fast, but recovers quickly after the stimulus is removed. Odors may change due to environmental conditions, eg smells tend to be more distinguished in cool, dry air.
Habituation affects the ability to discriminate odor after continuous exposure. The sensitivity and ability to differentiate odor decreases with exposure, and the brain tends to ignore the continuous stimulus and focus on differences and changes in certain sensations. When the odor is mixed, the conditioned odor is blocked by habituation. It depends on the strength of the odor in the mixture that can change the perception and processing of odors. This process helps to classify the same odor as well as adjust the sensitivity to complex differences in stimuli.
For most untrained people, the smelly process gives little information about the special ingredients of the odor. Their odor perception mainly offers information relating to emotional impact. However, experienced people, such as scent and perfume lovers, can choose their own chemicals in a complex mixture through olfactory only.
Smell perception is the main meaning. The sense of smell allows pleasure, can unconsciously warn of danger, help find a partner, find food, or detect predators. Humans have a surprising sense of smell (although they have only 350 functional olfactory receptor gene compared to the 1300 found in mice) correlated with an evolutionary decline in the sense of smell. The extraordinary human sense of smell is as good as many animals and can distinguish between different smells - about 10,000 aromas. Bushdid et al. It is reported, however, that humans can distinguish about one trillion odors.
Gordon Shepard proposes that retro-nasal olfactory routes (odors introduced into the olfactory mucosa through the oral cavity often as food) are partially responsible for the development of human olfactory acuity. He suggested the evolutionary pressure of diversifying food sources and increased complexity of food preparations that humans served with various odors, leading eventually to "richer repertoire of smells." However, animals such as dogs exhibit greater sensitivity to odor than humans especially in studies using short-chain compounds. Higher cognitive brain mechanisms and areas of the olfactory brain make it possible for humans to distinguish smells better than other mammals despite fewer olfactory receptor genes.
Different categorizations of main odors have been proposed, inter alia, which rely on seven major odors (by example):
- Musky - perfume/aftershave
- Dirt - rotten egg
- Spicy - vinegar
- Camphoraceous - camphor
- Ethereal - dry cleaning fluid
- Flowers (see also floral scent)
- Pepperminty - mint candy
Although recent advances have been made, the notion of primary perception is debated, and more likely the concept of a primary odor.
Analysis
The ability to identify smells varies among people and decreases with age. Studies show there are sex differences in odor discrimination; women usually outperform men.
Pregnant women also have an increased odor sensitivity, sometimes causing an odorous taste and smell, which leads to food addiction or reluctance. The deficit in olfaction also increases with age and the prevalence of taste problems (the sense of smell tends to dominate the sense of taste). Chronic odor problems are reported in small numbers to those in their mid-twenties, with numbers continuing to increase with overall sensitivity beginning to decline in the second decade of life, and then deteriorating significantly as they get older to more than 70 years.
In Germany, the odor concentration has since the 1870s been defined by Olfaktometrie , which helps to analyze the human sense of smell using the following parameters: odor concentration, odor intensity, and hedonistic assessment.
To establish the odor concentration, the olfactometer test is used, which uses the human nose panel as a sensor. In the olfactometric testing procedure, the odorless mixture and odor-free gas (as a reference) are presented separately from the sniffing port to a group of panelists, which are placed in the odorless neutral spaces. They were asked to compare the gas emitted from each sniffing port, after which the panelists were asked to report the presence of the odor along with a level of confidence such as guessing, foreboding, or certainty of their judgment. The gas dilution ratio is then subtracted by a factor of two (ie the chemical concentration increases by a factor of two). The panelists were then asked to repeat their judgment. This continues for some degree of dilution. The panelist response to various dilution settings was used to calculate the concentration of Odor in terms of European odor units (ouE/mÃ,³). The main panel calibration gas used is butan-1-ol, which at a certain dilution gives 1 ouE/mÃ,³.
General survey
The analytical method can be divided into physical, gas chromatography, and chemosensory methods.
When measuring odors, there is a difference between emissions and imaging measurements. Emission measurements can be performed by olfaktometri using olfactometer to dilute the odor sample. In contrast, olfactometri is rarely used for the measurement of immunity because of low odor concentrations. The same measurement principle is used, but the air test assessment takes place without diluting the sample.
Maps Odor
Measurement
Measurement of odors is essential for odor regulation and control. The odor emission often consists of a complex mixture of many odorous compounds. Analytical monitoring of individual chemical compounds present in such odors is usually impractical. As a result, the odor sensor method, rather than the instrumental method, is usually used to measure such odors. The odor sensor method is available to monitor the odor both from source emissions and in the ambient air. These two diverse circumstances require different approaches to measure odors. Smelter sample collection is more easily achieved for source emission than for ambient air odors.
Field measurements with portable olfactometers seem to be more effective, but the use of Field Olfactometers is not regulated in Europe so far, while it is popular in the US and Canada, where some countries set limits on receptor sites or along the perimeter of plant-emitting odors. , expressed in units of dilution to the threshold (D/T).
Different aspects of odor can be measured through a number of quantitative methods, such as assessing a clear concentration or intensity.
Early entry into a room provides the most accurate smell, before habituation begins to alter the perception of smell.
Smell sensation has 4 properties related to threshold and tolerance: odor concentration, odor intensity, odor quality, and hedonic tones.
Measuring concentration
The smell of concentration is a scattering odor. To measure the odor sensation, a smell is diluted to a certain amount to reach the detection or recognition threshold. The detection threshold is the odor concentration in the air when 50% of the population can distinguish between odorless and odorless samples. The recognition threshold is the odor concentration in the air where 50% of the population can differentiate from odorless and free-smelling samples. The recognition odor threshold is usually a factor 2 to 5 times higher than the detection threshold.
Measurement of odor concentration is the most extensive method of measuring odors. It is standardized in CEN EN 13725: 2003. This method is based on the dilution of the odor sample to the odor threshold (the point at which the odor is detected only up to 50% of the test panel). The numerical value of the odor concentration is equal to the dilution factor required to reach the odor threshold. The unit is European Odor Unit , OU E . Therefore, the odor concentration at the odor threshold is 1 OU E by definition.
To establish the odor concentration, the olfactometer is used which employs a group of panelists. Smelly mixes and odor-free gases (as a reference) are served from sniffing ports to a group of panelists. In comparing the odors emitted from each port, the panelists are asked to report if they can detect the difference between ports. The gas dilution ratio is then reduced by a factor of 1.4 or two (ie, the concentration increases accordingly). The panelists were asked to repeat their judgment. This continues until the panelists responded to certain and true two times in a row. This response is used to calculate the odor concentration in the form of European odor units (OU E /m 3 ).
The test person must meet certain requirements, such as the sensitivity of their perceived odor. The main calibration gas panel to verify the requirements used is n-Butanol (as 1 OU E /m 3 40 ppb/v n-butanol).
To collect odor samples, samples should be collected using a special sample bag, made of odor-free, eg. Teflon. The most accepted technique for collecting odor samples is the lung technique, in which the sample bag is placed in a sealed drum, and the vacuum is placed on the drum, which fills the sample bag as the bag expands, and draws the sample from its source. into the bag. Critically, all components that touch the odor sample, must be odor-free, which includes the sample line and fittings.
The human odor detection threshold is variable. Repeated exposure to unpleasant odors leads to an increase in olfactory sensitivity and decreased detection threshold for a number of different odors. It was found in a study that humans who really can not detect odor androstenone develop the ability to detect after repeated exposure.
Humans can distinguish between two different odors in concentrations by 7%.
There are a number of issues to be solved with sampling, this includes: - If the source is in a state of vacuum - if the source is at high temperatures - If the source has high humidity
Problems such as temperature and humidity are best addressed by using dilution technique of pre-dilution or dynamic.
Intensity
The intensity of the odor is the perceived odor strength. This intensity property is used to look for sources of odors and may be most directly related to odor disturbances.
The perceived sensation of odor sensation is measured simultaneously with the odor concentration. This can be modeled by Weber-Fechner's law: I = a ÃÆ'â € "log (c) b
I is the psychological intensity felt at the dilution step on the butanol scale, a is the Weber-Fechner coefficient, C is the chemical concentration, and b is the interception constant (0.5 by definition)
The intensity of the odor can be expressed using a scale of odor intensity, which is a verbal description of odor sensations that are numerically scored.
The odor intensity can be divided into the following categories according to the intensity:
- 0 - no smell
- 1 - very weak (smelly threshold)
- 2 - weak
- 3 - different
- 4 - strong
- 5 - very strong
- 6 - can not be tolerated
This method is applied in the laboratory and is carried out by a series of trained panelists/observers who have been trained to define the intensity appropriately.
Histone rate judgment
Hedonic assessment is the process of scaling smells in scales ranging from very unpleasant to neutral to very pleasant. It is important to note that the intensity and the hedonic tone, although similar, refer to different things. That is, the power of smell (intensity) and the pleasure of smell (hedonic tones). In addition, it is important to note that odor perception may change from unpleasant to unpleasant by increased concentration, intensity, time, frequency, and previous experience with a particular odor; all the factors that determine the response.
The overall quality set is sometimes identified as " FIDOL factors ", (short for F requency, I ntensity, D uration , O ffensiveness and L ocation).
Character
Character odor is an important element in assessing odor. This property is the ability to distinguish different smells and is only descriptive. First basic description is used like sweet, spicy, tangy, fragrant, warm, dry, or sour. The odor is then referred to a source such as waste or apple which can then be followed by reference to certain chemicals such as acid or gasoline.
Most commonly, a set of standard descriptors is used, which can range from scent to sewer. Although this method is quite simple, it is important for the FIDOL factor to be understood by the person who recorded the character. This method is most often used to determine the character of the odor which can then be compared with other odors. It is common for the olfactometri laboratory to report the character as a sample analysis of the additional factor post.
Interpreting dispersion modeling
In many countries odor modeling is used to determine the degree of impact of odor sources. This is the function of the modeled concentration, the average time (over which time the model steps are run (usually hourly) and percentile Percentile refers to the statistical representation of how many hours per year, the C concentration can be exceeded by the average period.
Sampling from an area source
There are two main techniques of odor sampling, direct odor sampling and indirect odor sampling techniques. Indirectly refers to the collection of samples from the airflow that has passed through the radiating surface.
Direct sampling
Direct refers to the placement of enclosures on or above the radiating surface from which the sample is collected, and the odor emission rate is determined.
The most commonly used direct methods include the flux chamber and wind tunnel which includes the UNSW wind tunnel. There are many other techniques available, and consideration should be given to a number of factors before choosing the appropriate method.
The sources that have implications for this method are sources such as biodegradable biofilters, which have vertical speed components. For such sources, consideration should be given to the most appropriate method. A commonly used technique is to measure the odor concentration on the transmitter surface, and combine it with the air volumetric flow rate entering the biofilter to produce the emission rate.
Indirect sampling
Indirect sampling is often referred to as a counter-count. This involves the use of mathematical formulas to predict emission levels.
Many methods are used, but all use the same input that includes surface roughness, wind up and wind upward concentration, stability grade (or other similar factors), wind speed, and wind direction.
In an indoor environment
The human sense of smell is a major factor in the sensation of comfort. Smell as a sensory system brings awareness of the presence of chemicals in the air. Some chemicals inhaled are volatile compounds that act as a stimulus, triggering unwanted reactions such as nose, eyes, and throat irritation. The perception of odor and irritation is unique to each person, and varies due to physical condition or memory of past exposure to similar chemicals. A person's special threshold before the smell becomes a disorder depends also on the frequency, concentration, and duration of the odor.
Perceptions of irritation from odor sensations are difficult to investigate because exposure to volatile chemicals leads to different responses based on sensory and physiological signals, and the interpretation of these signals is influenced by experience, expectations, personality or situational factors. Volatile organic compounds (VOCs) may have higher concentrations in limited indoor environments due to the limited infiltration of fresh air, compared with the outside environment; causing greater potential for toxic health exposure of various chemical compounds. The health effects of the smell are traced to the sensation of the smell or smell itself. Health effects and symptoms vary, including irritation of the eyes, nose, or throat, cough, chest tightness, drowsiness, and mood swings; all that diminishes as the stench stops. Odors can also trigger diseases such as asthma, depression, stress-induced illness, or hypersensitivity. The ability to perform tasks can be reduced, and other social/behavior changes may occur.
Occupants should expect remediation of an annoying and unexpected odor that interferes with concentration, reduces productivity, causes symptoms, and generally increases dislike for certain environments. It is important to set work exposure limits (OEL) to ensure health and safety or workers and comfort, since exposure to chemicals can lead to physiological and biochemical changes in the upper respiratory system. Standards are difficult to set when exposures are not reported and also difficult to measure. Labor populations vary in the degree of discomfort from smells due to a history of exposure or habituation, and they may not be aware of the possible risks of exposure to certain odor-producing chemicals.
Type
Some scents such as perfumes and flowers are sought after, with elite varieties ordering high prices. All industries have developed products to remove unpleasant odors (see deodorants). The perception of odor is also highly dependent on state and culture. The smell of the cooking process may be fun when someone is cooking, but not necessarily after a meal.
The odor molecule sends a message to the limbic system, the area of ​​the brain that regulates the emotional response. Some believe that these messages have the power to change moods, evoke distant memories, boost their spirits, and increase confidence. This belief has led to the concept of "aromatherapy" in which fragrances are claimed to cure various psychological and physical problems. Aromatherapy claims that fragrances can positively influence sleep, stress, alertness, social interaction, and general welfare. However, the evidence for the effectiveness of aromatherapy consists mostly of anecdotes and lacks controlled scientific studies to support its claims.
With some fragrances, such as those found in perfumes, fragrant shampoo, scented deodorants, or similar products, one can be allergic to the ingredients. The reaction, like any other chemical allergy, can occur anywhere from mild headaches to anaphylactic shock, which can lead to death.
Unpleasant smells play various roles in nature, often to warn of danger, though this may not be known to the subject who kissed her. The odors that some people perceive or disagree with can be considered attractive by others where there is more familiarity or a better reputation.
It is commonly seen that those who have an unpleasant body odor will not appeal to others. But research has shown that a person exposed to a certain unpleasant odor may be attracted to someone else who has been exposed to the same unpleasant odor. This includes pollution-related odors.
What actually causes a substance to unpleasant odors may be different from what a person feels. For example, sweat is often seen as an unpleasant odor, but it actually does not smell. It is a bacterium in sweat that causes odors.
Unpleasant odors may arise from certain industrial processes, harming workers and even industrialized populations. The most common source of industrial odors comes from sewage plants, refineries, animal rendering plants, and chemical processing industries (such as sulfur) that have odorless characteristics. Sometimes the source of industrial odor is the subject of community controversy and scientific analysis.
Body odor is present both in animals and humans and its intensity can be affected by many factors (behavior patterns, survival strategies). Body odor has a strong genetic basis in both animals and humans, but it can also be severely affected by various illnesses and psychological conditions.
Learn
The study of smell is a growing field but it is complex and difficult. The human olfactory system can detect thousands of aromas based on only very little airborne concentration of chemicals. The sense of smell of many animals is even better. Some fragrant flowers emit odor fur which moves upwind and can be detected by bees more than a kilometer away.
The study of odors can also be complicated due to the complex chemistry that occurs at the time of odor sensation. For example, metal objects containing iron are considered to have a distinctive odor when touched, although the vapor pressure of iron can be ignored. According to a 2006 study, this odor is the result of aldehydes (eg nonanal) and ketones (example: 1-octyl-3-one) released from human skin when in contact with iron ions formed in sweat-mediated corrosion iron. The same chemicals are also related to the smell of blood, as iron iron in the blood on the skin produces the same reaction.
Pheromones
Pheromones are the odors used for communication, and are sometimes called "air hormones". Female moths can release pheromones that can attract a male moth several kilometers downwind. Honeybee queens are constantly releasing pheromones that regulate nest activity. Workers can emit such odors to call other bees into the appropriate cavity when a bunch moves to a new place, or to "ring" an alarm when the nest is threatened.
Advanced technology
There is hope that sophisticated technology can do everything from testing perfume to helping detect cancer or explosives by detecting certain aromas, but the artificial nose is still problematic. The complex nature of the human nose, its ability to detect even the most delicate aroma, is at present difficult to imitate.
Most artificial or electronic noses work by combining the output of an array of non-specific chemical sensors to produce fingerprints of any affected volatile chemicals. Most electronic noses have to be "trained" to recognize any chemicals that appeal to the application before it can be used. The training involves exposure to chemicals to the responses recorded and analyzed statistically, often using multivariate analysis and neural network techniques, to "study" chemicals. Many electronic nose instruments are currently experiencing problems with reproducibility caused by various ambient temperatures and humidity. An example of this type of technology is the colorimetric sensor array, which visualizes the odor through discoloration and creates its "image".
Behavioral cues
Odor perception is a complex process involving the central nervous system that can generate psychological and physiological responses. Because the olfactory signal ends at or near the amygdala's odor is closely related to memory and can evoke emotions. The amygdala participates in hedonic or emotional processing of olfactory stimuli. Smell can disrupt our concentration, reduce productivity, generate symptoms, and, in general, increase dislike for certain environments. Odor may affect a person's liking, place, food, or product as a form of conditioning. The memory remembered by the smell is significantly more emotional and evocative than the odor remembered by the same cues presented visually or auditorally. The odor can be conditioned to experiential conditions and when later encountered has a direct effect on behavior. Performing a frustrating task in a scented room reduces the performance of other cognitive tasks with the presence of the same odor. Nonhuman animals communicate their emotional state through changes in body odor and body odor are an indication of emotional states.
The smell of the human body affects interpersonal relationships. The smell of the human body is involved in adaptive behavior, such as parental attachment to infants or the choice of spouses in adults. "Mothers can differentiate the smell of their own children, and babies recognize and prefer their mother's body odor rather than other women, and this maternal smell seems to guide the baby toward the breast and has a calming effect." Body odor is involved in developing baby-mother attachment and is essential for the child's social and emotional development that brings a sense of security. The certainty created by familiar parent body odors can contribute significantly to the installation process. The smell of the human body can also affect the choice of spouse. Fragrances are usually used to enhance sexual attraction and trigger sexual arousal. Researchers found that people choose perfumes that interact well with their body odors.
Body odor is an important sensory signal for the selection of a partner in humans because it is a signal of immunological health. Women prefer men with the major histocompatibility complex (MHC) genotype and smell differently from their own especially during ovulation. MHC alleles are beneficial because different combinations of alleles will maximize disease protection and minimize recessive mutations in offspring. Women biologically tend to choose the "most likely partner to secure the survival of their offspring and thereby increase the likelihood that their genetic contributions will be reproductively reproducible."
Studies have shown that people may use odor cues associated with the immune system to choose a partner. Using brain imaging techniques, Swedish researchers have shown that the brains of gay and straight men respond differently to two odors that may be involved in sexual arousal, and that gay men respond in the same way as a straight woman, although it can not be determined whether this is the cause or effect. The study was expanded to include lesbian women; the results are consistent with previous findings which means that lesbian women are unresponsive to the odors that males identify, while their response to female cues is similar to that of straight male males. According to the researchers, this study suggests a possible role for human pheromones in the biological basis of sexual orientation.
The smell can remind us of the distant memory. Much of the odor-related memory comes from the first decade of life, compared to verbal and visual memories that typically date from 10 to 30 years of life. Memories that evoke more emotional memory, associated with stronger feelings are brought back into the past, and have been considered less frequent than the memories generated by other cues.
Use in design
The sense of smell is often overlooked as a way of marketing the product. The application of deliberate and controlled scents is used by designers, scientists, artists, perfumers, architects, and cooks. Some apple scents in the neighborhood are in casinos, hotels, private clubs, and new cars. For example, "technicians at Sloan-Kettering Cancer Center of New York City are spreading vanilla-air oils into the air to help patients cope with claustrophobic effects of MRI testing," Aroma is used at the Chicago Board of Trade to lower the decibel level of the stock market. "
If the material is listed on a product, the term "fragrance" may be used in a general sense.
Scent preferences
The effect of perfume on sexual attraction
Both men and women use perfume to increase their sexual attraction to the opposite members, or the same gender. Indeed, when we discover that perfumes or aftershaves are working for us, we find it difficult to change them - perfumes can be as much of our personality as our personal style or likes and dislikes. The olfactory communication is completely natural in humans: we do not always realize that we have detected someone's special aroma when we have it. Without perfume or aftershave, we unconsciously detect the natural human aroma: in the form of pheromones. Pheromones are usually detected unconsciously, and it is believed that they have an important influence on our social and sexual behavior. Logically, then on our choice of perfume or aftershave influences how sexually attracts us. Do we choose perfume regardless of our natural scents (as dictated primarily by pheromones) or do we choose to use the scent we want, regardless of our natural odor? There are a number of hypotheses about why we wear perfume or aftershave, and whether it strengthens or reduces our natural scents.
In 2001, a study found that MHC (a major histocompatibility complex, a set of polymorphic genes important for human immune function, see MHC) correlates with the substances found in perfumes. This is an important finding because it shows that humans indeed, in fact, choose perfumes that complement or enhance their natural scent (their pheromone). This evidence offers much support for the hypothesis that perfumes are chosen by individuals to reinforce their physical health statement. Research shows that this good health advertisement, in fact, will increase the attractiveness of women against the opposite sex as has been shown by health markers. While strong evidence has been found to support the hypothesis that wearing perfume increases the attractiveness of women to men, little research has been done into the effects of aftershave on male appeal for women. More research has included the effects of women's natural odor and the attractiveness ratings of female males. What is interesting to note is that in many studies (for example), that scents predict attractiveness when female appraisers are not in the form of the contraceptive pill. For those who exist, there is no connection between attraction and body odor.
It makes sense that odors can increase or decrease the attractiveness ratings because the olfactory receptors in the brain are directly related to the limbic system, the part of the brain that is thought to be most involved with emotions. This relationship is very important, because if an individual associates a positive (pheromon-generated) influence, with his or her spouse, likes, and interests, the prospective partner will increase. Although not the usual evolutionary hypothesis, this hypothesis is one that recognizes how humans have adjusted their mating strategies to modern social norms.
Major histocompatibility complex (MHC) and body odor preferences
The main histocompatibility complex (MHC) is a genotype found in vertebrates including humans. MHC is considered to contribute to the choice of spouses in animals and humans. In sexual selection, women choose couples with different MHCs from their own genes, optimizing the genes for their offspring. The explanations of 'profit heterozygots' and 'Red Queen' for these findings fall under the 'pathogen hypothesis'. Because of the difference in MHC allele resistance to pathogens, preference for couples with different MHC compositions has been debated to act as a mechanism for avoiding infectious diseases. According to the 'heterozygous profit' hypothesis, the diversity in the MHC genotype is beneficial to the immune system because of the larger range of antigens available to the host. Therefore, the hypothesis proposes that the heterozygote MHC will be superior to the homozygous MHC in the fight against the pathogen. Experimental research has shown mixed findings for this idea. The 'Red Queen' or 'rare-allele' hypothesis shows that MHC gene diversity provides a moving target for pathogens, making it more difficult for them to adapt to the host MHC genotype. Another hypothesis suggests that preferences for different MHC-couples may serve to avoid inbreeding.
Body odor can provide MHC information. Although less known about how odor is affected by the MHC gene, the possible explanation is that microbial flora or volatile acids are affected by genes, which can be detected in body odors. Both female and male mice have both shown odor preferences for men with MHC-dissimilarity. Studies have shown that women prefer the smell of men with different MHC genes. In one study, women rated the scent of t-shirts, worn more than two nights by men, because it was more fun to kiss different MHC people. It has also been found that women are reminded of more than current or previous partners when smelling of people whose MHCs are not the same as those of smokers. A study of married couples found that the different MHC haplotypes among couples were more than hopes. Taking oral contraceptives has been found to reverse the odor of MHC dissimilarity preferences.
How do women preferences for aroma changes across cycles
Female preference for body odor changes throughout their menstrual cycle. The hypodesis of ovulatory shifts suggests that women experience increased sexual interest soon on relatively low low days of cycles for men with characteristics that reflect good genetic qualities. Body odor can provide significant signals about the genetic qualities of potential sexual partners, reproductive status and health, with a preference for a particular body odor that increases during the most fertile woman's day. ). Because certain body odors may reflect good genetic qualities, women are more likely to choose this aroma when they are fertile because this is when they are most likely to produce offspring with potential mates, with the risk of conception associated with a preference for the aroma of male symmetry. Men also prefer the smell of women at the point of their fertile cycle.
There are some scents that reflect the good genetic qualities favored by females during the most fertile phase of their cycle. Women prefer more symmetrical male fragrance during the fertile phase of their menstrual cycle than during their infertile phase, with estrogen positively predicting women's preference for symmetry. Women's preference for the masculine face is greatest when their fertility is at its highest point, and so is the preference for an attractive face. Other aromas found favored by women in the most fertile phase of their cycle are, aromas for developmental stability, and an aroma for dominance.
Source of the article : Wikipedia
0 Comments