These nuggets of information about anosmia and olfaction in general are reproduced from various news articles and books that I have read on anosmia and olfaction.

The number of Americans with an impaired sense of smell is estimated to exceed two million. Earlier estimates put the number of older Americans with smell-related disorders at 2.7 million; a new study suggests it is closer to 14 million.

According to the National Institutes of Health, more than 200,000 Americans of all ages visit physicians each year with smell-related problems.

A quarter of the people with smell disorders find that their sex drive disappears.

One study claims that joblessness goes hand-in-hand with smell deficiencies; another study says that the suicide rate among anosmics is higher than among the population at large.

Many epileptics exhibit considerable smell loss.

Premature newborns have a heightened risk of sleep apnea, but pumping a pleasant odor (vanillin) into their incubators seems to reduce the frequency of such spells, a study from France suggests. A previous study observed that pleasant odors led to an increase in their breathing rate, particularly during active sleep.

In a small sample of women with congenital anosmia, nausea and vomiting of pregnancy occurred in only one pregnancy, suggesting that olfaction is a highly selected trigger for nausea and vomiting of pregnancy.

90% of women in one study identified their newborns by olfactory cues after only 10 minutes to one hour of exposure to their infants. All of the women tested recognized their babies’ odor after exposure periods greater than one hour.

Anosmic male kokanee salmon have been shown to be less vigorous and persistent in their courtship than nonanosmic males, suggesting that either a female pheromone and/or high levels of hormone are necessary to maintain full reproductive behavior in male salmon.

Perfume smells strongest just before a storm. This is because moisture heightens our sense of smell; also, the low pressure makes volatile fluids (like perfume) spread from a person’s body even faster than normal. This is also the case, even on sunny days, in high-elevation cities, where the altitude keeps barometric pressures low all the time.

By the age of 20 years old, your sense of smell is only 82% as good as when you were born. By the age of 60, it has fallen to 38% and by 80, it is only 28% as sensitive as at birth. Yet although the sense of smell tends to diminish as people age, the olfactory neurons—the nerve cells that send the information about aromas in the air from our noses to our brains—are the only nerve cells in our body that regenerate.

An international team of researchers demonstrated that when they altered the smell center of a male fruit fly’s brain, the fly became bisexual, approaching male and female flies with indiscriminate ardor. The flies had very likely lost their ability to smell the signal that males emit to ward off other males.

Only 1 part in 10,000 of a fart is stinky. The distinctive smell comes from hydrogen sulfide, methanethiol, and dimethyl sulfide. The gases are similar chemically to the odorant added to natural gas so we can detect leaks. The sulfur-based gases are highly toxic, so we have evolved to detect them at very low levels. The brain perceives of the scent as offensive so we try to get away from it.

No matter how much you brush and floss, your morning mouth probably smells more of sulfur than spearmint. Over night the microorganisms that inhabit your mouth have several hours to eat and break down food into amino acids and peptides with their malodorous byproducts untouched by a toothbrush. Even if you refrained from brushing for the same number of hours during the day, your breath would not smell as badly as it does in the morning, because during the day you talk, chew, and swallow—activities what help keep saliva flowing.

It is theorized that people subconsciously select a perfume that amplifies the natural signal produced by their immune system so it accentuates the natural odor.

1% of human genes are devoted to olfaction. The only comparable system is the immune system.

There are 112 known types of atoms, but the vast majority of common smellable molecules are built of only five: carbon, hydrogen, oxygen, nitrogen, and sulfur.

Most edible smells tend to have low molecular weights.


Results on olfactory nest recognition tests confirm and complete previous results—anosmic Wilson’s storm petrels do not home.

Heredity determines the shade of yellow of the olfactory area. The deeper the shade, the more acute the sense of smell. Albinos have a poor sense of smell. Animals, which can smell with beatific grandeur, have dark-yellow olfactory regions; ours are light yellow. The fox’s is reddish brown, the cat’s an intense mustard brown.

All smells fall into a few basic categories: minty, floral, ethereal, musky, resinous, foul/putrid, and acrid/pungent.

Musk can produce a hormonal change women who smell it. In one study, women who sniffed musk developed shorter menstrual cycles, ovulated more often, and found it easier to conceive.

When you lose your sense of smell, the hippocampus and amygdala, the parts of the brain that have to do with emotions, are not stimulated. You may actually feel depressed. The smells that come through our noses appear to be mostly processed in that same part of the brain as the limbic system, which is associated with emotions such as anger, fear, pleasure, sadness and sexual arousal. It’s probably why smells can modulate and affect so many behaviors without our direct awareness of. The rhinencephalon (our “nosebrain”) can register a smell without us consciously realizing that we have picked up a scent. And in so doing, it affects our limbic system—tied to emotion, memory, and motivation.

Each person has an odor as individual as a fingerprint and each nostril detects odors differently.

Women at any age are usually more accurate than men in identifying odors. They score higher than males in sensitivity to odors, regardless of age group.

During ovulation, a woman’s sense of smell intensifies, but dulls soon after conception and throughout the first trimester of pregnancy to restrain sexual intercourse. Then smell intensifies, presumably for the protection of the developing fetus.

Selective olfactory deficits occur in 70% to 90% of patients with Parkinson disease, independent of disease severity and duration.

Clinical trials have shown that smokers actually have a better sense of smell than nonsmokers. This is because the carbon monoxide in the cigarettes totally blocks the enzyme cytochrome P450, which is responsible for breaking molecules down in the nose. When this enzyme is blocked with smoke, smell molecules aren’t broken down, and they hang out in the nose longer than usual, causing you to smell better.

About 1-2% of the human genome is allocated to production of receptors for the olfactory epithelium—a hint as to the possible importance of this chemical sense, which includes two anatomically distinct systems: the main olfactory system with sensory cells located in the upper part of the nasal cavity, and the vomeronasal organ with sensory cells on the nasal septum.

Decreased ability to smell is present in a high portion of adults with Down’s syndrome, many of whom are known to have brain pathology analogous to that seen in Alzheimer’s disease. It appears that this olfactory dysfunction occurs only at ages when Alzheimer’s disease-like pathology is present, and is therefore not present in children and young adults.

Many epileptics exhibit considerable smell loss.

According to a University of Pennsylvania study, when a woman is exposed to her partner’s sweat, it reduces stress.

According to a University of Texas at Austin study, during the 7-11 days after a woman’s period ends, she smells more attractive to men than at any other time of the month. When a woman is most fertile and about to ovulate, her body may emit a smell that draws men like moths to a flame.

In dogs, distemper virus infection can also cause loss of receptor cells and temporary or permanent anosmia. Tumors, inflammation, and irritation can all reduce or eliminate the ability to smell. Anosmic dogs and cats get along quite well, and their guardians seldom suspect a problem. Unlike anosmic people, they do not seem to have reduced appetites. Only when they are asked to hunt or use their nose does the pet guardian begin to suspect that something is amiss.

Obesity, diabetes, hypertension, malnutrition, Alzheimer’s disease, and multiple sclerosis are all accompanied or signaled by chemosensory problems like smell disorders.

Alcohol abuse can lead to Korsakoff’s syndrome, a severe mental disorder characterized by memory loss and disorientation. Studies show that Korsakoff’s syndrome, in turn, is associated with olfactory deficits: dysfunctions in odor identification, discrimination, memory, sensitivity, and intensity. They’ve also shown “uncomplicated” alcoholics, those without amnesia or dementia, also have impaired olfactory functioning.

Newborn deer have no scent; that is, predators cannot sniff them out. That means a mother can safely leave her fawn in the grass while she searches for food.

Great horned owls routinely prey on skunks. These owls don’t have a strong sense of smell, so they aren’t bothered by skunks’ overpowering odor.

To lay their eggs, green sea turtles cross oceans to return to the same beach where they were born. While they use the Earth’s magnetic field to help them navigate, scientists have learned that they also remember the exact smell of the soil or vegetation on the beach where they were born, and this smell guides them home.

There are possible olfaction-based mechanisms in human kin recognition and inbreeding avoidance. Three studies explored kin recognition through olfaction. They showed that olfactory cues may help mediate favoritism of blood relatives. They also showed that mutual olfactory aversion occurred only in the father-daughter and brother-sister nuclear family relationships. Recognition occurred between opposite-sex siblings but not same-sex siblings. Thus, olfaction may help mediate the development of incest avoidance during childhood (the Westermarck effect).

Recent work from scientists in Belgium and at the Johns Hopkins University indicates that even sperm may rely on a kind of smelling method for wending their way toward an egg. Sperm cells turn out to bear on their surface the same odor receptors stippling the nerves of the olfactory epithelium.

Freud believed that a blotting out of the sense of smell plays a fundamental role in the civilizing process. As a necessary part of the civilizing process, the regression of the sense of smell is nonetheless fraught with danger. The limitations it places on the libido lessen the individual’s capacity for happiness and can become the bases for psychoses and neuroses.

In the fifteenth century fragrant substances and antidotes systematically went hand in hand in both the prevention and the treatment of plague.

The odor of the goat, as well as that of other animals (cattle, horses, sheep, and camels), repels the fleas that spread bubonic plague. The same is true of the odor of some kinds of oils made from olives, walnuts, and peanuts.

People with depression, schizophrenia, or other psychological disorders can develop dysosmia, a condition that makes them believe that something pleasant-smelling has a bad odor

Schizophrenia and a range of other mental disorders are thought to be triggered by biochemical imbalances. These imbalances also alter the composition of exhaled breath and body secretions and physicians as long ago as the 18th century noted the anomalous breath odor of patients who would today be described as schizophrenic.

There have been attempts to isolate the smell of schizophrenia from sweat, and new analytical techniques are now making it possible to accurately identify chemicals present in minute amounts. There is already some evidence to indicate that conditions such as depression, which have similarities with schizophrenia, may also be diagnosed by testing skin or breath samples. It is known that bacteria in the colon produce other substances, so there may be a useful link to colon diseases.

Doctors have always relied on their sense of smell to diagnosis diseases, especially in the days before sophisticated technology. Typhoid fever is said to smell of freshly baked bread; diabetes of acetone, sweetish nail polish, or sugar; the plague of mellow apples; measles of freshly plucked feathers; yellow fever of the butcher shop; nephritis of ammonia; scrofula of stale beer; liver failure of ammonia; isovaleric acidemia of sweaty feet. “Menses breath” comes from a change in sulfur compounds in the body during a woman’s menstrual cycle. Patients with liver cirrhosis have aliphatic acids in the breath, while di- and tri-methylamine can be found in the breath of people with failing kidneys. A signature cocktail of alkanes and benzene derivatives are exhaled by people with lung cancer.

Behavioral studies of olfaction have demonstrated impairments in the ability of schizophrenic patients to detect and identify odors, and the olfactory familiarity judgment of male patients is often more deficient than that of female patients. MRI scans in one study showed that patients with schizophrenia exhibit actual structural deficits in their olfactory bulbs. In schizophrenics, ten out of ten have a smaller right olfactory bulb than a left one. Researchers are unsure of the implications of this. Another study suggests that olfactory abilities decline progressively over the course of the disorder.

In contrast to patients with schizophrenia, patients with severe eating disorders have intact olfactory function. This finding suggests that transient metabolic or nutritional disturbances alone cannot account for previously reported olfactory deficits.

The phenomenon of dogs detecting cancer has already been documented. According to at least two reports in The Lancet, people were prompted have sought medical attention after their pets showed an unwavering interest at moles or lesions on their skin. In one case, Parker, a pet Labrador, constantly pressed his nose against his owner’s pants in the same spot. The skin in that area was later deemed cancerous and removed. Parker then lost interest in sniffing his owner’s leg.

Optometrist John Downing, the inventor of the Lumatron phototherapy device and a light therapy practitioner for over 30 years, treated a woman who had lost her sense of smell four years prior to treatment. She regained her sense of smell after only one treatment of light therapy, and it returned more completely than ever before.

30% of an earthworm’s genetic make-up is for chemical detection of smells; they can smell things with their entire bodies because they have chemical receptors all over their skin. Snails can smell things with their tentacles and other parts of their bodies, including the front of the foot (the entire underside of a snail’s body is known as its foot). Snakes pick up odors with their tongues and octopuses have smell receptors behind their eyes. Flies have smell receptors in their feet and moths have them on their antennae.

One survey published in 2002 asked what people seek in potential mates. Men overwhelmingly placed a woman’s appearance at number one. Women, in contrast, judged another factor higher than any other factors: the way he smells.

A study presented in 2002 suggests that smells also affect how we judge appearance. When men evaluated head shots of women in a room scented with lavender and cinnamon, they were more generous in their assessments of the women’s appeal.

There’s new evidence that certain fragrances may actually make a woman look thinner. In studies at the Smell and Taste Treatment and Research Foundation, men were asked to guess the weight of a noticeably overweight woman standing in front of them. The men were divided into four groups and each group met on one of four successive days. On one day, the woman wore a citrus-floral scent; on another, sweet pea and lily of the valley; one another, a floral-spice mix. The woman wore no scent at all when meeting the last group. The floral-spice mixture knocked an average of 4.1 pounds off the perception of her weight. Men who really liked that fragrance guessed her weight to be a full 12 pounds under the control group’s estimate. The fragrances most likely make a man think that a woman weighs about 7% less than she does contain strong flowers like tuberose or carnations or combine floral notes with spices such as cinnamon, clove, juniper, coriander, or pepper.

Mice can discriminate genetic differences among potential mates by smell alone; they read the details of other animals’ immune systems. They tend to choose mates whose immune systems would combine with theirs to produce the hardiest litters. They do not base their choices on their perception of their own smell, but on the remembered smell of their parents. However, when female mice are pregnant, they choose to spend time with individuals who have a very similar kind of major histocompatibility complex (MHC) and thus a similar genetic make-up to themselves; researchers think this is because they want to be with mice who are likely to be related to themselves.

Swiss researcher Claus Wedekind carried out research which showed that women could distinguish between men who had different MHCs. Male subjects wore a plain T-shirt for two nights running and were not allowed to use any fragranced products. Women were then asked to smell the sweat-soaked garments and rate which ones they found most attractive. Dr Wedekind discovered that women found the men's smell pleasant when they had a different MHC from their own. The twist in the tale is that women who were on contraceptive pills chose T-shirts belonging to men who had a similar immunity complex to their own. This is perhaps because the contraceptive pill jams the olfactory radar by fooling the body into believing it is in the early stages of pregnancy; in other words, the women were acting like the pregnant mice, choosing men who shared more genes with them. The implication is that women who start dating men while they are on the pill are not choosing men who have the best genes for their children, and this could result in infertility or miscarriages. In fact, one University of Chicago study showed that couples with similar MHCs were more likely to suffer miscarriages.

Researchers in Germany have developed an electronic nose that can detect the MHC smells that mice use to choose mates with compatible genes. The device should make it easier to test the controversial idea that people also rely on smells, and that having the wrong ones may sometimes sow the seeds of divorce. The e-nose has already singled out mice with different MHC genes by sniffing their urine. And, as the team will report in Proceedings of the National Academy of Sciences, it can also distinguish the smell of blood serum from people with different MHC genes. The jury is still out on whether MHC smells affect our choice of partners. We probably mask MHC smells with perfumes and deodorants. So a partner might only subconsciously register them after a long exposure. Rather than being involved in the dating game, MHC incompatibility may manifest itself in today's high divorce rate.

Electronic noses also have the potential to spot cirrhosis of the liver and lung cancer by smelling someone’s breath or find other maladies like melanoma and some STDs. However, accurate readings with some of the current technologies can be thrown off by changes in humidity. Studies have also proven that electronic noses can detect tuberculosis bacteria, pneumonia, and urinary tract infections, as well as detect and discriminate among upper respiratory bacterial pathogens and blood pathogens. Every pathogen gives off a unique gaseous mix as it grows, and an e-nose uses chemical sensors to detect the gas that rises from a bacteria culture.

Astronauts tend to lose their senses of smell and taste. This is thought to be because to the congestion in the nose resulting from the increased capillary pressure as the heart no longer has to work against gravity. As a consequence the sinuses tends to fill up with fluid, giving rise to a feeling of stuffiness similar to a head cold.

In one Monell Chemical Senses Center, childless women who regularly sniffed underarm pads formerly worn by nursing mothers reported more sexual desire than a control group. It is suggested that breast-feeding odors may communicate that the environment is safe for reproducing.

Another study found that sniffing compounds from men’s sweat made women more relaxed. At the University of Northumbria, it was found that women exposed to men’s sweat hidden in an airless cubicle found the men’s photographs more attractive.

Many therapists say that complaints about the way a longtime partner smells aren’t uncommon.

An exposed nerve ending in the olfactory passage (the trigeminal nerve) is responsible for causing the cooling or prickling sensation that comes from menthol, mint, pepper, horseradish, rubbing alcohol, and other substances. This is why, although I’m anosmic, I can feel mint, rubbing alcohol, cleaning products, nail polish remover, etc, in my nose.

The big question “Is odor discrimination inborn” has been taxing many investigators over the years. Babies tested 50 hours after birth sense odors. Yet, according to some researchers, at this stage they do not discriminate between pleasant and unpleasant odors, although infants born to anise-consuming mothers have showed a stable preference for anise odor after birth, whereas those born to anise non-consuming mothers displayed aversion or neutral responses. Several studies have shown that pleasant and unpleasant odors both elicit the same kind of mild startle from babies. This evidence is certainly counter-intuitive and implies that response to odor must be learned. It also contradicts 1970s research which demonstrated that neonates (a few hours old) gave aversive facial responses to bad smells and neutral facial responses to pleasant smells. By as early as 3 days a baby can discriminate between a gauze pad worn by his or her own breast-feeding mother and that worn by an another lactating mother used as a control. There is also evidence from animal studies, such as the fact that merely washing the nipple of a mother rat will eliminate the attachment of her pup, that supports the idea of the importance of intrinsic odor. It has been suggested that there are semiochemicals (signaling odors) that elicit suckling behavior in newborn animals. What complicates this whole area is that there is prenatal olfaction. Thus babies are exposed to chemicals in the womb and this influences postnatal preferences. There is clearly experience-dependent learning in the olfactory system, but whether the response to certain smells (in particular malodors) is “hard-wired” is still a matter of debate. However, several studies have shown that babies suck preferentially from an untreated (naturally smelling) breast rather than an alternative breast that has been washed to eliminate its natural odor. An amniotic fluid (AF)- treated breast is preferred even more than a natural odor breast. Preferences for natural breast odors were more pronounced for girls than boys. While preferences for AF-treated breasts fade after birth, responsiveness to natural breast odors appear to persist. Chemical cues from AF also appear to calm neonates and help them adapt to their novel postnatal environment. AF odor likewise elicits positive (head orientation) responses by human infants. Babies exposed to AF smell cried significantly less than babies in the two other groups. The data are consistent with the hypothesis that the fetus may become familiar with chemical cues present in the intrauterine environment.

Some doctors are experimenting with giving children bursts of their mother’s odor, along with the anesthetic, during operations. Babies can smell their mother entering a room, even if they can’t see her.

The Stinking Corpse Lily is the world’s largest individual flower and is rare and endangered. It is just as well-known for its stench as its size. Occasionally a large flower bud resembling a pale orange cabbage breaks through the bark of the host vine and expands into an enormous blossom up to 3 feet in diameter and weighing up to 25 pounds. With an odor reminiscent of a stinking corpse, the blossom attracts carrion beetles and flies which shuttle the pollen from male to female flowers.

Durian, a big, green thorny fruit from southeast Asia, is considered "King of the Fruit" throughout the region, yet it bears a rancid stench. A few countries even ban the presence of durian in selected public spots due to its offensive smell.

During warm weather, egg-laying blowflies can locate a dead carcass or stinking flower within hours. They can smell the odor of a fresh, rotting carcass up to a mile away.

How we smell as individuals is determined by the number of sweat glands, the amount of body hair, diet, health, occupation, environment, medication, emotional health, mood, and genes. Also, blacks, whites, and Asians all have different immune-system proteins and this is one theory for why people of different races smell different. East Asians used to say that whites stank of butter (the butter smell arises from diacetyl—a very small molecule with two ketone groups; westerners tend to consume more butter and other dairy products than Asians). Meat-eaters often smell unpleasant to vegetarians. Hairy Westerners often smell unpleasant to Asians, who don’t have as many apocrine glands at the base of hair follicles as Westerners. Children smell different from adults, smokers smell different from nonsmokers.

Half the population has at least some sort of odor blind spot. (Only 2 percent of Americans have some form of color blindness.)

A dog’s olfactory tissues are similar to ours, but a dog has perhaps 100 million cells in its olfactory epithelium, compared to less than 10 million for a human and a mouse. A rat has about 10 million, a rabbit 20 million, and a bloodhound as many as 220 million. Dogs also have a larger portion of the brain devoted to processing of smell signals.

The apparatus for detecting odors is present in the nasal passages of all birds. Based on the relative size of the brain center used to process information on odors, physiologists expect the sense of smell to be well developed in rails, cranes, grebes, and nightjars and less developed in passerines, woodpeckers, pelicans, and parrots. Many seabirds rely on smell to find their food in the open ocean. They are attracted to odors produced by microscopic plants. Visual cues are probably also important but storm-petrels, in tests, were able to find pungent, oil-soaked sponges at night, indicating that they relied entirely on their sense of smell. They were even able to detect the lures from as much as 8kms away. Kiwis use smell to locate food such as earthworms during nocturnal probings. Their nostrils are located near the tip of the bill. However, on the whole, it is thought that birds rely more on vision more than smell. In spite of this, anosmic birds consistently have trouble finding home when released from unfamiliar sites. Whether the nasal passages are blocked or the cells that actually detect smells are destroyed or the entire nasal region is rendered inoperative by a local anesthetic, the results are the same: birds don’t arrive home after release from an unfamiliar site. Yet birds without a sense of smell find home perfectly well if released from a familiar site, raising the possibility that birds use smell in the absence of familiar visual landmarks.

Olfactory lobes tend to be larger in carnivorous birds than in those birds which eat seeds and fruit.

Some animals omit an odor as a form of defense. Among insects, odor is all forms of communication. Mammals prefer to use odors when they can, spinning scent songs as complex and unique as bird songs, which also travel on the air. Many mammals are born blind and must find their way to the nipple by smell. A mother bat, entering a nursery cave where millions of mother and baby bats cling to the wall or wing through the air, can find her young by calling to it and smelling a path toward it.

Some saints or mystics—either during their lives or after their death—are said to have emitted delicious aromas, often regarded as a tangible manifestation of their supernatural virtues.

The Monell Institute in Philadelphia has created “Stench Soup”—an odor mixture that smells so bad it makes you feel like throwing up. The Department of Defense is interested in it as a non-lethal weapon.

Monkeys don’t smell things as well as dogs do. The animals with the keenest sense of smell tend to walk on all fours, their heads hanging close to the ground, where the damp, heavy, fragrant molecules of odor lie. This includes snakes and insects, too, along with elephants (whose trunks hang low), and most quadrupeds. Pigs can smell truffles under six inches of soil. Squirrels find nuts they buried months earlier. Bloodhounds can smell a man’s scent in a room he left hours before, and then track the few molecules that seep through the soles of his shoes and land on the ground when he walks, over uneven terrain, even on stormy nights. Fish need olfactory abilities: salmon can smell the distant waters of their birth, toward which they must swim to spawn. A male butterfly can home in on the scent of a female that is miles away.

Studies show that both children and adults are able to determine whether a piece of clothing was worn by a male or a female, just by sniffing it.

Violets contain ionone, which halts our sense of smell. Although violets continue to emit a fragrance, we lose the ability to smell it.

There is almost no short-term memory with odors. It’s all long term.

Smells stimulate learning and retention. Children were given scents along with a word list, the list was recalled much more easily and better retained than when given without the scents.

Because animal musk is so close to human testosterone, we can smell it in portions of as little as 0.000000000000032 of an ounce.

We need only eight molecules of a substance to trigger an impulse in a nerve ending, but forty nerve endings must be stimulated before we smell something.

Not everything has a smell: only substances volatile enough to spray microscopic particles into the air. Weightlessness makes astronauts lose taste and smell in space. In the absence of gravity, molecules cannot be volatile, so few of them get into our noses deeply enough to register as odors.

Certain medications can inhibit smell and taste, but others, such as antihistamines, may improve it.

Researchers in Miami found that adults who sniffed lavender before and after tackling simple math problems worked faster, felt more relaxed and made fewer mistakes than those exposed to other odors. In a small British study, elderly insomniacs who sniffed lavender before going to bed fell asleep sooner and stayed asleep longer than those using sedatives.

People whose mood shifts in response to seasonal changes are more sensitive to scent, say researchers. However, their sense of smell is often less acute in the winter, when their depression dulls their superior smell abilities.

Researchers at Yale’s Psychophysiology Center studied how smell can decrease stress and increase alertness. They claim that the smell of spiced apples can reduce blood pressure in people under stress and avert a panic attack, and lavender can wake up one’s metabolism and make one more alert. The Chronicle of Higher Education reports that related tests have shown how fragrances added to the atmosphere of a room can increase typing speed and work efficiency in general.

Dairy and livestock farmers may lose some of their sense of smell from exposure to urine and manure gases.

At London’s Heathrow Airport, the scent of pine is sprayed throughout the terminals to keep passengers at ease.

Smell was the first of our senses. Our cerebral hemispheres were originally buds from the olfactory stalks.

Humans usually have a strong body odor, and anthropologist Dr. Louis Leakey thinks our ancestors may have had an even stronger odor, one that predatory animals found foul enough to avoid.

Pungent odors are absorbed by fats, and hair contains fat, which is why it absorbs smells like smoke or cologne.

Hyposmia is the diminished ability to smell, phantosmia is smelling scents that don’t exist, dysosmia is when everything has a bad odor.

About 70 percent of those who are asphyxiated from gas leaks are over the age of 65. It happens because they can’t smell.

Estrogen and testosterone levels may affect the turnover of smell and taste cells. Taste cells normally turn over every 10 days, smell every 30 days.

In the Elizabethan Age, a woman would keep a peeled apple in her armpit until it was saturated with her sweat, and then give it to her sweetheart to inhale. It was called a “love apple.”

Researchers once put the sweat of other women under the noses of 10 women at regular intervals. It took three months for the women to begin menstruating at the same time as the women whose sweat they were smelling.

Some researchers believe that we do indeed perceive, through smell, much of the same information animals do. In a room full of businesspeople, one would get information about which individuals were important, which were confident, which were sexually receptive, which in conflict. The difference is that we don’t have a trigger response. We’re aware of smell, but we don’t automatically react in certain ways because of it, as most animals would.

Only 20% of the perfume industry’s income comes from making perfumes to wear; the other 80% comes from perfuming the objects in our lives. In Venezuela, floor-cleaning products contain ten times as much pine fragrance as those in the US.

When a cat or horse gets a gaping mouth after smelling something strong, it is known as the flehmen response. S/he is employing a sense organ that humans lack—a small structure situated in the roof of the mouth known as the vomeronasal or Jacobsen’s organ. It is a small tube opening into the mouth just behind the upper front teeth, it is about half an inch long, and it is highly sensitive to airborne chemicals. It can best be described as a taste-smell organ and is extremely important to cats when they are reading the odor news deposited around their territories. It is performed by both males and females, in heterosexual encounters mostly by males, following actual naso-oral contact with urine scent marks or females. Females will respond in the same way to urine marks, if there is no male present. The precise role of the gape in sexual behavior has not been fully investigated, but in other species it has been found that a fully functional vomeronasal organ is essential for successful completion of the first courtship sequence, but that sexually experienced animals can rely on the olfactory sense alone to identify estrous females.

There is probably no lemon-specific or rose-specific receptor in the nose. Instead, the smell of lemon is represented by the activation of a characteristic and presumably small series of receptors. And though similar odors probably stimulate overlapping groups of receptors, the patterns will vary enough to allow a person to distinguish among the lemon smell of a real lemon, the fake lemon scent of a gum drop, and the version found in a lemon shampoo. With a thousand receptors to mix and match, the possible combinations for detecting smells are stupendously large,

There are few smells that people universally rate as either good or bad.

Body odor in Japan used to be considered a sign of poor genes and character. It immediately disqualified you from the military services.

The cardiologist who designed the stethoscope did so to avoid an assault on the nose. Heart problems used to be diagnosed by laying an ear to the chest.

Perfume began in Mesopotamia as incense offered to the gods to sweeten the smell of animal flesh burned as offerings, and it was used in exorcisms, to heal the sick, and after sexual intercourse.

One study showed that (i) unpleasant odors were assessed more rapidly than neutral or pleasant odors, and that this was specifically true (ii) during right nostril stimulation, and (iii) during pleasantness assessment, suggesting possible differential cerebral hemisphere involvement, with a right-side advantage for processing of unpleasant affect in olfaction.

It can be shown that male pheromones (androstenol/androstenone) from male sweat have a direct impact on female menstrual cycles and ovulation. Furthermore, female pheromones (copulins), which are present in vaginal secretions, influence male perception of females and may induce hormonal changes in males.

In one study, pandas from all reproductive categories displayed a dramatic increase in several measures of chemosensory responsiveness, both when visiting another panda’s enclosure and when encountering scent deposited in their home enclosure. Evidence for discrimination between odors encountered as a resident versus a visitor was minimal, but male pandas’ response patterns were suggestive of a territorial function. Evidence was also found for discrimination of sex and reproductive condition via chemical cues. Males showed a marked preference for female odors, investigating, licking, scent marking and vocalizing more in response to female than male odors. Males also vocalized more in response to estrous than nonestrous female odors. Nonestrous females licked more and estrous females vocalized more when encountering male than female odors. Data on vocalizations suggests a potential role for odors in the activation of sexual motivation. It is argued that the low reproductive success observed in captivity may be attributed in part to failure to provide sufficient opportunities for chemical communication via social odors that increase libido and promote natural mating.

The aquatic environment is well suited for the transmission of chemical information, and aquatic animals have evolved highly sensitive receptors for detecting these cues. Chemical cues are released during detection, attack, capture and ingestion of prey. The nature of the cue released depends on the stage of the predation sequence in which cues are released. Predator odors, disturbance pheromones, injury-released chemical cues, and dietary cues all convey chemical information to prey, who use these cues to minimize their probability of being taken on to the next stage of the sequence.

On another level, subtle scents may have mysterious powers to influence our relationships. Scientists maintain that close friendships and romantic attachments are forged via “olfactory bonding” that occurs within seconds of meeting. … Olfactory bonding may also mean that subliminal scents called pheromones by which other species signal sexual availability are at work in humans too.

A whiff of the right stuff may help migraine suffers. Doctors have long recognized that certain smells—cigarette smoke, perfume, paint—can bring on headaches, and now a study from the Smell and Taste Treatment and Research Foundation in Chicago suggests that the scent of green apples can banish migraines without medication.

People who have lost the sense of smell often gain weight. Even more intriguing are studies showing that merely inhaling certain food-related aromas can lead to weight loss.

Scent also appears to affect creativity, but here bad smells harm more than pleasant smells help. When researchers at the Graduate Center of the City University of New York tested the impact of odor on creativity by asking students to list novel uses for familiar objects (for example, pencils as hairpins), those exposed to the unpleasant chemical odors did worse on the tests than those exposed to almond or lily of the valley. Howard Ehrlichman, the psychology professor who directed the creativity study, attributes the differences to “real psychological changes brought on by smelling pleasant or unpleasant odors. These effects occurred under very sterile laboratory conditions…in the real world the impact of odors may be greater.”

Ira Lott, MD, at the Irvine Medical Center, University of California at Irvine, theorized that babies incapable of remembering smell may be prone to learning disabilities.

Dogs trained to sniff for human remains can pinpoint the location of a corpse at the bottom of a lake by sniffing the water’s surface for the gases and fats that float up from the rotting remains. They can detect the lingering scent molecules of a decomposing body up to fourteen months after the killer lugged it away.

Mental-health researchers have revealed an intriguing link between the sense of smell and the ability to connect with other people. A smell identification test was given to 138 people, including 70 who suffered from schizophrenia or related disorders .Everyone attempted to identify 40 cents from various lists of possibilities, such as chocolate, pizza, smoke, and lilac. Sense of smell was weak among the patients with schizophrenia, especially for those who had an impaired social drive (meaning they don’t or can’t form relationships). Of this socially malfunctioning group, 89 percent had a “Clinically significant impairment in olfaction,” compared with 12 percent of the other mentally ill patients. The brain systems that process odors may also govern social relationships.

An entire industry has been built on deterring animals through their sense of smell. If you love deer but don’t like them nibbling on your prized plants, try coyote urine in a box. Or if you want to keep geese from grazing on your lawn, sprinkle it with a concoction made from the bitter-tasting, smelly part of concord grapes. Other methods include using castor oil to deter moles, red pepper spray to irritate squirrels, and mustard to bother rabbits. Such methods offer non-harmful ways of discouraging critters from your yard.

Recent research has shown that a panel of women can discriminate between armpit swabs taken from people watching “happy” and “sad” films. Men were less good at this. Also, one study in Vienna recently demonstrated that the smell of fear can be detected (by women) in the armpit secretions of people who watched a terrifying film. The implication of this work is that a chemical signal is secreted in sweat which communicates the emotion. In further evidence of chemical signaling, armpit swabs taken from donor women at a certain phase in their menstrual cycle and wiped on the upper lip of recipient women were shown to advance or retard menstruation in the recipients depending upon the phase of the donor. We seem to possess the ability to secrete compounds that can relay information about our mood to another person.

Both behavioral and molecular studies point to a potentially important role of dopamine in olfaction. Parkinson’s patients, who have reduced dopamine levels, also have impaired odour recognition. Injection of dopamine analogues reduces olfactory sensitivity in rats.

Various drugs have been demonstrated to have an effect on the sense of smell, in particular drugs that affect calcium channels, nifedipine and diltiazem. These are thought to have their effect by blocking olfactory nerve transmission.

Olfactory hallucinations coupled with feelings of deja vu occur in “uncinate seizures,” a form of temporal lobe epilepsy, and sometimes there is a generalized intensification of smell.

Covering your unfortunate skunk-sprayed pet in tomato juice does not get rid of the skunk odor—it merely masks it. If you’re convinced that the tomato juice really is eliminating the skunk odor, it’s because you’re suffering from olfactory fatigue: a short amount of time of inhaling the skunk smell, your nose becomes immune to it. (This phenomenon explains why people can’t smell their own perfume and smokers don’t realize they smell like cigarettes.) To truly get rid of a foul skunk smell, place all of the following in a tub of water and bathe your pet for five minutes: 1 quart of 3% hydrogen peroxide, 1/4 cup baking soda, 1 teaspoon liquid detergent.

The Discovery Channel ranked the top ten worst-smelling animals in nature:

1. Tasmanian devil: These aggressive creatures emit a foul odor when they get stressed out.
2. Skunk: They spray a malodorous liquid as a means of self-defense.
3. Hyena: Hyenas mark their territory with a smelly substance secreted from anal glands and glands between their toes.
4. Turkey vulture: When threatened, these large birds may vomit as a defensive maneuver. Also, when they’re hot, they may excrete on their own legs to cool themselves.
5. Wolverine: These predators have scent glands that produce a strong, musk-like odor for marking territory.
6. Musk ox: These animals produce pungent urine for marking territory, an important part of the mating process.
7. Stinkbug: Some of these bugs are pests, damaging crops such as tomatoes and rice. One type of stinkbug, T. Papillosa, can spit its secretions a distance of 6-12 inches.
8. Beaver: These cute dam-builders have scent glands near the anus that produce a musky liquid called castoreum. The liquid is thought to play a part in attracting a mate.
9. Fox: Red foxes have scent glands near the anus and in the tail. The secretions smell like skunk spray and are used for marking territory. Their urine also has a strong, skunky odor.
10. Porcupine: Before mating, the male porcupine showers the female with urine. If she does not object, it shows that she is ready to mate.

The funerary rites of the ancient Egyptians attest to the great importance of perfumes, which were believed to be an intimate expression of divinity and whose use was important on two levels. Perfumed substances retarded the putrefaction of the ceased (a necessary condition for his survival after death), and by giving his body a pleasing smell, they turned him into a god, a “Perfumed One.”

The rhinoceros has poor eyesight. It relies on its strong sense of smell to find other rhinos, even when they are far away.

Komodo dragons’ keen sense of smell helps them zero in on rotting meat from more than a mile (1.6 kilometers) away.

Gazelles use their keen sense of smell to tell when a predator is sneaking up on them and elephants use their trunks to smell the air for danger that might be nearby.

Nonanosmic mother goats release oxytocin (OT) only when nursing their own kids, but not with aliens, while anosmic goats show an increase in OT levels regardless of the identity of the kids. Also, the amplitude of the response of both OT and prolactin (PRL) is lower in anosmic mothers than in intact mothers. Nursing behavior and milk production do not appear to be significantly affected by anosmia.

The ability of 24-hour-old lambs to discriminate between their own mother and an alien mother—that were either nonanosmic and accepting only their own lamb at nursing or anosmic and indiscriminately nursing alien lambs as well as their own—was assessed by a 5-minute, two-choice test. With nonanosmic dams, lambs spent significantly more time next to their own mother, whereas this was not so in the presence of anosmic dams.

Visual and auditory recognition was assessed in anosmic and nonanosmic ewes at 12 hours and 24 hours postpartum by a test of two choices: their own and an alien lamb. In the two-choice recognition test, at both 12 hours and 24 hours postpartum, both anosmic and nonanosmic ewes showed a preference for their familiar lamb. Although anosmic ewes showed no difference in their acceptance of alien and familiar lambs for suckling at 4 hours and 3 days postpartum, they nursed the alien lamb less at 1 month postpartum and showed more rejection behaviors toward it. This means that visual, auditory, or both those types of recognition can be rapidly established, independent of olfactory recognition.

Sex patterns of exploratory behavior in the open field, passive defensive behavior, and emotionality were studied in anosmic rats. It was shown that long-time anosmia increased the level of exploratory and locomotor activities in male rats and changed their behavior in stress situations from passive to active form. Anosmia didn't change characteristics of these forms of behavior in female rats.

Nine pregnant anosmic goats of the Creole breed were studied. At birth, interactions between all females and their young were observed for 1 hour. No differences were found in mother-young relationships between nonanosmic and anosmic mothers during this time, except that kids from anosmic females were slower to suck than controls. After 4 hours of uninterrupted mother-young bonding, mothers underwent three successive 5-minute tests in a predetermined order to study selective bonding: with their own kid, an alien kid of similar coat color and pattern, and an alien kid of dissimilar coat color and pattern. Nonanosmic goats readily discriminated between kids, and rejected the two aliens while accepting their own. By contrast, anosmic mothers showed no signs of discrimination and accepted the three types of kids. It is concluded that during the first postpartum hours of contact, mother goats memorize individual olfactory characteristics of their kid that serve as a basis for selective suckling and exclusive bonding. Furthermore, at this early stage, visual characteristics of the young do not appear able to compensate for the loss of olfactory cues.

In one study, children who lived in a household in which one or both parents drank alcohol to escape were significantly more likely to dislike the odor bottle that contained alcohol when compared with children whose parents did not drink to escape. Additional analyses also revealed that the fathers of children who rejected the beer odor reported drinking significantly more than the fathers of those who liked the odor.