FUN FACTS ABOUT THE SENSE OF SMELL:

• Humans have the largest ratio of brain weight to body weight of any creature on earth¹⁵
• Scientists have discovered that approximately 1% of our genes are devoted to sensing aromas¹
• Humans can smell up to 16 million odors¹⁶
• Our sense of smell is 10,000 times more sensitive than our sense of taste¹
• The sense of smell can be sharpened and intensified with use (and training)¹
• Smoking adversely affects the sense of smell; it can up to a full year for it to return¹
• No two people smell the same odor the same way; a rose may be sweeter to some than others²
• Inhalation is the fastest indirect route for the body to absorb volatile substances – research says it takes 1-5 minutes¹
• The nose smells directionally²
• The sense of smell is least acute in the morning; our ability to perceive odors increases throughout the day²
• We all have our own unique odor (smell fingerprint) and can be recognized by that odor² 
• Women have a more acute sense of smell than men at all ages.⁶
•  Women have an increased sense of smell at ovulation and during pregnancy – estradiol¹¹
• Study at Vanderbilt University in Nashville Tennesee showed that 90% of women tested can identify their baby’s smell after only ten minutes to one hour of exposure after birth ⁸*
• The odor produced by the fetus changes the pregnant mother’s urine and even alters the odor of the mother herself (Monell Chemical Senses Center study 1995)
• The fetus samples the outside world through the amniotic fluid¹; this influences postnatal preferences¹³
• Infants recognize their mothers very quickly by smell (bonding)¹
• Body odor may be linked to sexual orientation**
• Our ability to smell is at its peak at about age 8 and declines as early as age 15¹²
• As we get older, our sense of smell declines; we also lose our ability to discriminate between smells
• Smell is unique among the senses in its privileged access to the subconscious
• Your sense of smell doesn’t sleep
• Sperm may smell their way to the egg¹⁴
• Research has shown that your body position can influence your ability to smell (lie down and you become less sensitive)⁹
• Dogs and horses can smell fear in humans; sharks can smell 1 tsp of blood in the equivalent of 3 swimming pools of water¹
• Human males born without olfactory bulbs and therefore have no sense of smell have been reported to suffer from hypogonadism (testicular and penile atrophy)⁷
• The scent of grapefruit can cause men to perceive women to an average of six years younger than they really are²
• A combination of floral and spice scents can cause men to see them as an average of 4.1 pounds lighter in weight.²
• A combination of lavender and pumpkin increased arousal by 40%, as measured by blood flow.²
• The smell of peppermint can increase athletic performance.²***
• Many mental illness are characterized by a decrease in smell can be one of the earliest indications of approaching Alzheimer’s Disease ⁷****
• Astronauts tend to lose their sense of smell (thought to be because of nasal congestion as a result of increased capillary pressure)⁹
• Viagra may impair the ability to smell⁵
• Traumatic head injury can cause an irreversible loss of smell
• Low vitamin A levels may correlate to a loss of smell (the greater the pigmentation of the olfactory epithelium, the more sensitive it is to smell)
• Albino animals lack a sense of smell¹⁶
• Zinc has been used successfully to treat some smell and taste disorders.¹²
• Smell can be used to decrease seizures in epilepsy (One possible explanation is that because olfactory centers are next to regions where seizures begin in temporal lobe epilepsy, activity generated in these areas by the presentation of a smell prevents the spread of the synchronous activity from the epileptic focus.)
• Researchers found that what a scent is called can have an affect on whether or not people like it. For example, study participants were told that an odor was either cheddar cheese or body odor.
  
  

(from: Shutterstock 3/06/09)

*Humans can differentiate blood-relatives (mothers and children, but not husbands and wives) through olfaction. Mothers can identify their biological children but not their stepchildren through body odor, and preadolescent children can pick out their full siblings but not half siblings the same way (the theory is that this has a bearing on avoiding incest)¹⁷ 

**Researchers found that gay men and women had body odor preferences that were different from straight men and women. After evaluating 24 samples of underarm odor, gay men preferred odors from gay men and straight women. Odors from gay men were the least preferred by straight men and women and by lesbian women.¹⁰

***Peppermint has an affect on the reticular formation (in the brainstem), where arousal and sleep are modulated. Bryan Raudenbush, professor of psychology at Wheeling Jesuit University in Wheeling, West Virginia discovered with his research that the smell of peppermint can increase athletic performance.  Peppermint odor also helps people work out longer and harder. Additionally, Raudenbush found that peppermint or cinnamon scents make for more alert, less frustrated drivers.²

****“Schizophrenics, depressives, migraine sufferers and very low weight anorexics often experience olfactory deficits or dysfunctions.” One group of researchers even suggested smell-tests should be part of the diagnostic process for psychiatric disorders because many of them are so closely linked to olfactory deficits.¹¹ Alzheimers patients gradually lose the ability to recognize loved ones, and eventually their possessions, their houses and location of rooms – “all permeated with the subtle pheromonal secretions of the occupants”⁷

¹American College of Health Sciences. Aroma 201 Manual.

²Dembling, Sophia. “Dr. Smell”. Dallas Morning News.

³“Fun Facts with Professor Nosetradamus”. The Sense of Smell Institute. The Fragrance Foundation, Research and Education Division. www.senseofsmell.org.  Accessed 10/19/2010.

⁴Gordon, C.B. Practical Approach to the Loss of Smell American Family Physician 26 (3) 191-193. 1982.

⁵Gudziol, V., Muck-Weymann, M., Seizinger, O., Rauh, R., Siffert, W. and Hummel, T (2007) Sildenafil Affects Olfactory Function. Journal of Urology 177(1), 258-61. 

⁶Howard Hughes Medical Institute. http://www.hhmi.org/senses/d130.html Hughes et al. Climacteric. 2002 Jun;5(2):140-50

⁷Joseph, Rawn, PhD. Olfactory Limbic System. Reprinted from Neuropsychiatry, Neuropsychology, Clinical Neuroscience. 3^rd Edition. Academic Press. New York. 2000. http://brainmind.com/OlfactoryLimbicSystem.html.

⁸Kaitz M, Good A, Rokem AM, Eidelman AI. Mothers learn to recognise the smell of their own infant within 2 days. Dev Psychobiol. 1987 Nov;20(6):587-91.

⁹Lundstrom et al., (2006) "Sit up and smell the roses better: olfactory sensitivity to phenyl ethyl alcohol is dependent on body position". Chemical Senses, e-print ahead of publication,         doi:10.1093/chemse/bjj025.

¹⁰Martins Y, Preti G, Crabtree CR, Runyan T, Vainius AA, Wysocki CJ.Preference for human body odors is influenced by gender and sexual orientation.Psychol Sci. 2005 Sep;16(9):694-701.

¹¹Macalester College’s Behavioral Neuroscience Class. www.macalester.edu/psychology/whathap/UBNRP/smell/memory.htm. Accessed 10/19/2010)

¹²Monell Center (The world’s only independent, non-profit scientific institute dedicated to basic research on taste and smell) www.monell.org

¹³Schaal, B, Marlier, L, Soussignan, R. Human Fetuses Learn Odors From Their Mother’s Diet. Chemical Senses. 25 729-737. 2000.

¹⁴Spehr, M., Gisselmann, G., Poplawski, A., Riffel, J.A., Wetzel, C.H., Zimmer, R.K. and Hatt, H.  Identifiaction of a testicular odorant receptor mediating human sperm chemotaxis". Science  2003 Mar 28; 299 (5615), 2054-8

¹⁵Social Research Center. “The Smell Report”. http://www.sirc.org/publik/smell_emotion.html. Accessed 10/22/2010.

¹⁶Stoddard and Whitfield. Hearing, Taste, and Smell. Pathways of Perception. Torstar Books, Inc. New  York, NY. (Quoted in “Olfaction and Memory”.

¹⁷Wikipedia http://en.wikipedia.org/wiki/Olfaction. Accessed 10/22/2010.