Hormonal Manipulation of Olfactory Cues, or How to Lose a Guy in 10 days

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Body odors are important cues used for social and sexual discrimination. As was shown many times, animals can easily smell age-, health- and genetics-related  differences.  Recent study of our large-eyed relatives, ring-tailed lemurs, demonstrate that drugs can alter body scents and change behavior.

Researchers examined changes in endocrine and  semiochemical profiles of sexually mature female lemurs treated with hormonal contraceptives during their breeding season. Genetic diversity and kinship were estimated using 11–14 microsatellite loci and pairwise genetic distances. Gas chromatography-mass spectrometry (GCMS) was used to detect the volatile compounds in odor. A rater blind to the treatments scored lemur male behavior in regards to female odors. 

The conclusion? Contraceptives change chemical ‘signature’, minimizing distinctiveness and genetic fitness cues. No more can the males determine which females are genetically and physically beautiful. All contracepted females lost their individuality and started to smell funny.  

What about hormones and chemicals in our food?  Maybe one day humans will wake up and realize that something is lost? May it will happen  sooner rather than later...

For those interested in helping with our research of human environmental malodor - check our studies or this call for collaboration.   



Jeremy Chase Crawford,, Marylène Boulet,, & Christine M. Drea (2010). Smelling wrong: hormonal contraception in lemurs alters critical female odour cues Proc. R. Soc. B published online before print July 28, 2010

Odor-prints: individual but genetic connections unclear

Odor is like fingerprints or facial features - it's unique.  Yet no single measurement could be easily applied to recognize an individual.

GC/MS measurements can be used to analyze mixtures of acids, alcohols, aldehydes, hydrocarbons, esters, ketones, and nitrogenous molecules in human odor. Complex algorithms mining patterns help to pinpoint the signatures. But could these signatures be easily derived from genetic makeups?

Recent article published in the Journal of Chemical Ecology looked at the usual suspects -  major histocompatibility locus (MHC) and found that these genes do not determine major patterns. 


Volatile carboxylic acids are the most diverse class of known axillary odorants, and the pattern of these acids is genetically determined. These acids  - like vast majority of human odorous compounds - are produced by human microbiome, in this case by skin bacteria. Odors of 12 families, comprising 3 to 6 siblings,were analyzed with comprehensive two-dimensional gas chromatography (GC x GC) and time-of-flight mass spectrometry (ToF MS). the analysis onfirmed the presence of individual signatures. but failed to find odors specific to HLA genes.

Even though paternally inherited HLA-associated odors were proposed to influence women odor preferences, genetic basis of odors may be more complicated than previously thought.

References

Natsch A, Kuhn F, & Tiercy JM (2010). Lack of Evidence for HLA-Linked Patterns of Odorous Carboxylic Acids Released from Glutamine Conjugates Secreted in the Human Axilla. Journal of chemical ecology PMID: 20623248

Thompson EE, Haller G, Pinto JM, Sun Y, Zelano B, Jacob S, McClintock MK, Nicolae DL, Ober C. (2010) Sequence variations at the human leukocyte antigen-linked olfactory receptor cluster do not influence female preferences for male odors. Hum Immunol. 2010 Jan;71(1):100-3. PMID: 19833159 
 
Jacob S, McClintock MK, Zelano B, Ober C (2002) Paternally inherited HLA alleles are associated with women's choice of male odor. Nature Genet 30: 175-179  PMID: 11799397  PDF
 

Foods and Smells

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How many flavors are out there? We often hear only about these five - sweet, sour, salty, bitter and savory (umami), but there are so many more and they are important not only to our tastes but also health.

Remember that fresh grassy smell wafting up from the newly sliced tomato? It may be it's way of saying  "I'm good for you".

Stephen A. Goff and Harry J. Klee's article "Plant Volatile Compounds: Sensory Cues for Health and Nutritional Value?" published in a 2006 issue of Science explains why odors from foods may be nutritional or health signals that the human nose has learned to recognize.

Among the things emmigrants from less developed countries miss in USA is the scent of fresh tomatoes. One of the volatile compounds associated with the “grassy” tomato flavor, cis-3-Hexenal, is also an indicator of fatty acids essential to the human diet. Wild tomato contained more than three times the amount of that chemical than the cultivated version in the developed world. Two other contributors to tomato flavor — 2- and 3-methylbutanal — are indicators of the presence of essential amino acids and are also three times more common in the wild tomato. Same applies to commercial apples, strawberries, bread, cheese, even wine and beer.

Flavorful curcumin in tumeric has anti-inflammatory properties, compounds in ginger have antioxidants, and there are antimicrobial chemicals that contribute to the scent of onions, garlic, rosemary, sage, clove, mustard, chili peppers and thyme.

There are hundreds of volatile compounds in foods and beverages, often a major factor in how taste of foods is perceived.

What smells people enjoy the most?

Joanne Camas from Epicurious.com lists these 5 food smells:

1. Fried onions cooking
2. Banana bread baking (extra points if it has chocolate chips in it)
3. A perfectly ripe tomato as you slice into it, especially on a warm, sunny day
4. Coffee brewing
5. Garlic bread, fresh out of the oven
Most people commenting on this post listed baked breads and coffee as their top favorites too. Other choices include pies, spices and meats.

Here are some of the responses pulled from different blogs. What are your top five?

chefrosey 12:23:21 PM on 02/01/10

Chocolate
Fresh brewed coffee
Fresh baked bread
Fresh picked strawberries or an orange being peeled!
Any baked good coming out of the oven!

chef330 12:14:17 PM on 02/01/10

1. Onions sauteeing in butter
2. Chocolate Chip Cookies coming out of the oven
3. Just-picked peaches
4. Hot Apple Pie
5. European Butter - you can smell the flavor

Janet Tue Feb 2, 2010 2:22pm PST

apple pie baking in the oven
tralala311 Tue Feb 2, 2010 2:25pm PST

mmmm... GUMBO!!!

Habanero♥™ Tue Feb 2, 2010 2:32pm PST

Bacon, Baking Bread, Turkey, Pumpkin Pie, Molasses Cookies, Cinnamon Rolls.

Sherri Tue Feb 2, 2010 2:53pm PST

Coffee brewing, Chocolate Chip Cookies, Cinnammon Rolls, Bread, Pumkin Pie
__A_YAHOO_USER__ Wed Feb 3, 2010 9:21am PST
i think there's something about a roast that's been slow cooking all day that smells delicious, it'd be on my top 5 for sure.