The French say “je ne sais quoi” (literally, "I don’t know what") when describing a certain mysterious something that makes a particular person sexually attractive.

You’d think that with something as vital to the survival of the species as sexual selection, we’d all be very conscious of the cues we (and prospective sex partners) use for mate selection.

But as the French saying suggests, we are often not consciously aware of these cues. Numerous laboratory studies (where young adults rate the attractiveness of photos of members of the opposite sex, or smell clothes worn by test subjects of the opposite sex) have proven that although we know whom we prefer as prospective mates, we don't always know the exact reasons why we prefer them.

After reviewing a list of subliminal "come hither" stimuli that might  shed some  light on the mystery of physical attraction, I'll explain how--if you're so inclined-- you can take advantage of the new information.

Unconscious sexual cues

Based on recent research, here is a list of unconscious attractors, indicating which attributes unconsciously arouse our interest, along with which sensory modalities are thought to be responsible for communicating signals of sexual attractiveness.

  • Body and face symmetry (from smell alone) We can consciously sense when someone’s face is symmetrical. Women also unconsciously prefer scents (on t-shirts) of men who have symmetrical body and facial features (signs of health and genetic fitness). Exactly what the chemical signals of symmetry are is unclear.
  • Personality (from smell and visual cues) T-shirt sniff tests also indicate that we have a limited ability to determine which of the “Big 5” personality (e.g. Extraversion and Neuroticism) traits are dominant in another person from unconscious olfactory cues (again, scientists don’t yet know which chemicals are responsible). Apparently, we can also glean similar information unconsciously just by watching video clips of people’s behavior.
  • Illness (from smell) Putting aside obvious cues, such as the odor of infected wounds, new evidence suggests we can unconsciously detect olfactory cues associated with bacterial infection in another person. Both humans and animals tend to avoid mates that are ill.
  • Genetic diversity (from smell and taste) There is evidence that humans can sense, from both sweat and saliva, how close a match another person’s DNA is to their own by detecting major histocompatibility complexes (MHCs). In order to avoid mutations in offspring and stillbirths, mating with someone whose DNA (as evidenced by MHC’s) is very different from one’s own is a good idea. Also, combining your genes with someone with very different immune characteristics increases the odds your children will have robust immune systems. In my last blog, I speculated that people kiss on the lips because disproportionately large swaths of sensory and motor brain tissue respond to lip, tongue, and mouth stimulation. But some biologists now believe that we kiss on the mouth in order to “taste” the saliva of prospective partners for compatible MHC’s.
  • Non-familiarity (from both smell and visual cues) Research from kibbutz communities in Israel and colonies in Taiwan, where non-relatives are raised in close proximity, shows that humans prefer to mate with those who were not raised with them (mating rates among non-relatives who grew up together is very low). Again, low rates of mate-pairing among adults who grew up together may foster healthy genetic diversity. At least from the point of view of mate selection, familiarity really does breed contempt!
  • Similar personality (from smell) In a research article, "Birds of a feather do flock together," Wu YouYou and colleagues at Cambridge found that we are drawn to people—both as mates and as friends—who share our personality traits. Whether or not we are conscious of being attracted to people because they have similar personalities is unclear, especially in light the research just cited on “sniffing out” the Big 5 personality traits.

How to benefit from unconscious attractors

Okay, so we judge sexual attractiveness partly based upon cues we aren't conscious of. How can knowing this improve your life?

If you’re in the business of creating or using scents (for perfumes, deodorants, food additives or soaps) to make people and products more appealing, this new research offers fresh ways to stimulate people’s unconscious desires: Perhaps soap that emits “symmetry” and “extraversion” will sell better.

Even if you’re not in the scent business, there might be ways to take advantage of these new findings on unconscious sexual attractors.

Say, for instance, that you find yourself repeatedly dating (even marrying) “the wrong kind of person.” You don’t consciously seek out these types of individuals, but somehow, you end up with them.

Is it possible that a primitive, unconscious part of your brain is drawn to the scent (or another attribute) of “the wrong kind of person?”

If so, it wouldn’t be the only case of vestigial attitudes and behaviors that we inherited from our distant ancestors that no longer make nearly as much sense as they once did.

Most people’s innate preference for foods high in sugar and fat, for example, was highly adaptive when starvation was a constant threat. But today, with abundant food in most societies and skyrocketing obesity, attraction to food that is high in fat and sugar is the nutritional equivalent of being "attracted to the wrong type of person."

Similarly, our “temporal myopia” (the cognitive bias of valuing “now” much more than “later”), which can lead to impulsive, self-destructive behaviors (overeating, overspending, gambling, and drugs abuse) was logical 300,000 years ago when the average life expectancy was only 20 years, but today, with lifespans approaching 80, the “grab it now before it slips away” approach to life often creates more problems than it solves.

The short life expectancy that prevailed when our brains evolved to their current state—roughly 300,000 years ago—could explain why our brains cling to unconscious sexual attractors. “Until death do us part,” probably averaged about five years in prehistoric times, as the majority of humans died from disease, violence or infection by the age of 20. This suggests that long-term emotional compatibility between mates may not have been as crucially important as it is today. In ancient times, more primal, biological imperatives, such as genetic diversity and offspring fitness, could have far outweighed more subtle, emotional compatibility factors that determine whether or not modern relationships succeed.

Simply being aware that your nose may be getting you into the wrong type of relationships could be a valuable first step to entering relationships that work out better for you.

A second step might be to tune in more closely to olfactory sensations when meeting prospective mates. The fact that we’re usually unaware of such cues doesn’t mean that we can’t consciously experience them if we try hard enough. For instance, although you probably think you’re unable to track people from smell alone—like a bloodhound—researchers at Rutgers University and U.C. Berkeley demonstrated that humans can indeed track other humans across a lawn, just from scent, by placing their noses close to the ground.

Now, I’m not suggesting you plant your nose in someone’s armpit (or some other body part) upon first meeting them, but it might make sense to pay close attention to what your nose is telling you so you can at least be aware when someone you meet smells like people you’ve already dated who, ultimately, didn’t work out so well.

It may turn out that the presence of the “right” smell—that unconsciously turns you on—is a warning sign that you are being physically attracted to the “wrong” person.

Want to learn more about the awesome power of the unconscious? Check out the new book I have co-authored "The listening cure: healing secrets of an unconventional doctor" on "About the author" below.


C. Bushdid, M. O. Magnasco, L. B. Vosshall ,A. Keller Humans Can Discriminate More than 1 Trillion Olfactory Stimuli Science  21 Mar 2014: Vol. 343, Issue 6177, pp. 1370-1372

Christina Regenbogen, John Axelsson, Julie Lasselin, Danja K. Porada, Tina Sundelin, Moa G. Peter, Mats Lekander, Johan N. Lundström, Mats J. Olsson. Behavioral and neural correlates to multisensory detection of sick humans. Proceedings of the National Academy of Sciences, 2017; 201617357 DOI: 10.1073/pnas.1617357114

John P. McGann. Poor human olfaction is a 19th-century myth. Science, 2017; 356 (6338): eaam7263 DOI: 10.1126/science.aam7263

Alphus D. Wilson and Manuela Baietto Advances in Electronic-Nose Technologies Developed for Biomedical Applications, Sensors 2011, 11(1), 1105-1176

Wu Youyou, David Stillwell, H. Andrew Schwartz, ...Birds of a Feather Do Flock Together Behavior-Based Personality-Assessment Method Reveals Personality Similarity Among Couples and Friends, Psychological Science, January 2017

Jeffrey A. Hall, Chong Xing. The Verbal and Nonverbal Correlates of the Five Flirting Styles. Journal of Nonverbal Behavior, 2014; 39 (1): 41 DOI: 10.1007/s10919-014-0199-8

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You are reading

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When western medicine reaches its limit, reach for an alternative

Unconscious Cues That Define Sexual Attractiveness

Invisible forces that determine who we want and who wants us.

Why Do We Kiss on the Lips?

And, for that matter, why do we hold hands?