Why do you prefer certain perfumes for yourself?

Before we answer this question, a little about how vertebrates, including humans, choose mates. In vertebrates there is a complex of genes called the major histocompatibility system. This system determines what we will recognize as self and non-self, and governs our immune system, in other words which foreign lifeforms, such as microbes and transplants, we will reject. 

In humans, this system is called the human leukocyte antigen system, or HLA. When a person needs a transplant, he or she gets one that is matched to his or her HLA type, in order to decrease the chances of rejection of the transplant as non-self.

By contrast, it is to a person’s advantage to find a mate who is of a different HLA type, because their offspring will be able to resist a larger number of diseases. Further, if your mate differs from you in HLA type, you are less likely to be related to each other, so inbreeding is decreased. 

The molecules that make up our HLA type are shed into the environment as we shed skin cells, particularly in our sweat. Dogs use the scent of the HLA we shed to track people. Humans can also sense HLA types subliminally, though we don’t know the mechanism behind this ability.

Which brings me to the association between scent preference and HLA. 

First, do we choose perfumes in order to send identification signals? Havlíček and colleagues performed a curious experiment, in which people were asked to discriminate repeatedly among sweat samples from donors.* Each repetition included one sample from one donor (“odd-ball” sample) and two samples from another, and the task was to pick the sample that is different from the other two. For one set of samples, no fragrance was added to the sweat; for another set, a random fragrance was added to the samples; and for the third set, all three samples were spiked with the fragrance preferred by the person giving the “odd-ball” sample. While the participants were able to distinguish the odd-ball sample at a greater than chance rate in all the tests, the success rate was greatest when the sample was spiked with the fragrance preferred by the donor of the sweat. The authors of the study suggest that “naturally occurring variance in body odor is more preserved when blended with fragrances that people choose for themselves, compared with other fragrances. Our data are consistent with the idea that fragrance choices are influenced by fragrance interactions with an individual's own body odor.”

Next, is it our HLA types that guide us in some way in our choice of perfumes? Not every HLA type has been studied for this characteristic, because there is a huge number of possible HLA types. However, there are two tissue types that are very common in European populations, HLA-A1 and HLA-A2, which Wedekind and Füri for testing fragrance preferences.**

Here are the perfume preferences associated with each of these HLA types (derived from the graphs in Wedekind and Füri’s paper):

• HLA-A1: Like: vetiver, rose, violet, bergamot, tuberose; Dislike: musk, amber, castoreum, amber.
• HLA-A2: Like: sandal, vetiver, moss, cardamom, cinnamon, musk, amber, tolu, styrax, labdanum; Dislike: orris, rose, cedar, violet, tuberose, bergamot.

Shalimar perfume—probably the choice of women with HLA-A2.

Image from Wikipedia.

As you can see from these two lists, the likes and dislikes of HLA-A1 and HLA-A2 are practically the opposite in their qualities. The scents preferred by people with HLA-A1 are considered light, floral or citrus, and green. These scents activate the cool and cold receptors. By contrast, the scents that HLA-A2 carriers prefer are woody, earthy, and spicy, and activate the warm and hot receptors.

I’ve been typed, and I received HLA-A1 from one parent and HLA-A2 from the other. My choices of scents for myself are in HLA-A1 list, and not the HLA-A2 list, yet I carry both sets of HLA types. How can this be? 

I don’t know, but I have a guess. It comes from a study of women’s preference for male odor.*** Women who were typed and whose parents were typed were asked to smell odors obtained from men whose HLA types matched one of the women’s parents, and from men who did not match either parent. Importantly, the women did not know and did not recognize that the odors came from a human being, so the odors could be considered the equivalent of perfumes. (The title of the paper is misleading on this point.) The result: “A woman's preference was associated only with matches to inherited paternal alleles and not to the paternal alleles that she did not inherit.” In other words, if these samples had been perfumes she would have picked the scents for herself that matched the HLA type she inherited from her father.  

If this finding holds true for perfumes, I could say that in all likelihood I inherited HLA-A1 from my father, and the HLA-A2 haplotype from my mother.

Interestingly, my mother didn’t like the aromas in the HLA-A2 list very much either and in fact disliked musk intensely, while her mother (my maternal grandmother) liked perfumes with the aromas listed for HLA-A2 very much—until a bottle of Shalimar broke in her suitcase!***** So my guess is that my mother inherited HLA-A2 from her mother, and I inherited it from my mother! 

Oh, by the way, HLA type may dictate wine preference, too!****

* Allen C, Havlíček J, Roberts SC.Effect of fragrance use on discrimination of individual body odor. Front Psychol. 2015 Aug 7;6:1115. doi: 10.3389/fpsyg.2015.01115. eCollection 2015.

** Claus Wedekind, Sandra Füri Evidence for MHC-correlated perfume preferences in humans. Proc. R. Soc. Lond. B 1997 264 1471-1479; DOI: 10.1098/rspb.1997.0204. Published 22 October 1997

*** Suma Jacob, Martha K. McClintock, Bethanne Zelano^, & Carole Ober. Paternally inherited HLA alleles are associated with women's choice of male odor. Nature Genetics 30, 175 - 179 (2002)

**** Nicola Pirastu, Maarten Kooyman, Michela Traglia, Antonietta Robino, Sara M Willems, Giorgio Pistis, Najaf Amin, Cinzia Sala, Lennart C Karssen, Cornelia M van Duijn, Daniela Toniolo and Paolo Gasparini. Genome-wide association analysis on five isolated populations identifies variants of the HLA-DOA gene associated with white wine liking. European Journal of Human Genetics (2015) 23, 1717–1722; doi:10.1038/ejhg.2015.34; published online 11 March 2015.

***** Shalimar has a bergamot top note, but otherwise is considered a “soft amber” perfume, with “Oriental” notes of incense and vanilla.