Microbiome in Human Attraction

As it is Valentine’s Day, we’re diving into the world of human attraction and the surprising ways in which microbes play a role in shaping our choices in matters of the heart.

The Microbiome’s Role in Attraction

Factors such as facial features, hormonal characteristics, and personality traits have been believed to influence our preferences in a partner. However, Evolutionary biology suggests that individuals are inherently inclined to be attracted to mates who exhibit qualities conductive to successful co-parenting, thereby enhancing prospects of offspring. With the rise of microbiome research, scientists started to wonder if our microbes influence our choice of partners, and they found that the composition of one’s gut bacteria may play a subtle, yet significant role in influencing how others perceive and feel drawn to us romantically.

Fruit flies and Mice Study in Mating Preference

In a study, involving fruit flies, researchers observed that flies raised on different diets developed distinct microbiota. When these flies were given the opportunity to mate, they consistently preferred partners with the same microbiota, indicating a strong influence of the microbiome mate choice.

A similar experiment with mice showed that alterations in gut microbiota affected their preferences for potential mates. Interestingly, the treated males showed preference to interact with untreated females rather than those treated with antibiotics. This suggests that disruptions in the gut microbiota reduce the sexual attractiveness of females to males, possibly serving as a mechanism for males to prevent future offspring complications.

Fruit flies and Mice Study in Mating Preference
(Image retrieved from Science.org)

The T-Shirt Experiment

Have you ever wondered why your partner smells so good? It turns out that microbes are the secret ingredient. Our immune system plays a role in who we choose as a mate, and microbes influence this. The major histocompatibility complex (MHC) consists of unique immune proteins that contribute to an individual’s distinct odour, which is created by specific bacteria that consume our sweat, skin cells, and oils.

In a study, researchers looked at male and female students’ HLA genes (which are pathogen-recognition genes and part of MHC). The male students then wore a T-shirt for two nights, and the female students rated the odours of the shirts. The results showed that females consistently found the body odours of males more pleasant when their MHC composition differed. This suggests that, at a smell level, people might be subconsciously attracted to mates with MHC profiles that are unlike their own, which could contribute to increased diversity in the immune systems of their offspring.

THE T-SHIRT EXPERIMENT
Figure 1. Woman smelling a used T-shirt to evaluate the “attractiveness” of the smell. Image retrieved from ABC News.

The Love Hormone Connection

A microbiologist recently discovered a fascinating connection between microbes and our desire for connection and companionship. Through an experiment altering the diets of mice with probiotics, researchers observed a rise in the release of oxytocin, often referred to as “The Love Hormone”. Oxytocin plays an important role in fostering bonds between individuals, released when kissing, breastfeeding, and spending time with friends and family, and contributes to the connection between parents and their children. Additionally, elevated levels of oxytocin correlated with improved health indicators in the mice, such as thicker fur and increased confidence. This suggests that elevated gut microbes seemed to transform these mice into healthier versions of themselves, further emphasising the impact of the microbiome on attraction and relationships.

While the relationship between our gut microbiome and love is still under exploration, evidence shows that the connection between our gut microbes and our love life seems to be intertwined in the most interesting ways. Fortunately, if you want to enhance your gut microbiome, it be achieved through eating more fibre-rich foods, probiotics (found in fermented foods) like kefir, kimchi, and yogurt, and prebiotics in foods such as garlic, oats, and berries (Check Figure 2). Avoiding stress and exercising are also good ways to improve your microbiome.

probiotics and prebiotic food
Figure 2. Difference and examples between probiotics and prebiotic foods for a healthy and diverse gut microbe. (Image retrieved from Pinterest.com)

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