Written by Mallika Venkatramani
Catching the feels is worse than catching the flu – or is it? Turns out the two are related, considering that falling in love is indirectly linked to immune health. Mindboggling as it might sound, there might be some truth to this, as their connection boils down to the fundamental blueprint of our existence – DNA! That’s right, looking beyond eye colour and susceptibility to cancer, our genes possibly control who we fall in love with too.
There is not a single human population in the globe that does not have factual evidence of human love; feeling a special way about someone is in our biology. Just like eating, sleeping and defending, producing offspring is one of the basic activities of all species including humans. Not just any offspring, but nature wants us to produce offspring that has a robust immune system, capable of making it through the everlasting race of the survival of the fittest. This implies that falling in love, an important aspect in mate choice is a carefully curated process.
When it comes to choosing a partner, our major histocompatibility complex (MHC) genes play a big role. The MHC genes produce the MHC proteins, which coat the surface of the cells of our acquired immune system, such as B-cells. These MHC proteins function in boosting our immune system’s memory of various pathogens so that we don’t fall as sick when we encounter the same pathogen again. MHC proteins also allow our immune cells to recognise our own body cells (autorecognition) and not destroy them. Interestingly, certain regions of the MHC genes that produce these proteins vary significantly (hypervariable regions) from individual to individual.
This does not change their basic immune function, but rather, allows every individual to have an arsenal of defence against a unique range of pathogens. Hence, the more dissimilar the hypervariable regions of two potential mates, the broader the range of pathogens their offspring’s immune system will have the defence too.
But how would do our bodies know who has an MHC gene set that would best complement ours? A widespread theory is that MHC genes are the underlying basis of a unique cocktail of chemicals our bodies subtly emit, called pheromones. Pheromones, in turn, reflects our individual genetic character. These pheromones are picked up by other individuals’ olfaction (sense of smell).
Pheromones are involved in a range of functions, such as to signal alarm, to demarcate territory (dogs do this), and to facilitate mate choice. Hence, when our olfactory receptors receive stimulus from the pheromones of someone with a dissimilar set of MHC genes, we are more likely to be attracted towards them. Such observations have been documented not only in humans but in other mammals, birds, reptiles and insects.
So, what does this mean for us? We can say that attraction or love are important ingredients when selecting a partner, and we shouldn’t settle for someone who does not create this attraction in us. This fact is now being exploited by some dating apps that help you find a partner based on your DNA compatibility!
However, as much as there is strong evidence of MHC-driven mate selection, we must remember that humans are very complex creatures, and there more to the story than picking up a pleasant pheromone from a special someone. Personality compatibility, life history relatability, personal values, physical appearance and even ethnic backgrounds dictate partner choice in humans, on top of pheromone preferences.
But we can at least lay to rest this puzzle of why we gravitate towards some people and not others!
Share with your friends to explain why they have a crush on that person.