If you like your partners smell, chances are they have a different immune system than yours.
The nose knows
Maybe it’s just because I’m a romantic – but I can’t think of February without my mind immediately conjuring up an image of a wonderfully plump cherub, armed with a bow and arrow, on a mission to unite star-crossed lovers.
Now, I must confess – science doesn’t exactly support the idea of a flying, love-obsessed cherub. But when it comes to real-life chemistry, love might be driven by something even more unexpected... our noses.
The Sweaty T-shirt Study
In 1995, a Swiss scientist asked a group of men to wear a plain cotton t-shirt for two nights while also avoiding using or exposing themselves to anything else that was scented (think deodorant, or smelly foods) (1). Afterward, the shirts were put into identical boxes and women were asked to sniff each of the t-shirts and rate the smells from least-to-most attractive.
Turns out, women overwhelmingly preferred the scent of men whose immune systems were the most genetically different from their own.
The science – opposites really do attract!
Every human has a unique set of immune genes that make molecules to detect and fight off harmful invaders like viruses or bacteria. Collectively – the genes are called the Major Histocompatibility Complex (MHC).
Just like other genetic traits—such as hair colour or eye colour—MHC genes vary from person to person depending on their ancestry. So, in the sweaty t-shirt study, the woman used their nose to seek out potential partners who have a different set of disease fighting molecules than their own. Scientists call this MHC-dependent mate selection – we call it, not getting the ick from someone's smell.
From a reproductive standpoint, this makes sense – a more diverse portfolio of disease fighting molecules (inherited from two parents with different immune systems) may give offspring a survival advantage.
Of course, modern romance isn’t just about biology—shared values, emotional connection, and life circumstances all play a huge role. But next time you feel a mysterious pull toward someone, remember: your nose might be working as your own personal Cupid!
Cassie Stylianou
References
- Wedekind, Claus, et al. "MHC-dependent mate preferences in humans." Proceedings of the Royal Society of London. Series B: Biological Sciences 260.1359 (1995): 245-249.