A Practical Guide to the Science of Attraction

1. We value beauty because it signals health. The more symmetrical the face, the more attractive we all perceive it. Symmetry requires good genes and a peaceful pregnancy, so this evolved as an important reference point.
2. For female attractiveness, waist-to-hip ratio matters more than weight. The ratio signals fertility: 0.7 is the optimal European ratio and 0.8 is the optimal South American and African ratio. Men are actually pretty fickle when it comes to weight — in fact, when asked to pick from silhouettes of various weights, men who were just entering a cafeteria chose women who were significantly heavier than men who were asked upon leaving the cafeteria. This is because weight suggests access to resources (food), so hungry men wanted women that knew where to get the food.
3. We’re possibly attracted to people who have different immune systems from us. There’s some controversy in the studies, but research suggests that we tend to marry people with dissimilar MHC molecules, which are responsible for the immune system’s surveillance system. The more these vary, the more pathogens our offspring are able to detect and deal with, so likelihood of survival improves. We don’t know how people detect this; current theory is that we can smell it.
4. Men are attracted to women who are ovulating. Science can’t explain how men detect this one yet. Theories range from pheromones to slight changes in skin colour. Next time you’re out with friends, ladies, this might be impacting your luck that night.
5. Women are attracted to more masculine faces while they’re ovulating. These faces suggest higher levels of testosterone, which is a marker for strength and likelihood of survival. The rest of the month, though, women prefer more feminine male, because they’re more likely to be better caretakers.
6. We’re more likely to be attracted to people we meet in high-adrenaline scenarios. In one of my favourite studies, participants are sent across a “rickety bridge” to meet the researcher, where they rate her attractiveness. Compared to those who walked over on solid ground, men rated her as significantly more attractive when their heart rate and stress response were already elevated. So go-carting and rock climbing are pretty good date ideas when you really like someone.
7. The 7-year itch is actually the 4-year itch. There’s a statistically significant spike in divorce rates after 4 years of relationship. Current dominant theory to explain this is that this is how long it takes for a child to reach an age where only one parent is required. After this, it makes evolutionary sense to diversify. However, studies also show that the biological responses of love can often last for decades. Science hasn’t determined what makes the difference here yet.
8. There are so many factors at play that your chances are pretty good. No matter who you are or what you look like, odds are that you’ll eventually find that lasting mutual attraction.

Happy Valentine’s Day!