Researchers from the University of Pisa in Italy (the country of love!), discovered that both male and female hormones fluctuate like crazy when a new relationship blossoms. Love-struck guys experience a drop in their testosterone levels, which relates to aggressive, typically male behavior. Meanwhile, women who are falling in love get a testosterone boost. Hence, a biological invitation to bond, solidifying a relationship.

Researchers went so far as to say that when a new relationship blooms, men become more like women, and women become like men! This way, a better understanding develops to kick-start a relationship.

“Men, in some way, become more like women, and women become like men,” researcher Donatella Marazziti explains. And there’s a very good reason: We’re more likely to be attracted to, interested in or stimulated by someone who shares our personality traits. “This elimination of differences between the sexes is important because it lays the groundwork for conception, which is essential to our survival,” Helen Fisher, Ph.D., author of Why We Love shares.

But, unfortunately (or fortunately depending on how you look at it), this two-peas-in-a-pod feeling doesn’t have staying power. When researchers tested subjects one year later, they found that the testosterone levels of both sexes had resumed normal, pre-relationship levels.

The upside to all of this is two-fold. First, the temporary change allows us to fall in love to begin with. Second, it’s the differences between men and women that keeps a relationship interesting.