Regular readers of this blog will be familiar with the hormone oxytocin, often called the “love hormone.” Levels surge during sex and childbirth, and it has long been shown to reduce anxiety and play a key role in our sense of trust and desire to connect with others. But according to researcher Simone Shamay-Tsoory at the University of Haifa, oxytocin also appears to have some undesirable effects on our behavior.
Shamay-Tsoory found that people who inhaled a synthetic form of oxytocin while playing a money game showed higher levels of envy when they won less than their opponent and gloated more when they did better—though these negative behaviors ended once the game was over.
As she explains:

Subsequent to these findings, we assume that the hormone is an overall trigger for social sentiments: When the person’s association is positive, oxytocin bolsters pro-social behaviors; when the association is negative, the hormone increases negative sentiments.