Also nicknamed the "cuddle chemical", or the "love hormone", oxytocin has been shown by a wide range of work to play a role in social relations and maternal bonding, and is also released in sex.
Now it has been shown to turn people into trusting pushovers and brain scans reveal the reason why: inhaling the hormone lowers activity in the amygdala - a region linked with fear and danger - according to a study in the journal Neuron by Dr Thomas Baumgartner, Prof Markus Heinrichs and Prof Ernst Fehr at the University of Zurich.
The same brain circuits identified in the study could play a role in social disorders.
Tests are now under way to follow up the findings to see if the hormone, introduced as a nasal spray, could overcome feelings of awkwardness, warniness and anxiety felt by many in social situations, from parties to meetings.
So called social phobia is the third most common psychiatric disorder after depression and alcoholism, affecting around one in 10 adults.
Trials of the nasal spray are under way on 120 patients to help treat the pathological shyness by one of the team, Prof Heinrichs.