Oxytocin is the bonding hormone. For women, its levels and effects vary throughout a lifetime, being very high during events connected with labor and breastfeeding. It initiates contractions after birth, allows milk to let down, and makes mom and baby a unit.
In the equation of men and women, oxytocin is an important factor as well. It is released during sexual intercourse, creating the afterglow effect and a sense of emotional connection.
Psychiatrist Rene Hurlemann and neuroscientist Keith Kendrick did some research on oxytocin and its effects on emotions and empathy. Half the men in their experiment had the aerosol shot of oxytocin, the other half got a placebo.
"On the whole, the men in the oxytocin group exhibited 'significantly higher emotional empathy levels' than those in the placebo group."
Another study at the Centre de Neuroscience Cognitive in France centered on the effects of oxytocin and autism. An oxytocin spray was given to children with mild autism. Afterward the children were more engaged with the people around them, and were better able to read social cues and body language.