Oxytocin is a short-lived substance your body produces that has to do with feeling connected to people. Though it is perhaps more associated with females (especially relating to childbirth, breastfeeding, and maternal instinct), it's important to all people, male and female. I think it's even correlated to overall happiness, which is perhaps unfortunate for me as I've felt lacking in oxytocin for years.
Anyway, more recently ocytocin has also been linked to morality and trust. Here's Paul Zak's short (16 minute) presentation on that topic:
I find it really interesting to learn about the neurology and biological basis that drives people to be how they are, so maybe you'll find that interesting too.