Why do we touch?

http://www.psychologytoday.com/blog/the-moral-molecule/200810/handshake-or-hug-why-we-touch

Interestingly, women were more susceptible to the effect of touch: they had larger changes in oxytocin and sacrificed more money to those who trusted them. This may be why at lease anecdotally, women touch others more than men. Oxytocin not only is a potent anti-anxiety agent, it activates reward pathways in the brain. Yes, our brains are designed to make it feel good to be good-even to strangers.

So, hugs or handshakes? Either one, along with a display of trust, is likely to cause oxytocin release and increase the chances that this person will treat you like family even if you've just met him or her. We touch to initiate and sustain cooperation. That's a pretty neat trick for a little nine amino acid molecule!