When fathers hold and play with their children, oxytocin and prolactin kick in, priming them for bonding.
And the people with higher levels of oxytocin were more generous in the amounts they chose to return to the original investor.
I think the most surprising thing to me was the oxytocin story.
oxytocin ox·y·to·cin (ŏk'sĭ-tō'sĭn)
A short polypeptide hormone that is released from the posterior lobe of the pituitary gland and stimulates the contraction of smooth muscle of the uterus during labor and facilitates release of milk from the breast during nursing.