Human relationships are intense and long lasting, and differ in a number of ways from those of our fellow mammals. However, we still have little idea of what motivates us to continue to invest a considerable proportion of our energy and time in such relationships.
A new study suggests that unlike rodents, which have been the focus of studies to date, we, along with our fellow primates, rely on endorphin rewards to motivate us to maintain our complex relationship networks. This new study argues that, while oxytocin and vasopressin have a role to play in the initial stages of attraction, it is the endorphin system that allows such relationships to endure and persist.
http://www.ingentaconnect.com/content/brill/beh/2011/00000148/F0020009/art00001
Journal
Behaviour