Article:   http://www.livescience.com/23500-why-men-love-breasts.html
New Theory on Why Men Love Breasts
Natalie Wolchover, Life's Little Mysteries Staff WriterDate: 26 September 2012 Time: 06:34 PM ET

Larry Young, a professor of psychiatry at Emory University who studies the neurological basis of
complex social behaviors, thinks human evolution has harnessed an ancient neural circuit that 
originally evolved to strengthen the mother-infant bond during breast-feeding, and now uses this
brain circuitry to strengthen the bond between couples as well. The result? Men, like babies, love breasts.

When a woman's nipples are stimulated during breast-feeding, the neurochemical oxytocin, otherwise known as the "love drug," floods her brain, helping to focus her attention and 
affection on her baby. But research over the past few years has shown that in humans, 
this circuitry isn't reserved for exclusive use by infants. 

                                 http://www.livescience.com/23500-why-men-love-breasts.html