The following article says it all.

Breasts: The Real Reason Men Love Them ~ By Larry Young, Ph.D. and Brian Alexander

Jokes about bosoms, and men looking at bosoms, are such a comedy staple they've become a kind of go-to cliché. How many times have we seen a man talking to a curvaceous woman only to have her point to her own eyes and say "Hey, buddy, up here!"?

It's funny -- or, at least, it was funny the first dozen times we saw it -- because it's true. The male eye does have a way of drifting south. But why? Why are heterosexual men so fascinated by women's bosoms that we sometimes act as if the bosoms are the seat of the soul?

Well, we happen to be heterosexual men. We also happen to be men interested in biology -- one of us, Larry, is one of the world's leading experts in the neuroscience of social bonding. So we've been thinking about this, and, in our new book, The Chemistry Between Us: Love, Sex, and the Science of Attraction, we propose an answer.