Well: Now, a Kiss Isn’t Just a Kiss

Why do we lock lips in romantic relationships? It’s complicated, according to researchers at Oxford University. It’s less about sex and more about assessing potential mates than you may think.

Source: http://well.blogs.nytimes.com/2013/10/28/now-a-kiss-isnt-just-a-kiss/?partner=rss&emc=rss

as an example explained here as explained here resource