Still another fascinating human oxytocin study was published last week. Adam Guastella, from the Brain & Mind Research Institute, University of Sydney, gave 69 men a whiff of oxytocin and then showed them photos of faces. Some of the faces were happy, some neutral, some angry.

The next day, they showed the men some of the same photos mixed with new ones -- sans oxytocin. They asked them which ones they remembered; the men who had inhaled oxytocin were more likely to remember the smiling faces.

Adam Guastella also is doing a trial using oxytocin during couples psychotherapy, to see if it makes the couples more open and connected, thereby increasing the progress they make. Beate Ditzen did an experiment a couple of years ago in which couples snorted oxytocin and then engaged in an argument. Those who got oxytocin were better able to resolve the dispute with less anger.

At LiveScience.com, Meredith Small reports on the study in a post with the provocative title, How Birth Control Lets Us Down. Her premise is that because lactating seems to be the state in which we release the most oxytocin, when women don't have children or have fewer of them, we're missing out on the positive emotional benefits:

...the oxytocin universe has altered for many women. In Western culture today, women barely lactate at all, leaving them just as physiologically ready to hold a grudge, to never forget the face that did them wrong, as any man.

Too bad. Perhaps what we need is more lactation, by men and women, or a daily shot of oxytocin to help us all put on a happy face.

Of course, oxytocin is released in response to all sorts of social interactions. And, while estrogen seems to enhance its effects, making women more open to bonding or to forgetting those angry faces, men certainly fall under its influence as well.

Small makes another interesting and very important point, though: In situations or cultures where women do tend to be the ones to center the family and maintain social connections, this skill is not always valued:

Problem is, those good social skills, that penchant to forget the faces of those who are angry or neutral, has not always helped women. Instead, men, who are never awash in oxytocin and who apparently never forget an angry face, usually see women as emotional Pollyannas, silly creatures always ready to forgive and forget.

Of course, she is engaging is some stereotyping. Women certainly hold grudges, sometimes better than men, perhaps because a breach of the social bond is more devastating. And men are certainly awash in oxytocin, although their neurochemistries can make its effects less obvious.

See "Oxytocin enhances the encoding of positive social memories in humans."