As our ancestors evolved over millions of years in small bands, continually interacting and working with each other, it was vitally important to communicate in hundreds of ways each day. They shared information about external "carrots" and "sticks," and about their internal experience (e.g., intentions, sexual interest, inclination toward aggression) through gestures, vocalizations - and facial expressions. Much as we developed uniquely complex language, we also evolved the most expressive face in the entire animal kingdom.

Our faces are exquisitely capable of a vast range of expressions, such as showing fear to send signals of alarm, interest to draw others toward an opportunity, or fondness and kindness to increase closeness and the sense of "us." These expressions include seemingly universal signs of six fundamental emotions - happiness, surprise, fear, sadness, anger, and disgust - as well as more culturally and personally specific expressions. For example, I know that very particular look that crosses my wife's face when she thinks I'm getting too full of myself!

Of course, there is no sense in having evolved an extraordinary transmitter - the face - unless we also developed an extraordinary receiver: our remarkable capacities to recognize, sense, and infer states of mind in others from subtle and fleeting facial expressions.

So here's the question: how often and how well do we use this great receiver? Walking down a busy sidewalk, standing in an elevator, waiting in line at a deli: people usually don't look very much at the faces around them, and if they look, it's briefly and without really seeing. Or we grow familiar with the faces around us each day at home or work and then tune out, make assumptions - or are simply uncomfortable with what we might see, such as anger, sadness, or a growing indifference. With TV and other media, we're also bombarded with so many faces from around the world, and it's easy to feel flooded by them, and increasingly numb or inattentive.

But as natural as this is, you pay a price for it. You miss important information about the wants of others, and their hot buttons, true aims, anxiety or irritability, or good wishes toward you. You lose out on opportunities for closeness and cooperation, and you learn too late about potential problems, including misunderstandings, ruffled feathers, saying yes but meaning no, or simply boredom with what you're saying.

More generally, you lose out on the chance to feel connected and part of an "us" - which has been so crucial for well-being, stress management, regulating negative emotions, and coping with life throughout our long history on this planet. Further, when you are not attuned to the faces of others, you can't give them the deeply important experience of feeling recognized, seen, and understood - which, besides not being kind to them, will often boomerang back to hurt you. And in the broadest sense, receiving the faces of others across the world is an important step toward stitching the fabric of humanity closer together, using the ancient threads that bound us to friends and family long ago on the Serengeti plain.

Look at people in passing you do not know, on the sidewalk, in the mall, in a restaurant, etc. Try this also with people you interact with, where it's natural to have some eye contact. And experiment with recalling or imagining the faces - or seeing them in photos or videos - of key people from your past.

When you look:

�  Don't stare or be invasive. Look with respect.

�  Just take a few extra seconds to get past superficial features - young or old, male or female, stiff or smiling, handsome or not - and take in more of the person. Let him or her come into focus as a unique individual, with specific qualities, such as weariness, good humor, firmness, residues of anger, kindness, perkiness, hopefulness, looking for things to like in life, etc.

�  In particular, look at and around the eyes and mouth, which are major regions of social signaling in our faces.

�  Let yourself not know about the person - especially with people that are familiar to you. It's OK to note to yourself what you see - "stress" . . . "kindness" . . . "determination" - or to reflect a bit, but mainly be like a child looking at a human face for the first time, startled and delighted by its magnificence.

�  Have a sense of receiving, of letting in, of registering the other person in a deeper way than usual. As it happens, let yourself be moved by the experience.

As you look in these ways, notice any difficulty with taking in faces, which inherently involves opening to others. For example, it could feel a little overwhelming, since a face is such an intense stimulus for human beings as a profoundly social species. Or painful longings for more closeness could be stimulated. Help yourself by receiving faces in small doses, and by staying centered in yourself "here" while knowing that face is over "there."