They stand with chin out, eyes front, shoulders squared. They're just kids, eighteen or nineteen years old, part of America's armed forces, sworn to obey their leaders and defend their country unto death. What might they be thinking? ... feeling? Their faces have no expression. But inside, their bodies churn with emotion. They're like the rest of us. Though seemingly controlled, our bodies are geared to respond to outer stimulus, sending and receiving wordless messages. Through signs, signals and cues, we communicate non-verbally on a daily basis.

From infancy, we are exposed to wordless messages such as voice tone, gesture and stance. We send signals through our choice of clothing, food and work. We also read signals and cues, making evaluations and judgments as to a person's class, education and status long before a word is spoken. Sometimes the readings are accurate, sometimes not. For example, in Pygmalion, a cockney flower girl is passed off as a duchess on the strength of new manners and acquired speech. In A Streetcar Named Desire, we are shown a picture of Stanley Kowalski having courted his wife while in military uniform, a stark contrast to his ripped t-shirt and unshaven face in civilian life.

Non-verbal communication was probably generated long before speech, with the caveman pointing at a mastodon, gesturing toward a failing fire or grunting to soothe the baby. Rather than being replaced later by the specifics of language, it has blossomed and become increasingly complex, accounting for more than half of human interaction. An early study of non-verbal communication was done in 1872 and described by Charles Darwin in The Expression of the Emotions in Man and Animals, quickly followed by scientific research in the fields of psychiatry, biology, and anthropology. They concluded that many of our emotional responses are instinctive and generated internally.

As parts of the brain evolved, particular areas were designated for certain tasks. The forebrain delivers our emotional response. Here in the hypothalamus is where the limbic system evolved from the neural structure that had been earlier designated for smell. It governs the autonomic nervous system, namely the fight-or-flight mechanism as well as aggression and anger, emotions experienced on the battlefield. It can also reveal feelings when we decide that something stinks as we respond through a sneer or curled lip. That humans have the largest limbic system of any vertebrate makes them the most emotional and should come as no surprise.

A second mass of brain tissue, called the amygdala, governs aversion cues such as dry mouth, sweaty palms or the reaction to freeze or crouch, in which the head is slightly forward of the shoulders and the shoulders forward of the hips. Working through the hypothalamus, it stimulates hormones into the blood stream generating avoidance and interrupting rational thought. It is here where the body is instructed to kick up an oxygenated blood supply, making the heart race and the lungs take in more air, even though the person has not performed any strenuous physical activity. The respondent might feel muscles tense or adopt protective facial expressions. In basic training, the reaction might cause inner turmoil or emotional distress. Later, it could propel a fighter in the direction of a trained response, making the difference between life or death.

Another part of our body, called the enteric brain, centers our gut reaction to events. Located in the nerve cells and circuits of the bowel area, it can express the full feeling of contentment or sense of queasiness at the sight of something disgusting. Made up of millions of neurons, it goes beyond a general spontaneity and is a rapid response to events before being worked through intellectually. Today, economists recognize that many business decisions are made in just this way. In Japan, a process called shinyo sees the center of hara, the abdominal region, allowing a trained and refined gut reaction to take precedence over other forms of decision-making. Application in wartime is obvious, for when events accelerate, there is little time to ponder.

Where innate factors affect how humans communicate and experience feelings through body language, cultural elements can cause variance from one group to another. The use of space, or circle of aggression, can be of enormous importance.

Edward hall, in his book The Silent Language, identifies body distances as intimate, personal-casual, social-consultive, and public. Different cultures establish their own norms. This can sometimes be seen at social gatherings where members of different cultures are making small talk, all the while doing a kind of conversational dance as one edges forward, the other steps back. Their dance signifies how each is struggling to re-establish familiar and comfortable space. In Japan, one sees another kind of space control where one places the palm of the hand vertically forward in front of the nose while bowing, lengthening distance ever so politely. And who hasn't seen the wartime movie where an NCO is barking commands in the face of enlistees, a deliberate violation of personal space, in order to establish dominance.

In spatial orientation, distance is not the only telling sign of relationships. Alignment of our upper body automatically aims at those we like and angles away from those we don't. In staff meetings, angular distance substitutes for linear distance. Studies show that during conferences, members will address those beside them when there is a strong leader, but address those across from them when the leadership is diverse. But the central position always conveys a message of authority and sends the image of a unified negotiating team. For example, the president of the United States will sit at the center of the conference table during Cabinet meetings where he can easily be seen and can address as many as possible. On the other hand, a round table implies a gathering of equals reminiscent of Arthurian knights.

Relative elevation can also communicate non-verbally. The phrase to look up to is conditioned early on. Toddlers look up to their parents. Children sit while teachers stand. Judges preside from a raised platform. Political leaders speak from a stage. Taller men and women are perceived as more dominant, and athletic looking people perceived as more assertive and self-reliant.

Our eyes also reveal a great deal. We all have seen the shifty-eyed con-man or the liar who blinks nervously, giving himself away. Soldiers are familiar with the thousand yard stare, when confronted by an assailant seemingly looking through rather than at them. Police called to a crime scene might be confronted with the target stare where there is a narrowing of eyes and a prolonged direct glare. Each represents a threat. For that reason, direct eye contact rarely lasts more than a few seconds. In Japan, children are taught to focus on a speaker's neck in order to avoid eye contact; although in the United States, listeners are encouraged to gaze into the speaker's eyes to convey a sense of attentiveness, sincerity and honesty.

Some non-verbal signals such as nodding for yes and shaking the head for no, or a shrug indicating I don't know, are pretty universal, but they aren't always reliable. This is especially true in foreign countries where the spoken language is unfamiliar. Something a simple as a handshake can send the wrong signals, for some Middle Eastern and Asian cultures prefer a gentle touch rather than the powerful executive grip which is seen as domineering. Failure to shake hands can sometimes damage any hope of a positive relationship. But in Islamic cultures, men don't offer to shake hands with women, for touching between men and women who are unrelated is forbidden. The hand signal meeting thumb and index finger to form a circle is seen by most cultures as meaning okay, but in some cultures it has a sexual connotation and is considered a big insult.

Certain gaffs can be discounted as minor, but others can be serious enough to create a real threat as wounded egos seek what is perceived as justice. As our lives become increasingly global, we need to learn the language of others but also be cognizant of that which remains unspoken. A mother's cautionary maxim, Your actions are so loud, I can't hear what you're saying, is still valid as we cross over to foreign shores.

A final note. Scientist have found that disturbances in non-verbal communication can be more severe and prolonged than disturbances in verbal communication. This could well explain the complications of post-traumatic stress disorder (PTSD), especially in wartime. It could also be a longtime factor in how the United States is judged by other countries. Hence, every G.I. has to become an ambassador. Every traveler an emissary. Every politician a statesman. Actions speak louder than words. How we are perceived, whether it be false or true, can influence our country and our world for generations to come.