SOMETIME in 1988 I came to know a person in Zamboanga City whose way of showing feelings defied my understanding of emotions. Male and married, he spoke softly and showed no sign of roughness or aggression—even at times when my own aggression meter rose.

I learned from his wife that his way of speaking came from his family. Even when pissed off, only those who closely knew him could detect the mounting aggression in his mind.

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That experience taught me the surprising diversity of mankind. But still, investigators who study on the differences between men and women maintain that the physical cues of male anger are easier to perceive than that of females.

Well, Ursula Hess of the University of Quebec at Montreal (Canada), Reginald Adams Jr. of The Pennsylvania State University (USA), Karl Grammer of the University of Vienna (Austria), and Robert Kleck of Dartmouth College (USA) took up the scientific challenge.

Interests in the science of facial expression and identity became noticeable around mid-1980s. During this period, scientists could only propose theoretical models based on available knowledge in the facial functions and the neurological dynamics involved.

Scientists in early 2000s, however, observed overlapping and interacting systems in facial expression. The models from the past just appeared oversimplified.

Hess and colleagues found that pure expression of emotions can be identified more with males than with females.

This means that it is more likely correct to say that the angry face is that of a man rather than that of a woman (the basis of the title of this column). But that is not true with the emotions of fear and happiness.

Hess reported—in the 2009 issue of the Journal of Vision—that femininity can be perceived in emotions involving “a smaller percentage of anger and a larger percentage of happiness.

In addition, with lower percentages of fear and higher percentages of anger, perceptions of masculinity increased again.”

In short, a man’s face is true to its emotions when he is angry; and a woman’s, when she is happy or in a blend happiness and fear.

The friend I knew in Zamboanga must be an aberration in the language of science today. That’s one obvious limitation of the discipline. The limits of science are the limits of the theory—take note, not law—of probability.

Probability is the best mathematical expression of the most predictable chance. But it is still a chance, not a pure cause-and-effect situation (CAES). Even in the measurement of CAES, science can never claim the absolute.

Still, the best estimate is better than no estimate at all.

Joseph Butler wrote: “But to us, probability is the very guide of life.” And who says there is absolute certainty in life.