One indication that human nature is not completely determined by culture is facial expressions. Evidence shows that a number of facial expressions are related to similar emotions across cultures.
Psychologist Paul Ekman showed photographs of faces to people in twenty different western cultures and eleven different isolated and pre-literate groups in Africa. Here is what he found: 96% of western respondents and 92% of African respondents identified happy faces. Disgust and contempt show similar findings.
Humans often display their feelings on their faces and what they show is common across cultures for at least these three emotions.
The universality of facial expressions is strong evidence that being able to "read" someone's emotions is biologically based. Still, it is possible to view this ability as something acquired, not biologically determined. To address this possibility, Ekman examined the facial expressions of neonates and found that their expressions were patterned, not random. Newborns everywhere look disgusted in response to bitter tastes, show distress on their faces in response to painful stimuli, and interest in response to novel sounds and other sensory changes. It is unlikely that an infant less than a month could have learned these expression. It is, therefore, safe to say that they are innate.
Ekman also reports that blind children show the same facial expressions for particular emotions as sighted children. Since they couldn’t have patterned their expressions from having observed them in others, "studies of blind infants and children generally support the position that many facial expressions result from innate factors rather than depending on visual learning."
Cultural readings are built upon this base. For example, a study of Chinese participants showed that Chinese-Americans were quicker to accurately read the facial expressions of other Americans than they were of Chinese residing in China. Similar findings were observed with Tibetans residing in China and Africans living in the U.S. In both instances people more quickly and more accurately described the feelings behind the facial expressions of those in their host countries than did those living in their former countries.
While it is true that cultures modify the rules around emotional display and therefore modify facial expressions, it is beyond dispute that smiles are understood as revealing happiness, frowns sadness and pulled down mouths disgust.
Underlying obvious differences between cultures and individuals there are basic emotions common to all. Furthermore, these basic emotions are displayed in the same ways and we understand what others are feeling simply by looking at their faces.