Final answer:
The human expression of humor or amusement, which is often shown by smiling, closely resembles the primate expression known as a 'fear grin.' Both humans and primates use facial expressions as part of visual communication to express emotions. This similarity highlights the universal nature of certain expressive patterns across different species of primates.
Step-by-step explanation:
The prototypical human expression of humor or amusement closely resembles the primate expression of fear grin. This similarity among primates, including humans, can be observed in various emotional expressions that are considered universal. For example, primates use visual communication such as facial expressions and gestures along with vocalizations to convey emotions.
According to the work of scientists like Paul Ekman and Charles Darwin, certain facial expressions are universally recognized and are associated with specific emotions. These expressions have been categorized into seven universal emotions: happiness, surprise, sadness, fright, disgust, contempt, and anger. While the human smile is associated with happiness and amusement, chimpanzees exhibit a facial expression known as a fear grin that can resemble a smile but typically indicates a non-threatening stance in chimpanzees.
In essence, facial expressions are an important aspect of nonverbal communication in primates, providing insight into the similarities and differences between humans and our closest relatives, the nonhuman primates. Understanding these expressions is crucial for primatologists in their research on primate behavior.