Communication can be defined to include both signals and symbols. Signals are sounds or gestures that have a natural or self-evident meaning [example of someone crying (=emotion), laughing (=emotion), animal cries (=indicating fear, food, or hunt). In this regard, we can consider that most animal communication is genetically determined and includes hoots, grunts, or screams that are meant to mean only one thing and are used every time in the same situation. So there is only one way to express one thing and it never changes. Animal communication tends to consist primarily of signals.
In contrast, human communication is dependent on both signals and symbols. Symbols are sounds or gestures that have meaning for a group of people-it is the cultural tradition that gives it meaning (e.g. green light=go; teaching a child letters (see Faces of Culture video). Symbols have to be learned and are not instinctive; the meanings are arbitrary.
Some of the debate regarding human versus primate communication stems from observations by scientists in the field. For example, scientists who have observed vervet monkeys in the wild consider at least three of their alarm calls to be symbolic because each of them means a different kind of predator- eagles, pythons, leopards-monkeys react differently to each call. Interestingly, infant vervets often make the "eagle" warning call when they see any flying bird and learn the appropriate call as they grow up. This is similar to human infants who often first apply the word "dada" to all adult males, gradually learning to restrict it one person. It is possible, therefore, to consider such calls as symbolic.
So-if monkeys and apes appear to use symbols as least some of the time, how can we distinguish human communication? For one thing, all human languages emply a much larger set of symbols. Another and perhaps more important difference is that other primate's vocal systems tend to be closed (different calls are not often combined to produce new, meaningful utterances). In contrast, human languages are open systems (capable of sending messages that have never been sent before and the ability to combine symbols in an infinite variety of ways for an infinite variety of meanings). The following exercises are designed to help you think about the similarities and differences between humans and nonhuman primates in terms of the way we all communicate.