Primates

Deception is not a uniquely human capacity. Accounts of deception have been documented among many nonhuman primate species, including macaques (monkeys), baboons, gorillas, chimpanzees, and orangutans. Nonhuman primates [Page 776]tend to exhibit patterns of deception that appear to serve two key evolutionary functions: survival and reproduction. To these ends, primates have also been observed hiding food, bluffing to avoid threat and punishment, and hiding courtship behavior from fellow primates. In other instances, primates have exhibited deception in playful ways that do not directly impact day-to-day survival or reproduction.

Deception in nonhuman primates has also been linked to the size of the brain's neocortex as well as the complexity of their social system. Given the complexity of both the form and function of these acts of apparent deception, deceitful primate behavior has spurred debate about the potential for nonhuman primates to experience consciousness, engage in higher order thought processes, and understand the mental experiences of fellow primates—responses that otherwise appear uniquely human.

Recent research has found that frequency and complexity of deception is strongly related to brain size in nonhuman primates. Particularly, it seems to be the size of the brain's neocortex—relative to the size of the animal—that is linked to deception. The larger the relative neocortex in the primate species, the more that primate species seems to deceive. In primates with very small neocortices relative to their size, such as lemurs and bush babies, there are not many recorded instances of deception. Yet, in primates with larger neocortices, such as gorillas, chimpanzees, baboons, and orangutans, many instances of complex tactical deception have been observed. The neocortex is largest, relative to body size, in humans—the only primate species unarguably known to exhibit intentional deception. These findings, however, do not answer the question regarding whether or not nonhuman primates are consciously using deception.

Nonhuman primate deception has been commonly referred to as tactical deception because it serves the function of actively deceiving others for personal gain, but is not necessarily intentional. It is also not passive, which distinguishes it from other forms of deception such as camouflage. Although tactical deception has been observed in several nonhuman primate species, the existence of intentional deception—which is commonly observed in humans—is still heavily debated. The following examples of primate deception represent tactical deception, though arguments have been made regarding the intentionality of these actions.