Intentional Deception

Using studies conducted on captive chimpanzees at Arnhem, Frans de Waal concluded that primates utilize intentional deception, concealing true conditions and projecting false images. He argues that, in animals that learn the effects of communication, voluntary signal production can lead to social manipulation for one’s benefit. Krebs, Dawkins, and Smith debate whether communication emerged from attempts to manipulate others or cooperate. Regardless, the short-term advantage to the individual must be balanced against long-term group stability. In essence, once deception predominates, communication becomes impossible. While many types of animals possess “species-typical” behaviors that camouflage their condition, de Waal argues that intentional deception that comes from an understanding of signal meaning should display much greater diversity (de Waal, 1992). For example, false injury display among ground-nesting birds was described by Swarth, Grimes, and Allen in 1935-1936. The behavior is attributed to efforts to decoy predators away from vulnerable nests. De Waal argues that intended deception requires much more sophisticated cognition, including a sense of self, an understanding of signal meaning to others, and the motivation to manipulate. Menzel’s work in the 1970’s appears to elucidate these elements in chimpanzees. In a series of experiments, Menzel observed that subordinate chimpanzees with knowledge about food location will lead other subordinates to the cache, but lead the group away when a dominant male is present. (Menzel, 1974). The experiments appear to demonstrate intentionality, manipulation, and flexibility that are consistent with purposeful deception. Efforts to quantify episodes of deception by Byrne and Whiten reveals species-specific differences, with chimpanzees engaging in frequent intentional deception relative to other great apes like gorillas. Surprisingly, strepsirhines do not appear to engage in such behavior at all (Byne and Whiten, 1992). Research continues, and recent work by Wheeler identifies the use of false predator warning calls by capuchins in order to secure more food than other group members.

A recent paper identifies innovations in stone-throwing behavior by a chimpanzee at Furuvik Zoo in Sweden. The chimpanzee, named Santino, has been observed collecting stones and caching them in seemingly strategic locations. He later uses these caches, throwing stones at zoo visitors during dominance displays. Wary visitors have learned to back out of range when Santino acts aggressively. According to observations made by Osvarth and Karvonen in 2010, Santino has recently started hiding his stone supplies under hay piles and behind logs. He has also started throwing stones without engaging in aggressive displays. The authors argue that Santino is innovating, concealing his ammunition and intentions to deceive his targets (Osvath, 2012). This conclusion is keeping with De Waal's argument that intentional deception should produce diverse strategies in response to new challenges.