Washington, DC -- Researchers studying the behavior of animals in their natural environment have long heard the calls of animals separated from their group and what was assumed were call-backs from the group to reassure the lost member. But, new research based on the field work of husband and wife team, Drew Rendall, Ph.D., and Karen Rendall, Ph.D., suggests that what were assumed to be "call-backs" were actually more call outs from other lost members of the group and that even mother baboons do not call back to their infants when the latter are lost and cry out.
Are the mother baboons just unfeeling? No, suggest the Rendalls and their colleagues in their article "Proximate Factors Mediating 'Contact' Calls in Adult Female Baboons and Their Infants," authored by Drew Rendall, Dorothy Cheney, PhD., and Robert Seyfarth, PhD., and published in the March issue of the Journal of Comparative Psychology. What the baboons lack is what psychologists call "the theory of mind," the ability to recognize that other animals have knowledge, thoughts and feeling apart from their own. The researchers postulate that the baboons did not use their voices to call back to the lost child because they do not understand that their vocalizations can be used to influence the mental state or behavior of another animal. In this case, that hearing their mother's call back could calm an anxious infant and inform him or her of their mother's whereabouts.
The Rendalls base their conclusions on 14 months of field study in Botswana where they observed the behavior of female baboons. Their findings included the fact that the baboons used barks and other forms of vocalizations to call out when they became separated from their group, but never responded vocally to others' calls -- even in the case of a mother baboon and her own infant. While the mother did sometimes rush toward the call of her child in an effort to locate them, they did not use their voice to reassure the child that they were coming.
"They certainly recognized their own infants' cries and were very motivated to find their kids," says Drew Rendall, "but somehow they don't make the connection that 'if I call, it will affect what my kid knows'."
There could be ecological reasons why mother baboons don't return their infants' calls in the wild, suggests Rendall. For example, replying might call more attention to the lost infant and, thereby, put the infant at greater risk from predators.
But, if, as the authors suggest, primates lack a theory of mind, this identifies a fundamental difference between the communications of primates and humans. Most researchers have previously identified syntax as the major difference between human and primate communications. However, this research points to fundamental differences in psychological mechanisms that underlay communication. There are three levels at which animals can respond to other animals: purely automatically, without thought; with some thought about what the other animal is doing; and with thought about what the other animal is thinking. It's this third level that requires a theory of mind.
If baboons have no theory of mind, they may well extract information from others' vocalizations, but they likely don't produce calls with the intention of influencing others. That is, they appear not to understand that by calling out they can change the mental states of companions.
This research follows a large literature on the theory of mind in human children. Research seems to show that a theory of mind -- understanding that others have minds that allow them to think, remember, infer and even deceive -- is one of the milestones of early childhood, becoming evident sometime after or about the fourth birthday.
Article: "Proximate Factors Mediating "Contact" Calls in Adult Female Baboons (Papio cynocephalus ursinus) and Their Infants", Drew Rendall, Dorothy L. Cheney, Robert M. Seyfarth; Journal of Comparative Psychology, Vol. 114, No. 1.
Full Text of the Article is available from the APA Public Affairs Office.
Lead author Drew Rendall can be reached at: d.rendall@uleth.ca
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Journal of Comparative Psychology