By Danielle Sloan
What makes human cognition unique from that of other animals? This question is far from new and has an extensive history here at Vassar, where Margaret Floy Washburn spent her career searching for possible answers. In her 1908 book, The Animal Mind, she expressed her belief that gaining knowledge on animal cognition is highly similar to doing so on our own, both being derived by the inference of observed behavior. She believed that our actions vary from the actions of animals by degree and not by kind.
Recently, Marc Hauser, professor of psychology, biological anthropology, and organismic and evolutionary biology in Harvard’s Faculty of Arts and Sciences, has theorized that there may indeed be specific differences in mental capacity between humans and non-humans (Hauser, 2005). Hauser has conducted research in various fields of cognitive science including animal behavior and communication, the evolution of language, domain-specific systems of knowledge, and morality. He says this so-called “humaniqueness” is a set of evolved mechanisms that differentiate human and animal thought. These mechanisms consist of key differences which make humans capable of creating imaginative solutions to new problems. The four unique elements of human thought are the ability to combine and recombine various types of information and knowledge to gain new understanding; to apply the same solution to one problem to a different situation; to create and understand symbolic representations of computation and sensory data; and to separate modes of thought from raw sensory and perceptual data.
According to Hauser, these key abilities have created new paths of evolution that other animals have not utilized, creating the foundation upon which cultural evolution has been constructed. He believes that animals have “laser beam” intelligence, in which there are specific solutions for specific problems. In reference to tool-use, a specific tool has a specific function. In comparison, humans have “floodlight” intelligence, which allows us to apply a certain solution to multiple problems. Other animals are capable of this kind of intelligence, but in highly limited ways when compared with humans. Hauser says the cognitive gap between humans and other “smart species” such as chimps, elephants, and dolphins is “greater than that between those animals and worms”.
In the past it was thought that the one of the main cognitive abilities of humans that other animals lacked was the use of tools. However, many animals utilize simple tools. Still, no other animals create multi-functioning tools by combining materials. One study involving the selection of effective stone tools by wild capuchin monkeys shows that these monkeys, when faced with stones differing in friability and weight, choose, transport, and use the most effective stone to crack nuts (Visalberghi, et al., 2009). Eight capuchins that routinely use tools to crack open palm nuts were tested in an area frequently visited, from which all stone hammers were removed. In each trial, there were one functional stone and one or two nonfunctional stone(s). Testing occurred opportunistically, and a trial started when the subject was provided with a nut and subjects received ten trials in each condition. Even when visual cues were unavailable, such as with artificial stones, the monkeys were still able to distinguish the functional one from the others by moving, lifting, and tapping them. Thus, the capuchin monkeys search for the weight, the critical functional feature, even when other cues like size are identical or contradict the critical feature. They then resort to the aforementioned techniques, implying an understanding that not all tools which look appropriate necessarily are so. Thus, these capuchins did not simply learn through trial-and-error to identify stones of certain mineral composition or size, but may understand that critical feature of the stone was weight, and evaluated their choices accordingly. They therefore use more than past experience when examining objects for use, taking in to consideration the task at hand. Thus, the gap between human and other primate cognition in reference to tool-use appears, like Washburn suggested, to vary by degree rather than by a specific type of ability or lack thereof.
Another study explores the use and modification of branches for fly switching by Asian elephants (Hart, et al., 2001). Elephants are known for having the most cerebral cortex available for cognitive processing of all primates. The elephants were given branches that were too long or bushy to be effectively used as switches. They modified the branches in different ways, the most common of which involved holding the main stem with the front foot and pulling off a side branch. Thus, non-humans are capable of both picking the “right” tool, as the capuchins did, for the job and creating the right tool for the job through modification, like the elephants. There remains a clear difference between modifying a tree branch to creating highly efficient tools. Whether this difference is based on Hauser’s four critical elements of humaniqueness is unknown, and at this time the extent to which these elements may influence the cognitive gap between humans and non-humans cannot be measured.
Balter, M. (2008). AAAS annual meeting: How human intelligence evolved—is it science or ‘paleofantasy’? Science, 319(5866), 1028.
Hart, B. L., Hart, L. A., McCoy, M., & Sarath, C. R. (2001). Cognitive behaviour in Asian elephants: Use and modification of branches for fly switching. Animal Behaviour, 62(5), 839-847.
Harvard University (2008, February 22). What Is The Cognitive Rift Between Humans And Other Animals?. ScienceDaily. Retrieved February 28, 2009, from http://www.sciencedaily.com/releases/2008/02/080217102137.htm
Hauser, M.D. (2005). Our chimpanzee mind. Nature. 437, 60-63).
Visalberghi, E., Addessi, E., Truppa, V., Spagnoletti, N., Ottoni, E., Izar, P., et al. (2009). Selection of effective stone tools by wild bearded capuchin monkeys. Current Biology, 19(3), 213-217.
Woodworth, R. S. (1949). Margaret Floy Washburn. National Academy of Sciences biographical memoirs. 25, 273-295.