Tools Used By Primates

Tool used by primate mammals. Animals can be said to possess a level of cognition based upon their use of tools for problem solving, an endeavor previously considered the sole domain of humans.

"Cognition is the ability to relate different unconnected pieces of information in new ways and apply the resulting knowledge in an adaptive manner" (Boysen, 18). Thus, any individual who exhibits understanding of causal relationships and is able to use that understanding as a means of problem solving, must be defined as cognitive, or thinking. It has long been believed that humans alone dominated the intellectual sphere of thought in the animal kingdom, but research has demonstrated that not only do many other animals, from insect to bird, use and create tools in order to accomplish given tasks, but monkeys and apes, in particular, are able to make use of tools in a "human" manner. This leads to a new understanding of what separates humans and our nearest relatives, and how much separation really exists.

It is necessary to define what is meant by "tool-use" in order to examine its existence, and the results, which may be extrapolated by tool-use in animals. A tool is anything not part of the body, which is used to accomplish a given task. This varies from a stick poked by an orangutan into an anthill (in order to obtain ants), to feces flung by a monkey at a predator, to a human shooting a bird with a rifle, to an elephant scratching his flank rubbing up against a tree. Any object, which is taken up or used for the specific purpose of accomplishing a task, is a tool. The presence of need for a tool must also be considered a factor. An ape does not need to store water in containers when water is plentiful, nor will he if there is nothing with which to store the water anyway. One may not discount tools used in captivity, but not in the wild as inconsequential, for they prove that when presented with a potential tool, primates can create an actual tool.

Tool-use by primates shall be discussed in terms of monkeys (primarily capuchin monkeys) and the great apes (who shall be divided furthermore into chimpanzees, orangutans, gorillas, and humans-who shall be assumed to be the basis of comparison for all others).

As compiled by Beck (51-65), monkeys have been known to utilize tools as follows: thrown branches to discourage threatening or pursuing individuals; wiping of wounds with lightly masticated leaves; thrown rocks; sticks used for clubbing, throwing, prodding, prying lids, and to reach objects and rake them in; and rocks for pounding upon tough fruits or nuts. The use of tools by monkeys is done primarily when in captivity, but is not limited to such times. Monkeys will also cooperate with each other in the use of tools, demonstrating a significant level of communication. Howler monkeys will help to wipe the wounds of their comrades and almost all monkeys are willing to play with each other using sticks. Monkeys are more limited in tool use, however, than the great apes (with the exception of gorillas).

Gorillas, who appear to be the most intellectually limited of the great apes, do not use tools in all of the ways that monkeys use them. Because of their simple diet of nettles and leaves, tools are mostly pointless (Discover, 47). They do use sticks as clubs and as dropped weapons; they also use containers, when in captivity, to store water and they will use anything from leaves to rope as a sponge to draw water from an unreachable locale and they then suck the "sponge" dry (Beck, 67-75). Chimpanzees will do all of those and also use sticks to "reach and rake," and can dismantle various objects by prying and levering. Some chimps can even dismantle entire "play" set-ups within their cages at their own initiative. They will lever cage bars further apart so as to stick their heads between the bars and widen their viewpoints. They will fish for termites, dip for ants, pick locks, use sticks to touch things, which they prefer to avoid (dangerous or unpleasant objects/animals or new chimps), use poles for balancing and climbing, clean themselves with leaves, and bait pretty with food. Orangutans have also been known to braid "straws" into ropes upon which to climb and swing and they will remove inefficient aspects of their tools, such as leaves upon a digging stick (Beck, 79-10).

A common zookeeper's anecdote helps to explain ape behavior when faced with tools. Suppose a screwdriver is dropped into the cages of a gorilla, a chimpanzee and an orangutan. The gorilla will promptly ignore the object until he steps on it an hour later. He would then shrink in fear and after a while approach and attempt to eat it. Once he discovered that it was inedible, he would drop it and ignore it thereafter. The chimp, on the other hand, would notice it immediately, grab it, use it as a spear, hammer, probe, mille, toothpick, and just about anything else other than a screwdriver. He would then guard it zealously and become bored with it only after several days. The orangutan would notice it, but ignore it so that the zookeeper would not notice his own error. If the zookeeper did notice, then the orangutan would rush over, grab the tool and relinquish it only when given food. If the keeper didn't notice it, the orangutan would wait until night and then use it as a lockpick to escape (Beck, 69). This sort of story is not empirical proof of anything, but it is a useful means of evaluating the actions and abilities of the animals in general.

Despite the similarities in backgrounds of the primates, it is quite clear that gorillas are the most inefficient tool users, and so they will not hold a significant part in this paper. Chimpanzees and orangutans, however, are capable of feats similar to a young human, or even beyond. Both demonstrate incredible abilities of problem solving. "Studies"¦have suggested that chimpanzees are capable of mental attribution, perspective taking, and empathy, which all require causal understanding" (Boysen, 25).

Both chimps and orangutans will put great thought into accomplishing goals, such as obtaining food. They can use sticks to reach out and grab food or, when faced with the necessity, will eventually think to reach for successively longer sticks with the sticks they have until they finally get the stick they need to rake the food to them. They will also stack objects in order to reach suspended food or they will balance a pole and then climb it (using a foot or hand against a wall for balance) in order to obtain the food. The animals know, after a bit of thought and experimentation, that certain actions will result in given results. This is the understanding of causality.

Most human children do not understand causality until they've had a few years to learn. As an example, "chimpanzees were able to attribute knowledge to an experimenter who witnessed the hiding of food and not to one who did not" while many children do not understand that you can see them when they are not looking at you (Boysen, 25).



The primates also understands that by digging into an anthill or termite burrow that they will get the insects to climb onto whatever stick they are using. In this way, they are able to obtain food. Furthermore, they understand that ants bite and will do so if the primate stays too close to the hill. In order to avoid being bitten, the apes will remain far away, run up to the hill, poke their sticks in to obtain ants, and then run away or climb a tree to eat the ants in safety. This is an excellent example of problem solving. The primate wants food, but doesn't want to get bitten and it manages to accomplish both goals.

Chimpanzees and orangutans fascinate researchers because they "readily demonstrate complex manipulative abilities in the home, laboratory, or zoo environment, where they demonstrate considerable facility with tools and can even manufacture them" (Bard, 103). Despite this, however, people continue to downplay the abilities of these animals. This is the result of speciesism, defined as an attitude "in which the capacities of another species are underestimated on grounds of the presumed superiority of all things human" (McGrew, 216).

Primates continue to astound researchers with their abilities, yet still many argue that such abilities are instinct, rather than thought. There is no basis for the belief that animal tool use is governed solely by instinct. There is, however, significant evidence of animals using tools in order to overcome given problems. According to Carel Van Schaik, "of the four great apes, three-chimps, orangutans, and humans-have now been observed to use tools in the wild. The simplest explanation is that the apes' common ancestor did too" (Discover, 47). The use of these tools would then be a learned skill, which was passed on, but mostly lost among gorillas. The nature of said tool-use would then be no different between species of ape, for it would have been learned from the same source.

When artifacts attributed to early humans are compared to those created by modern primates' use of the stone flakes in order to obtain meat from bones, there is little difference. "Some [artifacts] would be unattributable to species if they lost their museum labels" (McGrew, 230). The actions of these primates mimic that of early humans and draw parallels between the two. It seems that tool-use simply did not develop beyond that point for other primates. From Van Schaik's research, it may be drawn that "the real quantum leap of intelligence did not happen 6 million years ago among the earliest hominids but 16 million years ago among the earliest great apes. It was then"¦that animals first evolved insight-an ability to make connections between concepts, recognize cause and effect, and plan actions" (Discover, 47).

One therefore wonders how "intelligent" humanity's closest relatives really are. A chimpanzee named Kanzi is an example of that of which primates are capable. Kanzi's mother was a failure (despite hard work on her part) at communication by symbols between man and chimp. Her son Kanzi, however, upon entering the study, before having been taught anything, was able to make use of a few symbols. It seems that he learned from association with his mother and the other apes. But Kanzi had other tricks in store for his 'teachers.' He learned how to obtain rock flakes without the knapping, which humans thought to be necessary. Then, when faced with no real alternative, he learned how to knap stones simply by watching people do it. No attempt whatsoever was made to help him position his hand correctly or make use of the proper arm motion. He also learned to understand and act upon human speech without being taught. Merely by association, he learned many words, which the scientists spoke and the men were then forced to speak by spelling words out loud so that he could not understand what they were saying (2Disover).

In the wild, great apes and many monkeys are both willing and able to manufacture and use tools, including: flaked stones, tree branches, sticks, leaves, rocks, and even entire small trees (bent so as to be of use). These primates demonstrate capacity to think and to act, which is at least equal to that of human children (if not superior). In his important work, Man the Tool-Maker, Kenneth Oakly stated, "possession of a great capacity of conceptual thought"¦is now generally regarded by comparative psychologists as distinctive of man. The systematic making of tools"¦required not only for immediate use but for future use, implies a marked capacity for conceptual thought." This definition has become vague and it no longer separates man from his fellow primates. Because of their tendency to use tools, it may now be seen that other primates demonstrate conceptual thought and that this attribute is, therefore, no longer singular to mankind. It is time for mankind to forget much of what he feels he had 'learned,' which, in reality, he merely invented as a function of his own ego and instead turn towards an actual understanding of his animal relatives.

Works Consulted

Beck, Benjamin. Animal Tool Behavior: The Use and Manufacture of Tools by Animals. New York: Garland STPM Press. 1980.

Berthalet, Arlette and Chavaillon, Jean (editors). The Use of Tools by Human and Non-human Primates. Kim Bard. Oxford: Clarendon Press. 1993.

Discover. "Tooling Through the Trees." Carl Zimmer. November, 1995.

Discover. ?. September, 1994.

Journal of Comparative Psychology. "Comprehension of Cause-Effect Relations in a Tool-Using Task by Chimpanzees." Saray Boysen, Luca Limongelli, and Elisabetta Visalberghi. 1995, Vol 109, No. 1.

Journal of Comparative Psychology. "Performance in a Tool-Using Task by Common Chimpanzees, Bonobos, and Orangutan, and Capuchin Monkeys." Dorothy Fragaszy, Sue Savage-Rumbaugh, and Elisabetta Visalberghi. 1995, Vol 109, No. 1.

McGrew, W.C. Chimpanzee Material Culture. Cambridge: Cambridge University Press. 1992.

World Archeology. "The stone-tool technology of capuchin monkeys: possible implications for the evoluion of symbolic communication in hominids." Gregory Westergaard. 1995, Vol 27 (1).

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