Rational Animals

For thousands of years, human beings have assumed a far superior intellect to other creatures on this planet; it is certainly obvious that no other animal has developed such complex civilizations and technology. Yet many animals are capable of developing tools and weapons, solving problems, and possibly even being self-aware. These findings challenge the long-standing philosophical tradition that places a solid division between these animals and human beings.

The most practical use of intelligence is the ability to solve problems that come up in a daily environment, and mental ability can be measured by an animal’s capacity to solve such problems. Several experiments have shown that through trial and error, animals can eventually figure out a solution to a problem. This “guess and check” method may not be the only way, however. One study confronted adult ravens with a piece of meat that was hanging on a string but unreachable due to a wire screen. The ravens figured out how to pull the string up by trapping it against their perch with their foot and pulling. Remarkably, this was done on the ravens’ first try, without the benefit of trial and error [1].

Capuchin monkeys use stones to crack nuts for food. Courtesy of www.nsf.gov

Similarly, another indicator of intelligence is a creature’s ability to manipulate its environment using tools. One group of wild capuchin monkeys has apparently developed this ability, as its members utilize stones to crack open nuts for food [2]. The fact that this has only been found in one group of capuchins implies that it is not an instinctive behavior, but one which was discovered at some point in the past and has continued until today. Young capuchins, and capuchins who are less proficient at this task, will watch the more experienced and able monkeys and learn techniques from them [2]. This illustrates the ability to evaluate other animals’ expertise as well as an understanding of ways in which objects can be used to help an individual accomplish its objectives.

An animal may also demonstrate some level of intelligence by evaluating what it knows and deciding how confident it is in its knowledge, a phenomenon known as metacognition. This was demonstrated by rats in an experiment. The rats were trained to tell the difference between short-sound signals and long-sound signals, but there was a large variance in the length of the signals. Upon hearing a signal, the rats were then offered the chance to guess if it had been long or short, winning a large reward if they were correct. If they chose not to participate, then they received a small reward; if they guessed wrong, they got nothing. The rats were less likely to participate when they heard a signal that was closer to the boundary between long and short [3]. This indicates that the rats were able to judge how sure they were, and in the case that they were less confident opted for the guaranteed reward rather than risk a penalty for guessing incorrectly.

The use of language—organized sound patterns—to communicate with other entities that an animal recognizes as fellow individuals is another quality which some animals possess which may indicate cognitive ability. Dolphins, for example, are able to not only understand words made up of visual symbols but also realize that moving these symbols around changes the meaning of what is being expressed [4]. This is remarkable because although some possible forms of animal language, such as whale song, may be instinctive, human language patterns have to be learned. That is, unless there is some commonality among all forms of human and animal language. If that is the case, however, proclaiming the uniqueness of human communication seems unsupported.

Self-awareness, a more philosophical definition of intelligence that requires an individual to have a sense of itself as a living being, is a more difficult trait to test for in animals. The primary way that scientists investigate for the presence of this characteristic is the mirror test; for this test, an animal is painted or marked in some way and then placed in a mirrored tank or cage so that when it awakes it sees itself. If the animal realizes that the creature in the mirror is itself, it will notice the marking and try to groom itself. This has been observed in chimpanzees and in dolphins [5]. This discovery of self-awareness could indicate that some animals truly are individual, thinking beings.

Scrub Jays exhibit memory and have a sense of time. Courtesy of www.nps.gov

More evidence for the existence of self-awareness comes from experiments showing the ability of an animal to use memories and a sense of time to help determine its actions. When released into a laboratory tray five days after they had hidden peanuts and worms there, scrub jays (a species of bird found in Florida, the Western U.S., and parts of Mexico) retrieved the peanuts first—although they tend to prefer worms, they knew that the worms had decayed in the intervening time [6]. Rats were put through a similar experiment: they were placed in a maze where one location had a store of chocolate. An hour later, they were placed in the same maze, but the chocolate had been removed such that the rats, obviously, did not find any. Twenty-four hours after that, they were placed in the maze with the chocolate having been replaced in the same location as before. After a few trials, the rats figured out the pattern: if put in the maze one hour after finding chocolate, they would not look for it again; if it had been 25 hours, they would [6]. These experiments demonstrate that the subjects were able to distinguish between events that they had experienced in the past, which may indicate an individual consciousness.

It could be said that “intelligence” is the sum of these different mental abilities, and by that definition humans would for the time being be safe in our superiority assumption. In time, however, it is possible that cognitive experiments will chip further and further away at our lead. In any case, people must now face the humbling possibility that we are not categorically different mentally from some animals. Although this does not in fact imply much more moral worth to vegetarianism (people do not usually eat ravens, monkeys, or dolphins, and most of the animals mentioned in this article eat meat themselves), it does indicate that some species deserve to be considered capable of thought. No longer should it be sufficient to define human beings as “rational animals.”

References:

1. Heinrich, Bernd, and Thomas Bugnyar. “Just How Smart Are Ravens?” Scientific American 296:4 (2007): 64-71.

2. Ottoni, Eduardo B., Briseida Dogo de Resende, and Patricia Izar. “Watching the Best Nutcrackers: What Capuchin Monkeys (Cebus Apella) Know about Others’ Tool-using Skills.” Animal Cognition 8:4 (2005): 215-19.

3. Foote, Allison L., and Jonathon D. Crystal. “Metacognition in the Rat.” Current Biology. 17:6 (2007): 551-5.

4. Marino, Lori. “Quick Guide: Dolphin Cognition.” Current Biology. 14:21 (2004).

5. Reiss, Diana, and Lori Marino. “Mirror Self-Recognition in the Bottlenose Dolphin: A Case of Cognitive Convergence.” Proceedings of the National Academy of Sciences of the United States of America. 98:10 (2001): 5937-42.

6. Roberts, William A. “Animal Memory: Episodic-like Memory in Rats.” Current Biology. 16:15 (2006).