One of the biggest controversies in the field of Linguistics is whether or not animals can be taught a language. Birds, bees, dogs, apes, parrots, even humans have a communication system; however, “human language has a number of characteristics that set it apart from other communication systems” (Wilson 568). There have been many experiments conducted on a variety of different animals, but the most common animal tested is the chimpanzee. “They share close to 99% of their genetic material with human beings” (Wilson 578). Since humans are so similar to chimps, many scientists wonder if they can teach them to learn a language that is not natural to them. These experiments resulted in both hope and disappointment. Although some scientists believe they have successfully taught an ape human language, other scientists disagree with their claim (Wilson 578). Understanding what language is key in deciding if apes can be taught a language. Is language a form of communication? Language is the last boundary standing between man and beast (Gardin). According to Charles Hockett, human language has nine properties: mode of communication, semanticity function, pragmatic function, interchangeability, cultural transmission, displacement, arbitrariness, discreteness, productivity, and recursion (Wilson 540). Animal communication, however, only contains cultural transmission and arbitrariness. “No animal communication system appears to display displacement, discreteness, productivity, or recursion” (Wilson 571). In order for any language to be a language a person must be able to make complex sentences, carry a conversation, and converse about new ideas, the future, or the past (Wilson 572). One of the most important aspects of language is syntax. Kako conducted a study of the syntactic elements of comprehension in three separate animal experiments, where he formed his conclusion about syntax having three forms. “The first form is a set of rules by which units can be organized into larger units. The second form of syntax involves all the properties found in human language. The third form is a set of properties that make up the core of syntax” (Hoffmaster). The core features of syntax are: discreteness, discrete combinatorics, category-based rules, and argument structure. For example, Irene Pepperberg, an animal psychologist, bought a parrot and named him Alex. She was determined for Alex to use human language to communicate. Alex was trained using the model rival technique, where another person is brought in to demonstrate proper learning to Alex when he chooses not to cooperate (Wilson 583). Pepperberg did an experiment where Alex was trained to identify four different shapes, five different colors, and three different materials. Alex responded to the following questions, “what is the same between two objects?” and “what is different between two objects?” (Wilson 584.) “Pepperberg claimed that her evidence supports the idea that Alex had well-defined mental categories and conceptual representations” (Wilson 584). Therefore, Kako believes that all animals show discrete combinatorics and category-based rules (Hoffmaster) . However, Kako delays judgment on argument structure since Alex only knew a few action words, and gave inconsistent responses when tested with requests containing too many words of one type (Hoffmaster). “There is no evidence that any of the animals show knowledge of closed-class items. For the sake of simplicity in training, these kinds of words are usually left out, or not required of the animal”(Hoffmaster). It is much simpler for Alex to learn to put 'want' before saying the item he desires, than to say 'a' or 'an' before an item. Alex was not taught how to pluralize words with an 's' because Pepperberg did not want to cue him as to the quantity in questioning (Hoffmaster). “How do we know that Alex wasn’t just a very sophisticated mimic, learning what sound to make to correspond to a given