I. Language & Communication
Language is a uniquely human trait and even among human traits it occupies a special place. Language uses symbols and rules to communicate information. In humans those symbols are seemingly arbitrary patterns of sound. As we will discuss, animals have not been demonstrated to possess language, despite attitudes and claims to the contrary in the popular press. Animals can and do communicate with each other, but the flexibility and complexity of their powers of communication fall short of language.

An amazing thing about human language is that among other uniquely human skills, is its universality. For instance, reading ability is not language, but an acquired skill of processing visual and/or spatial information and recognizing that specific visual and/or spatial patterns correspond to a word. Not everyone can read, either because of a reading disability or a lack of education, but they can speak a language. Some people are very good at mathematics but others never seem to be able to master it. Some people may have exceptional musical talent but others have no musical ability. Some people have excellent strategic thinking ability and can master a game like chess while others cannot. But practically everyone can master at least one language and often people master more than one.

A. Aspects of Language
Language is structured and productive. By structured we mean that there are basic elements which are combined to produce more complex elements. By productive we mean that a limited number of complex elements can be combined according to rules for the production of almost limitless coherent meaningful utterances. But those utterances would still be meaningless without comprehension by the receiver of the message. Therefore, not only language requires not only the capacity to accurately generate and broadcast a message that uses arbitrary symbols to represent information but also the capacity to quickly and accurately detect and interpret those symbols sent by others as well.

B. Levels of Language: Units & Processes
For instance, the simplest unit of spoken language is the phoneme, the basic speech sounds that a human mouth can make. The human vocal speech apparatus can produce a little over 100 phonemes. No language uses all possible phonemes. For example English has about 40, Spanish has 24 and Japanese has 21. Morphemes are made up of phonemes and are the smallest unit that carries a meaning. This includes simple words but also prefixes and suffixes which affect meaning. For example, the prefix "un-" reverses the meaning of "done" when they are combined to form "undone." The suffix "-or" changes the meaning of "act" when they are combined to form "actor." These morphemes form words which we combine to make phrases and sentences. The typical adult English vocabulary contains about 40,000 words from which to make essentially a limitless number of meaningful sentences. However, people in some jobs and careers may acquire vocabularies of up to 100,000 if we take into account their career- or job-specific terminology that the average person may not understand. For instance, as a neuroscientist I am familiar with words like "polysialylation" and "R-2-amino-5-phosphonopentanoate" while a plumber will be familiar with terms like "sump" and "hose bibb" while a chef may be at ease talking about a "roux" and "caramelization."

C. Effects of Context
Context for our purposes refers to the circumstances and conditions of a message that are important for the production or comprehension of that message. Context can clarify a seemingly ambiguous message and as such adds another layer of complexity beyond phonemes, morphemes and sentences. For example, consider this vague bit of text: "The procedure is actually quite simple. First, you arrange things into different groups. Of course, one pile may be sufficient depending on how much there is to do. If you have to go somewhere else due to a lack of facilities, that is the next step; otherwise, you are pretty well set. It is important not to overdo things. That is, it is better to do too few things at once than too many. In the short run this may not seem important but complications can easily arise. A mistake can be expensive as well. At first the whole procedure will seem complicated. Soon, however, it will become just another facet of life." What does that rambling bunch of phonemes, morphemes and sentences mean, exactly? Is it someone trying to describe how to make homemade candles? How to make a batch of illegal street drugs using common household chemicals? Or are they simply trying to talk a freshman through how to do laundry? See? Context can change a lot of meanings.

II. Development of Language
Language development in children follows a pattern that strongly suggests that humans have a biologically-based predisposition to acquire language. However, they need the presence of other people to acquire and fully develop their capacity. Therefore, their experience and environment determines how their language skills develop, though they do not require formal educational instruction to do so.

A. What is Acquired?
From birth to one year of age, infants babble. However this babbling is thought to be purposeful, that the infant is generating every possible phoneme. However during latter part of this period the infant starts to focus on the phonemes of their native language. From about one year to two years, speech begins; initially, with single words and progressing to simple 2-3 word sentences. By a year and a half, the child typically has a vocabulary of about 15 words. In part because of the limitations of vocabulary the child will overextend concepts. For instance, a child may refer to dogs, cats, cows and horses (indeed, any and all, four-legged furry animals) as "puppies." From two to three years of age their sentences develop and become more grammatical and by four years old their sentences often sound like those of an adult, despite no formal academic instruction. By six years of age the typical child’s vocabulary has reached about 15,000 words. From age 18 months with 15 words to 6 years with 15,000 words is a rate of almost 10 new words each and every single day; all without the child ever taking a formal language class.

B. Learning Processes
There is some contribution of processes such as imitation and conditioning to the acquisition of language. However, it is generally accepted that these processes alone cannot account for the scope and rate of language acquisition in children. In fact, it was the biologically- and cognitively-based arguments of linguist Noam Chomsky against the behaviorist positions championed by B.F. Skinner in the field of language acquisition that are widely credited for countering the influence of behaviorism and beginning the rise of cognitive approaches in psychology. For example, clearly children can and do sometimes simply imitate the utterances of others. But if imitation was the sole or chief way that children acquire language children would never say things like, "all gone milk," but they do. It is exceptionally unlikely that a child would ever hear an adult utter such a sentence in order to imitate it. Similarly if conditioning was the sole or chief way that children acquire language then it would be a relatively simple matter to quickly and efficiently correct them when they make errors. We'd likely not have to hear for days or weeks or months on end children use double negatives like "Nobody don't like me" or "I made the wrong mistake."

Dan Slobin has suggested a kind of a middle ground between a purely hardwired biologically-based inborn language acquisition device that Chomsky proposed and a purely behavioristic approach rooted only in learning and environmental experience. Slobin proposes learning a language requires learning certain language-specific modes of thinking. Based on his cross-linguistic study of language development, Slobin developed some generalizations about how children develop their grammar, which he called "operating principles." These include:

1. The phonological forms of words can be systematically modified. This principle states the generalization that children often engage in a great deal of playful modification of the pronunciation of words. Children will add syllables to words (reduplication) and will add diminutive ending (dog, dad, blanket to doggie, daddy, blankie). The principle helps children pay attention to the ends of words.
2. Underlying semantic relations should be marked overtly and clearly. In English, word order expresses the functional (semantic) relations, and one can see that children are aware of the meaningful significance of word order.
3. Avoid exceptions. There are hundreds of examples of children overregularizing grammatical morphemes, such as the past tense "–ed".
4. Pay attention to the ends of words. Evidence from a number of languages suggests that grammatical markers that are suffixes are learned before those that are prefixes or prepositions
5. Pay attention to the order of words and morphemes. As evidence, Slobin points to the tendency worldwide for children to adopt one of the word orders they hear in the language around them, although they are capable (and occasionally do) create their own word order. Word order helps children encode the functional relations discussed earlier.
6. Avoid interruptions or rearrangements of linguistic units. Slobin hypothesized that interrupted or rearranged units would be more difficult since they would demand a greater burden on the child's short term memory. As evidence for the principle, he mentions that early complex and coordinated sentences are expanded at the end of the sentence and points to the child's early yes/no question, which are produced with rising intonation alone rather than a different word order.

C. Innate Factors
The evidence for innate inborn processes at work in the development of language includes a variety of factors. One piece of evidence is the richness of knowledge required and the speed at which it is acquired. Remember that between 18 months and 6 years of age children acquire new words at the average rate of about 10 a day, each and every day without any formal instruction, simply doing whatever it is that kids naturally do. Furthermore, children from around the world, in all cultures and languages (even deaf children using sign language!) go through the same stages of language acquisition at the same time. This is suggestive evidence of an innate preparedness for language.

Another bit of evidence is the existence of critical periods for the learning of language, both in the production and comprehension. The first year of life is critical for acquiring the phonemes of a language (or languages). As we have said before, during the first year the babbling infant goes from being capable of producing all possible phonemes to focusing on the phonemes of their native language. Therefore if a second or third (or more) language is to be learned, the earlier the additional language(s) are begun the better. This also applies to sign language. The younger the brain is, the more adaptable it is and the better the results will be obtained when learning language. For example, two individuals speak English from birth. One is ten years old and also learned French from birth and the other is twenty years old and also learned French from the age ten. Both then have 10 years experience from French. The ten year old will be better able to speak understand and translate French than the 20 year old (also with 10 years experience with French). The difference will be especially evident in a challenging environment such as trying to participate (speaking and listening) in a French conversation in a noisy and distracting environment such as in a crowded restaurant at lunch. The ten year old will exhibit greater proficiency in the French language.

Evidence of the lack of language in non-human animals can also be seen as indirect evidence for a biological predisposition in humans for language. Granted animals can and do communicate. For instance, animal courtship rituals, territory claiming, alarm calls are examples of communication in animals. However, the messages communicated involve very limited acts, images or sound limited to very specific meanings. The flexibility and symbolic nature of human language is not approached to any degree. There have been attempts to teach primates such as chimpanzees and gorillas human sign language or other novel symbol based languages. While they do seem to be able to communicate some ideas they combine the symbols very, very differently than a human would. For instance, the gorilla Koko can and does appropriate form the sign for banana when she wants to eat a banana, but she may repeat it over and over. Also she apparently uses unusual signs to stand for common words, Like the sign for "nipple" to stand for people, the sign for "lips" to stand for women and the sign for "foot" to stand for men, according to her handler and champion, Dr. Penny Patterson. Only one primate the pygmy chimpanzee (also called Bonobos), Kanzi has shown the ability to properly alternate the signs for "Kanzi bite" and "bite Kanzi" to appropriately distinguish when she bit a playmate or was bitten by her playmate. So, the answer to the question, "Do animals have language" is a "no", but with a "maybe" in the case of Kanzi. As Chomsky said, "If an animal had a capacity as biologically advantageous as language but somehow hadn't used it until now, it would be an evolutionary miracle, like finding an island of humans who could be taught to fly."