The Language of Children and Apes

Learning a language and how to use it is a very complex task, one that children seem to be born to do.  They are able to become fairly competent in their respective native languages by the age of four.  How do they do this, and is this trait found in other species?  The answer to these questions can not only give us incite on child development but it can also help to shed light on the evolution of language. 

Most linguists agree that children are able to learn language because they are born into an environment that encourages it and with an innate mechanism that predisposes them to it.  Most children are able to acquire language by the time they are four.  When they reach six months they are already capable of distinguishing between sounds differences that are present in their native language.  They prime their vocal chords and speech apparatus by cooing and babbling and by eight months their babbles start to simulate real words.  By the time they are ten to twelve months of age they start to say their first words, are combining words from 18 to 42 months of age, and display an understanding of word order and grammar, even if it is presented in overgeneralizations.  It has also been seen in deaf children who try to communicate through sign language to one another that if there is no set grammatical pattern present, they will create one themselves.

While some of these steps may seem trivial they are very important to the child’s development in language.  It is also important that the children learn in a specific time frame, within the critical period.  It has been seen that children who do not learn to speak and rules of grammar before the age of ten have I much harder time learning the language and are less likely to master it at the same level as other children their age who learned earlier.  One example of this can be seen in feral children and more specifically in Genie.  She was discovered at the age of thirteen, in her home locked in a room tied to a potty chair. She had never been socialized and did not even know how to walk.  Researchers tried to help her learn but even after years of work she was never able to reach the same level of competence as other people her age were normally at.

Humans seem to be built to talk.  We are provided with the larynx and the pharynx in the throat, the proper anatomical structures, and specialized areas in the brain that allow us to speak.  In contrast, when looking at other animals, none of them seem to have developed the same ability to communicate through language, although some have come close.  Many scientists have worked with some of our closest relatives, chimpanzees and bonobos to try and understand their ability for language.  One famous case of this was that of Kanzi the bonobo and his trainer Sue Savage-Rumbaugh.  She taught him how to communicate by using words through a lexigram geometric symbol system.  Kanzi started to learn how to use the lexigram symbols when he was little as Sue was attempting to teach his mother through an operant conditioning system.  She realized that Kanzi was learning the symbols by observing her work with his mother without needing to be rewarded.  Sue decided to switch her tactics and to teach Kanzi through immersing him in language.  Kanzi was able to learn over 200 lexigram symbols and was able to combine the symbols with gestures to communicate more complex messages.  While Kanzi was able to learn a large vocabulary and to understand simple sentences even with multiple subjects he was never able to learn grammar.

By looking at the process that children go through to learn language and seeing the difference between their ability to learn language and that of the apes we can see that the mechanisms for speech, both the metal capacity and the physical attributes, evolved in humans at some point after we split from our common ancestor so many years ago.  We can get a better understanding of how are brains have evolved to produce the ability to speak and why other animals can’t.  We can see that our brains most likely evolved to include grammar as an innate characteristic after we were able to have a vocabulary and use signs to try and communicate what we want or how we feel. 

Sources and other readings:
Speaking Bonobo
Symbolic Cross-Modal Transfer
Salient Speech Sound Differences
Language Comprehension in Ape and Child
Gray, P. (2010). Psychology (6th ed., pp. 397-432). New York: Worth Publishers.
Some videos to check out:

FOXP2

Language is one of of the major factors that make us distinctively different from animals. There is not much evidence on the evolution of our complex language, however in relatively recent scientific history strides have been made. In 2001 the gene FOXP2 was identified by geneticist Anthony Monaco’s group at Oxford University, in collaboration with cognitive neuroscientist Faraneh Vargha-Khadem and colleagues at the Institute of Child Health in London (Balter). This is the first of many genes that gave humans the ability of speech. The FOXP2 gene appears 200,000 years ago, at the same time that modern humans emerged. Further solidifing that this gene and changes to this gene have had direct influence on the development of language for humans. This implies that the FOXP2 helped to make human culture possible. The FOXP2 is not the only gene that is involved with human language, but it is the first one to be discovered. Scientist Wolfgang Enard expresses that there could be from 10 to 10,000 other genes involved with human speech and language(BBC). Presently mutations of the FOXP2 gene cause speech and language disabilities. This is how the gene was discovered by analyzing the KE family who portray many of these speech and language disabilities. The actual identity of this family is not known but they have been used for these scientific purposes. Scientists later on found the gene encodes a protein with 715 amino acids. Our common ancestor mice have only 3 changes in the amino acid sequence. There are also only two changes in the sequence between chimpanzees and humans. Consequently the two changes in the sequence that occurred between chimpanzees and humans are much more significant than the change from mice to chimp. Since mice and chimp have relatively similar speech capabilities.

The diagram above illustrates the differences in the sequencing of the amino acids.

The discovery of FOXP2 was exciting and is continously debated on the overall importance of the gene. There have been claims that it is the gene of language or the gene of grammar, both of which are fantastical claims. The evolution of language relies on much more than the mutation of one gene, but that does not make the discovery any less important. It gives scientists a starting point to explore more possiblities and create new hypotheses on the evolution of language. 

Youtube Clip


Sources
'Speech Gene' Tied to Modern Humans

First language gene discovered

FOXP2 and the Evolution of Language