An Introduction to Language (by Victoria Fromkin and Robert Rodman, Third Edition, 1974) defines language as "rule-governed arbitrary symbolic communication."
The "rule-governed" and "arbitrary" parts might seem contradictory, but they're not. That language has rules is self-evident whether you are a prescriptivist (someone who believes there are correct and incorrect ways to use language) or a descriptivist (someone who believes that as long as communication is occurring, it's language; so the primary role of the linguist is not to enforce rules but to document them). Being that my master's degree is in historical linguistics, I'm strongly of a descriptivist bent; if I thought there were an inflexible lexicon and set of grammatical rules that never ever changed, I'd kind of be out of a job.
The arbitrary part is less obvious. It has to do with the sound-to-meaning correspondence. Dog in English is inu in Japanese, chien in French, kare in Hausa, and hundur in Icelandic; none of those words are, in fact, especially doggy in nature. Other than a handful of onomatopoeic words like bang, oink, meow, and hiccup, the connection between a word and its meaning is essentially accidental.
Curiously, humans are the only species on Earth that we are certain have true language, by the Fromkin and Rodman definition. There's long been a suspicion that dolphin and whale vocalizations might be language, but as of this writing, that remains conjecture. Recently, there have been some interesting studies of other primates indicating that certain features of language might exist outside of Homo sapiens -- a paper out of the University of Warwick last week suggests that orangutan vocalizations might exhibit recursion, the nesting structure you see in the children's rhyme "This is the House That Jack Built." The researchers found that the sounds orangutans make are grouped into clusters, and those clusters put together in at least two additional tiers of structure, hinting that their vocalizations might have a much richer information-carrying capacity than we'd thought.
Another recent study, this one out of the University of Vienna, found that chimps might use drumming as a means of long-distance communication -- that the spacing of beats when they drum on tree roots varies but is non-random. Like the recursion found in orangutans, the fact that the rhythm of drumming in chimps isn't just random noise opens up the possibility that it might be meaningful. The researchers found that different chimps have different rhythmic styles, and that groups also developed their own unique patterns of drumming -- suggestive that drumming in chimps could be a cultural phenomenon.
How we developed language, and (likely) no other extant species did, is still open to question. There are some interesting genetic pieces to the puzzle; the forkhead box protein 2 (FOX-P2) gene seems to be an important one, as the human variant of FOX-P2 isn't found in any known living species other than ourselves, and mutations in that sequence result in significant problems with learning and utilizing language. (Genetic studies of Neanderthal remains found that Neanderthals had an identical FOX-P2 gene to that of modern humans; obviously we can't be sure that they had language, but it seems likely.)
Actually, it was genetics that got me thinking about this topic today; yet another study, this one out of Rockefeller University and Cold Springs Harbor Laboratory, did a gene insertion on mice, replacing the murine version of the NOVA-1 gene with the human variant. The human NOVA-1 has only a single base pair substitution as compared with that of other mammals, but -- like FOX-P2, damage to this gene is known to impair language learning and production.
And when you replace a mouse embryo's NOVA-1 gene with a human's, the resulting adult mouse is capable of making strikingly more complex vocalizations than your ordinary mouse can do.
"When adult male mice were genetically altered with the human NOVA-1 variant, their squeaks during courtship didn't become higher pitched like the pups," said Robert Darnell, who was lead author on the paper. "Instead, their vocalizations included more complex syllables. They 'talked' differently to the female mice. One can imagine how such changes in vocalization could have a profound impact on evolution.... NOVA-1 encodes a protein that can cut out and rearrange sections of messenger RNA when it binds to neurons. This changes how brain cells synthesize proteins, probably creating molecular diversity in the central nervous system... The 'humanized' mice with the NOVA-1 variant had molecular changes in the RNA splicing seen in brain cells, especially in regions associated with vocal behavior."So we're one step closer to figuring out a uniquely human phenomenon. That communication in the animal world exists on a spectrum of complexity is certain, but by the Fromkin/Rodman definition, we're kind of it for true language, as far as we know. How we gained that ability is still not entirely clear, but its advantages are obvious -- and it may be that mutations in two regulatory genes are what kickstarted a capacity for chatter that in large part is responsible for our dominance of the entire biosphere.
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