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Neuroscience
New Ideas About the Origin of Language
Did Language Develop Because Trade Developed?
Posted May 1, 2010
There's some new research coming out of the University of Rochester that sheds a bit of light on the origin of language in humans. What these researchers were looking into was if there's one certain area of the brain that gives humans advanced language capabilities over other animals. To this end, they designed a great experiment (which was published in the latest edition of the journal Proceedings of the National Academy of Sciences) to determine if different brain regions were used to decipher sentences with different types of grammar.
Languages like English use word order to establish meaning. "John hugs Susan" means John is subject doing the hugging, while Susan is the one feeling the squeeze. But other languages, like say Spanish, rely on inflection-and suffixes tacked onto the ends of words-to convey subject-object relationship (while word order remains interchangeable).
Sign language, though, can do both. So the researchers put native signers inside an MRI machine and showed them video of other native signers signing 24 sentences twice. One time they would sign using the sentence with the word-order arrangement, the next time would use inflection for emphasis. What the researchers found is that there are two separate parts of the brain used to process these two types of different sentences.
A sentence that draws its meaning from word order draws on the parts of the prefrontal cortex that we use to put information into sequences, while the inflection type lights up the temporal lobe which specializes in dividing language into separate parts.
This suggests that one of the crucial distinctions between human and animals lies not in the architecture of the brain, rather in the ways we establish connections between locations within that architecture.
Richard Granger, head of the Brain Engineering department at Dartmouth University, has come to similar conclusions. Granger has spent much of his career looking for the parts of the human brain are actually different from other animal's brains. "The first thing you need to know is you can count the neurological differences between humans and animals on the fingers of both hands," he told me not too long ago. "Mostly they're tiny, inconsequential blips. None account for things like language, for any skill we would put under the Cartesian heading of ‘human specialness.'"
What accounts for those skills, according to Granger, is brain size. If brains are computers than both humans and animals have the same hardware and the same software, ours just comes in a bigger box. Because of that bigger box, our neurons have more space to make more connections with other neurons. In the wiring diagram of the brain, we have more wires. And this bigger box and these few more wires are the source of our superpowers.
This is essentially the argument Granger, alongside UC Irvine psychiatrist Gary Lynch, made in their recent book Big Brain. It's also what the University of Rochester experiment points towards, but it raises a very interesting question.
If, as these ideas seem to claim, the development of language actually required the recruitment and wiring together of a bunch of preexisting computational structures within the brain, this begs the question of causation. Meaning all mammals have these same brain structures so why did this ability develop in humans and not in other animals?
According to Richard Leakey, Homo sapiens did not posses the necessary anatomy to produce language until about 300,000 to 400,000 years ago. Meanwhile, Steven Pinker has argued that since all modern humans have identical language abilities along with a universal grammar, it makes sense that language appeared concurrently with the first appearance of modern humans about 200,000 years ago. Furthermore, there was a more than a tripling of brain size during the period between the first appearance the genus Homo (in the form of Homo habilis) about two million years ago until Homo sapiens appeared, suggesting that the brain developed in that period partly in order to accommodate the new language centers.
There is a totally different theory which looks at the spread of tool use--a spread that could only have happened if language existed for various tribes to tell others about how to make and use these tools. Conscious tool making (as opposed to using whatever rock is at hand) didn't begin until about 200,000 years ago, but it wasn't until about 35,000 years ago that tool making became a really dynamic process, suggesting that real language might not have developed until 35,000 years ago.
But there's something in the University of Rochester research that makes this last part especially interesting. Matt Ridley has a new book coming out called The Rational Optimist. It's a fantastic read essentially arguing that specialization and the trade that emerged from specialization was the essential driver of human cultural evolution. It's a great book and one I'm not going to destroy by summarizing here, but I do want to mention that there may be a direct link between Ridley's argument and these new ideas about language.
Ridley argues that one of the main drivers of cultural evolution is the exchange of ideas that comes from trade (among many other examples, he points out that when governments get rigid then economic monopolies develop-with everything being done for the good of the king-and this has a stunning tendency to destroy civilizations). But trade requires communication between groups of people who speak different types of languages. And since communication requires having a brain that is flexible enough to understand different forms of sentence structure, it can be argued that it was trade between different groups of early humans that forced the brain to start recruiting other structures to try to understand the bizarre tongues being spoken by other speakers.
If this idea is correct then the tool use argument comes a lot closer to the truth about the development of language than Leakey or Pinker's ideas, which also mean that language is a much more recent development than many believe.
