Babel's Dawn

Unique Properties of the Human Mind

Cats that look like humans and humans that look like cats are unknown to nature, but commonplaces of speech. How can that be?

The April issue of the Journal of Anatomy is devoted to review articles on the evolution of humans. The result is as handy as an up-to-date textbook. What’s more, all the articles appear to be free. So I suggest readers jump to the journal’s table of contents and start downloading those PDFs. The article most directly concerned with issues on this blog is “A natural history of the human mind: tracing evolutionary changes in brain and cognition” by a team from The George Washington University’s Mind, Brain and Evolution Center (Chet C. Sherwood, Francys Subiaul, and Tadeusz W. Zawidzki). The most useful part of the article for readers of this blog is probably its listings of mental traits that humans share with apes and traits that are unique to humans. Listening, sharing information, and expressing a boundless imagination all rest on the unique traits.

Broca's Area in Chimpanzees?

Broca's area was the first region of the brain identified as specializing in speech production.

Broca's area is the best known region of the brain that is critical to speech production. If damaged it produces difficulties in speaking grammatically-complex sentences. It is one of those areas whose evolution seems critical to the story of speech origins. Now comes a report from the Yerkes National Primate Research Center that chimpanzees have a homologous region of the brain that is active when they communicate. (See: Jared P. Taglialatela et al March 11 Current Biology, abstract here) The authors speculate that "the neurological substrates underlying language production in the human brain may have been present in the common ancestor of humans and chimpanzees."

Brain Changes for Language

I'm getting a little backed up as I go over the Barcelona results and prepare to review a couple of new books. Meanwhile news continues. I have a story on the backburner, but I see that another blogger has done a good job of presenting it, so why don't I just send browsers over to that site? Check out Neurophilosophy's account of brain changes to support language right here.

Mirror Mirror, on the Wall

Shakespeare's mirror was technically primitive, yet somehow he could see deep into the truth.

Poetry is emotion recollected in tranquility sayeth an old literary giant. An article in the latest Current Directions in Psychological Science takes that a step further and says all of language consists of a respit from emotional control. Two Italian neuroscientists, Leonardo Fogassi and Pier Francesco Ferrari, argue in “Mirror Neurons and the Evolution of Embodied Language” (abstract here) that a central difference between animal cries and human speech is that the cries are under the control of the brain’s emotional circuitry while speech is part of the perceptual (sensori-motor) apparatus.

call production is nonhuman primates is correlated with intense emotional states, with the main function being to signal urgent or imminent events. [p. 136]

Cheep-cheep vs Mama

Birdsong has more to tell us about the biology of speech than one might expect, according to an “eBriefing” posted by Alisa G. Woods for the New York Academy of Sciences (the eBriefing is here). It is true that birdsong serves the common communication task of controlling relations rather than directing attention, so we would expect birdsong and speech to have evolved through different selective pressures. But they both depend on social learning. The sounds of song/speech are not the inevitable result of genes and anatomy, so they are not like the sounds crickets make. Crickets need no guidance in how to make their noise, and surely they sounded the same in Caesar’s day. With speech, however, we know for a fact that the speech sounds made by modern Italians do not match those used by Caesar’s Romans, and there has likely been some drift in the songbird sounds as well.

Young songbirds and speakers must both learn, first, to recognize the sounds their parents make and, then, to make the same sounds themselves.

Conference: Women Speak Better

Women articulate better than men says Bart de Boer, assistant professor of artificial intelligence at the University of Groningen (Netherlands). It is well known that men and women have differently organized vocal tracts. The larynx is lower in human vocal tracts than it is in other primates, but in human males the larynx is even lower yet. The difference is thought to account for much of the distinctively male and female voices.

Using a computer model, Dr. de Boer was able to test a variety of models, including ape and possible Neanderthal tracts. Human vocal tracts can do a better job of generating speech sounds than apes (although ape vocal tracts can do surprisingly well), but females articulate better than men. This is of theoretical interest because it suggests that the male larynx did not descend so far to serve purely linguistic needs. It also enabled Dr. de Boer to give his presentation the provocative title of “Why Women Speak Better than Men” (abstract here).

Conference: FOXP2 May Be Older

The FOXP2 gene, the only gene known to be language-related, is usually said to be between 100 and 200 thousand years old; however, that date is based on a technically flawed analysis and the correct date for the gene's origin may be 1.8 to 1.9 million years ago, according to a report presented today (Nov. 7) in Stellenbosch, South Africa by two representatives from the University of Hawaii's School of Medicine, Karl Diller and Rebecca Cann.  (Abstract here.)

This blog is in no position to consider the technical argument made, but if the date stands up it will push the discussion back to the beginnings of Homo rather than at its end, where many people put it today.

The Human Larynx

One price of loving language is that there are always more books to read than time to do the reading. I’ve only now gotten around to reading Freedomland, a novel by Richard Price that was all the buzz in 1998, I noticed this bit of dialog:

“Jose.” His name was as natural in her mouth as a cough.

It got me thinking about the FOXP2 gene (discussed here) that fine tuned control over the  lower jaw. One of the things we can do with that lower mouth is cough and clear our throat more easily than people without the mutation. It seems a trivial task compared with speaking precisely, but one peculiarity of human anatomy is the way our windpipe (trachea) and esophagus are available to  each other. The system allows us to speak, but at the risk of choking to death, so we have had to evolve special solutions to the risk while waiting for the invention of the Heimlich maneuver.

Chimpanzees, of course, do cough (even lungfish can cough) and I am guessing they even spit out phlegm from time to time. But choking to death on food? Among primates, only we humans seem to be so lucky. The reason for the problem is that the human larynx has moved from its position in the lower part of the mouth where, in animals, it seals off the trachea as food and drink is swallowed.

Time's Cover Story

Time magazine’s cover story this week (Oct. 9, 2006 issue, available here) is a semi-technical report on research into what the human genome explains, or more precisely, what it will explain once we understand its details. The conclusion is, “Within a few short years, we may finally understand precisely when and how [a creature emerged that could ponder its own origins].” What we understand today turns out to be a bit more skimpy.

The article includes a reference to the FOXP2 gene discussed in today’s post and shows what Simon Fisher was talking about when he complained about genes being considered abstractly rather than biologically. The Time piece says:

The human FOXP2 gene … may nevertheless explain the emergence of all aspects of human speech, from a baby’s first words to a Robin Williams monologue.

All aspects of human speech! If you are going to overstate something, you might as well go whole hog.

The Human FOXP2 Gene

The September issue of Cognition, a psychology journal, includes an article (abstract) by Simon Fisher in Oxford that reviews the current understanding of the FOXP2 gene, sometimes called (in a gross mischaracterization) “the language gene.” Fisher was a member of the team that originally reported the gene in a letter published in Nature (available here).

News of a gene linked to language caused an immediate sensation and has inspired extensive research and even more speculation. If you believe that speech evolved from sign language, there is peer-reviewed, published material saying FOXP2 supports your case (e.g., here). If you believe the critical step in language was the rise of a recursive syntax, again there is FOXP2 material for you to cite (see here). Schizophrenia is your field? Check out FOXP2 (e.g., here).

There has, of course, also been much experimental and clinical work exploring this important discovery. (For an example of recent clinical work confirming FOXP2’s impact, see here).