Evolutionary tidbits

To reiterate my understanding of the biological roots of our humanity, I see human empathy as something special and it laid the foundation for symbolization and that enables us to think and talk about everything and nothing and to create it if it is not already there in reality.  Through our empathy we humans are keenly aware of another’s mind, that they have subjective considerations, and how we can interact with each other mindfully.  Symbols carry this social effort forward with scope and power.

This empathic capability is centered in the right hemisphere that processes kinesic communication and maintains Empathy Central in the temporal-parietal junction where knowledge about our relationships contributes to what the academics call ToM (theory of mind).  Anyway, my thought is that this keen sensitivity to others’ minds became integrated with our mirroring capabilities, so that certain actions could be replicated readily upon observing them in another.  This replication of mirrored actions comprises the invariant forms of social communication, and when our mirroring system came to include vocal signals, so that we could hear a conspecific vocalize/verbalize and reproduce that sound and not just the objectively observable motoric behaviors, e.g., lifting a cup to drink.  This is the functional significance of the arcuate fasciculus on both the right and left sides, but especially on the left, where the af enables the repetition of what we just heard another say (see my post of 4/24/2014 on the arcuate fasciculus and mirroring).  Putting together, i.e., integrating, the awareness of another’s mind and the knowledge produced by the mirrored invariant behaviors led to symbolization, at first linguistic and then artistic (ask me to explain that sometime).  Symbols, if you remember, have a deep structure (what resides in our minds subjectively) and a surface structure (what we use to formulate and then communicate those subjective musings), and voila! language, art and the cultural wealth of our kind.

That said, I have been reading Georg Striedter’s Principles of Brain Evolutionand find a couple of evolutionary tidbits that help to carry my speculative imaginings forward (and I find nothing so far contrary to this path). Consider that human eyes are almond shaped and that our irises are surrounded by white sclera while the eyes of other primates are round and the irises surrounded by dark sclera (though the sclera hidden within the eye socket is white.  Striedter interprets this to show that we humans monitor each other’s gaze and so gather more information about the other’s subjective musings; further that our eyes’ structure facilitates this with its almond shape and white sclera shows that such kinesic communication is important evolutionarily. I see this as an example of our keen awareness of the other’s mind.

Think of some examples of this.  Parents follow the gaze of pre-verbal infants and move to facilitate their exploratory activity.  As Michael Tomasello explains, joint action is a critical advance in our social coordination and eye gaze is an important means by which we cooperate, e.g., one holds something still while another performs a more intricate action such as a nurse clamping a wound while another stitches it up, or one hunter with a bow shifting gaze to match another’s and finding prey.  Finally in this regard, in my early career I learned about the challenge of hearing impaired children (and adults) who must watch the other’s hands to communicate about a task that needs to be seen to be learned. Eye gaze is important in juggling these gaze shifts and we humans have extra talent for this.

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joint gaze and joint action

Streidter also discusses the size of our brains in absolute terms, compared to our body mass, relative to other animals, the amount of cortex relative to the medulla, etc.  He points out that large brains are ‘expensive’, e.g., they require high protein diets, they pose problems for live births due to mismatch between skull size and birth canal, and they pose challenges to communication between neural areas.  This last comes about because areas farther away take longer to communicate with each other and that poses a problem for timing.  Much of our neural processing depends upon the simultaneity or temporal match of parallel processes.  Our brains have evolved with some work-arounds such as long, thicker nerve tracts that nerve impulses travel along faster than thin fibers.  Our brains have many more modules and these connect especially to those nearby with some longer fasciculi, e.g., the arcuate fasciculus, the superior longitudinal fasciculus, the claustrum and the corpus callosum, bearing the burden of longer range communication.

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The arcuate fasciculus is part of the superior longitudinal fasciculus. Thicker axons help nerve impulses travel long distances faster.

Now here is another interesting tidbit.  Our corpus callosum is relatively smaller than those in other primate species, i.e., our cerebral hemispheres are less connected than might be expected.  Streidter says the data show that the human brain is more asymmetrical than other species’ brains; this works because our two hemispheres specialize in different functions (yes, even as they perform much of the same functions, one leads, and while brain damage when young can be compensated for, damage when older is less so because the specialization has become at least partially irreversible). Again this difference in connectivity is relative; I have posted here before that studies of our connectomes show females generally have more bilateral connections, i.e., they make more use of their corpus callosum, while males have more connections within each hemisphere than between.

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corpus callosum with part of right hemisphere cut away

Now this bit of information speaks to two issues.  First is that females and males (please remember that I use the terms in a relative manner and appreciate all manner of androgeny in our variations) approach interactions differently.  This is especially noticeable in preschoolers where girls are both more verbal and tuned into relationships and boys are somewhat less verbal and their attunement to others is, shall we say, less robust.  Actually, talking with my 30 something daughter and others, this difference may even be accentuated in mature humans (maturity, again, is a relative term, guys).  In any event, the functioning of the connectome when emphasizing social and linguistic information together would use the corpus callosum more fully and that would correlate with a female sort of pattern.

The second issue here goes back to my thesis that symbolization arose from, first, the integration between the keen empathic apprehension of another’s subjectivity and the invariant behavioral forms that operate in mirroring, and then, second, once the connections are formed, their separation into the surface and deep structures of our symbols.  Human brains are more asymmetrical and this I associate with the differentiation of function between Empathy Central on the right side and linguistic functions on the left, e.g., one side is pragmatic and the other syntactic/semantic.

The last tidbit comes from Streidter’s analysis of the human brain’s enlarged lateral prefrontal cortex (adjacent to motor and premotor areas) primarily on the left side.  This relatively species-specific area serves, Streidter hypothesizes, our abilities to use our hands and words in very flexible, facile, novel and unconventional ways.  We are able to do things hitherto unseen, un-imitated and even unimagined until we do them.  This includes our words as well as our hands.  This highlights one of the great paradoxical strengths of our language. We use words, conventional symbols with socially established meanings, to say many things that have never been said before, i.e., they are novel and unconventional.  We do this day in and day out in small and large ways for mundane and profound topics.  Back in the day Noam Chomsky focused on this generative capacity to demonstrate the theoretical poverty of behaviorism, and we are still learning about this today.

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lateral prefrontal is in lower blue area towards the front

So a long post.  Funny how tidbits expand when I am (you are too hopefully) having fun and learning about our humanity, eh?  Travel on.

Dogs, language and laterality

The linguistic lateralization of our dog buddies spotlights a theoretical mystery

Many news outfits have published stories about a recent study wherein dogs were trained to lie still enough in an fMRI while listening to humans talk to them. The results indicated that our evolutionary partners processed emotional tones on the right side of their brains and specific words on the left, just like humans. The more we study dogs, the more we find how smart they are and how much we have adapted to each other for interaction. Check out the research done by Brian Hare and colleagues.

I first read about the fMRI study in Science News from 10/1/16. It provides a good summary (as they usually do—what a good magazine) and then they ended the article with the idea that because dog-human relations have only developed over the last 30,000 years, too short a time for evolutionary progress to produce such linguistic abilities, “some older underlying neural mechanism for processing meaningful sounds is present in other animals”.

This highlights for me the theoretical mystery on the biological nature not just of language but of symbolization in general (so it includes art as well). As I have said before, understanding symbolization is the holy grail of understanding ourselves biologically, and so let me render a conceptual outline of this mystery. First consider the bond between dogs and humans and that emotional communication through voice (and sight) is processed by the right side of the brain in both of us. We have researched this broadly in humans as intonation or non-verbal vocal communication, and/or kinesics. All of this to my mind is empathic communication and its processing is right sided; we find a cortical area for its integration there at the tempo-parietal junction that I call Empathy Central but the academics call ToM (Theory of Mind). Do dogs have an Empathy Central area? Unknown for now but I am taking bets they do and planning on how to spend my winnings.

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Looking left, currently bored

Next consider this basic feature of lateralization. The right side processes emotional expression and empathic communication just like it processes the current perceptual-motor domains, i.e., the right side processes the specious present. The left side then directs its energies towards information displaced in time and space, initially as a supplement to the specious present by recognizing and recalling information and then increasingly as a virtual domain for information to be composed independently from current objective events. Language, as a symbolic function, is so powerful because it allows us not only to control the input and retrieval of displaced information from memory, not only because it allows the composition of new information from imaginal processes, but also and especially because it allows us to communicate about what isn’t there in front of us but exists only in our minds, apprehensible only to oneself and in symbolic communication.

So when the article ends by asking what the underlying neural mechanism might be, my answer is not about language but about its precursor in the symbolic control of displaced information. Why should that be lateralized to the left? Ah, because timing is important. The right side matures at a faster pace than the left, due primarily to the differential effect of testosterone which slows the left’s maturation more than the right’s (and so males show more distinct patterns of lateralization and more language problems from sometimes too slow a pace on the left side). The right side develops the capabilities to process current information early on while the left side is coming online, so to speak, a bit later, and when it does come on line, it is not totally in sync with the right sided processes for the specious present. Its information is displaced (read out of sync) almost from the beginning of the incipient specious present. Symbolic processes enable finer, more powerful control of such displaced information. So the right side focuses more on the current coin of interaction, i.e., empathic communication, and the left side more on non-current, i.e., displaced, information. Verbally this relies on lexical knowledge, the processing nexus of which is in the left temporal-parietal junction. As we learn more about animals, especially mammals, we will find the precursors of these underlying neural mechanisms in virtually all of them. You can count on it.

A couple more quick notes. It would seem likely that dogs were domesticated and became our close buddies because the genetic streams feeding their evolution ran close to ours—our brains are sympatico in how they process social information.   Human genetic streams, however, also evolved a lower larynx and hyoid bone, greater breath control, and oral-facial musculature thereby enabling articulate speech and even more critically to our humanity, gave rise to longer cortical fasciculi. The arcuate fasciculus is a prime example here. Remember that it carries the surface structure of words on the left side between front and back so that we can repeat what we just heard said. On the right side it might could carry emotional expressions for mimicking. (See my most popular post from 4/24/14, Arcuate fascicles, mirror neurons, and memes). The important feature here, however, is that these long fasciculi facilitate the composition of invariant information forms, e.g., words, discrete emotional forms, and their expression. (And how about art and its special modes of symbolization? Ah, beautiful). The creation of these invariant forms is what enables the separation of deep and surface structures and the subsequent development of syntactic control of their compositional connection. The creation of these invariant forms, both long-standing (lexical items) and in passing (conversation), by the welter of connectome activity in the presence of ambient flux is the remarkable basis for humanity’s intelligence and it has grown from deep roots.

Finally, remember to mark your calendars for Mammalian Heritage Day on November 2 and celebrate those roots. Travel on.

How quick and subtle we are

When I worked as a speech-language therapist many years ago, I led parent workshops to help them understand and promote healthy language development. One facet of this was to present how complicated articulation was and how normal development of articulation varied a great deal. For example, many children say “tow” for “cow” early on in their speech development and self –correct (grow out of it) after some months. I always emphasized how complicated and how skilled a linguistic performance was. A common issue was how chronic ear infections affected development; speech is not easy to understand with the distortions resulting from middle ear congestion and from 6 months to 18 months, the brain is learning to process the auditory stream in a very specific manner in order to understand speech with facility. Likewise, speaking is a highly skilled behavior. A simple sentence, such as, “I want to go outside,” takes less than a second to utter and involves the articulation of around 14 phonemes, each requiring its own positioning of the vocal tract, i.e., lips, tongue, pharynx and larynx. Precise movements made in milliseconds with finely modulated breath control. Even our laughing is different from chimps’ laughing because of our breath control. I found it amazing that some 2 year olds, mostly girls, spoke with great clarity and was not amazed that some 4 year olds, mostly boys, still spoke with an errant phonemic pattern. speechsignal So speech is quick and subtle—I haven’t even broached topics of individual voice and interpersonal effectiveness and persuasion. (Remember Walter Cronkite saying, “And that’s the way it is” and we knew it was). And while we are discussing quick and subtle, let’s consider musical performance. I started reading Music, Language and the Brain by Aniruddh D. Patel, a comprehensive review of research on the topic. I can understand the linguistics and brain well enough but I struggle with some of the musical concepts. Dr. Patel discusses some research made possible by computer technology over the past decade or so into the timing of piano playing. Wow! Looking at one classical piano sonata, a researcher measured the length of all the eighth notes. Theoretically these are all of the same length and when computer reads a score, all the notes are the same, thus the flat, machinelike quality of some computer music. When a good pianist plays the score, however, the notes vary in length, with the average eighth note lasting 652 milliseconds with some lasting only 400 msecs and others going over 800 msecs. This variation is intentional as it results from the human player’s interpretation of the piece—these tiny variations convey the pianist’s musicality and expressiveness.  It is his  or her art. music-notes Other researchers manipulated musical pieces to approximate various degrees between very standardized computer plays to natural human performance. People were able to detect very subtle differences and always preferred the one closer to the natural performance. Yes, computers are fast and helpful; human art is quick and delightful. John Henry wins this one. Travel on.

Language roots 2.0: Streaming

How about a wild thought following up on my last post about the integration hypothesis of language’s origin that posits two ‘layers’ combined to produce human language, the expressive layer exemplified in bird song interacting with the lexical layer exemplified by the silver gibbon’s songs (as well as communication about the world by other mammals). If you understand these two layers as the result of structures changing in the evolutionary stream due to genetic shift, you can conjecture that the hemispheric development so different in birds and mammals reflects these two streams or layers. So how could they merge into one confluent stream?

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         Their embryos develop quite differently. Bird embryos first form as masculine and then some are feminized by hormones. Their songs, mostly by males, function in mating and territorial behaviors. Mammalian embryos form as female and then some are masculinized by hormones. Their calls function in broader social behaviors, expressing emotions, organizing the group, and having some referential properties, e.g., specific calls for specific dangers. On the face of it, beginning with a female brain looks to have more advantages.

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         Mammalian brains show more lateralization. This is in part because testosterone, the masculinizing hormone, slows the development of the left hemisphere (which plays a role into why males seem to develop more slowly and have more language disabilities). Mammalian brains, being at base female, show an essential proclivity for social interaction, especially through the empathic flow of relationships. Then, as the left side comes on line later, so to speak, the right side has developed its capabilities for the current moment and interaction leaving the left to process information displaced in time and space along with its inherent tendency to communicate. And without current referents evident in the ambient, lexical organization becomes very important. So, maybe here are the two streams, two roots of our linguistic abilities, developed and joined as sexual dimorphism effected embryological development. Just supposing.

Biological roots of language

Good news, roots fans, on two fronts, one a report to be discussed in another post of a game chimpanzees play better than humans, and this one, a report from linguists detailing the integration hypothesis, wherein human language evolved from two lines, primates and birds.

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The integration hypothesis posits two features of animal communication which merged to produce the virtually unbounded creativity of human language.  First, the expressive layer derives from birdsong, thus the picture of a mocking bird, one of my favorites and frequenter of our farmyard, which sings a a great variety of songs, often copying other birds while also carrying on its own favorite triplets of various forms. This component is reflected in the melodic features of our language.  The second is the lexical layer, derived from primate communication, and is reflected in the semantic content of our language.  The researchers cite a primate on the endangered species list, the silver gibbon, that is unusual in that it sings, i.e., it has a complex repertoire of sung vocalizations (as opposed to regular calls, such as grunts, clicks, whistles, etc), as it communicates with its conspecifics, kin and familiars.

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The researchers are not sure how these two evolutionary lines would have merged but their effort is to understand the antecedents of human language, which we can only do indirectly.  Certainly more research will be helpful.  For example, is the gibbon’s vocalization lateralized to the left hemisphere?  Birds, we know, have a distinctly different neurological pattern because their brains embryologically start as male and then some are feminized.  Mammalian embryos start out with female brains and then some are masculinized.  And of course, some of the changes result in variegated patterns.  

What makes this research so interesting is that much of the world denies any biological antecedents of human language; they cannot see any intermediate steps leading up to the remarkable generative capability we have.  However these scientists are looking with new eyes and finding much to see (and to hear).  Here is a link:  http://newsoffice.mit.edu/2014/human-language-deep-origins-0611                                                    

Conversation, music, culture and the membrain

No, I spelled it the way I need to spell it, MEMBRAIN.  I may not have been as clear or explicit as I would have liked below (and you may not feel the need to scroll down through all of this) so let me be so now. If it is in the mind, it got there through the brain.  What we are conscious of or our subjective domain or what some  call our interiority is created and maintained by the MEMBRAIN.

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The MEMBRAIN, like all membranes so important to life, keeps the inside in and the outside out and then selectively passes energy and material in and out.  Like Dr. Who’s TARDIS, the MEMBRAIN’S interior is larger than its exterior, a lovely feature perhaps in order to mirror the universe in which we live and learn and imagine.  Counter to what most consider goes into the mind, even though our consciousness seems dominated by perceptual stimuli from outside our body and its brain, our interior is also filled with energy (read information) from within our body and brain.  But again, if it is in our mind, it came through the MEMBRAIN, and if it comes out of our mind through behavior, including especially symbolic expression, it came out through the MEMBRAIN.  Specialized channels for language and art forms, e.g. music, have evolved for the human MEMBRAIN, and when such symbols come to be shared in a socialized reality, we have culture.

That said, let’s look at how conversation and music have changed culturally.  One of the conversational maxims articulated by H. P. Grice back in the 1960s was that conversation must be informative.

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Seems like a basic feature, but some people and some cultures consider the information they hold within as private and personal property, not to be shared lightly, analogous to some people in some cultures disliking having their photograph taken.  It steals their image and is not proper.  So in some cultures or in diplomatic circles or poker games, conversations are not as informative or straightforward as they could be.  One virtue of science, then, is the effort to convey information with transparency so that others may  judge the full truth of the matter.  The point here is that we  control the permeability of the MEMBRAIN.

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I have recently finished reading This is Your Brain on Music by Daniel Levitin, an interesting and informative book (more later on some interesting points and also my quibbles with it).  He points out, as others like Angelique Kidjo have done, that music originally was, and in many cultures and moments still is, participatory.  The performer-audience gig did not arise until a few hundred years ago after many millennia of music making.  (Levitin points out that bone flutes are some of the earliest artifacts of Homo). This frames early music as a sort of simultaneous conversation, everyone listening and playing at once or in a call-response/verse-chorus form.  Just listening without participating was a rather prominent cultural change and the MEMBRAIN functions differently, letting energy in and keeping energy in rather than expressing it outwardly.

As an final aside here, when I began working with preschoolers as a speech-language pathologist, I observed many story time circles (or singing circles etc.).  Children have learned language through conversation (you listen and respond in ongoing and rapid fashion) and have then to learn how to listen audience fashion as the teacher reads a book, a basic attention span skill for our systems of education.  More recently I saw a video of a Buddhist school in which the students all shouted and talked at once as they debated fine points of their teachings, quite a different model for educational discourse.  All acquiring MEMBRAIN skills for sustaining our interiority.