The Two Faces of Humanity
Here at RoberTreboR we have a thing about duality. We like to see opposites joined to make a whole. Today we want to discuss why mammals usurped the Dinosaurs as the main beastie here on Planet Earth.
Do we really know what killed the Dinosaurs? Certainly various catastrophic and climactic events shaped the flora and fauna of the time, but there is evidence that dinosaurs were already in decline in the period preceding these events. Many suggest that mammals with their fur coats were able to "out-last" the reptiles when the conditions got harsher. However there is another physiological element that almost certainly came into play, namely their brains.
What specific part of the mammalian brain you ask? The rationale can read like an advertisement in a computer magazine; "The Mammal-being with it's new Cerebral Cortex (Corpus Callosum) processing system gives the most versatile architecture yet for your adaptive/computation needs." This adaptation brought out the latest in brain enhancement, more highly differentiated cerebral hemispheres along with a higher bandwidth connection (memory bus). This piggybacked onto a reptilian cerebellum allowed what had previously not existed, better dual processor capability. The dual processor addition occurred to a lesser extent earlier on (in amphibians?) due to a highly incompatible but mutually beneficial pair of adaptive behavior traits. Most animals needed decent Reaction/Decision speed (Real-time, high speed) in order to escape immediate danger, while there was a requirement for analytic capability (planning capacity, slower) for longer term adaptations that couldn't be handled in DNA. Single threaded programs performing both functions at the same time require a LOT more "tweaking" in order to maintain the most beneficial combination of them both.
Why did this brain change give mammals such an advantage? The increased memory and speed in the new Cortex allowed the potential for what had previously been impossible, better "Artificial" Intelligence. And moreover, with the redundancy factor, a not-unimaginably small probability of two functioning AIs in the same Consciousness/Animal. AI, of course, has many different levels of complexity, the lower levels are size and speed dependent (this relation somewhat mutually incompatible) where increases in size increase memory capacity, but slow down processing speeds due to longer communication distances. As well, greater memory spaces require more time for data loading which competes against the maximum possible age of an organism. Later levels of AI require hard-coded linguistic/communication protocols/grammars encoded in DNA to facilitate data uploading. This shows up in humans externally as language learning (verbal), but is also seen in postural/facial and pheromone/scent communication in "lower" animals. The Corpus Callosum probably also uses enhanced parallel data transfer protocols to transfer images, sounds and brain structure states from one hemisphere to the another.
So this advantage helps mammals how? In a nutshell, with the more pronounced cerebral hemisphere separation, the possibility of division of labour between real-time and analytic (multi-threaded) processes develops. True benefits would depend on the degree of co-operation/communication between the hemispheres. This ability in mammals to task share between hemispheres allows a MUCH larger degree of self-adaptive behavior. This allows for better migration (short term) versus location (long term) adaptive strategies. In short, it allowed the mammals to "out-think" and "out-adapt" the reptiles at non-evolutionary scales (i.e. decent adaptive behavior no longer needs to be encoded in DNA).
How does this manifest itself in Humans? Well, hemisphere redundancy would allow for a kind of competition between the hemispheres to determine which hemisphere becomes "Top Dog". This shows up in early childhood/infancy as "handed-ness". It is the rare individual who manipulates his environment without preferentially using one hand or the other. In fact, depending on the complexity (time constraints?) of the task, it is not unusual for individuals to exclusively use one hand or the other. Why this shows up in the general population as a right-handed rate of about 85% is somewhat of a mystery. However, I feel that it may be beneficial for DNA to "stack-the-deck" in favor of one hemisphere or the other. Task separation is so much a part of mammalian brain processes, that evolution may have given the left hemisphere (LH) some extra "hard-wiring" to give it a head start on "real-time" processing. For most individuals, the advantage of dual-processing forces the right hemisphere (RH) to assume a "subservient" role of analytic processing. As suggested earlier, non-compliance in the non-dominant hemisphere can lead to a number of identifiable psychological disorders. (ADD/HD, autism, schizophrenia, bipolar/manic/depressive disorders, to name a few.)
Once a dominant (real-time) hemisphere has been determined, task separation can begin in earnest. What becomes a verbalization centre in the LH is mirrored in the RH with semantic and grammar processors (train of thought?). Depth perception in LH becomes 3D visualization in RH. Personal interaction in LH becomes external delegation of tasks in RH, et cetera. Communication between the hemispheres has to attain a certain level of communication in order to facilitate co-operation. With this in mind, I suggest that the Corpus Callosum almost certainly behaves in parallel to transfer more detailed brain states. Increased sophistication coupled with a potential for multi-threaded processing potential in each hemisphere increases the need for a feedback mechanism to co-ordinate brain activity. This is none other than what we call consciousness and it has its manifestations as well.
Acquiring language skills allows the consciousness mechanism to maintain an "internal mental dialogue" to co-ordinate behavior. There almost certainly exists a non-verbal variety of this train of thought in "lower" animals, but I am no longer able to relate to it enough to describe it, since I've been in Verbal Train-of-Thought mode from the age of about 3 years(?). Our internal dialogue can manifest itself in behavior like "talking to oneself". This behavior increases the number of neural pathways involved in "consciousness" and adds auditory feedback to help co-ordinate brain activity. If there was only one self-aware computational thread in the brain, then the feedback inherent in the act of talking to oneself would not serve as useful a purpose.
As both hemispheres learn and grow, inter-brain communication can become more sophisticated. Tasks that rely on balance and hand/foot/eye co-ordination can help increase this sophistication by exercising/increasing the neural pathways connecting different parts of the brain. At the risk of exposing my ignorance, I will use a musical analogy to illustrate brain task division. Piano playing at the early levels relies on the left hand (RH) for repetitive bass chord manipulations while the right hand (LH) plays the "melody" in real-time. Guitar players chord with the non-dominant hand and pluck the tune with the dominant hand. Woodwind/reed instrument players also have upper and lower register separation for dominant and non-dominant hand.
The degree of separation of hemisphere functions and the level of intelligence in Humans is so evident, that failure to negotiate an "acceptable" division of labour results in a number of psychological disorders (consult any number of abnormal psychology books for an up-to-date list). But when seen in the right light, these maladaptive scenarios in psychology allow us to consider the real possibility that two separate individuals exist in almost ALL of us, and that it is almost certainly a result of brain structure redundancy and the relative isolation of brain hemispheres.
To finish off, I would like to point out that the learning of communication protocols (languages, et al) manifests itself externally in readily identifiable traits as a sort of hierarchy:
When both hemispheres understand facial expressions, smiling and expressions become apparent as well as self-recognition in a mirror (or other reflective surface).
When both hemispheres understand speech, then "talking to oneself" can be observed.
When both learn how to write, then diary writing can be observed.
When both learn decent symbolic/emotional/semantic internal communication, then meditation can be observed.
When the non-dominant hemisphere learns a new/decent communication protocol, then we "hear" God.
©2004 Robert Martin Farries
Questions/suggestions? rfarries@telusplanet.net