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If you are suggesting information processing as a reason why we sleep, I disagree. The evidence our central nervous system (CNS) provides suggest that the basic processes of sleep evolved in the brainstem before those elements in the cortex associated with the synthesis of information. Although our conscious acuity appears to be enhanced by the sleep process, that is a relatively recent advantage of sleep rather than the primal reason why we sleep. The elements of our brain structure associated with information processing are relatively recent compared to those primitive elements associated with the mediation of our energy stores and autonomic systems. Our recent brain elements arise from and are dependent upon the primitive elements of our CNS for functionality. If the primitive elements do not function efficiently, this can and does affect the efficiency and function of dependent recent elements. The functionality of our brainstem is dependent on the sleep process. When that process is disrupted, it has a rippling affect on hierarchical functions of our brain. According to my read of the latest findings, our brain experiences two distinct functional states of cognitive active rather than some type of sectioning: Waking state [conscious] and the state of dreaming (unconscious). Because our mental acuity and memory is enhanced after sleep periods inclusive of dreaming, some sleep researchers believe this process is some how associated with memory consolidation. If sleep improved our mental acuity and memory, we should find the elderly of sharper mind than they were in their youth since the elderly tend to sleep longer. However, that is not the case. Atonia, rather than dreaming itself, enhances the production of Orexin-A, which has be shown to reverse the affects sleep deprivation with the benefit of dream sleep. If some mental analyses or processing amid dream sleep was essential to the brain's functionality, orexin alone would not have proven as effective in deprivation study. We dream as a consequence of vestigial activity in the brainstem associated with the mediation of our metabolism amid prolonged periods of inactivity and rest. This activity is a vestige of the neural processes ancestal animals likely evolved to endur extended periods of nutrient privation.

You and I are really not that far apart on our assessment of thalamic function. However: If this references thalamic processes amid the active state of dreaming, our individual assessments differ. Although dreaming is an interpretive process, sleep and dream research suggest that it is not quite the restorative and consolidating process many have come to believe. The evidence in dream study suggests that atonia rather than dreaming provides our brain with what it requires to reach optimum conscious acuity. There is convincing evidence that we owe our conscious acuity to the periodic release of muscle tonicity that occurs at the onset of dreaming rather than the mental activity that occurs amid this state. Dreaming is a response to the activations in the brainstem arising from vestigial neural processes associated with the conservation and redistribution of our energy stores amid prolonged periods of inactivity and rest. When the brainstem becomes active amid sleep, our cortex does what it was evolved to do and that is to interpret subcortical neural impulses and directives. Although believed to originate from periodic impulses from the pons, the hypothalamus is most likely the source of the impulses and directives that inspire our dream content. When you consider the primary role of the hypothalamus in its mediation of our sleep, feeding, sexuality, and other survival processes, its contributions to dream content is quite convincing.

In a book I wrote about the evolution of the dreaming brain, I said that mind is the environment of cognitive activity within brain structure that arise from brain function. My study of brain evolution suggested to me that mind could be quantified by a capacity to integrate sensory information, from divergent sensory sources, through a process that produces behaviors independent of instinct; i.e., a mind enables proactive behaviors above and beyond those considered reactive. My investigation suggests that thalamic function, after the emergence of sight, gave ancestral animals the rudiments of thought and the burgeoning ability to overrule their instincts. From my perspective, a brain, human or otherwise, with thalamic structure is suggestive of the capacity to produce a mind and, by extension, a consciousness. Although I believe the presence of thalamic structure suggests the capacity to produce consciousness, the quality of that consciousness is suggested by other contributory factors in brain function. All this to say that, from my perspective, the thalamus is the center of mind and consciousness. When the thalamus first evolved, my study suggests that its primary function was to integrate divergent sensory input (sight, sound, taste, and touch), which generated focused responses to sensory stimuli and the development of brain structures (basal ganglia) that enhanced this process. The effects of this process and brain developments were behavioral responses increasingly more coordinated and appropriate to stimuli. The adaptation of such focused behaviors gave these early animals a capacity to distinguish necessary from unnecessary responses, which allowed them to mediate their energy expenditure more efficiently. Such mediation allowed for the development of those brain structures that promoted habituation (limbic system). Through the routine, familiarly, and security habituation promoted, my study suggest that these early animals began to expand the range of their sensory environment and corresponding behaviors. Facilitating this expansion required the sophistication of memory, which led to the evolution of cortical structure. In decorticate studies, neural isolation of the cortex from subcortical structure resulted in sustained cortical deactivation throughout the survival period of test animals (Jouvet, M. and Jouvet, D. "A Study of the Neurophysiological Mechanisms of Dreaming." Electroenceph Clin Neurophysiol. [1963]: Supplement 24.). This is consistent with the functional hierarchy of brain evolution; i.e., recent brain developments enhance the function of prior developments and are dependent on those prior structures for functionality. The contemporary thalamus is the primary structure in the brain where decisions are neurologically made about which sensory information, excluding olfactory, should reach the cerebral cortex. In this way, thalamic function decides the focus of cortical evaluation. There are more neural relays from the cortex to the thalamus than vice versa. This is consistent with how cortical attenuation of consolidated sensory input from the thalamus enhances thalamic function. As a scaffold, around which mind and consciousness are constructed, the thalamus does not engage thought or abstraction but rather inspire the process and consolidate the resulting directives. As for the unconscious mind, its circuitry--as suggested by brain activations and deactivations amid dreaming--is distinct from that of the conscious mind. A hypnotized brain, in my view, is merely a more focused conscious mind rather than an accessed unconscious mind. Amid dreaming, the sleeping brain experiences a partial cessation of contact with its tactile (including auditory) sensory environment. Amid this cessation, the active dreaming brain is unencumbered by the mental demands and responsibilities physical reality and the sensory data it generates. To place dreaming within the context of sleep, is deceiving. The dreaming brain is as electrically active as a waking brain; therefore, dreaming could be consider an altered state of consciousness amid the sleep process. However, there are significant differences between the consciousness of the waking and dreaming brain as suggested by specific differences in areas of activation and deactivation in the brain between the two states of brain function. However, returning to the OP, the thalamus is the primitive within us that uses a thinking cap (cortex) to attenuate its responses to stimuli. I believe that attenuation accounts for the number of relays from the cortex to the thalamus.

What "cannot be known" is only evidence of a limit to our understanding of a phenomenon rather than the nonexistence of a cause for that phenomenon. To believe otherwise is analogous to suggesting that what we don't see, doesn't exist because it is beyond our spectrum of vision. When we close our eyes, does the world cease to exist because we can't see it? Does a cause not exist because it is not known or has not been determined? In another well known example, does a falling tree make a sound when no one is there to hear it? I think it best to suggest that a cause exist for a phenomenon with the caveat that its cause has yet to be determined when that cause is unknown or unknowable. Any thought to the contrary borders on the supernatural rather than science--in my opinion.

I'm no physic's expert, but your example doesn't seem to be a very good one. Just because we don't know or understand why a uranium atom decaded at that precise moment doesn't mean there is no explanation or cause for that moment of decay. Your example appears to illuminate the depths of our ignorance on decaying uranium blobs solely rather than some empirical lack of causality in that decay--in my opinion.

Referred to as hypnogogia, yours is a fairly common experience that often occurs during the brief period between wakefulness and sleep. The experience may include voices, loud noises, sharp sensations, bed shaking, lucid paralysis, imagined room intruders, and, of course, tinnitus among various other types of sensory experiences. That sound you hear is most likely the amplified ringing many older adults hear imperceptibly. Exposure to loud noises and the continuous use of earphone devices over the years is the likely cause. As you drift into sleep, you may be experiencing an increased sensitivity to ambient noises in your sleep environment as many of us do. Unfortunately, that sensitivity could be enhancing your tinnitus. Although I advise that you visit a sleep specialist, noise cancelling devices and natural sound generators have shown some effectiveness in easing the symptoms of this kind of sleep disturbance. I hope this helps.

Simply stated, we can not. We cannot employ certain mental faculties to the full extent of their use without an original sensory source of input as reference. Although the cogenitally blind, for example, can imagine the tactile shape of an object previously touched, they cannot fully conceive in mind the shade, colors, and other visual nuances of the object. How can a congenitally blind individual fully comprehend, imagine, or reason the distinction between light and dark or red and orange without ever having a visual reference for comparison? From another perspective, much of what we know and are able to do mentally and physically is predicated on what we have learned and experienced. What we learn and experience provides our brain with the data input its mental response systems (imagination, reason, memory, etc.) requires to effectively navigate the physical, mental, and emotional realities of life experience. Without that input, those systems are effectively impaired by what could be considered omissions in their reference database. Feral children, perhaps, provides the best example of how what we do and do not learn and experience shape the mental faculities we employ.

A specific area of the brain (prefrontal), associated with the formation of sustained memory, experiences a condition of low activation (hypofrontality) during the dreaming (REM) phase of sleep. This area, among other functions, mediates our assessment and consideration of consequence and consequential experience. Its low activation amid dream is a response to our dreaming brain's diminished conscious connection to our physical sensory (sound and touch) environment. What we remember most about our dream content begins to form during our arousal from sleep as our prefrontal function is once again stimulated by incoming (afferent) data from our physical sensory array. Consequently, dreams that incorporate stimuli from our sleep environment (e.g., cold room) are how our arousing brain integrates the internal experience of dreaming with afferent stimuli from our sensory environment. Arousing from dreams about urinating with a need to do so, is likely caused by the dream itself rather than a bodily need. This is a case of mind over body wherein the compulsion to urinate is inspired by the content of the dream rather than an afferent perception that has been integrated into the dream. Although not entirely his fault, Freud was wrong. Freud's ideals about the nature of dreams and our mental construct were predicated on his observations of aberrant examples. Unfortunately, Freud did not have access to the kind of imaging technologies nor brain and sleep research that we presently enjoy. If he had, he would have realized that dreaming is merely the synthesis of brainstem activations amid the sleep process. He would have understood that these activations do not originate from our senses and, therefore, are not perceived by the brain as originating from our sensory environment. Because these activations do not contain data that our brain recognizes as reality, they do not stimulate the kind of memory and gross-locomotion responses we apply to true physical/material experience. It's difficult to make an accurate count of how many dreams we experience during each cycle of REM; however, REM occurs at 90 minute intervals during normal sleep on average. The longer we sleep, the more time spent in REM per interval. Our brain is predisposed by evolution to remember experiences of real physical/material consequence. Although we may not be mindfully aware amid a dream that our experiences aren't real, atonia and hypofrontality suggests that our brain is very much aware. Atonia is the cessation of the muscle readiness essential to our responses in physical reality. Hypofrontality suggest a cessation of the assessment process associated with our consideration of consequential experience. There are studies that suggest a strong association between dream sleep and conscious cognitive functions. However, the stronger studies are those that show that atonia rather than dreaming is the component of sleep process that is most essential to our conscious mental acuity. Although some of us may have construed our dream experiences as reality, the possibly of that happening is most likely not the reason our dreams are so easily forgotten. We have to think about the evolved nature of brain function, memory, and dreaming to understand why. Dreams aren't reality and memory was evolve as a survival strategy for reality. Dreaming is a response to subcortical stimuli that does not activate a part of the brain that contributes significantly memory when we are consciously awake and aware. One of the most prominent distinctions between the dreaming and waking brain is the kind and degree of data available to each.

Is dreaming a type of imagined experience or is it something more substantial? If dreaming is anything more than imagination, could dreams truly be substantially meaningful or relevant experiences? As wanderings of an idle mind, what we imagine is meaningful to us on some level. Although frequently not time well spend, our imagination could be a source of insight, innovation, and stress relief. Einstein, whose "thought experiments" produced extraordinary insights, is a great example of meaningful and relevant imagination. However, evidence in brain study suggests that dreaming is likely not imagination. Imagination is a consciously directed activity of a wakeful brain, whereas, dreaming appears to be the random and directionless activity of a sleeping brain. Although it occurs amid sleep, dreaming isn't sleep. EEG and PET studies of the dreaming brain suggest that it is as active as a waking brain. Because dreaming involves a brain as active as one that is consciously awake and aware, dreaming could be categorized as an altered state of consciousness amid the sleep process. However, there is evidence suggesting that dreaming is more than the hippie trip of an idle mind amid sleep. Rather than random and directionless, dreams are perhaps more meaningful, relevant, and directional than a majority of us may perceive given how little many of us care to know about their exact origin and nature. This is not the stuff of Freud or Jung, who both missed the mark considerably. If you have interest, I welcome your thoughts.

Why are our dreams so easily forgotten? Although not the only one, one explanation is that dreaming is a mechanism for ridding the brain of useless data; i.e., dreams are irrelevant data and are not meant to be remembered. Here's the short answer suggested by the research I did for a book about the dreaming brain, which I wrote a couple of years ago. Memory was evolved to preserve the physical well-being of ancestral animals before those animals developed dreaming brains. What these ancient animals likely remembered most were those experiences that had a real impact on their physical/material survival. Consequently, as descendents of these animals, certain parts of our brain that involve memory appear to become active only in the presences of real physical/material sensory experiences. Although it may appear otherwise, dreams do not involve real physical sensory encounters; i.e., physical/material sensory experiences do not reach our dreaming brain the way these experiences do when we are consciously awake. Because our dreams do not involve real physical experiences that are actually perceived through our bodily senses, parts of our brain--associated with memory--remain inactive and we, consequently, do not give our dreams the concurrent priority and attention that produces a sustained memory of them. We forget our dreams easily because they are not concurrent with true physicality. I welcome your thoughts.

Here's an article describing research suggesting a link between our cortex and that of a species of marine worms, which further extends our brain's evolution back some 600 million years: http://news.discover...uman-brain.html The article goes on to describe how these pre-brain structures in early animals "probably consisted of a group of densely packed cells that received and processed very basic information about food and the environment. The structure may have enabled our ancestors crawling over the sea floor to identify food sources, move towards them, and then later to integrate previous experiences into learning." The goal of this research, the author quotes, "'is to reconstruct and understand the evolution of brains in animals, to trace their neuronal composition and their function from the very beginning of animal evolution to something as complex as today's human brain,'" Aspects of what this article discusses appear to be consistent with some of my comments regarding relatable aspects our central nervous system to an earlier time in its evolution.

Not being a physicist, but having great interest in and considering most thoeries regarding this subject, I believe that something cannot spring from nothing. Everything had a beginning and that beginning was something we may never truly understand. Even if one perceives some supreme consciousness as the progenitor of our universe, something came before it to bring that consciousness into being. Everything came from something or somewhere and no speculation, no matter how reasonable, could convince me otherwise. To believe otherwise, in my opinion, is magic not science.

To paraphrase this process from prior comments elsewhere, when evolutional biology provides very little about the emergence of specific behavioral qualities expressed through brain function, we begin by evaluating the anatomic minutia of each brain segment relatable to existent primitive species with those qualities, then look for similar species in the fossil record, explore the likely compelling evolutionary pressure (environment, population, survival resources, etc.) influencing the behavior of those prior species and, based on those pressures, surmise the demands (e.g., feeding) leading to the emergence of the neural developments (e.g.,Glossopharyngeal and Intermediate Facial), known to promote those behavioral qualities.

Forgive my lengthy absence from our little discussion: Contemporary brain studies suggest how enriched environmental experiences are compelling factors in brain growth and development (e.g., Uylings, H. B. M. "Development of the Human Cortex and the Concept of 'Critical' or 'Sensitive' Periods." Language Learning, Jun2006 Supplement, Vol. 56, p59-90, 32p, and Perry, B. D. "Childhood Experiences and the Expression of Genetic Potential: What Childhood Neglect Tells Us about Nature and Nurture." Brain and Mind, 2002, Vol. 3, p79-100.). In Uylings's article, for example, he describe how "Global neglect (i.e., minimal exposure to language, touch, and social interaction during the first 5 years of life) leads to a permanently smaller head circumference, smaller brain size…." However, Uylings goes on to say, "This does not mean that the brain cannot change further in adulthood; for example, environmental enrichment remains capable of challenging the brain, even in adulthood." Further studies in experience-dependent neural plasticity support Uylings's conclusions on how experience influence brain development (e.g., Kleim, Jeffrey A.; Jones, Theresa A.. "Principles of Experience-Dependent Neural Plasticity: Implications for Rehabilitation After Brain Damage." Journal of Speech, Language & Hearing Research, Feb2008, Vol. 51 Issue 1, pS225-S239, 15p, and Holtmaat, Anthony; Wilbrecht, Linda; Knott, Graham W.; Welker, Egbert; Svoboda, Karel. "Experience-dependent and cell-type-specific spine growth in the neocortex." Nature, 6/22/2006, Vol. 441 Issue 7096, p979-983, 5p.) Opposite of nutrition, my position is that experiences related to the more rigorous effort of sustaining a meat diet led to our animal ancestry's meteoric (IMO) brain growth and cognitive development above competing species. Clearly, given our ancestry's likely competitors, foraging among trees is not the same as savaging for meat. Maintaining a meat diet likely, as it does among contemporary animals, demanded a level of cunning, cooperation, and ingenuity exceeding that of more acclimated animals as our primate ancestry migrated from forest to savannah.

I disagree. As my position regards an association between atonia and feeding in the brainstem that could be relatable to the evolutionary process; consideration of other areas are, therefore, irrelevant. The NTS supports my idea of a tonicity promoting area (via NREMS) of the brainstem, associated with sleep, that could be linked to processes associated with feeding, which involves the viscera. ...true NREMS- and REMS-generating mechanisms exist exclusively in the forebrain and brainstem, respectively [...] the thalamus engages in both NREMS and W "True NREMS" meaning sustained NREMS. Although the NTS does not generate sustained NREMS, its association with visceral related activities suggests a relationship between those activities and the propagation of sustained NREMS through a primitive element of our CNS. The Triune theory presents a popular perspective of the brainstem as relatable to an earlier, more primitive incarnation of brain structure, which you have yet to deny. If we agree that brainstem structure suggests an earlier time in brain evolution, then what does that structure suggests about its earlier time? How do we go about the process of accessing what the brainstem suggests about the progression of brain development from an earlier evolution? When evolutional biology provides very little about the emergence of specific behavioral qualities expressed through brain function, do we begin by evaluating the anatomic minutia of each brain segment relatable to existent primitive species with those qualities, then look for similar species in the fossil record, explore the likely compelling evolutionary pressure (environment, population, survival resources, etc.) influencing the behavior of those prior species and, based on those pressures, surmise the demands (e.g., feeding) leading to the emergence of the neural developments (e.g.,Glossopharyngeal and Intermediate Facial), known to promote those behavioral qualities? When, for example, no peer reviewed research exists on the primal emergence of the tonic/atonic expressions of brain function, how do you suggests we access and assess those factors leading to that emergence?

To which my response was, "All of Dr. Jouvet's work is available online. Try a Google Scholar search." And now, your reversal: Initially you dismiss Jouvet's work as irrelevant without even a glance. Then, in the very same post, you state your willingness to concede it may indeed have some relevance. Now, it seems we are back to square one. To be clear, as stated in prior post, we are looking for an association between the mechanisms for atonia and those for rest and food privation in the segment of brainstem relatable to ancestral animals (Triune Theory). All papers available through Google Scholar (GS) are peer reviewed, including Jouvet's should you once again care to consider them. However, while perusing GS, I found this peer reviewed article suggesting a connection between mechanisms for NREMS (a tonic state) and visceral activities. Villablanca, J. R. (2004). Counterpointing the functional role of the forebrain and of the brainstem in the control of the sleep-waking system. J Sleep Res., 13(3), 179-208. Specifically: The article suggests that this site, n. tractus solitarious, in the truncated, mesencephalic brainstem is the only area capable of promoting NREMS, which is a tonic state. The viscera association with the solitarius and its NREMS (tonic state) mediation in the brainstem coupled with the unstable nature of tonicity in mesencephalic animals suggest a connection between the need to feed and the sustained tonicity of NREMS in the mesencephalic brainstem. At the very least, this article associates visceral activities with sleep/wake processes through a segment of brainstem relatable to an earlier time in brain evolution according that segments position in the Triune model.

I welcome your cordial and insightful perspective and agree with much of what you have said. Sleep involves a confluence of neural functions arising from brainstem components evolving at various stages in our CNS's evolution, as its recent-to-primitive contiguous structure suggests. Although we may have a general understanding of the neurological and neurochemical mechanisms of sleep, these mechanisms by themselves do not tell us much about the origin and evolutional path of sleep. When we evaluate these mechanisms in context with how our CNS likely evolve, I think we can form a cogent evolutional perspective of how these components of sleep arose and why they persist today. The individual components explain themselves but, individually, they do not speak to the history of the sleep process. That history provides a fascinating perspective of why we dream—in my opinion. Indeed, macro study doesn't explain the emergence of the individual components that constitute contemporary brain structure. Studying how the function of those components contiguously emerge and fit together offers, in my opinion, a unique perspective on the emergence of mind, memory, consciousness, and various other aspects of brain function. Indeed, we know a great deal about what sleep and the absence of sleep do from brain and body. However, the nature of contemporary sleep tells us very little about its initial adaptation or its compelling evolutional circumstance. I began a study of that adaptation and circumstance during research for a book about the dreaming brain, which I wrote several years ago. The experience caused me to question contemporary notions about the confluence of functions that produce mind and consciousness and the significance of specific structural developments. It was fascinating to discover how--through decorticate research--cortical structure and function may not be as essential to some cognitive behaviors as I had thought.

You misunderstand; my reference to arrogance regarded my initial comments, which I sought to clarify in subsequent comments regarding the non-existence of a clear, integrated theory. If you reread my comments, you should find that I was expressing no assumption regarding information in your possession. Again, if you reread all my comments in this discussion, you will find that I expressed no direct or indirect comments regarding your personal attributes or motives. In answer to your question, I consider any theory or statement regarding the nature of consciousness as speculative that does not include foundational aspects of brain evolution. Although your comments appear to suggest there is literature that cogently merges the nature of consciousness with brain evolution, I have not found any. If you are aware of such, I'd be delighted to review and discuss it. No, I understood the text above because I wrote it. What I didn't understand was having written that text without using a metaphor that was unclear, which suggests to me your belief that I should have used an unclear or obscure metaphor to better explain my position. In review of your subsequent comments, perhaps you meant I should have used a metaphor that is clearer to you. By footprint I meant some neural evidence of that earlier form, which we can walk (metaphorically) or trace back to a beginning. Nitpicking over innocuous details such as this, forestalls more meaningful discussions—in my opinion.

To prejudge evidence as irrelevant without what seems the slightest consideration or knowledge of that evidence's content suggests your biased conviction, which validates my position regarding evidence in adverserial discussions. And yet, I have provided citations to such evidence, contrary to your claim that I have not. Your approach notwithstanding, I support my position with the available evidence when no new evidence or evidence to the contrary exists. I consider neuroanatomy texts as reliable guides and resources to the basic available research regarding the functional nature and structure of our CNS. Where the mechanisms for atonia and the afferent neural systems associated with feeding reside in the brainstem have not changed since their initial discovery. That these mechanisms reside in the same segment of brainstem isn't a coincident of evolution. As early as research by Sir Charles Sherrington, atonia has been known to engage when decerebrate animals were not being fed or otherwise physically stimulated. You did receive the proper citations for my thoughts regarding this issue. Now, as an afterthought, maybe there is relevant material in Jouvet's work? Careful, you may ruin my perception of your psychology. All of Dr. Jouvet's work is available online. Try a Google Scholar search.

Who says that we lack the "slightest understanding?" I can go on Google, Amazon, or a searchable academic database and find dozens of books and hundreds of articles about the evolution of the human brain, of intelligence, and of specific cognitive functions. Are you just saying that individuals speculate on the topic without understanding, or that science lacks it in general? An arrogant statement? Granted; however, from my perspective, a clear, integrated theory of brain evolution and consciousness emergence does not exist. Who speculates this? Classical Freudians? You've mentioned two parts of the classical Freudian tripartite model of the psyche (leaving out the superego--I'm not certain why) and the concept of a "complex"--by which you mean, perhaps, the Jungian concept of the complex. These theories have been significantly discarded by the mainstream community of psychology. To be so gauche as to quote myself from a previous post: These were merely speculative examples in an ongoing discussion rather than an all inclusive, detailed description or discussion of those examples. was expressed without the use of an unclear metaphor. Follow what footprints how? "…without the use of an unclear metaphor." What? I don't understand. Should I have used an obscure metaphor?

You selectively attack evidence you believe to be irrelevant without proper study or discussion. As I have said, as your reply evince, no sound evidence of significance and relevance to a topic in adverserial discussion would be amenable to the opposition.

It seems you only know one mode—attack! You make one claim here, and then a variation on that claim. First, that the relative lack of sensory acuity (compared to other animals) among early primate ancestors compelled cortical growth on an evolutionary scale. Second, that relative lack of sensory acuity, as well as relative lack of speed, and relative lack of stealth compelled this growth. Is it sensory acuity, or is it all three? It's not particularly novel to suggest that h. sapiens occupy a niche in which a relatively high degree of cognitive skill, and relatively low degrees of physical strength or senses are used to make a living. To make more specific variations upon that claim requires some more evidence. To make it in general terms is largely to recite what's already well-known. If I may simplify, in research some have suggested that larger brain size among ancestral primates may have occurred as that ancestry moved from a herbivorous diet to meat consumption. The idea is that the increase in protein consumption, associated with a carnivorous diet, may have led to this growth. My position, on that issue only, is that there could have been factors more compelling than dietary intake. In describing those factors, I suggested how certain sensory and physical disadvantages might have led to behaviors that could have resulted in increased brain size and development. In support, I briefly described how such disadvantages might have required reasoning capabilities and, by extension, brain power beyond those of competitors adapted to sensing, stalking, and capturing source of sustenance adapted to avoiding same. With a bit of patience and cordial inquiry from respondents, I would have further explored how experience has proven the most compelling factor in sustained brain growth. Brain studies of domesticated animals, for example, have shown as much as a thirty-five percent reduction of growth in their visual cortices relative to non-domesticated species. Presumably—given the unstable diet of non-domesticated animals compared to those in domestication—this size variance arises from the limited visual experiences of domesticated animals relative to the rich and varied experiences of wild animals. the mental demands associated with obtaining meat likely stimulated the larger brain developments we have found among the primates considered ancestral to humans is somewhat incomplete, given that brain-to-body mass ratio has steadily increased along the mammalian line since very early mammals during the mesozoic. Also, the rapid advances in encephalization during the history of the early hominids we're talking about occurred long before the technology associated with hunting had arrived. Thus, the "mental demands" of obtaining meat are really the mental demands of scavenging--a strategy not unlike what mammals had already been employing for millions of years. One would have to make a case that scavenging meat and scavenging vegetable matter are qualitatively dissimilar. Indeed, what one group of savannah mammal have adapted to do after "millions of years" is not reflective of what others were required to learn and do over a few hundred or thousand of years. Evolution obviously selected for certain groups of primates with mental capabilities exceeding their sensory and physical limitations. Given your obvious erudition, I am astounded by this comparison between plant and meat savaging. This is not about the development of tools but rather the changes in brain development likely compelled by dramatically altered survival conditions and demands. My conclusion are rooted in what contemporary brain studies suggest about compelling factors in its growth and development. If you are sincerely interested in those, then we can explore a few.

If you wanted to be civil, you would have set that tone from the outset. Clearly, you did not. Although I'd rather this not be adversarial, I think it's best to have some idea of what could be an opposition's psychology in such discussions. That psychology suggests to me that no matter the evidence, no position I espouse will be perceived as sound. Therefore, this simply becomes a point/counterpoint discussion rather than a cordial and enlightened exchange of ideas, which I had hoped to engage. Nevertheless…: It was unclear because you either ignored or didn't understand prior statements outlining the direction of my comments regarding the various components of sleep arising at varying stages in brain evolution. Without some inherent agenda as a hindrance, I think anyone reading those statements will find the direction I outlined quite clear. I hardly think any wording would have suited given your subsequent comments: If you had read my prior comments, this is what you would have found: Nearly every species enters a state of rest that could be interpreted as sleep. This suggests a common evolutionary advantage to the sleep process among sleeping species; i.e., we would not have sleeping species if sleep did not offer some survival advantage to ancestral species....When we examine the neurological components of sleep in most animals, we find that its various attributes arose at varying stages in neural evolution.…If the brain evolved from some earlier form, we should be able to find some footprint of that form, which we can trace back to some earlier point. Most researchers agree that the brainstem is a primitive component of our central nervous system. Of the brainstems components, the spinal brain (myelencephalon) appears to be the most primitive segment because it most closely resembles the notochord development we find in existent species of primitive animal life….When we examine the afferent neural systems of the spinal brain, we find those associated with feeding. This infers that ancestral animals at this stage in brain development engaged behaviors requiring the intake of nutrients….movement most likely evolved with the evolution of the metencephalon where we find more sophisticated afferent neural systems associated with sound detection. The ability to detect sound suggests ancestral animals at the stage where they were orienting themselves either away from or towards sensory stimuli. And the point: Early spinal brained animals were probably not as mobile as later metencephalic animals. This suggested lack of mobility infers that these animals had to adopt a strategy that allowed for survival in the absences of readily available nutrients…. During the atonic stage of sleep, we find a suspension of muscle readiness with energy devotion to organs more critical to our survival. Atonia appears to be mediated by the metencephalon/myelencephalon brainstem segments. This suggests that the earliest components of sleep evolved as a means to sustain survival through periods of prolonged food privation. Using your analogy to describe the path of the earliest factors leading to the earliest evolved component of sleep (atonia): 1 thru 4) Mechanism x exists in what most researchers agree is the most primitive aspect of our CNS that is relatable to the complex animals likely ancestral to humanity. Mechanism x suggests a primary compelling factor in the behavior of early complex species leading to the emergence of the earliest component of sleep behavior (atonia) where mechanism x resides. OK, so here's something. First off, I'm not sure if we could really call these processes "vestiges," since they have clear extant function. The components of contemporary sleep emerge from and rest upon functions that are vestiges of an earlier time in our brain's evolution. Because the tenor of my original post eluded (IMO) your initial understanding, I sought to summarize the intent and direction of my thoughts in as few words as possible. If this was a cordial and enlightened exchange, you likely would have asked me to elaborate further at which point we would have explored the details of how I arrived at my conclusions in more amenable terms and tone. Instead, as it seems, you pounced on somewhat concise individual statements as detailed descriptions and conclusions, which leads to misperceptions and false assumptions. As I have said, I can provide you with the evidence I relied on to reach my conclusion but they would likely not be sufficient in adversarial discussion. However, for those of more enlightened interest who might be following our little discussion, the Triune theory of brain evolution explores the evolutional stages of brain development defining the brainstem as its most primitive stage. The various components of the sleep process emerging from the brainstem was largely revealed by Dr. Michel Jouvet through a series of papers beginning in the late 1950's and continuing through the to the late '60's (e.g., Jouvet, M., Michel, F., & Courjon, J. [1959], Sur un stade d'activité électrique cérébrale rapide au cours du sommeil physiologique [CR Soc Biol., 153, 1024-1028] and Jouvet, M. [1967], Neurophysiology of the states of sleep [Physiological Reviews, 47(2), 117-177].). The segments of brainstem and the specific neural developments associated with each, as reference in my comments, can be explored at your leisure through any college level neuropsychology or neuroanatomy text (e.g., Kolb and Wishaw's Fundamentals of Human Neuropsychology or Notle's The Human Brain: An Introduction to Its Functional Anatomy.). .

Again, my comments here were to show how the primitive aspects of our central nervous system (CNS) suggest the behavior of the first complex animals at the metencephalic stage of neural evolution. Prior developments suggest feeding as a primary pursuit and capability among early complex animals, as might be found among animals anchored to a primordial sea floor. Newer, contiguous development suggests the emergence of gross locomotion in support of what might have been increasingly complex feeding habits. Indeed, there may have been, as at present, organisms capable of movement without a CNS. However, our CNS structure suggests the evolutional path of brain development in the complex animals ancestral to humanity. Agreed; the word is paleontology. Why we sleep is tied to brain evolution, which is suggested by its recent-to-primitive structure and supported by the similar structures we find among animals in the fossil record. My intent was to engage in a productive discussion of the sleep process as suggested by its various components in brain evolution and structure. We sleep because the functionality of our recent brain developments is dependent on the vestigial processes of earlier development evolved to sustain the viability of the vital systems, of antecedent animals, through periods of rest and food privation. Rather than engage in equally productive discussion and contribute substantive comments, you'd rather mollify what certainly appears to be a personal esteem issue by selecting passages out of context to support a skewed perception of my comments. [headdesk][ Agreed; the word should have been lateral.

Hello All, While researching how our brain evolved to dream for a book I wrote a few years ago (Neuropsychology of the Dreaming Brain), I learned much more about the nature of mind, consciousness, and unconsciousness than I could find in any one specific text. It amazes me how much we speculate about our mental nature and construct without a cogent perspective of brain evolution. To speculate about the nature of the mind or investigate the nature of brain function without the slightest understanding of how our brain evolved is like, in my opinion, constructing a building without considering its foundation. For example, what is the mind? We speculate the mind to be a mixture of id, ego, and complexes when we have empirical evidence which defines the mind as an environment of cognitive activity within the brain that arises from brain function. If the mind is indeed a product of brain function, we can further quantify the nature of the mind by how and when the brain evolved that function. If the modern brain evolved from some primitive form, we should be able to find and follow the footprints of that form back to its beginning. Should you like to join me in further discussion, I welcome your thoughts.