Evolution, Life and Why Our Brains
Developed the Way They Are
Evolution, Life and Why Our Brains
Developed the Way They Are
There are a number of reasons – aside from my own fascination with this subject – that I believe it's very useful to have a look at how our modern human brains got to where they are today. Personally, I think it's crucial (which is why I'm taking the time to gather a small sampling of the relevant material and write out this chapter) but it's okay if you just consider it useful. If I do my job right and you follow along carefully, however, I think I may convince you that knowing how our brains developed from an evolutionary perspective is very important in understanding how your brain got to the point it's at and why it works the way it does which, if you're reading this material, could well mean that at this point you are having mental health difficulties.
While I believe this blog and the material I present within it will be of interest to virtually anyone, I do not want readers to lose sight of the fact that my main purpose is to create better and deeper understandings of mental health problems and further, to teach how to either cope with them better or even, perhaps, to eliminate them altogether (yes, it's possible in a considerable number of cases, particularly in the under 30 set). So I ask that all readers bear this in mind as we go along, whether you yourself suffer from mental health difficulties, a family member or close friend or associate does or whether you're just a decent human being and want to further and broaden your understanding of mental health issues.
As I mentioned in the chapter on basic brain anatomy, our brains – the current 21st century homo sapien brain – didn't just pop out of the oven as is; there were million and millions of years of “R&D” that went into them. The human brain just happens to be the current (1) pinnacle of that evolutionary development.
Before I go on about the human brain and to better understand exactly what it is that it does (and very often doesn't do), I think we need a basic working definition for brains in general.
I am aware that that this is overly simplistic but for our purpose today we're going to think of brains at their essence in two elementary ways; they are a) collections of neurons and the connecting wiring between the neurons and b) those collections of neurons process sensory information from a given organisms' environment and produce reactions, behaviours and strategies that will guide it through that environment and procreate. To give a few examples at the lower end of the scale, we have fruit flies, bees and worms. Yes, these simple life forms have “brains”; that is, a collections of neurons that guide them through their simple (and generally very brief) lives and all of which are used by neuroscientists as research subjects in order to gain understanding of neuronal circuitry in general and even human neuronal circuitry (if you're so interested, check out this post on The Remarkable Bee Brain).
Somewhat higher up from there we have lizards, frogs and so on (now we're getting closer to what our brains look like). A little higher up yet we have birds. Higher yet we have mammals. (2) Primate species are high up on the mammal range. And at the top we have the human brain. (3) While all these examples of brains vary greatly in sophistication, design and purpose (and by “design” I am not talking about “intelligent design” - IE: the belief of many that some sort of higher being had a hand in the design of life but the evolutionary process), they are at their essence collections of neurons that process information in order to guide their host through its given environment.
Which paints a rather less glamorous and romantic picture of the human brain than what we people are used to thinking of ourselves, but there you go. However, for our purpose in understanding what goes wrong when we experience mental health difficulties, it's important to remember what our brains essentially are and what their core purpose is. While our brains are vastly more complicated, they still basically perform the same function of that of all organisms' brains – to interpret sensory data around us and create reactions to that data along with behaviours and life strategies thus guiding us through and (hopefully) adapting to our given environments in an at least somewhat successful manner (which bears repeating because I do regard this as essential in understanding ourselves). The human brain has of course some unique additional "equipment" - such as much more advanced language abilities, greatly superior predictive functions and vastly greater states of consciousness not to mention some very key macro and micro anatomical differences - that allow human brains to do much more with that sensory data than any other species on earth (or at least at this point of Earth's history).
I consider this so important because in several ensuing chapters and throughout this blog, we're going to learn to see and understand the importance of environmental factors in affecting a) the development of our individual brains (and thus “who we are” as individuals) and b) how our individual environments affect and create our reactions. And we're going to see how it's those “reactions” to our environments, our own individual worlds, that are at the crux of our mental health issues. So what we're looking at in this chapter sets the table for understanding all of that.
And again, if I do my job correctly as we go along in many of the following posts in demonstrating our brains' relationship with our individual environments, then what I am going to teach later on will go a whole lot better. And at its core, what I teach is a) how to better train your brain to react more optimally to the environment around you and b) how to better manage your environment to better suit your particular set of neurons.
There are three quite distinctly different basic regions in the brain:
The most elementary part is the brain stem which houses regions that control our most basic functions such as breathing, heart rate, etc. The pineal gland – crucial in sleep-wake cycles – is also located here. The brain can sustain and survive horrendous injuries to various areas and the owner continue to live (albeit likely in a highly disabled or altered state) but damage to the brain stem results in brain death and breathing and heart pumping would have to be artificially sustained. Recovery from damage to this area is extremely rare.
Now, let's just touch briefly on the limbic system. This is a very important are for us to understand, as we'll see when we look at this region in more detail later on, for this part of our brain has an enormous influence on our behaviours. All our emotions and emotional responses arise from here and all our incoming sensory input is first routed through and "analyzed" by various "hardware" in this region before being passed on to the higher neocortex regions (if at all). Core nodules for memory formation are also to found here where our more advanced human functions are controlled or the frontal lobes where higher human emotional regulation is housed.
What is important for us to understand here today is that it is because this region evolved prior to the neocortex that it is first in line in processing sensory data. Furthermore, and perhaps more importantly, when we look at the human brain's "energy economy" and how the brain prioritizes energy allocation throughout the brain, we'll see that under many circumstances the limbic region again gets first priority over higher cortical regions and cognitive processes. The human brain - more than any other animal brain - is a massive energy consumer and when we examine this in more detail, we'll deeply understand why our brains are so prone to melting down when we are run down and low on energy, why we get so emotional and why behavioural regulation becomes so difficult. We'll also see how this can become a chronic condition.
A lot of behavioural issues and psychiatric disorders begin to make a lot more sense when we understand the brain's “chain of command” and what influences or affects this chain and why. Understanding this will also give us great insight into how we can better control or deal with what's going on with us or how those around us can better help and support us.
To put the brain stem and limbic region in evolutionary historical perspective, these regions began developing millions of years ago and thus were the main areas of control for the vast majority of human development, a point we'll come back to later.
Humanoid brains as we know them today began to increase in size about eight million years ago and the vast majority of this increase took place in the final stage of brain evolution, the cortical regions, the area in purple in the illustration above. You'll recall from the post on basic brain anatomy that all higher human cognitive functions are located in the neocortex. All modern mammals have rather robust neocortexes but so called “social animals” have the most developed neocortex, a group that includes all primates, elephants, dolphins and whales, and dogs. Social activity implies and involves higher levels of sophisticated organization and related skills and are thus associated with higher intelligence. The “social brain” is located in the frontal lobe (or pre-frontal cortex or PFC) and it is largely this area that “took off” in human evolutionary development starting around 200,000 years ago when what we now term as “culture” really began to emerge in homo sapiens (although evidence of cultural leaps forward goes back much earlier, it is this period in which it really “took off”).
Culture, Societal and Brain Evolution
What really sets modern humans apart from other animals of high intelligence is cultural and societal organization and thus cultural, societal and brain evolution must be viewed together when trying to understand modern human behaviour. For clarity's sake we need to roughly understand what is meant here by “culture” and “society”. The former refers to things such as tools (starting from stick and stone tools), art (cave drawings, etc), body/facial ornamentation (the use of shells and bones, simple face painting and or tattooing, etc) and then language, music and dance and so on. The latter refers more to group organization and rules within such. All seemingly simple stuff but critical to remember when we look at ourselves in our modern society and cultures and why individuals struggle, which is the foundation I'm attempting to establish in this post.
Much of brain evolution is a “chicken or the egg” question, IE: did this cultural and/or societal development spur more brain development or vise versa? In other words, did a given brain development spur the use of tools or did the discovery of the usefulness and advantage of a given tool use spur additional brain development? In actuality, both are true but of course it's not that simple.
All evolutionary leaps forward are due to genetic mutations or variations (yes, I know this sounds tediously boring but bear with me, throughout the course of this blog - or a virtual e-book as I think of it - we'll see that all these details are important in understanding what goes wrong and why when we suffer a psychiatric condition or crisis). So first comes a genetic mutation or variation, (a particular set of genes – those involved in communication, say) changes (or mutates or varies in genetic study parlance) in a freshly born being, that mutation or variation sparks something “new”, that new thing turns out to be advantageous giving that being a leg up over competing members of its species or rival groups, this advantage “catches on” (I'm being breathtakingly simple here) and away we go, we have a new advancement in a particular species. This is the process that brought about all the various past incarnations of homo erectus and thus eventually homo sapiens – us.
For one very simple example, at some point in the last several hundred thousand years a particular member of a particular branch of homo erectus (we're still talking pre-modern homo sapiens here) was born with some genetic variations which created some brain variations which in turn caused that member to be able to depict something in that person's environment (usually something important to survival) in a drawing or perhaps a carving. Others began to imitate this and thus an aspect of culture was born. A similar process was involved with the first dance movement, first musical arrangement (such as rhythmically thumping a coconut with a stick), language and everything else we now associate with human culture. Something similar would be true with societal organization although this would have preceded cultural developments (and we can see this process at its more infant stages with how higher social species such as baboons or orcas organize themselves).
So it's safe to say that a new brain development – one caused by genetic variations – initiated the new cultural or societal development. But – but! - that development would not have taken wider hold had it not been adapted by many other brains (generally through a "mirroring" process) and it is this wider adaption by other brains that spurred forward homo sapien's rapid brain development (to put this all VERY briefly and simply).
Something that is now becoming well understood to be very unique to human brains (and this too would have been the result of a long process of genetic variation) is we have a much larger capacity for “neuroplasticity” than that of any other species and, more importantly, for longer periods throughout life. Neuroplasticity is a massively important concept and feature of our brains (which I introduce here) but briefly it is the brain's ability to adapt and change to novel circumstances. It is this ability that has allowed first homo erectus and then homo sapiens to … well, learn and adapt to so many different things and develop our enormously complex (comparative to other animal species) social and cultural lives. And it is this “plastic malleability" that allowed a new discovery to be learned and adapted for so quickly.
And it is this process – a new discovery followed by wider learning and adaption of that discovery – repeated countless times that created the evolutionary process that created our current human brain forms.
So back to our “chicken or the egg” question, it was genetic mutation and variation that created the new cultural or societal development but then it became the learning and adaption of that new development that created bigger and better brains gradually and slowly over the preceding several million years, most rapidly so in the previous 200,000 years.
As mundane and scientifically blah-blah-blah 'who cares?' as this all sounds, as you begin to understand how “we” developed in this manner, it is my hope that some light bulbs will go off and grand “aahh-haa” moments will occur in your head where all kinds of things about who and what you are and why begin to click into place. If it's anything like what I often experienced as I discovered all this and began to put it all together, it'll be almost orgasmic (3).
I hope cover genetics more in future chapters/installments but I just want to touch on a few things quick, something that's going to be a HUGE part of understanding psychiatric conditions and why they occur in poor you (or me for that matter).
The “stuff of life” is DNA. We share close to 98% of our DNA with other primates and among all humans on earth of whatever race or ethnicity, we share 99.9% (making us all essentially brothers and sisters). But with genetics and DNA, the devil, as they say, is in the details and the details that make us each absolutely unique is contained within that 0.1%. You'll recall from the previous chapter that every brain is as unique as a fingerprint; that no two brains – at present or any brain throughout history – are alike. Not even those of identical twins who start out at conception with the exact same DNA (because the two fetuses develop from a single egg that splits). The three pound blob of jello like substance between your ears is unlike any other in human history (there, now don't you feel special!). And that uniqueness is due to how your particular batch of that .1% of DNA was arranged from prior to conception, through conception and fetal development and, as it turns out, all through your life. From what your parents did, were exposed to, consumed at the point of your conception, to how you developed in your mother's womb and what was going on with her during that time, to early childhood development through to teen years development and even throughout adulthood ALL causes genetic code to “switch” this way or that and thus make “you” who and what you are at any given point during your lifetime.
And one of the prime and most influential “switches” that knocks a gene (or more likely a set of genes) this way or that? Stress hormones. When we start looking at the stress response system and what goes on within that, why and the “downstream” consequences, I can almost guarantee you that orgasmic 'aah-haa!' 100 watt light bulb epiphanies are going to explode in your mind. But that's for later. Back to brain evolution.
Let's return now to some very fundamental points of understanding.
One is that our brains evolved and adapted very, very slowly over millions of years. I'll get to in a moment why this is very important to keep in mind.
Two is that a great number of our brain areas and sub-regions and “hardware” evolved millions of years or hundreds of thousands of years ago and, more importantly, under conditions that bear little resemblance to today's life and current living environment. This is critical to understand and bear in mind because it is how your brain – your unique only-one-like-it-on-earth brain – is interacting with your environment that may be at the root of your emotional/mood/psychiatric problems. HUGE, HUGE thing to understand and a MASSIVE point of this blog and ebook.
Let's look at the first point in graph form. Well, two graphs.
These are not exactly the graphs I'd like to show but they were the best I could find to illustrate my point - our brains evolved over millions and millions of years prior to the population and technological explosions of the past century or so. Our environments, cultures, social structures and everything else our brains had to interact with, interpret and develop responses to evolved verrrrryyyy slowly over millions of years prior to the past century or so.
To put this rapid recent change in perspective, if we put mammal evolution (and thus the majority of our brain hardware development) and then homo sapiens evolution (higher cortical stuff) within a twenty-four hour clock, more advanced modern homo sapien brains would be about two minutes before midnight and this rate of societal and cultural and technological change our brains have had to adapt to in the past two centuries or so (going back to the time of the industrial revolution), would have taken place in the last 1/100th of a second before midnight.
There is no better adaptive species in the four billion year history of life on earth than homo sapien but that rate of environmental change vastly outstrips the pace of brain evolution and adaption. To put it another way, our brains evolved for conditions very, very different from today's world and it is not reasonable to expect them to have evolved for and adapted completely and seamlessly to today's environment. Sure there are "early adapters" and "outliers" (both evolutionary parlance for members of a species that adapt quicker) but as much as we "think" we've adapted and are handling all this change well, clearly we are not.
A big part of my argument as to why mental health disorders have exploded in the past sixty years (roughly since the fifties) is that our brains are a) not evolving to handle all this change as much as we'd like to think and a good deal of psychiatric disorders are part of the reaction to that "mal-adaption" and b) this rapid rate of change has vastly altered all the environmental, cultural and societal conditions our brains spent millions of years of adapting for and c) the most important point, is under stressful conditions, it's going to be the "less evolved portions" of the brain - the limbic region and brain stem - that in great part "takes the wheel" when we're under stress.
When we start looking at how our brains are designed and adapted for social worlds and social/family order and structure and support, we'll get a much, much clearer idea of why many of us break down in or under certain conditions. Which is what we'll be addressing in future pieces.
The final thing to understand and remember about this human evolutionary process is that it was, is and will forever be a messy business. For every evolutionary “success” there have been probably millions of failures (many of which are, of course, taking place today) and there'll be millions more. As evolution is life, what this means is that life is messy. Yes, Virginia, life is messy. This means that your life is messy. This means ALL lives, on some level at some point, are messy. Get used to it.
The goal here of course is to better guide you (or a loved one, friend, etc) through the mess.
- evolution is a slow adaptive process
- rapid environmental change over the last century or so has outstripped the brain's ability to fully adapt to new conditions
- much older brain 'hardware' and 'programs' are left over from our long evolutionary development and it is these regions that take control in many (though not all) of us during times of stress
- the human brain evolved and adapted for different stressors than we have today
- the human brain (well, all brains) evolved for more natural surroundings than our current environments provide
If you would like to know more about a different understanding and approach to mental health disorders presented in this blog, please see more at the Taming the Polar Bears Table of Contents and Reading Guide
(1) As evolution - and the study of evolution - is a constant and ongoing process, it is a process that is far from finished. The projected “life” span for earth is another several billion years so I think it's safe to assume that much evolution will continue to take place. As high and mighty as we think our particular species is – homo sapien – we're just a tiny blip in the big picture of life on earth, we will at some point pass out of existence and other life forms will evolve in our place. We can only hope that something better evolves than our current incarnation.
(2) While placing mammal brains above bird brains on the scale of sophistication is generally true it's not that clear cut either. There have been many discoveries in recent years about higher cognitive abilities in crows and that in many bird species.
(3) This is not human snobbery nor our historical human sense of superiority over other animal species, the human brain is demonstrably and functionally more sophisticated than that of any other species (our often disastrously poor utilization of it notwithstanding) and there are some key bits of neuronal hardware that human brains are equipped with which other species lack, the basics of which I hope to examine in a latter chapter.
(1) source citation coming in a future edit of this post
- A) It is this massive brain reorganization that gives rise to the dreaded "terrible twos".
B) It is possible that various critical regions can develop during this period without the crucial stimulation necessary but it is highly unlikely. It is also possible for certain aspects to be developed later in life but they'll never be what they were had they undergone the necessary stimulation in the first place
(3) We'll get to this in more detail later, but meanwhile the hardline 'genetics rules the roost' types drive me batty. Of course genetics is at the crux of all life but it is how genes are expressed or turned on or off at birth and all through our lives that creates a great deal of "who we are" at any one point.
(4) At some point I'll get around to digging into what happens in that neurogenesis process in premature babies; IE: how the neurogenesis works when the baby is already out of the womb. If the gestation period is not full term and we look at the average rate of neuronal production, migration and development that would normally take place, it simply logical to assume that a lot of neuronal development has yet to take place in a premature baby and understanding some of the specifics of that could give us some very interesting insight into what goes on and why in people who were born prior to full normal gestation. Which is by no means any kind of judgment or assumption, only another angle to look at in understanding any such person's behaviour and cognitive abilities.
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