The Little Book of Big Stuff About the Brain

The true story of your amazing brain

Andrew Curran, Ian Gilbert

• Publisher: Crown House Publishing
• Year: 2008
• Print ISBN: 9781845900854
• eBook ISBN: 9781845902094
• Topic: Education
• Subtopic: Education General

Designed as a cover to cover read which leaves the reader with a working knowledge of the human brain from its first evolution 2 billion years ago to the present day. A light-hearted look at the brain aimed at a lay audience. It especially focuses on the neurobiology of emotional intelligence and in many ways is the neurobiological explanation of why emotional intelligence is so important to health, wealth and happiness.

Chapter 1

where it all came from

So how can I start to share with you the amazing science behind the theories about your brain and how it works so that you can hopefully understand yourself better? I love stories, and for me all good stories have a beginning, a middle and an end. I plan therefore to start the story of your brain right back at the first beginning we can really get any handle on - the beginning of life as we know it (Jim).

A really, really long time ago when the first land dwelling life was crawling on probably 17 wobbly legs out of the primeval swamp, your far distant ancestor probably looked extraordinarily ugly and had all the thinking ability of a rather unpleasant, two–month–old wet sponge. In fact, that very early ancestor was very probably not something you would have wanted to take home to meet your mother.

Nature is of course interested in change and growth (by and large). So after another really, really long time the wet sponge gradually grew a nervous system (you have to have a nervous system if you are going to do any of the most basic functions - such as moving, eating, having babies, etc.). That nervous system (through a process of incredibly complex evolution) ended up as the deepest and most primitive part of your brain, the so–called reptilian brain (the green bit in Figure 1). This was the first step towards evolving what P. D. MacLean1 has called the triune brain, the ultimate expression of which is seen in you.

Figure 1
The deepest and most primitive part of your brain, the so-called reptilian brain (the green bit).

The reptilian brain is a pretty simple soul (Figure 2) and is pretty poor at responding to novel situations2^;3. It represents the most basic form of complex higher nervous system evolution and had pride of place in the evolutionary tree about 400 million years ago. It sat in the heads of the immediate ancestor of the mammals (to which you of course belong), the birds, and those most ferocious of ferocious things, the dinosaurs (Figure 3). Its entire life aim was (and is) to preserve its own existence. It did this with little concern for any other life forms on the planet. This central need for self–preservation is of course a fundamental part of all our survival - the problem with lizards is that they do it as islands of individuality, not as functioning parts of a larger social group (which isn’t a problem if you are a lizard, but is if you happen to be a human being!). And of course you still have a fully functioning, self–serving reptilian brain set deep into your brain.

It has a set of relatively primitive structures that are essential for the basic needs of being able to move, smell and see. It also carries the central structures that keep your heart beating and your lungs pumping - pretty important really for staying alive! It is these structures that are irreversibly damaged in the tragedy of ‘brain stem death’ - which I am sure you have heard about on television and in films, if not in your own life. Finally, it has a primitive form of what in you has become your amyg–dala. This very early and primitive emotional structure is to do with what are called ‘flight or fight’ reactions, i.e. either run from whatever is threatening you - or hit it4^;5! The amygdala (of which I am going to tell you a great deal more later) also carries the centre(s) for sexual arousal.

Figure 2
The reptilian brain is a pretty simple soul and is pretty poor at responding to novel situations.

Figure 3
The reptilian brain sat in the heads of the immediate ancestor of the mammals, the birds, and those most ferocious of ferocious things, the dinosaurs.

Outside these essential but ultimately basic functions the reptilian brain’s ability to perform more complex tasks is extremely limited. In fact it is estimated that in its most highly evolved state (and the well reported example of this highly evolved state is the Mexican green lizard) this brain is capable of 27 different behaviours. These behaviours (whilst they might tax the brain of my uncle Thomas at three in the morning after a good Friday night feed of drink) are not complex and involve things like moving from the heat to the shade, from the shade to the heat, and finding water. The most complex behaviours that reptiles get up to are to do with active and passive stances (Figure 4)³. These are slightly more complex and involve a small lizard crouching down submissively when confronted by a large lizard, and the larger lizard standing up aggressively. This stops the larger lizard from attacking the smaller lizard and therefore wins as a top–notch survival behaviour. In human behaviour the very same thing still goes on - after all in every corridor of power exactly the same survival behaviours can be witnessed!

Figure 4
The most complex behaviours that reptiles get up to are to do with active and passive stances.

Its desire for survival makes the reptilian brain egocentric, self–serving and appetite–driven, and it is almost certainly without a conscience of any sort. In terms of our own evolutionary tree this brain had probably reached the peak of its development about 250 million years ago, perhaps longer. As I have said from this brain the birds, the dinosaurs and we humans developed. To turn into the sort of brain a bird or a dinosaur or a mammal could use the higher parts of the reptilian brain grew in different directions. In mammals there was increasing attention to smell as a major sense and then finally the development of a complex cortex (that’s the main bit of our brain that you can see when you look at a human brain - it’s all covered in lumps and bumps and looks like a huge walnut), which of course is what finally differentiates ourselves and other primates from the rest of mammals.

Birds of course grew a birdbrain (!) and as for the dinosaurs we don’t know what their brains looked like. As all we have ever found are just the empty skulls of dinosaurs it is almost impossible to know what the structure of the dinosaur brain was from these. It is interesting to see that there is an increasing thought (as portrayed so lovingly in the Jurassic Park films) that dinosaurs may have been nurturing creatures - though for smaller creatures to be part of the nurturing process for Tyrannosaurus rex must have been a very short and extremely painful experience! This concept of the dinosaurs as nurturing, if it is correct, suggests that at least in part their brains may have developed along similar lines to our own - nurturing requires a very specialist part of the brain as I will discuss next.

The next step in the evolutionary process was to attach higher brain to the reptilian foundation. In the case of mammals this seems predominantly to have been the limbic or emotional brain (also called the paleomammalian brain) (Figure 5)6. The effect of this was to transform our rather repellent self–centred reptiles into increasingly social animals who nurtured their young and lived together in communities^2;7. Not that these early mammals set up a National Health Service designed for the egocentrically challenged but they did increasingly seem to function as co–operating individuals rather than islands in a tempestuous life. In you this part of the brain is huge and occupies a great deal of your higher cortex. In fact it has been argued that an entire layer of...

Table of contents

• Cover
• Title Page
• Dedication
• Contents
• Foreword
• Introduction: all it takes is love
• Chapter 1: where it all came from
• Chapter 2: a first look at the wiring
• Chapter 3: now we get down to the nitty–gritty
• Chapter 4: making those chemicals dance to a learning tune
• Chapter 5: the bits that do memory
• Chapter 6: why two halves make more than one whole
• Chapter 7: growing a brain
• Chapter 8: behave or else
• Reference list
• Index
• Copyright