“Left in the Dark” – The origin of left/right brain split, bipedalism, violence, big brain, and our break away from raw plant diet

‘Left in the Dark’ outlines a radical yet simple diagnosis of the human condition and brings with it the possibility of a relatively easy human scale solution. By drawing mainstream attention to the basic proposal it is hoped that it will require immediate dismissal based on evidence or lack thereof. Or alternatively it will initiate a chain reaction requiring the immediate treatment and prevention of what would inevitably be the underlying cause of our species wide insanity.

…Recent reaction from a broad spectrum of eminent academics and ‘experts’, they have all by degrees signed up for the basic proposal. Humanity is suffering from the effects of species wide brain damage. The implications are mind-blowing, if it is correct it is easily the most important discovery in recorded history as it impinges on absolutely everything we think or do


…Evolutionary biologists have long been puzzled by what is perhaps the chief mystery of human origins: the explosive and rapid expansion of the human brain in size and complexity over a vanishingly small span of evolutionary time. There is also the mystery of hemispheric lateralization and the apparent de-integration of the right- and left-hemispheric functions that we humans suffer. In this work, the authors postulate that it was not always so; the universal myth of a pre-historic Golden Age, they maintain, is a racial memory that reflects our primate evolution in an arboreal, rainforest environment in which humans possessed mental and psychic abilities that have since become lost or atrophied in the profane ages that followed. That rainforest environment favored a frugivorous diet rich in flavonoids, MAO inhibitors, and neurotransmitter precursors, and relatively low in steroid containing or X inducing elements. This dietary regime both mimicked and fostered a state, reinforced by positive feedback loops, in which pineal functions, including neocortical expansion and hemispheric integration, were potentiated; moreover, these neurochemical feedback loops were amplified in succeeding generations via the regulation of gene expression in the developing foetus, independent of conventional evolutionary mechanisms of mutation and natural selection. Climate changes or other environmental catastrophes forced several lineages of hominids as well as archaic/early humans out of their forest-dwelling ancestral home into much harsher savannah or grassland environments. As a consequence dietary regimens shifted toward roots, tubers, grass seed and a greater proportion of animal protein, triggering a reversal of the positive feedback loops that had sustained pineal potentiation and hemispheric integration in the paradisiacal, forest-dwelling Golden Age. Pineal dominance was disrupted by steroid-mediated, testosterone-driven functions primarily due to the reduced consumption of flavonoids and other steroid-inhibitory dietary factors. Changes in the dietary patterns that were forced on the population by this migration put an end to the rapid evolution of the human brain and triggered its devolution, ultimately resulting in the damaged human neural architecture that we suffer from today, and the myriad mental and physical deficits that are the legacy of our biological ‘fall from grace’.

It is not the place of a foreword to present the central tenets of a complex theory in detail; what is alluded to here is only the barest outline of an elegant hypothesis that plausibly elucidates many baffling aspects of human evolution, brain science, and physiology into a coherent explanatory framework. Ecologists have realized for several decades that the complex interrelations of plants and insects are largely mediated through plant chemistry, and that the interactive dynamics we can observe in these processes is a reflection of millions of years of plant-insect co-evolution. Evolutionary biologists have long suspected that similar co-evolutionary processes, mediated by interactions with plant secondary products, have influenced the evolution of vertebrates, including primates. The hypotheses presented in this book are incomplete, and are even now being refined and developed; however, even in their present form they present a credible foundation on which to build a better understanding of who we are, and how our puzzling human species got to be the way it is.


One evening, about half way though writing this book, I had a game of table tennis with my teenage daughter. We were both feeling a little stressed from our respective days. We wanted to talk and table tennis often helps the two-way communication. Something about hitting the ball to each other enhances communication. On this occasion it wasn’t quite working so on a whim we both swapped hands. We began to play left-handed. The change was immediate and very apparent. We both became calm, tension dropped away and the peaceful atmosphere that ensued was quite palpable. We looked at each other and were amazed at the difference. I knew at that moment that Tony and I were on to something that was not a mere scientific or intellectual curiosity but something real and profound.

Tony has been working on the issue of brain organisation and perception for over fifteen years, and we have been collaborating since 2002. His role is inspiration and research, mine translation and scribe. The theory presented in this book has grown and developed during this time, and it is heartening that, every week it seems, research is appearing that not only fits but also supports this new paradigm. We are in contact with many of these researchers who have offered help and encouragement, and we are especially grateful to those who have added their comments here.

The pivotal moment for the thesis came in 1995 after Tony spent three days and nights awake. His over-stretched left hemisphere fell asleep leaving his right awake, functional and free of the left’s influence. The next twenty minutes were not only euphoric but also deeply intriguing. During this brief window he investigated the capabilities of his unhindered right hemisphere and found its perceptual abilities superior to his normal self. This experiential research confirmed Tony’s initial ideas of laterality and brain function, the implications of which are far-reaching. We could all be suffering from an evolutionary glitch that has affected how we perceive, think and behave.

If we look at our global society, it is apparent that all is not well. Despite good intentions and attempts at cooperation, we live in a very fragmented and violent world. There is war and genocide, we are inflicting havoc on the only planet that sustains us, and we are having increasing problems with interpersonal relationships. It seems we are incapable of behaving anywhere near the ideal we would like to maintain. These problems are becoming more intense in our present era as increasing population and dwindling resources exert more and more pressure.

The Golden Age

It was not always so…. The Greek philosopher Dicaearchus, of the late fourth century BC, tells us more – god-like men lived a life of leisure, health, peace and friendship, without care or toil, or the desires that lead to feuds and wars. ‘Their life was easy for their food and all things grew spontaneously.’ But these halcyon days came to an end – there was progressive degeneration…. Now, as is very apparent, we are afflicted by disease and suffering. Men have turned to wickedness, decadence and materialism. There is pain, sorrow, continual dissatisfaction and craving.

The Fall of Mankind

Nearly every culture has a tradition about this fall of mankind. In almost every one it came about because man strayed from the way of the gods. Adam disobeyed God’s instructions and ate the forbidden fruit. In a Zambian myth, the first man, Kamonu, started to kill the animals created by the god Nyambi and was then forced from his garden. And the Hopi say that when the people began to depart from the instruction of the Great Spirit:

There came among them a handsome one [] in the form of a snake with a big head. He led the people still further away from one another and their pristine wisdom. They became suspicious of one another and accused one another wrongfully until they became fierce and warlike and began to fight one another.’

Richard Heinberg in ‘Memories and Visions of Paradise’ says: ‘ nearly every tradition ascribes the loss of Paradise to the appearance of some tragic aberration in the attitude or behaviour of human beings. While in the Golden Age they had been ‘truth-speaking’ and ‘self-subdued’, living with ‘no evil desires, without guilt or crime’, they now succumbed to suspicion, fear, greed, mistrust and violence.’ Something happened which resulted in the loss of a former state of divine beingness. In its place arose the state of fear, mistrust and craving which has led to all the woes that we are experiencing today. Paradise has been transformed by our machinations into our present materialist, fear-based age of plastic and prozac. Could these myths actually be a cultural remembering of a time when we really were perceptually more complete; to a time in which there was less fear, less violence, less craving and more contentment? If so, today, in an age characterised by so much distraction, we have truly forgotten what we were and who we are.

Two Perspectives

The mythic traditions of paradise allude to our naked, forest-dwelling, fruit-eating past. Various cataclysmic disasters portrayed in tales of floods, vulcanism and meteor impact brought the days of perfection to an end. These disruptive, earth-shattering events initiated a change in man too – a single divine self was split into two and the more fallen, delusional self assumed overall control. The impetus to treat this condition and the ingenious techniques devised to access the suppressed ‘god-side’ of man gave rise to religions.

These ancient traditions are mirrored by our scientific view of the past and present. Anthropologists tell us that our direct ancestors lived in the tropical rain forest – and our closest relatives, the fruit-eating apes, still do. Various disciplines, including climatology and palaeontology, have found that the evolution of many forms of life have been profoundly affected by repeated ecological catastrophes. And from the sciences of neurology and psychology we know that we have two distinct selves. The latest research in this field is now revealing that the dominant side is perceptually limited and continually makes up confabulated tales to cover its fractures of reality. The dormant side, in contrast, has exceptional latent abilities – even its capacity for pleasure is more encompassing.

It is a deeply held scientific assumption that humans not only represent the pinnacle of evolution but that advance proceeds apace. This view however is in conflict with observed behaviour – our inability to harmoniously coexist with each other and the increasingly rapid exploitation of the earth suggests we really are suffering from a psychological malady. The two versions of human history – one poetic, contextual and right brained, the other analytical, rational and left brained – are remarkably similar. The only significant point of disagreement is degeneration verses advancement. Currently the advancement argument holds sway, yet evidence from both versions suggests that this interpretation is flawed. If the side that has reached this conclusion has been negatively modified in some way – can we trust its judgement?


Two Sides To Everything

An investigation into the characteristics of the left and right sides of the human brain reveals certain anomalies. Facts about how our brains work coupled with such oddities such as handedness, sleepwalking and religious experience are all clues to a ‘second system’ hidden within us that has a higher level of abilities than we realise. A new theory of how this may have arisen explains why accessing this second system is not straightforward. Over the course of our evolutionary history we have suffered a deleterious change in our consciousness that has affected not only how we act but also who we are. The consequences of this are far-reaching.

… What is becoming clear is that the human mind has untapped powers. The new theories outlined in this book offer unique insights into these latent abilities, how they arose and why accessing them today is problematical.


Fig 1a: the double brain

Before proceeding further we need to understand a few fundamentals about the structure and function of the brain. Animal brains are basically dual structures. As far as we know both sides are essentially alike in structure and function. There are differences but in humans and to a lesser extent some ape brains, these are more significant. Some change has occurred in our evolutionary history. Although the two hemispheres of the human brain look like reciprocal halves of a soft grey walnut there appear to be differences in what each can do. Certain functions, most notably speech, seem to be lateralised. Although our understanding is Left Hemisphere Right Hemisphere continually being upgraded, it is broadly accepted that logical concepts like time, sequence, speech and language are largely handled by the left side, and creativity, spatial awareness and pattern recognition by the right.

…Despite feeling that we are a single unified self, our two contrasting hemispheres each have their own way of perceiving the outside world. The extent of these differences in perception is enough to suggest that we have two separate minds, and, in a way, two distinct selves within each one of us

…The function for speech is located in the left hemisphere in 98% of right-handed people and over 65% of left-handers. As speech is closely associated with the way we think and reason, the left hemisphere became known as the dominant or major hemisphere. This view was reinforced when it was discovered that the movement of the right (usually dominant) hand was also controlled by the left side of the brain.

While the two hemispheres can co-operate with each other, each half contributing its particular abilities to the task at hand, there are times when the two sides are in conflict. …the left has become the major player. It in effect keeps the right shackled.

…In our western society we value speech particularly highly. We are excited by the first words our children speak and actively encourage them to name things. Then, for the rest of their childhood we tell them to ‘hush the noise’ and ‘turn down the volume control’. Eastern, African and Native American peoples have a quite different cultural view of language. There is a much greater trust in reading a person’s wants and intentions through facial expression and actions. There is a distinct preference to communicate with small children via body language and touch rather than words. Rather than relating from a distance (talking to the baby in a cot), these mothers will hold their babies close and feel their needs. Some peoples, such as the Gusii of Kenya, will talk to their babies much less than we do in the west. Their children will learn to speak at a later age than western kids do but they catch up in the end and the slow start gives them a chance to develop greater body awareness. Perhaps in our modern societies we have either lost or cannot easily access an ability to listen to the body due to the over dominance of the language system.

Free from the left

Advanced research techniques that are now coming on stream are beginning to reveal that the right hemisphere actually has the capacity for a much greater function than ever imagined. Ideas of left hemisphere superiority are falling by the wayside. The new orthodoxy is that both hemispheres have an equal level of complexity but differing functions. However there are clues that could tip the balance the other way.

It has been found that there are chemical and pharmacological asymmetries between the hemispheres…

Even more startling research is beginning to show that the right hemisphere, if somehow freed or decoupled from the left hemisphere, has latent abilities that exceed what we usually regard as normal…

…Betty Edwards, in her popular book ‘Drawing on the Right Side of the Brain’, summarises the left-brain function very succinctly.

‘The dominant left verbal hemisphere doesn’t want too much information about the things it perceives – just enough to recognise and categorise. The left brain, in this sense, learns to take a quick look and says, “Right, that’s a chair (or an umbrella, tree, dog, etc.).” Because the brain is overloaded most of the time with incoming information, it seems that one of its functions is to screen out a large proportion of incoming perceptions.’

…In everyday life, we all come across examples of the left hemisphere imposing a kind of rigid censorship on the right. Most of us know individuals who are otherwise intelligent and apparently high functioning, but have a total inability to sing, draw or paint. This complete lack of artistic ability is sometimes called a mental block, and it may literally be true. The block may be coming from the left hemisphere exerting too much dominance over the right.

…For now, we may conclude that the left hemisphere is dominant, not because of any superior skills, but simply because it is suppressing the right. This strangulation may not only cause the right brain to become atrophied through under use…


Handedness is a unique feature of humans. It is a physical symptom of the dominance and preference of one side over the other. The body is mainly connected via the nervous system to the brain in a crossed-over way. Thus the dominant left hemisphere controls the right side of the body including the right hand while the right hemisphere controls the left side. Most people are right-handed because in most people their left hemisphere is the dominant one. However, this control can be overridden. In cases of damage to one hemisphere or even the removal of one side of the brain, the remaining half can take complete control of both sides of the body.

While most people are right-handed, there is a variation in the population. Some can use both hands to a greater or lesser degree, and some are genuinely left-handed. About 90% of people are right-handed and 10% left…

Although the use of a preferred hand is the most obvious difference between left and right-handers, it is not the only difference. Left-handers show less lateralisation than right handers…

Thanks to some very meticulous research, carried out in California by Roger Sperry and his students, we now know much more about how our hemispheres operate. Sperry has done groundbreaking work showing that we have two types of reasoning skills – verbal and non-verbal. As the term implies, verbal involves language, non-verbal involves other abilities such as pattern recognition and spatial awareness. He has demonstrated that verbal and non-verbal skills are controlled by the left and right hemispheres respectively…

… The degree of preference for one hand increases throughout childhood. Young children are generally ambidextrous but from around the age of four one side becomes more dominant. Lateralisation is usually complete by the age of ten and this is marked by changes in how the brain operates. From an analysis of children’s art we know that, at around ten, the concept of what a thing looks like takes precedence over direct observation. The left hemisphere’s way of processing based on classification, words and symbols takes precedence over spatial and holistic perception. It appears that the activity of steroid hormones, which increases as we get older, plays a part in these changes….

Accessing the right brain

…Whilst day dreaming, we are in at least partial right hemisphere mode. We access it when we are absorbed in activities like playing instruments and listening to music, when we are lost in painting and unaware of the passage of time and when we are in a beautiful landscape and it seems that time stands still. Moments like these have been termed ‘peak experiences’.

… Why does reducing the influence of our left hemisphere in favour of our right have such a positive effect? If the left hemisphere is so much the complete and sophisticated side of our brain, why is it apparently such a relief to escape its mode of function and flee to the right side? There is something of fundamental importance here.

Is handedness helpful?

… there are no plausible theories to explain handedness in terms of evolutionary selection pressures. It is more logical therefore to assume that handedness is a by-product, and not a very useful one, of cerebral dominance. Because we blindly assume that humans are now at their highest development, handedness is regarded as a positive trait – something inherently human and so, naturally, good. But it could be argued that handedness is a symptom of dysfunction – an indication of a flaw in the human make up.

Interestingly, there is some evidence that deliberate manipulation of normal brain function can shift the body towards a greater ambidexterity. For example, significant alterations of handedness occur when the brain is deprived of sleep. Sleep deprivation experiments have shown that the left hand (in normally right-handed individuals) can be used with increasing ease and ability with increasing hours of sleeplessness. There appears to be a cross over point in which the mind is confused as to which hand is dominant but this then settles into a more balanced ambidexterity. It becomes easy to move the hands and arms in synchronicity. The lack of sleep then seems to suppress the left hemisphere allowing an evenhanded state to emerge. This disappears as soon as normal sleep patterns are resumed, reestablishing the dominance of the left hemisphere.

… If handedness is not a result of human evolution then perhaps it is a symptom of some sort of imbalance or malfunction.


Scientific literature suggests that the lack of sleep can be dangerous. Medical evidence indicates it can cause psychosis and even death but this is by no means the whole story…

Dr Tomatis believes that the need for sleep is exaggerated. His findings suggest that the cortex needs constant energy inputs via sensory intake and, as most people don’t have enough mind stimulating activities, they turn to sleep as an escape and a refuge..

Reducing sleep has been used as a positive tool in many spiritual contexts to alter states of consciousness. Many religious traditions advocate the use of short or extended periods without sleep in order to access spiritual insight and such practice is even hinted at in one of the most ancient texts of all – the Sumerian Epic of Gilgamesh:

Who will assemble the gods unto thee, that thou mayest find the life which thou seekest? Come, do not sleep for six days and seven nights.”

…Sleep deprivation and spiritual practice come together in some form in most religions. Buddhists regularly engage in all night periods of meditation (linked to the lunar cycle) and most monastic traditions have some restrictions on sleep, usually starting observances before dawn. The Buddha himself attained enlightenment after, according to one account, spending seven days and nights awake, in deep meditation, under the Bodhi tree. In North America too, the vision quests and sun dances of the indigenous people entail days and nights of continual practice… Could it be that an explanation may lie in a differential requirement for sleep between each half of the brain?

If the right hemisphere needs less sleep than the left then it follows that a normal level of sleep is necessary to maintain the left hemisphere’s function, including its dominance. Reducing sleep may therefore be a means of exploiting this weakness. By starving the left hemisphere of its recharge time for long enough to run its ‘batteries’ down, its overall function may decrease along with its ability to suppress and maintain control. The opportunity to stimulate and reengage the potential of the right hemisphere, whilst free from this control, may be the basis of many powerful techniques used, in the past and present, to achieve higher consciousness function…

One of the authors (A.W.), for over a decade, has personally experimented with up to eleven days and nights of sleep deprivation. On one trial (over eighty hours spent awake) he experienced an extraordinary change of perception that he describes as ‘all-encompassing religious bliss’. He believes that for a period of about twenty minutes the left side of his brain went to sleep leaving the right side awake and functioning freely. This conclusion was reached from other incidental affects such as an initial block that prevented him from talking. After some internal mental investigation, that seemed far from rational or linear, a few grunts and broken syllables started to emerge. And when the speech mechanism was restored, there were several interesting differences. The voice sounded more resonant than normal. There was expression without the precursor of thought and there was some poetic element to its structure too.

When a more normal sense of consciousness returned, the quality of the voice changed and so did the syntax. The euphoria dampened a little too. There was still tremendous joy but, in parallel, there was a sense of confusion and bewilderment. Something wanted to know what had been going on. The self that had been to sleep felt it had missed out on something. When it woke up it wanted to find out who had been running the show.

…It appears that by limiting the amount of our sleep we may, under certain circumstances, be able to reengage these lost abilities.

Hidden Potential

Over the following weeks, as A.W.’s sleep deprivation experiments continued, other abilities emerged, which were consistent with greater access to right brain functioning. The first was an ability to juggle, coupled with a change in visual perception that allowed the track of all the balls to be followed simultaneously. Not a huge scientific breakthrough perhaps, but interesting nevertheless because juggling does require a complex level of co-ordination. It is the sort of task the left brain with its step-by-step mode of functioning has great difficulty with. This type of ambidextrous ability was tested at a later date during more formal sleep deprivation trials.

Another associated change noted was an enhancement of peripheral vision. Number plates of cars could be read as they sped by and full on vision was enhanced too. When looking at trees, the perception incorporated all the leaves and the shapes of the leaves in detail and at once. There was a heightened awareness and clarity. It seemed that the filter the left brain imposes on perception was beginning to be by-passed.

Around this time, childhood memories were experienced at a profound and exquisite level too. Details of the patterns of carpets and curtains, smells and even emotions felt at the time were almost fully brought back to life. Accessing such vivid memories, though unusual, can occur spontaneously. Some shamanic traditions hold that we all can remember everything that has happened to us in great detail. They tell us that if certain techniques are engaged we can virtually relive events from our past. These techniques that in some respects parallel meditation, quieten the left hemisphere’s sense of self and by sweeping the head from side to side engage the right to allow the deeply buried memories to emerge. This procedure indicates that the most functional and deepest part of our memory lies either within our right brain or is accessed via its function. Because our (less efficient) left brain is dominant, we routinely experience difficulty accessing more than our superficial memory. We are dominated by a part of our brain that either filters out the detail or doesn’t retain it.

…A similar heightened ability can be accessed with sound. Occasionally a piece of music can be heard with ‘different ears’ and every note and phrase takes on heightened clarity, relationship and meaning. Perhaps all it takes to tap into all these latent functions is a suppression of left hemisphere dominance. If we can develop and expand the techniques for doing so maybe we can all gain glimpses of a different kind of mental processing. Reading pages of text in an instant and listening to several conversations at once may be just the tip of a fascinating iceberg. Right hemisphere function may include telepathy, direct knowing, a highly developed intuitive ability, enhanced immune function and, most importantly, a wholly different sense of self.


Of all the many extraordinary abilities and powers that humans apparently possess, one of the most controversial yet fascinating is telepathy. Many scientists dismiss the phenomenon but subtle two-way communications have been well documented between mothers and children, twins, sisters and others near relatives. This ability has been kept alive to a much greater extent in the Australian Aborigine population and by the African Bushman. Aboriginal people prefer to walk together in total silence because whilst walking they speak in the ancient way with ‘telepathy’ rather than voice. When they feel a sense of anxiety, they may sit down and enter a meditative state. Each part of their body is associated with a relative or a geographic location. When a part twitches, by touching that place they can visualise what is happening to the relative or at the location. These practices have been repeatedly observed by anthropologists to be accurate and effective. Perhaps the main reason this means of communication is not experienced more widely within our western culture is because it is blocked by the business in which we are usually immersed. We may be convinced too that these functions are beyond the normal range of human ability – thus any unusual experiences tend to be dismissed. However in such cultures where these communications are commonplace, access just takes concentration and the ability to still the internal dialogue…


To investigate some of the issues around sleep and enhanced body/brain function, a pilot study under Professor David Collins took place in September 1998 at Manchester Metropolitan University. Two subjects (including A.W.) stayed awake for five days and four nights while being tested and monitored round the clock. One further element to the experiment was that the two individuals had for a number of years been maintaining an almost exclusively raw diet, rich in fruit. We will be returning to the chemical and evolutionary significance of ancestral diets in the next chapter, but this unusual combination of factors meant that this experiment was unique.

It was expected that the longer these two subjects were deprived of sleep the more they would exhibit decreases in co-ordination and functional ability, however this did not occur. In fact some abilities actually increased as the experiment progressed. Professor Collins, who was trained in the military to deal with the affects of sleep deprivation, was surprised for this was not what he had found before.

During the five-day experiment stamina, physical abilities, co-ordination and mental responses were investigated and breath (gas analysis), heart rates and brain activity (EEG) were monitored. These trials were repeated at three hourly intervals around a 24-hour cycle and, once a day, brain activity was further checked using co-ordination trials. These tested the response to written instructions that appeared on a screen. For example the word ‘green’ would flash and the response would be to hit the green button.

Physical tests included jumps to measure height reached, and bouncing a ball against a wall, catching it alternately with each hand to measure co-ordination (this was timed). There were specific tests for left and right hands too. One involved putting pegs in a board; the task was timed for each hand. The results for all these tests were, from a standard viewpoint, unexpected. For instance, in the pegboard experiment initially the right hand was quicker but as the experiment proceeded the left hand improved its performance so that overall it actually achieved the faster times. Another test involved balancing on a ‘seesaw’ device. This was difficult and to begin with the plank just crashed from one side to the other. It took much effort to achieve any sort of balance at all but on the last day of the trial A.W. stood up and balanced perfectly. This puzzled Professor Collins for he had found in the past that balance was one of the abilities that markedly decreased with tiredness.

… the overall results from the other tests show dexterity, strength and co-ordination increased rather than declined. It appeared that sleep deprivation in conjunction with a raw food diet was responsible for an unexpected and anomalous result.

Previously Professor Collins had worked with athletes who had achieved highly unusual and enhanced ‘once in a lifetime’ performances. These athletes described their mental state at these times in almost mystical language. They reported transcendent, fluid and flowing states. As such descriptions are more often associated with ‘religious’ experiences that occur when the left hemisphere’s influence is reduced, it might indicate that the phenomenal performances could have involved a similar neural crossover.

…The sleep deprivation experiment provides additional evidence for this thesis – higher performance is accessed when the right brain takes over from the left. It appears that the nutritional input was a factor too. Could the biochemistry of something that approached a human ancestral diet have helped reactivate right hemisphere function?…


…Let us assume that sometime in the past the neo-cortex was effectively a single consciousness system: that is, there were no marked structural and functional differences between the two hemispheres. It was just one whole brain. At some point in time, however, something went wrong and damage was sustained to this highly sensitive system. This resulted in a progressive change in the most delicate structural components of the brain and this, in turn, changed the very nature of man’s experience – it altered his consciousness. In simple terms, the evidence we will present suggests that the human brain has suffered a significant long-term decline in structure and function. The damage is primarily restricted to the dominant half of the brain. This has created a distorted experience not so much of the outside world, but of the inner world – our very feelings of who or what we are. This is a mental state that is extremely hard to escape from. When the escape does occur it is usually brief and transient, but it can be profound, often being described in terms of bliss or religious ecstasy. A very different sense of self can emerge in conjunction with these experiences – a much greater, all encompassing sense of oneness that is described in some form by all religious traditions. Many of us may have some inkling of this other state but it is unfamiliar and far from our ‘normal’ consciousness. That it exists at all, and is almost always regarded as positive, could indicate that the equipment we use to assess how we feel or what we experience is flawed. As our immune system, hormone system, and just about everything else is effectively run by the brain, this represents a somewhat disturbing picture… the damage starts and is at its greatest in the earliest phase of development in the uterus, but it continues throughout our lives, rapidly accelerating with puberty in males and, to a lesser extent, menopause in females. Damage may be slightly greater in males as more testosterone is produced. It is also pertinent to note at this stage that the activity of steroids like testosterone are ameliorated by biochemical elements that were present within our ancestral diets and are still present in fruit.

If there is the slightest possibility that our self-perception equipment is indeed damaged, then not regarding its repair as an absolute priority would perhaps be the most telling symptom of the severity of that damage. It is quite possible that with a restored consciousness system, perception would be more vivid, tastes enhanced, vision brighter, sounds clearer and we would become far more joyful. It would feel sensual just to be in the body and our physiology, from the immune system to digestion, would run more efficiently too… We might find we had other abilities too. In a study on the mystic traditions of the aborigine people, the eminent author and anthropologist A.P. Elkin gathered compelling examples of higher ‘psychic’ powers. These included clairvoyance, telepathic communication, remote viewing, psychic healing, and journeys to other worlds. The fact that all these have been reported from other cultures too indicates they are part of the human repertoire. Instead of regarding such powers as abnormal perhaps we should ask whether our inability to access these things today points to a genuine decline in our functioning.

Is it possible that we really do possess an alternate self that has a greater range of abilities…


From The Forest

The ‘Left in the Dark’ theory offers persuasive new explanations for the rapid enlargement of the human brain, our hairlessness, the length of our childhood, why we walk on two legs and our aggressive nature – questions that have perplexed researchers since Darwin. Strong evidence is also presented that shows for a crucial period of our evolutionary history our distant human ancestors were primarily forest-dwelling fruiteaters, not animal hunters, as is commonly supposed. Archaeological research, primate nutrition and human anatomy all point to the same startling conclusion.

Primates evolved, diversified, came, went, lived, still live, reproduced and ate in the forest. Primates have arboreal origins and, in the very distant past, the lineage that gave rise eventually to the higher apes switched their diet from an insect-based one to one based on flowers, leaves, shoots, nuts and fruit. This may have happened in the region of 70 million years ago. Primates in general have certain traits that include a larger brain to body ratio than most other mammals. Can this be linked to this change of diet?

Other groups of animals show a similar correlation. Fruit bats have a larger brain/body ratio than their insect eating relatives (up to twice the brain size) and so do parrots. The intelligence of these birds has led researchers to jokingly classify them as ‘honorary primates’ because their ability to categorise objects and grasp abstract concepts like the similarity of shape and colour rivals that of chimpanzees. Species of primates that have a high percentage of fruit in their diet tend to have proportionately larger brains than do their cousins that eat a more leafy or omnivorous diet. These examples clearly show that changing from an insect based diet to a fruit one is linked to an increase in brain size.

The primates that ate more fruit and came to depend on fruit would of course have to live in the forest because this is where fruit grows. In the warm wet climate of the tropics there is little seasonal variation and so trees such as figs could (and still do) provide fruit all the year round. Along with nectar, fruit by its very nature is a ‘free lunch’ provided by the plant kingdom. It is designed to be eaten, its quality as a food is a reward for seed dissemination and it can be gathered with relatively little effort. It is the most obvious food source for primates and hominids, and, as we will detail later, the fossil evidence of hominid dentition strongly suggests fruit was the most important element in their diet. Fruit is a very good food source. It is rich in nutritive value, easily digested and low in toxicity. The normal mechanisms of evolution would have acted on both primates and tree species so that they became adapted to a life of inter-dependence.

It is of benefit to the fruit trees to make the fruit as healthy a food as possible. Healthy primates mean better seed dissemination – thus there may have been degree of co-evolution at work here. If certain fruit, for instance a variety of fig, not only tasted better but made the hominid feel better then this variety would have been selected more often and hence dispersed more efficiently. (This scenario is entirely plausible for figs contain chemicals that elevate neurotransmitter activity, which can in turn affect a hominid’s mental state.) If the chemicals in the fruit also enhanced neural expansion, a feedback mechanism may have been initiated; more fruit means more fruit biochemistry means more neural expansion and more fruit dispersal. Selecting only the more powerfully loaded fruits would fuel this process even more. The hominids may have unwittingly managed the forest environment by selecting and dispersing the most beneficial fruits. With more chemically rich fruit available, the more fuel there would be for acting on the hominid’s neural system. A mechanism such as this could have led to a very rapid evolutionary leap.

There would have been dozens of different lineages and dozens of branches on the primate tree of evolution; some are known, some are waiting to be discovered and probably many more will be forever lost in the mists of time. But the key ingredient on the branch or group of branches that lead to the hominid line was a dietary specialisation on fruit and this necessitated a life in the forest. Unfortunately for the hominid researcher, animals do not tend to fossilize in tropical forest environments. This is a point worth emphasizing. If no fossil hominids have been found in tropical forest environments it does not mean they were not there. No fossil chimps and bonobos have been found in this environment either and they definitely were there, and still are, eating a mainly fruit/plant based diet.

The current model of human evolution is based on a very limited number of fossil finds, while the fossil record of the great ape ancestry is almost entirely absent. (In fact there is not enough fossil evidence from human and hominid lines to categorically prove this or any other hypothesis of human evolution.) This gives credence to the hypothesis that the fossil remains of hominids that have been discovered represent populations that left the forest, but it in no way discounts the notion that a source population remained in the forest. If no remains of the forest apes survived as fossils, why should remains of forest humans? The fossil remains that we do have are likely to represent humans that had spent many generations out of their optimum environment and as such cannot give a true representation of what was really happening in the forest. The rather simplistic theory of hominid descent, that is implied rather than stated, is that the Ramapithecines were the ancestors of the Australopithecines that were the ancestors of the Homo line. Within the Homo line there was Homo habilis that was the ancestor to Homo erectus that in turn was the ancestor of Homo sapiens; ‘A’ leads to ‘B’ leads to ‘C’ etc. We suggest another pattern that maintains an evolving population within the prime forest area from which offshoots emerge. Species ‘A’ in the forest evolves into species ‘B’ which remains in the forest but an offshoot of ‘A’ emerges onto the savannah and its remains are fossilised and later given the name Ramapithicus. An offshoot of species ‘B’ leaves the forest and its fossilised remains are given the name Australopithicus. Thus the few fossil remains of hominids that have been discovered represent waves of evolutionary ‘dead ends’ (as far as continuing brain expansion is concerned) that left the forest. Many different lines of temporarily successful hominids could have followed this evolutionary route. Meanwhile the hominid lineage that lead to Homo sapiens continued to develop back in the fruit-rich, leafy and womb-like environment.

We propose that from the earliest days of primate fruit eating, the chemicals included in the diet started to short circuit the normal evolutionary mechanism. The chemical cocktail that is present in fruit started to modify the way our genetic blueprint was actually read and interpreted. (This process is known as transcription.) Powerful biofeedback loops were created which affected assimilation and biochemical function. DNA transcription would have been affected directly, very gradually at first, but at some later point a critical mass was reached which initiated rapid and profound changes. Juvenility was extended and brain size increased markedly as a result of this new biochemistry.

This was not merely a nutritional effect that fluctuated with season and whim. A specialist fruit diet provided a small but constant flow of these active bio-chemicals. They were present all the time, through countless generations, and significantly the chemicals would have influenced foetal development during pregnancy. As far as the primate’s internal chemistry was concerned, it could have been an internal gland producing these physiologically changing chemicals for they were so continually present.

These primates were plugged into the tree biochemistry continuously and over millions of years. (External oestrogen-like chemicals in our present environment are causing biochemical changes in both humans and other animals today. This is a similar effect and confirms this mechanism is not merely theoretical. For example, some river fish have been found to become hermaphrodite in response to pesticide run-off, and it is possible that the sperm count in men is dropping due to residues of birth control pills that end up in our water supplies.)

Each genetic line would respond to this continual biochemical intake in a different way. Each line would be unique – a subtle variation on the model. There could have been hundreds of genetic ‘starting points’ and hundreds of different outcomes. Specialising in fruit eating is not a magical route that is going to automatically result in the development of a brainy super-hominid. But as traits such as increased brain size and extended juvenility are seen to a greater or lesser extent in the higher apes as well as hominids, it appears that the correlation between brain size and fruit eating is strong.


The continual assimilation of the chemicals found in tropical fruits would have had a direct affect on the mechanisms of juvenility. If there was an inhibition of the internal mammalian hormones that normally built up to a level that triggered sexual maturation, profound and rapid change could have occurred. If, for instance, sexual maturity were delayed for a year or two a very different animal would emerge for the whole neuroendocrine system would have had a longer period to grow and develop beyond its previous parameter. This hominid with a longer juvenile period would be different to its ancestor that wasn’t eating this chemically rich diet. Though the neuroendocrine system (the system ultimately controlled by the brain that produces hormones) itself plays a central role in the regulation of juvenility, the forest fruit, we hypothesize, introduced a gremlin into the works. It effectively caused an extension of the juvenile period as well as changing the very mechanism that regulated the juvenile period. This led to a fast track of evolutionary change.

Could this have actually happened? The evidence suggests that it may have done. We know that within humans today, the period of rapid brain development ends at puberty. It would have been no different in our distant past. We also know that the chemicals present in fruit have the ability to suppress the steroids that induce sexual maturation. Thus their action could have created a window of opportunity for additional brain development. This would have resulted in a primate with a modified neural-endocrine system, for a bigger or more developed brain would run this system in a slightly different way. The progeny from this hominid with the bigger brain would in turn be exposed to a changed internal chemical regime. Not only would the foetus be exposed to a changed environment in the uterus (because its mother has a modified neural-endocrine system), but also the resulting brain would pump a slightly different complex of chemical messengers itself. The effect could therefore build with every succeeding generation creating a lineage with an increasingly modified biochemistry, which would build individuals with an increasingly different structure and function, even though there had been no change in the DNA codes.

So the diet of forest hominids could indeed have caused an extension of the juvenile period and this would have allowed a longer period in which the brain could grow and develop which would presumably have provided scope for enhancement of function. The pressures and opportunities that resulted from these primary changes would have led to other adaptive developments. A longer juvenile phase could have led to an increase in height because the major period of bone growth and particularly bone lengthening occurs at this time. And this may have had further consequences; an arboreal life style could have been progressively restricted because a taller, long-boned hominid would not have been quite so agile in the trees. A bigger brain would have needed more time to develop in the uterus before it could function outside; thus we can speculate that there would have been an extension of the gestation period too. A bigger brain would have led to a bigger head size, but head size couldn’t increase beyond the limits imposed by the constrictions of the birthing process. So a maximum gestation period would have been reached. If the gestation period became any longer and the foetus any larger, the birthing process would no longer be feasible. (As it is, humans appear to have more difficulty giving birth than other animals.) But with such a large and complex brain, this available period of gestation would not have been long enough to complete the brain’s development. In the higher hominids, this would have led to a situation in which the infant’s brain would not have been fully functional at birth. At birth, the infant would have still been in a prenatal state that would necessitate an increased level of maternal care. This would have created behavioural and physiological pressures. These pressures would have been present to some degree in the early, smaller hominids but they would have been increasingly significant as body and brain size increased.

The period of pregnancy, the size of the baby, its helplessness at birth, and for an extending period of time thereafter, would have put many demands on the mother but in effect, on the whole troupe/social group as well. Solutions to these pressures may have been varied but in one or more lines of hominids, bipedalism may have been an answer. Standing and walking upright may have been a response to dealing with the extended postnatal stage. Uniquely in the later hominids and especially in humans, the foetal stage in effect continues after birth. A large helpless baby needs to be looked after and protected. It would have become increasingly difficult for the mother to carry this helpless and growing child around in the trees, so a sustained period on the forest floor may have been a likely option. Because human babies are helpless for so much longer than the infants of closely related primates they became proportionately more demanding for longer. Solutions to this enforced ground-dwelling phase need not have included bipedalism but this mode of locomotion does have some advantages in these circumstances. And almost certainly it was a necessary precursor to maximum brain expansion. It is not the only solution however; chimpanzees sometimes walk rather inefficiently on two legs part of the time, so partial bipedalism or continued four-legged locomotion would have been the preference of some primates. But becoming upright could have been an efficient solution to a burgeoning problem. Walking on two legs frees up both arms to carry the infant. It increases the visual range, a helpful adaptation on the less secure forest floor, and it allows both hands (in the case of the mother one hand) to be used for foraging.

Bipedalism may have even been a response to a flooded forest floor. The Congo River basin, the home to our closest living relatives, has areas that become seasonally inundated with water. The Amazon, the Congo’s sister system in South America, has a total forested area the size of Great Britain that is flooded for six months of the year. Could such a habitat have provided an impetus towards walking upright? Elaine Morgan in her thought provoking book ‘Scars of Evolution’ sets out the case for an aquatic phase in the evolution of hominids. The so-called ‘aquatic ape theory’ does have some elements that are intriguing, though more for the questions it raises rather than its ultimate conclusions. For instance, Morgan identifies many of the structural and functional problems of walking with a perpendicular spine (spinal compression, back pain, inguinal hernia, varicose veins and haemorrhoids) that would be partially ameliorated by spending large amounts of time wading in water. She then goes on to point out that:

‘Walking erect in flooded terrain was less an option than a necessity. The behavioural reward – being able to walk and breathe at the same time – was instantly available. And most of the disadvantages of bipedalism were cancelled out. Erect posture imposes no strain on the spine under conditions of head-out immersion in water. There is no added weight on the lumbar vertebrae. The discs are not vertically compressed. (An astronaut in zero gravity gains an inch in height in the first days in space, and immersion in water is the nearest thing to zero gravity on planet Earth.)

In water, walking on two legs incurs no more danger of tripping over and crashing to the ground than walking on four. There is no distension of the veins because immersion in water prevents the blood from pooling in the lower limbs. Water thus seems to be the only element in which bipedalism for the beginner may have been at the same time compulsory and relatively free of unwelcome physical consequences.’

If the pressures we alluded to earlier were forcing our hominid lineage to spend more time on the forest floor and that forest floor was flooded for part of the year, perhaps there was a need to wade through water to access the fruit trees within their territory. But could this provide a pressure that resulted in bipedalism? We feel it is unlikely, though undoubtedly an upright stance would be of benefit in these circumstances. The theory perhaps makes more sense than the orthodox view that tries to bamboozle us into believing that, several million years ago, a population of apes or early hominids, living on the savannah, chose to stumble around on two limbs instead of running easily, like chimps and baboons, on four. Elaine Morgan again asks could they have:

‘… stood up, with their unmodified pelves, their inappropriate single-arched spines, their absurdly under muscled thighs and buttocks, and their heads stuck on at the wrong angle, and doggedly shuffled along on the sides of their long-toed, ill adapted feet.’

And the reasons proposed for this unlikely transition – that we stood up to hunt meat, or pick grass seeds, or to carry food back to our families, or to minimise the area of our bodies we exposed to the sun – do not stand any serious scrutiny. The two free arms would have been useful to carry food and a large and helpless infant, and the erect posture may have helped to spot savannah predators, but these advantages are likely to have been a ‘secondary benefit’ not the driving force. We also know that bipedalism became a specialised feature of hominids not in the later stages of their evolution but as far back as four million years ago. The ‘Lucy’ skeleton, one of the best known species of early hominid, Australopithecus afarensis, has been characterised as a ‘bipedal chimpanzee’ and recent work in Kenya has unearthed an even earlier species of bipedal hominid known as Australopithecus anamensis. The structure of the pelvis and the knee joints of Lucy and her cousins show that they were upright walkers, but the length of their limbs and the structure of their hands and feet also attest to their arboreal nature. These early hominids were perhaps less adept in the trees than present day apes, and less efficient bipeds than Linford Christie, yet this ‘half way house’ was successful for this adaptation endured for some two million years. These early hominids were living in the forest, eating a diet probably not dissimilar to that of chimpanzees and bonobos, and the elements of that diet were found primarily in the forest canopy.

The veracity of this scenario has been strengthened by the very latest finds at Kapsomin in Kenya’s Baringo district. In December 2000, the Kenya Palaeontology Expedition (KPE) reported the discovery of what is almost certainly a new species of hominid. The excavating team, that included Martin Pickford from the KPE and Brigitte Senut from the Museum of Natural History in Paris, unearthed thirteen fossils belonging to at least five individuals, both male and female. These finds represent a hominid that is far older than any other previous discovery. It has been tentatively dated at least 6 million years old, which means it would be some one and a half million years older than Australopithecus anamensis, the previous most ancient hominid, and older than ‘Lucy’ too.

This new hominid has been popularly dubbed ‘Millennium Man’ but its Linnean name Orrorin tugenensis attests to its discovery in the Tugen Hills. What is most exciting about the find, however, is the creature’s structure. An almost perfectly fossilised left femur shows Millennium Man had strong back legs that enabled it to walk upright, giving it hominid characteristics that relate it directly to the bipedal lineages. The postcranial evidence also suggests that Orrorin tugenensis was already adapted to habitual or perhaps even obligate bipedalism when on the ground. A thick right humerus bone from the upper arm points to its considerable tree-climbing skills and the length of the fossil bones show the creature was about the size of a modern chimpanzee. The teeth and jaw structure suggest a similar dentition to modern man. It had small canines and full molars that indicate that it would have eaten a diet of mainly fruit and vegetables.

Preliminary analyses therefore indicates that the hominid was about the size of a chimpanzee, an agile climber, that it walked on two legs when on the ground and ate a diet of fruit and vegetable matter. Although it is easy to fall into the trap of extrapolating from minimal fossil finds, this outstanding discovery does strongly support our hypothesis that bipedalism developed in the forest in an animal that was an agile tree climber and ate a diet of primarily fruit and leaves.

Further studies of Orang-utans by Dr Robin Crompton of Liverpool University also indicate that the first stages of bipedalism developed in the trees. He has looked in detail at the ways these large primates move along branches and has noted similarities between their gait and fully functioning bipeds. This work, together with the associated evidence we have noted, strongly suggests that the initial stages towards bipedalism arose in the trees, and the other pressures that we have identified encouraged the process on towards a fully functional twolegged gait.

Pressures acting on the infant stage may have further propelled bipedalism. Apes can climb from a very young age but human infants are very different. After a long period of being completely dependent on their mothers, there is a period in which they are more independent but not developed enough to climb on their own. This would have provided a window of opportunity for the infant to experiment with different modes of locomotion. It may have been of great benefit for the young child to develop an efficient way of getting around during the increasingly long period before it had the strength and dexterity to climb into the trees. And successful children would survive better and pass their traits to their children. If we look at the way children develop their motor skills today, we can see that they are not strong or balanced enough to climb until well past the age they struggle to become upright. In the context of our arboreal origins it is worth pointing out that even today, as adults, we still possess impressive climbing abilities. In the rainforests people regularly climb trees to gather honey and fruit. In ‘developed’ societies too many people enjoy climbing as a sport and gymnasts, particularly on the parallel bars, display superb arboreal skills.

The point we would like to emphasise in all this is that bipedalism developed within the forest and the primary instigating factor was the changes brought about by the biochemistry of the diet. The developmental window would have become longer as the juvenile period extended. Initially there may have been an enforced two or three months on the ground but as the biochemical changes took effect this may have been extended to a period of one, two or even three years. The hominid’s arboreal features would have been retained as much as possible but these would have been progressively constrained by the hominid’s increasing size. We can see then that this change is not coming through the normal DNA selection route but via physiological changes brought about by the action of the chemicals contained in the diet.


It is all too easy to assume a simplistic picture of human evolution. The story goes that we separated from our nearest relatives, the chimps and bonobos, somewhere around seven million years ago and this line led via various strands of hominids to the Neanderthals and us. The true scenario was in all probability much more complex and fragmented.

Various lineages would have branched off, moved away from the forest, migrated, settled along coastlines, lived and eventually died out. There may have been back-crossings, for different lineages would certainly have been genetically compatible for a long time. Llamas and camels, separated by five million years of evolution, are still able to interbreed – these hominid lines would have been much closer. Some evidence of Human/Neanderthal interbreeding has been suggested from recent finds in Southern Spain. Thus we can safely speculate that different races of hominids would have changed physiologically and then by crossbreeding returned to nearer the hypothetical source population. A highly complicated weaving of strains could have occurred which would cloud and confuse the picture of human ancestry. But at least one lineage would have remained in the forest, after all this was the safest and most nurturing habitat to dwell in. These populations would continue to be subjected to the physical and biochemical pressures imposed by this hot-house environment.

Inevitably over time, further changes would have occurred and one may have been a result of the necessity to increase the efficiency of vitamin D absorption. There has been a great deal of confusion about our hairlessness – why should Homo sapiens be so lacking in body hair? Even Charles Darwin could see no advantage of nakedness to man. The ‘Father of Evolution’ concluded that ‘our bodies could not have been divested of hair through natural selection’ but somewhere along the line this is presumably what indeed did happen.

Ideas to explain our nakedness have included:– deterrence to parasites, a cooling system, a lure to increase our attractiveness to the opposite sex, and a response to living mainly in water. None of these explanations are particularly convincing. Hairlessness has not deterred ticks and leeches. In hot scenarios, fur actually protects against the sun and in the at night. And no other primate has lost its hair, certainly not as a sexual adornment. The water theory may have more substance. Parallels have been drawn with large aquatic mammals that have developed layers of blubber under a smooth, hairless or closely furred skin. We do indeed have fat tissue beneath our skin but fat just wouldn’t have been an issue for a hominid living on a diet of mainly fruit. It is difficult to get fat on a diet of wild fruit. Most of the enlargement of the human blubber layer is a symptom of overeating, which is increasingly easy on a diet of particularly refined carbohydrates.

Did our ancestors then really spend eons living in water? Is it possible that, sometime between leaving the forest and reaching New York, humans went through a phase of living almost entirely in water? How did they deal with powerful predators like crocodiles? A naked ape in the water would have been extremely vulnerable to such ferocious creatures. (Even today salt-water crocodiles occasionally terrorise villagers living near estuarine swampland in Southeast Asia.) Unlike other mammals, unless we actually learn to swim, we can easily drown when we fall in water – we do not seem to have any instinctive swimming ability. This would be a surprising oversight for an animal with an extended aquatic phase. And why does our skin go all wrinkly when we sit in the bath or swim in the sea? We just don’t appear to be well enough adapted to be an aquatic species, yet anomalies exist that have not been satisfactorily explained. Why do we have far more sebaceous glands than our nearest primate relatives do? And why do we sweat when most animals pant to reduce body heat? A new explanation is required. All current theories are seriously flawed.

If water was an element in our development it must have only been a contributory factor. It is just tenable that in the evolutionary history of mankind there was a period in which water created some adaptive pressure. Along the huge river systems of the Congo and the Amazon the usual boundary between water and forest is blurred due to seasonal inundation. If water was a factor in establishing bipedalism and hairlessness, it may have been that during the wet seasons water came into the forest, not that mankind’s ancestors left the forest to live aquatically. It is interesting to note that in the Congo gorillas spend time foraging for tasty shoots of water plants. They spend much time in the water but haven’t become hairless. Could this sort of lifestyle really be the reason humans became hairless? It is doubtful.

Vitamin D is important to our health; without it we cannot absorb and assimilate calcium. A deficiency of this vitamin can cause bone disorders like rickets and a weakness of bones certainly would be a major disadvantage when living even a partially arboreal lifestyle. Vitamin D is unusual as it is in short supply in an exclusively plant-based diet and our bodies do not absorb it very efficiently from animal products either. But cells in the skin can manufacture it when the skin is exposed to sunlight. A hairy primate gathering fruit in the tops of the canopy would be subjected to enough light to maintain vitamin D production but a larger primate forced to spend more time on the dark forest floor may have needed to increase the efficiency of the production mechanism. It is possible that hair loss resulted as a response to this pressure, for the sunlight that filtered down to the forest floor would need to be utilized to the maximum. It is vaguely possible however that the continued arboreal life style, with at least some time spent in the upper canopy searching for fruit, could have exposed the top of the head to deleterious effects of direct sunlight. The retention of hair on the scalp could thus provide in these circumstances a positive benefit. Not a strongly convincing argument but perhaps it is a little more likely than another suggestion that we have played around with – that head hair provides a convenient hand hold on an otherwise slippery parent.

More seriously, there may also be a steroid factor here. Vitamin D is chemically very similar to a steroid. Did the steroid-suppressing chemicals in the fruit inhibit the activity of vitamin D, making the need for a more efficient absorption mechanism all the more vital? Perhaps this extra selection pressure tipped the balance in favour of hairlessness. An imbalance of steroids could also explain the anomaly of our over-active sebaceous glands. We know that if males are castrated the activity of the sebaceous glands (and acne) decreases. So it is possible that today our sebaceous glands are working overtime in response to a heightened internal steroid environment. When we were naked in the forest our internal steroid activity would have been lower due to the continuous chemical effect of the steroid suppressing chemicals assimilated via our diet.

Losing hair in the tropical forest environment would not have incurred any major penalties. And while it is extremely unlikely that hairlessness came about as a mechanism for sexual attraction, the sexes may have come to like the look of each other this way. Hair loss may have even had some other advantages such as enhancing radiant heat loss though, as other primates in such environments retained their hair, this may have been a minimal or secondary benefit. Naked skin would also increase the efficiency of sweating as a cooling mechanism. Most animals do not sweat anything like as much as humans but regulate their temperature by panting. The problem with sweating is that it involves substantial loss of water but this would not have been a serious disadvantage in the humid forest, particularly for an animal that ate a fruit/leaf diet that comprised 80% to 90% water. But transfer this trait to the savannah and it does become a serious drawback. Savannah hominids living under the glare of the sun would have to cope with the dangers of dehydration. Certainly sweating as a way of cooling the body, like so many other traits that we regard as uniquely human, could not have evolved in this habitat. All in all, the savannah model is looking increasingly untenable. It has even been discounted now by previous stalwart supporters like paleoanthropologist Phillip Tobias.

It is easy to assume that there was just one lineage that turned into an animal as advanced as a human. Though this may have been the case, it is more likely that there were many branches and many different adaptive solutions to the problems posed by all the various environmental pressures. But, in the one particular lineage that happened to survive, all these solutions that we have been discussing came together. There may have been human-like hominids that were not naked in the forest. There may have been a human-like lineage that didn’t develop such efficient bipedalism, but the one lineage that brought all these elements together is the one that survived.


The tropical fruit diet of our ancestors, as we have constantly reiterated, had a marked effect on our anatomical and physiological development. The most significant effect however was reserved for our brains. We believe the biochemistry of a fruit diet became the necessary foundation for a chemical drive that turned relatively big-brained primates into great apes and extremely large-brained humans. The chemicals within our ancestor’s fruit diet fueled gradual change and were essential to maintain this change, but what emerged from this was an internal feedback loop that at some point compounded the effect. This second wave of chemical

change was an internal mechanism. Maybe neural development in great apes has gone as far as it can without this internal mechanism really taking off. It must be remembered that gorillas, chimpanzees and humans are genetically extremely close and, of the three, humans are genetically closer to chimpanzees than chimps are to gorillas. Why then are there not three species of African great apes? Why are we so genetically close, yet so different?

As natural selection cannot fully explain the difference, another mechanism must be responsible. We suggest that this internal biochemical mechanism is the crucial missing part of the jigsaw that propelled humans into a completely different league as far as brain size is concerned. Out of the millions of species that have arisen on this planet, humans display unique traits. Does this not imply there has been a unique process going on? It is encouraging to read that Professor Colin Groves, author of one of the most respected books on primate and human evolution, has also suggested that brain growth may not have been selected, as such, but happened fortuitously as a result of the changing tempo of our patterns of growth. In a personal communication he confirmed that he still thinks it is likely that human brain expansion occurred as an ‘epiphenomenon of neotony’. We will be exploring the detail of the fundamental biochemical pathways and biofeedback mechanisms that affected these patterns of growth in the next chapter.

The ideas of Professor Groves are supported by the fact that bonobos possess great latent intelligence. This intelligence arises from their big brains, not vice-versa. Bonobos do not use tools in the forest, at least to the extent that chimps do, but when transferred to a different environment, i.e. when kept in captivity, bonobos display a greater capacity for tool use (and possess higher levels of cognitive skills) than chimps. In their natural environment, bonobos do not actually need to use tools, as everything they require for survival is readily available. The implication is that bonobos have a greater capability for intelligence than they need, and thus intelligence is a result of their big brains rather that big brains arising out of the need to develop such things as tool use. As Colin Groves believes – big brains are a byproduct of some evolutionary mechanism.


At some stage humans left the forest. At different phases along the hominid evolutionary way individuals, groups and tribes would have left the forest ecosystem to disperse or find new territory. Pressures like climate change and accompanying forest contraction may have also be significant. If they were adapted to eating fruit and the fruit was plentiful, there would be no overt pressure to leave and indeed chimps, bonobos and gorillas are still there, eating a mainly vegetarian diet. We do know however that a cooling climate around the critical time would have resulted in forest shrinkage. Waves of hominid species and even the race that came to be known as Neanderthals may have been forced out of the prime habitat while the hypothetical lineage that we have been following (and it would have been the best adapted one) stayed in the forest. But even this lineage left perhaps somewhere in the region of 200,000 years ago. It is accepted that around this crucial juncture there was a reduction in global temperatures and rainfall, which led to a fragmentation of the forest. If a big central band of forest split, the populations within it would be fragmented too. If then these smaller forests declined from climactic or even celestial pressures, the populations within would be rendered homeless.

Something evidently forced the whole population out. Perhaps a catastrophic event like a meteor impact tipped the balance. We are now beginning to realise that these catastrophic events were far more numerous than previously thought. In ‘Evolutionary Catastrophes’ Vincent Courtillot states; ‘over the past 300 million years our planet has been battered by at least seven major ecological catastrophes’. An extraterrestrial impact or violent volcanism may have knocked out the fruit producing capacity of the remaining forest for long enough to have forced an intelligent human to look elsewhere for sustenance.

From mitochondrial DNA analysis we know that at some time in the past our population was extremely small. The billions of humans on our planet are all descended from perhaps as few as 5000 individuals. This suggested bottleneck could have been as a result of an ecological disaster that ravaged population levels, though it is likely that populations in the forest were always small and inbred. Large numbers of humans did not appear until very much later in our history. Bonobo and chimpanzee populations today are relatively small and the breeding rate low, despite the excessive amount of sexual activity particularly displayed by the bonobos. We will be looking at why a predominantly fruit diet may have been a contributory factor to this low level of fertility and slow breeding rates later.

Leaving the forest was a highly significant change. The adaptations we have looked at in previous sections (a big brain, an extended juvenile period, a loss of hair, an efficient twolegged gait and a partial ground-dwelling habit) all stem from the chemical effects of a fruitbased diet. When this drip feed of fruit chemicals was interrupted, some change was inevitable. It would almost certainly be deleterious, as it would to any creature ousted from its natural habitat. A naked and placid hominid, from an environment in which everything was provided, was suddenly exposed to new and harsh conditions. The biochemistry that its optimum neural function depended upon was gone and it had to fend for itself in extremely different circumstances. But a big brain and intelligent adaptability would have given our ancestors a better chance of meeting the challenges of a different environment. Humans have a physiological adaptability too – we are able to survive on many different types of diet ranging from totally plant-based to almost exclusively animal. But despite this, when the fruit part of the equation was lost, neural and physiological function must have been negatively affected. Without the biochemistry that was the foundation for our unique development, changes would have been rapid and irreversible. These changes could have even led to the initiation of an unstoppable negative feedback mechanism: even if the forest became habitable again and humans returned to their former way of life, there would have been no guarantee that the brain expansion process would have restarted. During the intervening period, without the forest biochemistry, structural changes would have been initiated; different biochemistry builds different structures, which leads to the emergence of different traits.

We have paid a major price for this change of lifestyle. Although, from the classic survival/competition perspective we are more successful now than we have ever been (and there are some six billion of us), we suspect that the brains of our close ancestors living in the forest had greater potential than ours do today. We may have slipped away from an opportunity for even greater and possibly more balanced brain development which would have given us much greater function and a more benign sense of well being than we possess today. The forest legacy has left us with a colossal piece of equipment between our ears – give us a problem and we will solve it – but without the foundation of the optimum chemistry provided by a fruit-based diet we may no longer be able to access its optimum performance.


A classic and rather romanticised image of a placid but physically capable and strong primate/hominid living a carefree life in the forest may not be too far from the truth. It is highly likely that the inherent physiological and psychological state of our ancestors would have been one of underlying ease and contentment. Pumping chemicals from the forest fruits into the hominid system would have limited aggressive behaviour. Steroids are linked to aggression and, as we have seen, many of the chemicals found in fruit suppress steroids. They dampen down the effects of testosterone in particular.

The role of androgens, such as testosterone, in precipitating aggressive behaviour is clearly displayed in hyaenas. In these extraordinary animals females are not only dominant but also highly aggressive – young females regularly kill their siblings. This aggression has been linked to high levels of testosterone. In fact the females have more testosterone than the males and even possess pseudo male genitalia.

Internal steroid activity would have been altered when humans left the forest and fruit was lost as the major part of the diet. Not only would steroid suppression have been lifted but also eating different foods instead would have made matters even worse. Meat contains steroids, thus a change to a carnivorous diet would have caused a major biochemical upset – not only would the steroid suppressing elements in the diet have been lost but also extra steroids would be taken in. Recent research has found that eating animal fats increases levels of testosterone: A double whammy is the current phrase that springs to mind.

It is sobering to note that humans killed in excess of 100 million fellow humans in the twentieth century alone. Today we live surrounded by mental, emotional and physical torture. There is cruelty to others and to the animals we live with, and we are rapidly destroying the planet that sustains us. Is it possible that this sickness (and it really is a sickness) stems from an imbalance in our biochemistry initiated by the loss of steroid suppression all those years ago? Without doubt, something has gone wrong. In his famous book ‘The Ghost in the Machine’ Arthur Koestler drew similar conclusions:

‘When one contemplates the streak of insanity running through human history, it appears that Homo sapiens is a biological freak, the result of some remarkable mistake in the evolutionary process. The ancient doctrine of original sin, variants of which occur independently in the mythologies of diverse cultures, could be a reflection of man’s awareness of his own inadequacy, of the intuitive hunch that somewhere along the line of his ascent something has gone wrong. (p267)

To put it vulgarly, we are led to suspect that there is somewhere a screw loose in the human mind. We ought to give serious consideration that somewhere along the line something has gone seriously wrong with the evolution of the nervous system of Homo sapiens. We know that evolution can lead into a blind alley, and we also know that the evolution of the human brain was an unprecedentedly rapid, almost explosive, process. Let us note as a possible hypothesis that the delusional streak which runs through our history may be an endemic form of paranoia, built into the wiring circuits of the human brain.’ (p239)

Would it not be wonderful to identify the mechanism of our insanity, for then we could do something about it? Real healing and restoration of a balanced consciousness may be realistic but initially we need to recognise the depths and significance of the problem.


In the forest, the human brain was expanding and expanding at a phenomenal rate. Sometime at around 200,000 to 150,000 years ago this process came to an end. The brain stopped expanding and started to shrink. This key point in our evolutionary journey has been noted but rarely addressed, and its significance comprehensively ignored.

Christopher Ruff, of John Hopkins University, and his colleagues thoroughly analysed the fossil record to determine the evolving body mass and brain size of the Homo species leading up to us. The results show that the assumption of a straight progression from a pea brained ancestor to the ultra-brainy modern Homo sapiens is decidedly shaky. Hominid brains appear to have remained fairly constant in size for a long period from some 1.8 million years ago until about 600,000 years ago. But then, from 600,000 years to 150,000 before the present, fossils show that the cranial capacity of our ancestors skyrocketed. Brain mass peaked at about 1,440 grams. Since then brain mass has declined to the 1,300 grams that is typical today. Of course brain size alone does not tell the whole story. Brain size also correlates with body size and the peak of brain size roughly corresponds to the peak in archaic Homo sapiens body size (the Neanderthals). The decline in size of the body in Homo sapiens sapiens (modern humans get two ‘wises’ in our name, but do we really deserve it?) over the past 50,000 years has raised our ratio of brain to body size to just above Neanderthal levels. Yet we have done this by shrinking our bodies to a greater extent than our brains have shrunk. There is some evidence that our brains are still shrinking, and may have done so over the last 10,000 years by as much as 5%.

This very recent period of brain shrinkage coincides with a major dietary change, for it was around this period that cereals and grain came to the fore. Cereal grains may be the foundation of our diet today and responsible for the huge explosion in our numbers but they may not be the best of foods for optimum function. Indeed studies of skeletons from early agricultural societies show ill health accompanies the initial transition to eating more grains and cereals. Skeletons dug up from the East Coast of America, dating from around 1000 AD, the era when Native Americans switched to corn-based agriculture, are smaller than earlier skeletons. Studies of skeletons from other societies undergoing this transition show signs of deficiencies such as anaemia. Clark Larsen, the physical anthropologist who studied the East Coast skeletons has stated that ‘just about anywhere that this transition to cereals occurs, health declines’.

It is thought that humans from such agrarian societies were lucky to live beyond thirty years. In contrast forest apes, such as chimpanzees, can live for some sixty years. We can reasonably assume that humans in the forest lived easily as long if not longer. Furthermore, if man in the forest was as long lived or even longer lived than chimps, it would provide a strong argument for the notion that this was both the most natural and most suitable place, particularly in terms of diet, for a human to live.


If the evolution of the unique human system were somehow linked with our ancestral diet we would expect the human system still to be best adapted to something approaching this. While there is continued debate on this subject, few dissent from the view that there is an increasing problem with the food we are eating in our sophisticated time-stressed modern world. In just one six-week period, newspaper headlines in the United Kingdom announced: ‘World alert over cancer chemical in cooked food’ (Daily Telegraph May 18th, 2002); ‘Children at risk from the junk food time bomb’ (Daily Mail May 31st, 2002); and ‘Anti-social conduct may be linked to diet, says study’ (Guardian, June 26, 2002). This is a small sample of worries arising from recent research. Today, we are told we risk diabetes, heart disease and cancers from eating the ‘wrong sort of food’. Weight problems caused by an addiction to high fat and high sugar convenience foods, or simply an ignorance of the alternatives, carry the risk of these and other diseases manifesting in later life. One in ten children under four is now classified as obese and health problems resulting from being overweight costs Britain some two billion pounds a year. It has been estimated that, if we continue eating a ‘junk food’ diet, in forty years’ time half the population will be obese. Furthermore specialists also fear that anaemia due to poor nutrition in early life can have long-lasting effects on a child’s mental development and learning ability.

Although longevity has increased over the last few centuries, many folk live the last years of their lives with the fear of disease, if not the actuality of it, but old age and disease do not necessarily go together. In the remote Andean highlands of Ecuador, there are communities of people who it is claimed live for 140 years or more and who remain agile and lucid right to the end. Death from heart disease and cancer is unknown in these high mountain valleys but rife in nearby towns. David Davies, who has made a study of these ‘Centenarians of the Andes’, found that the people who have the best chance of a healthy old age are those that actively use their minds and bodies, even towards the end of their life span. He looked at many elements of their life and environment from genetic factors to the tranquility and lack of stress in their way of life. The folk who lived longest were found amongst those that lived on a subsistence diet, which was low in calories and animal fat. Typically, the main meal of the day was eaten in the early evening and was made up of very small wild potatoes, yucca, cottage cheese and maize or bean gruel. Melons were eaten for dessert. Sometimes green vegetables, cabbage, marrow, pumpkins were added to the menu and sweet corn cobs were often taken to work for lunch. The people working in the fields ate fruit throughout the day. The climate is ideal for citrus fruits, and many other ‘hedgerow’ fruits such as mora (like a blackberry), guava and naranjhuila are abundant too. Meat was only eaten rarely, a type of cottage cheese was made from goat or cow milk, and eggs were eaten raw or almost raw.

Though these people are very healthy and extremely long-lived we mustn’t necessarily jump to the conclusion that this diet is perfect for the human system – their diet is restricted by the environment they live in. However, if we look at other communities of long-lived folk the parallels are striking. The Hunzas of north-east Kashmir also live in mountainous regions and have a diet that includes wheat, barley, buckwheat, beans, chick-peas, lentils, sprouted pulses, marrows, pumpkins, cottage cheese and fruit – the famous Hunza apricots and wild mulberries. Meat is again only eaten rarely and, because fuel is in short supply, when food is cooked it is usually steamed; a method of cooking that is the least damaging to the chemical nutrients in the food. Hunzukut males, like the people in the Andean Highlands, are also reported to live to 140 years of age. So, we must conclude that these diets are, at the very least, much more suitable than the ones we depend on in the affluent industrialised countries.

There seems to be no definitive study that has so far convinced society as a whole that nutritionally we are barking up the wrong tree (or at least not picking from the right one). But there are many scraps of information that support the thesis that a more natural diet is the most beneficial option. Lymphocyte production and hence resistance to illness is boosted by consuming the nutrients that occur in optimal proportions and quantities in uncooked vegetables. There are also a huge number of cases in which raw food, particularly fruit and vegetable juices, has seemingly cured a wide range of illnesses. Migraines, skin complaints, tuberculosis, mental disorders, heart disease, cancers and a host of other diseases have responded favourably to a diet rich in raw food. There are clinics, foundations and institutions throughout the world that offer therapies based on ‘living nutrition’. Such diets are much closer to our ancestral diets than the chips, pies and biscuits that adorn most of our supermarket shelves.

As with all organisms, hominids in the course of evolution were locked into the biological matrix of their environment. Whether our diet consisted of insects, fruit or meat it was all biologically active material. Some primates today eat a bit more of this or that – much coverage has been given recently to meat-eating chimps but this comprises a relatively small percentage of their diet. Despite their skill in capturing live prey, chimpanzees actually obtain about 94% of their annual diet from plants, primarily ripe fruits. Primate biochemistry is largely based on plants and a plant-based diet is what hominids were eating during their evolutionary development. A pictoral representation of an early human living in the forest, lounging around eating fruit, may be more accurate than one in which he is dressed in animal skins, spear in hand, on the hostile open plains.

The lack of plant material in the fossil record has led, according to Richard Leakey, to an over emphasis on meat eating as a component of the early hominids’ life. He also finds some of the recent work on tooth analysis ‘surprising’. The teeth of Australopithecus robustus fall into the fruit-eating category. The patterns of wear and the small scratches left on the enamel appear very similar to that of the forest dwelling chimpanzees, yet here was a hominid which was supposed to live on the plains in an era when the climate was dry and the vegetation mainly grass. The examples of Ramapithecus teeth that have been similarly analysed show exactly the same pattern, and the teeth of Homo habilis, the first creature to be awarded Homo status, also has smooth enamel typical of a chimpanzee. This evidence is extremely relevant. All the early hominids and their great ape cousins were mainly fruit eaters. The teeth of Homo erectus suggest a more omnivorous diet. The enamel from their teeth show scratches and scars that are compatible with grit damage possibly from consuming bulbs and tubers. As a response to a cooling climate and a contraction of the forest, did this species widen its diet to adapt to a new environment? Some forest would have remained intact along the wetter river systems. Chimpanzees and gorillas survived there along with, we suspect, another hominid whose teeth were very well adapted to fruit eating – Homo sapiens. Primates, given a choice, will select fruit in preference to any other food. Fruit is a rich, nutritious and easily digestible food. If it is available, this is what all the great apes prefer o eat. However other foods are eaten regularly. Our nearest relative, the bonobo, eats between 60% and 95% fruit depending on the fruit productivity of its specific habitat. The rest of its diet comprises mostly shoots and herbs and a small amount of insects, eggs and the occasional small mammal. Fallback foods like bark may also be eaten in times of fruit scarcity. What humans in the forest ate is of course unknown but it is likely that they would have eaten a similar balance of foodstuffs. They would not have been purely ‘vegetarians’. Even figs (perhaps the most preferred food) contain a small amount of insect matter as their pollination mechanism results in eggs and larvae of small wasp species remaining in the fruit. These insects may have served as an important source of essential micronutrients such as vitamin B12 as well as providing a little extra protein.

As they were the most highly intelligent animals in the forest and fruit was the best food, it is likely that humans developed strategies to maintain a high percentage of fruit all the year round. Being efficient bipeds would have given them the potential to travel easily between widely separated fruit sources. The quest for distant fruit trees may have even honed their bipedal adaptation. The larger arboreal primates are known to travel on the ground between distant fruit trees, as it is more efficient than travelling in the trees. Archaic humans, being better-adapted bipeds than apes, would have found this way of life much easier.


There has been much study and even more speculation about what sort of diet our teeth and guts are best designed for. From the type of dentition, gut length and toxicity of foods like meat, a very strong case can be built for Homo sapiens being designed to eat and process a largely fruit-based diet. The brain’s requirement for food and the gut’s requirement for energy, optimal acid/alkali balance and the structure of the intestines all point to a frugivorous diet. A shift to fruit specialisation answers all the problems and anomalies that have spawned countless conflicting theories.

Katherine Milton, Professor of Anthropology at Berkeley University, California, has carried out important work on diet and primate evolution. Her research has led her to believe that ‘the strategies early primates adopted to cope with the dietary challenges of the arboreal environment profoundly influenced their evolutionary trajectory’. This has a great significance for us today for the foods eaten by humans now bear little resemblance to the plant-based diets anthropoids have favoured since their emergence. She believes these findings shed light on many of the health problems that are common, especially in our industrially advanced nations. Could they be, at least in part, due to a mismatch between the diets we now eat and those to which our bodies became adapted over millions of years?

The plant-based food available in the forest canopy comprises fruit and leaves but subsisting on this diet poses some challenges for any animal living here. For a start, it is high in fibre that is not only difficult to break down and hence digest but also takes up space in the gut that may otherwise be filled with more nutritious foods. Many plant foods also lack one or more essential nutrients such as amino acids, so animals that depend on plants for meeting their daily nutritional requirements must seek out a variety of complimentary food sources. Fruit is usually the food of preference for it is rich in easily digested forms of carbohydrate and relatively low in fibre, but its protein content is low too (their seeds may be protein rich however). Leaves offer a higher protein content but they are lower in nutrients and contain much more fibre. Balancing these constraints have led to different strategies that are reflectedin behaviour and physiology. Colobine monkeys have compartmentalised stomachs (a system analogous to ruminants) that allows fibre to be fermented and hence processed very efficiently, but humans and most other primates pass fibre largely unchanged through their digestive systems. Some fibre can be broken down in the hind-gut of these latter species but the process is not as efficient as that in the Colobus.

Milton’s research focused on two contrasting species of South American primates howler and spider monkeys. These two species are about the same size and weight as each other and live in the same environment, eating plant-based foods, yet they are very different. Howler monkeys have a large colon and the food passes through its digestive system slowly, whereas spider monkeys have a small colon through which food passes more quickly. These physiological differences relate to dietary specialisation. The foundation of the howler’s diet is young leaves: 48% of their diet is leaves, with 42% fruit and 10% flowers. The spider monkey’s diet comprises 72% fruit, 22% leaves and 6% flowers. Another fundamental difference is that, although these animals are the same size, the brains of spider monkeys are twice the size of howlers. Very significantly, Milton comments that ‘the spider monkeys in Panama seemed ‘smarter’ than the howlers – almost human’. This is something we have commented on before: big brains and a diet high in fruit appear to go together. Why should this be so? Could this brain enlargement result from the need to memorise the location of productive fruit trees, as some have suggested, or did, as we propose, elements within the fruit itself fuel this change more directly? Animals such as squirrels, and even birds like jays, memorise the locations of stored food most efficiently without an overlarge brain thus it seems that something else must be responsible. Although Milton has concluded that it is quite difficult for primates to obtain adequate nutrition in the canopy, she observed that spider monkeys consume ripe fruits for most of the year, eating only a small amount of leaves. Bonobos also appear to find enough food to eat easily, for much of their time is spent in other ‘social’ activities. Thus, being a fruit-eating forest primate appears a very viable option – but one question remains: if fruit is so low in protein, how do these fruit specialists obtain an adequate supply of these essential nutrients?

Milton found that spider monkeys pass food through their colons more quickly than leaf-eaters such as howler monkeys. This speed of transit means that spider monkeys have a less efficient extraction process but, as much more food can be processed, it more than makes up. By choosing fruits that are highly digestible and rich in energy, they attain all the calories they need and some of the protein. They then supplement their basic fruit-pulp diet with a very few select young leaves that supply the rest of the protein they require, without an excess of fibre. Of course, by processing so much fruit, a large quantity of chemicals that naturally occur in fruit will also be absorbed. It should also be noted that wild fruit contains a higher percentage of protein than the cultivated fruit that is available to us humans today. It is clear that many wild primates are able to satisfy their daily protein and energy requirements on a diet largely or entirely derived from plants. It is likely that our ancestors in the forest did too.

The wild fruit that we propose was the mainstay of our ancestral diet for the longest and most significant part of our evolutionary history contains more fibre than the fruit we buy today in our shops. Chimpanzees take in about 100 grams of fibre a day compared to about 10 grams that the average western human consumes. At one time it was believed that humans did not possess microbes capable of breaking down fibre. Studies on the digestion of fibre by 24 male college students at Cornell University, however, found that bacteria in their colons proved quite efficient at fermenting the fibre of fruit and vegetables. The microbial populations fermented some three-quarters of the cell wall material, and about 90% of the volatile fatty acids that resulted were delivered to the blood stream. It has been estimated that some present day human populations with a high intake of dietary fibre may derive 10% or more of their required daily energy from volatile fatty acids produced in fermentation.

Furthermore, recent experimental work on human fibre digestion has shown that our gut microflora are very sensitive to different types of dietary fibre. We are very efficient at processing vegetable fibre from dicotyledenous sources (flowering plants like fig trees, carrots and lettuces) but are less so from monocotyledens (grasses and cereals). This provides yet another pointer to the archaic diet of humans as being largely fruit-based and indicates that the grass seed that we eat so much of today in cereals, biscuits and much else is a poor substitute. The chimpanzee gut is strikingly similar to the human gut in the way it processes fibre. As the fraction of fibre in the diet increases, both humans and chimpanzees increase the rate at which they pass food through the gut. These similarities indicate that when food quality declines both these primates are evolutionarily programmed to respond to this decrease by increasing the rate at which food passes through the digestive tract. And this compensates for the reduced quality of the food available.

It appears that the human system then, like the chimps and bonobos, is designed for a plant-rich fibrous diet. We are not designed for a diet high in carbohydrate and low in fibre or significant quantities of animal protein. Meat eating in man has been, on an evolutionary time scale, a very recent development. It certainly couldn’t have influenced the development of our physiology. Though the passage of food through the guts of spider monkeys, chimps and humans is faster than leaf specialists like howlers, it is much slower than carnivores. Meat hanging around in the digestive system is bad news because of its inherent toxicity. The transit time for the passage of food through a carnivore’s gut is between 7 and 26 hours while for humans it is between 40 and 60 hours.

Though we do have a shorter colon and a longer small intestine than the great apes (and this has led one camp of researchers to speculate that our intestines are more similar to those of carnivores), these differences are more appropriately explained by a specialist fruit diet, not a carnivorous or grain-based one. Fruit is easier to digest than leaves, tubers and stems, and has a lower fibre content. Thus a specialist fruit eater would not need such a long colon as other apes that have more fibrous bulk to deal with.

Another feature of humans, that is strongly indicative of our vegetarian origins, is our inability to synthesise our own internal vitamin C. This trait is very rare but, where it occurs, the animals concerned (such as guinea pigs) eat a plant-based diet. In these cases ample supplies of the vitamin are available within the food. Vitamin C plays many extremely important roles within the human body. Research seems to be always finding more functions for this ‘miracle chemical’. These have been summarised by Dr. Ross Pelton in his book ‘Mind Foods and Smart Pills’: Vitamin C stimulates the immune system, enabling one to better resist diseases. Terminal cancer patients taking megadoses of vitamin C have been found to live longer. It promotes faster wound healing and reduces the amount of cholesterol in the blood. It is a powerful detoxifier and protects against the destructive power of many pollutants. In addition, it protects the body against heart disease, reduces anxiety, and is a natural antihistamine. A severe deficiency causes scurvy, and eventually death. Increasing intake has been found to increase mental alertness and brain functioning in a variety of ways. Vitamin C is the main antioxidant that circulates in the blood. When available in sufficient quantity, blood carries it around the body, washing over the cells to create a bath of protection. Whenever a free radical turns up, a molecule of vitamin C gives up one of its own electrons to render the free radical ineffective. According to Pelton, this process may take place somewhere between 100,000 and a million times a second, depending on the body’s level of metabolism and the amount of vitamin C available. Unfortunately, with each radical decimated, a molecule of vitamin C is lost, so the body rapidly loses its supply of vitamin C.

Vitamin C is a key player in keeping our neural system healthy. The body has a system that operates like a kind of a pump to concentrate vitamin C around our nerves and brain tissue. These tissues have more unsaturated fats than any other organs in the body, making them more vulnerable to attack by free radicals and oxidation. The vitamin C pump removes vitamin C from the blood as it circulates to increase the amount of vitamin C in the cerebrospinal fluid by a factor of ten. The pump then takes the concentrated vitamin C from the cerebrospinal fluid, and concentrates it tenfold again in the nerve cells around the brain and spinal cord. Thus our brain and spinal cord cells are protected against free radical damage by more than a hundred times as much vitamin C as our other body cells.

For such an important chemical, it is extremely odd that we are dependent on vitamin C from outside sources. But how much of it does the body need? Research carried out by the Committee on Animal Nutrition demonstrated that monkeys needed around 55 mg. of vitamin C per kilogram of body weight. When this measure is extrapolated to humans, a 150-pound person would need a daily intake of 3,850 mg. Nutritional science recommends that a human needs 45 mg. each day. This is just enough to prevent scurvy but not enough to keep the body functioning at an optimal level. We would not, and indeed do not, obtain the sort of levels our bodies really need from a diet high in meat and low in vegetables/fruit, but we would from one high in fruit, shoots and leaves. Analysis of wild plant foods eaten by primates shows that many of these foods contain notable amounts of vitamin C. The young leaves and unripe fruit of one species of wild fig was found to contain some of the highest levels ever reported. Our closest living relatives, the great apes, eat a diet that contains between 2 and 6 grams of vitamin C every day. When our ancestors were living in the forest they would have consumed similar amounts.

In contrast, we can and do produce our own vitamin D. This vitamin cannot be obtained from a leaf/fruit based diet but it can from a carnivorous one, thus if we were designed to eat meat we would have less need to synthesise our own. Being able to synthesise vitamin D and not vitamin C is then a strong indication of our true ancestral diet and the one we are really adapted to. Accumulating evidence for meat being an unhealthy food option further strengthens this case. One recent study showed that vegetarians were 24% less likely than non-vegetarians were to die of ischaemic heart disease.

Carbohydates also appear to be problematical when eaten in large amounts. A diet high in carbohydrates, especially refined carbohydrates (cakes, biscuits, pasta, etc), dumps large amounts of glucose rapidly into our bloodstream. This can cause insulin resistance in which the absorption of glucose from the bloodstream is disrupted. This in turn can lead to obesity, adult onset diabetes, hypertension, heart attacks and strokes. It can also lead to an excess of male hormones, which, amongst other effects (aggression), encourages pores in the skin to ooze large amounts of sebum. Acne promoting bacteria thrive on sebum. Up to 60% of 12 year olds and 95% of 18 year olds in modern society suffer from acne, yet it is almost unknown in subsistence societies such as the Kitava islanders in Papua New Guinea and the Ache of the Amazon. The Inuit people of Alaska also used to be free of acne but they began to be affected by these skin complaints after they started to eat processed foods.

The problem with eating highly processed carbohydrates may be further reaching still. If refined cereal consumption results in an excess of male hormones it could have a knock-on effect on the immune system for we know that the thymus gland starts to shrink in response to these hormones at the time of puberty. (More carbohydrates lead to more testosterone which shrinks the thymus gland that is seat of much of our immune response.) Grain products have also been associated with coeliac disease, an auto-immune condition of the gut and some researchers suspect they trigger rheumatoid arthritis too.

It is highly significant that these foods have the ability to alter the quantity or at least the activity of our hormones. It is another example of the way our diet can affect the way our bodies work. It is possible, probable even, that they also affect the way we act and thus moderate our sense of self. If we compare refined carbohydrates with fruit, we can see that fruit has a much lower glycaemic index, which means it is digested more slowly thus avoiding the problems of the ‘glucose rush’. The chemicals within fruit also reduce the activity of sex hormones. They thus have the diametrically opposite effect to that of refined cereals. There is a view held by some that meat, and particularly the high protein content of meat, was somehow responsible for the enlargement of our brains. The assumed ‘higher quality’ meat diet theoretically allowed more energy to fuel the brain with a shorter small intestine. This reasoning is flawed on several fronts. Firstly, meat is supposed to be easy to digest and to be a high-energy food but fruit is much more easily digested and provides more readily available energy too. Secondly, if there were a sufficient external pressure to bring about such a change as a shortening of the gut, we would expect other adaptations and changes towards a carnivorous diet as well. Certainly we would not expect adaptations to be heading in the opposite direction. Our teeth, for instance, are nothing like the teeth of a carnivore. The teeth of our nearest relative, the bonobo, are much better adapted to eating meat than human teeth are, and bonobos hardly eat any meat. In fact it is known that bonobos are, if anything, more intelligent than chimpanzees and it is chimps that eat at least some meat. So, if bringing meat into the diet of an ancestral human was enough to shorten the gut and expand the brain (both major changes), where are the parallel changes in areas that would be needed to cope with a meat diet?

If we look at areas such as dentition, the physiology to digest meat and the ability to catch it, we find nothing that looks even vaguely carnivorous. If we lined up the three most evolved species of primates – chimps, bonobos and humans – we would have to conclude that humans are in fact the least adapted to eat meat. Humans have much smaller teeth and they cannot chase the meat nearly so well. Also there is a structural distinction between carnivore guts and frugivore/vegetarian ones. Our guts are like the non-carnivores – they are folded, smooth and still significantly longer than a carnivore gut. There is a difference in saliva too. Carnivore saliva is acid but the saliva of humans is alkaline which provides the right functional environment for digestive enzymes, such as amylase, to break down starch. Now, if we ask what sort of food really fits these human adaptations, we have to conclude it is fruit. Fruit fits the brain/gut energy equation; the shorter gut, the ease of digestion, the low toxicity and the small teeth. Fruit is easy to assimilate and the nutrition it provides is in a form that needs very little conversion to the real requirement of the brain – glucose. (The sugar in wild fruit tends to be rich in glucose and fructose compared to cultivated fruit that has been bred for its sweeter tasting sucrose content.) Humans thus have a proportionately shorter small intestine than chimps and bonobos, not because of increasing levels of meat in our diet but because of an increased specialisation on sugar-rich fruit. High quality fruit is low in toxicity and provides all the fuel the brain needs. Meat conversely is more difficult to digest, particularly without cooking, and then to turn protein into sugar requires yet more energy. So meat as an energy food doesn’t make as much sense as fruit that is full of fruit sugars which are easily assimilated and take little conversion. The anatomy and physiology of our digestive system support the case for the biochemical role of tropical fruit in human development. However, the case could be stronger still if we could show that the human brain in archaic times actually worked the digestive system in a way that extracted the nutritive elements within the plant based diets more efficiently. More research needs to be done in this area but preliminary indications (private research) hint that a digestive system run without interference from the left hemisphere may do just that.


We need to look at the whole matter of protein requirement in a little more depth. Perhaps we do not need as much as is widely assumed. The time of our life when we need the richest and highest quality of nutrients is in our first few years of life, when our bodies and brain tissues are growing most rapidly. It is surprising then to discover that human breast milk has a protein content of less than 10%. Breast milk is sweet and rich in fat, providing sugar to physiologically fuel the baby and fat to build it. It is a low protein food.

Recent research has illuminated the vital necessity of adequate polyunsaturated fats for brain development, particularly in forming nerve fibre membranes. But in their first four months, babies do not produce the enzymes needed to make certain long-chain fatty acids. The only source of these acids is in the milk they consume. The food mothers eat during their breast-feeding stage has been found to affect the balance of fats in their infants. In one study, the baby of a mother who ate a diet that excluded all animal products had twice as much polyunsaturated fat in its adipose tissue than did babies whose mothers were omnivorous. The conclusion was that babies breast-fed by mothers who ate an exclusively plant-based diet have better brain development because of the role of polyunsaturates in the growth of neural membranes. This study again points to the suitability of a fruit-based diet and its link to neural development.

In the first year of life, no less than 60 percent of a baby’s energy intake fuels brain growth. Referring back to Katherine Milton’s spider monkey study, we could ask whether they were really eating leaves for their protein content. They may have been primarily after additional essential polyunsaturated fats.

Fatty acids play an essential role in the structure and function of the brain. (Two of them alone, arachidonic acid and docosahexanoic acid, constitute 20% of the dry weight of the brain.) These are biologically highly active compounds that perform numerous regulatory functions in the brain and the rest of the body. Many of them can be synthesised by the body if the diet provides enough of the raw materials for construction, but some, such as linoleic (omega 6) and alpha-linolenic (omega 3) acid, are only available from the food we eat. Wild foods routinely eaten by monkeys contain notable amounts of alpha linolenic and linoleic acid. The diet of our human ancestors would have been similarly rich in these essential fatty acids. In fact analysis of wild plant foods eaten by free-ranging primates shows that these foods are generally high in the nutrients we know are necessary for human health too. Natural primate diets contain a greater proportion of many minerals, vitamins, dietary fibre as well as the essential fatty acids than that of modern humans. It is likely then that the present recommended daily requirements for these dietary components are set far too low.

Animal studies have also shown that neural integrity and function can be permanently disrupted by deficits of fatty acids during foetal and neonatal development. These nutrients are extremely important. Research has indicated that infants may benefit markedly from the long chain polyunsaturated fatty acids naturally present in breast milk. It is highly likely that most of us are chronically short of these nutrients as they are in short supply in our modern diet and, even more crucially, are absent from many baby formula foods.

Considerable evidence is now accumulating that indicates that deficiencies in essential fatty acids is a major contributory factor in a range of interrelated childhood disorders including attention deficit and hyperactivity disorder, dyslexia, asthma, allergies and even autism. It has also been shown that correcting these deficiencies can significantly improve health.

Appleton Central Alternative Charter High is a school in Winsconsin that caters for students with behavioural and learning difficulties. In 2003 they instigated a well-being and health food program. The junk food vending machines were removed and proper lunches were offered that included raw vegetables, fresh fruit and whole grain breads. ACA staff assert that students’ disruptive behaviour and health complaints diminished substantially. Students also seemed more able to concentrate. They became more stable too, so those mental health and anger management issues were easier to manage. Teacher Mary Bruyette said she saw changes ‘overnight’. She noticed a considerable decrease in impulsive behaviours, such as talking out, fidgeting and the use of foul language. Henceforth she has had fewer disciplinary referrals to the office for students who could not settle down and do their coursework. Complaints of headaches, stomach aches, and feeling tired also lessened. Students were no longer hungry mid-morning or mid-afternoon. According to Principal LuAnn Coenen, negative behaviours such as vandalism, drug and weapons violations, dropout and expulsion rates, and suicide attempts are now virtually non-existent.

The school also experimented with junk food days – days when the students reverted to a diet of chips, brownies, candy bars and sugared sodas. Students became tense and ‘wired’. They were unable to focus and complained of stomach aches and tiredness. Students and staff mutually agreed to abandon such days. The negative effects of such junk food have been further highlighted in the recent shock film – ‘Super Size Me’.

Just replacing sodas with water can make a significant difference. Most humans today are chronically dehydrated. This simple fact causes much ill health. According to Dr F. Batmanghelidj (in his book ‘Your Body’s Many Cries For Water’) many of the degenerative diseases of the human body are caused by a simple lack of water. He has concluded from his studies that asthma, diabetes, arthritis, angina, obesity, Alzheimer’s, high cholesterol, hypertension, dyspeptic pain and many other maladies are signals from a body that is desperately thirsty. We are much more prone to dehydration if the bulk of the food we live on is dry. Fruit and vegetables have a much higher water content than grain and wheat-based products. That our bodies work more efficiently when we live on the diet that provides not only the nutrients that we need, but also basics like our water too, is further evidence for this being the one we have been ‘designed’ for.


In this chapter, we have presented the framework for an alternative mechanism that we think was fundamental to the evolution of humans, hominids and perhaps to the great apes too. We have argued that humans are best adapted to a diet high in fruit and that this diet played a significant role in our development. Primates evolved in an environment with a unique biochemistry. This environment may have been stable for millions of years, and, over such long stretches of time, this rich chemical matrix would have had a very real effect. If in the distant past, humans and proto-humans ate a diet consisting mainly of fruit, then the chemicals contained within the fruit would have flowed through their bodies for countless generations. This biochemical influence could have caused, for instance, a lengthening of the juvenile period and much else besides. In the next chapter we will look in detail at these biochemical pathways and how they acted on the human system.

Left In The Dark PDF



One thought on ““Left in the Dark” – The origin of left/right brain split, bipedalism, violence, big brain, and our break away from raw plant diet

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