The kinship and partnership between human kind and dog has existed for many thousands of years.  We have benefitted from that relationship in a multitude of ways, some clearly utilitarian – such as when dogs have served the role of guards, herders, hunting aids, and sled pullers – but of equal value, dogs have been our beloved companions, who through their unbounded love, affection, loyalty, and sometimes uncanny perceptiveness, allow us to connect to deeper emotional layers of ourselves, to nurture the esteemed human qualities of kindness and love, and to allay the stresses of daily life in ways human relationships often fail to do.  Yet, despite this acknowledged indebtedness to ‘man’s best friend’, the most important role dogs played and one which changed the fate of the planet, has been lost in the margins of time – as the sole enabler for the emergence of modern man, Homo Sapiens.  This relationship was directly responsible for the ascendancy of human beings, and the demise of the Neanderthals.  Had dogs never been domesticated, our species’ would not have its defining highly honed intelligence level, and we would likely still be sharing the planet with Neanderthals.  

Anyone familiar with the study of human evolution will know that the swift disappearance of Neanderthals from all areas where modern humans moved into, is one of the long standing mysteries in anthropology.  Neanderthals were a highly successful hominin species that thrived right across Europe, southwest Asia, and Siberia for around 300,0000 years before modern humans arrived.  Their survival amidst some of the most challenging climatic conditions during the last global glaciation attests to their resourcefulness.  Yet, within the span of a few decades humans completely obliterated Neanderthal populations everywhere, presumably by outcompeting them.  We were plainly smarter, it appears: we had more-refined tools, larger social and cultural networks, we developed an aesthetic sensibility as revealed by the first wall murals, figurines, and musical instruments ever created, we moved into areas of the globe Neanderthals had not succeeded venturing into, and most telling, we acquired a chin – not possessed by any other hominin species – which serves as a point of muscular attachment facilitating minute movements of the lips associated with speech.  Neanderthals it seems, never had the ability to communicate anything so complex as to require a highly developed language, a further sign of their lower relative intelligence level.  These differentiating attributes of intelligence are all the more perplexing when one considers that Neanderthals had brains that were as voluminous as ours, on average.   How can one explain this parity is brain size, but disparity in intellect, between Neanderthals and humans?  I believe the answer lies in examining the relationship between instinct and intelligence.

There is a most fundamental connection between instinct and intelligence at a neural level that has previously not been suspected, but which has tremendous explanatory power.  It reveals that instincts place a constraint on intelligence level in all organisms, and furthermore, losing instincts allows brains to achieve their full potential intelligence level.  The salient points of the argument (found at www.humansexualevolution.com) can be summarized as follows:

• Brains require neurons to tell them what to do, and this requires neurons to get activated and send a nervous impulse to other neurons.
• A neuron never works alone, but instead forms a temporary working group with other neurons that all fire synchronously (viz. together) to produce a combined neural signal whose strength is the summed strength of all neurons comprising the group
• At any instant, there are many such independent neural groups. Each of these temporary groups of activated neurons represents one different thing that the brain could do in the next instant to time, for example, have a particular thought, observe something, initiate a movement, focus visual attention at some object, etc.
• The group of neurons with the greatest neural strength of operation wins out over all the other neural groups with lesser neural strength of operation, in so doing is able to dictate what the brain commands next, and occupies the seat of consciousness for the instant that it operates.
• Another neural-group battle begins anew in the next instant of time between different groups of neurons, all vying for control of consciousness. The content of the succession of dominant neural groups defines what we perceive as the stream of consciousness.
• Intelligence is simply any experience-based response, and is categorically different from instincts, which are inborn responses to environmental stimuli.
• Experience-based responses (viz. intelligence) and instincts vie for control of consciousness because both require large scale control of movement, and therefore can’t work properly simultaneously because each may be trying to tell the brain to respond to the environment in ways that require conflicting movement responses.
• In nature, operation of instincts have such essential life-supporting and species-survival roles, that nature ensures that they must generally be able to displace from the seat of consciousness any prescription for behavioral response stemming from experience. To be able to do so, the number of experience-linked neurons that can form a single group, and their combined strength, must be less than that corresponding to instincts.
• Increased intelligence however, requires more and more input from past experience, and this requires more and more neurons becoming simultaneously involved in conscious decision making and problem solving- which is to say, larger neural groups. However, given than instincts are characterized by neural groups that are relatively fixed in size – and I hypothesize – do not grow proportionately with increases in brain size, they therefore constrain intelligence level in all animals possessing them.
• The loss of instincts would therefore eliminate the constraint on the number of neurons allowed to form a single group, thus permitting greater use of prior experience in decision making - the prerequisite for increased intelligence.

Based on this neural model, it is clear that the key to higher human intelligence was losing the sexual instinct.  My hypothesis is that of all hominins that ever existed, only Homo Sapiens – our species – was ever able to lose the sexual instinct.  Losing the sexual instinct allowed Homo Sapiens to start on the road to maximizing the potential intelligence derivable from the existing size of their brain, allowing huge increases in intelligence without significantly increasing brain size.  Neanderthals conversely, must never have lost their sexual instinct, and this would account for their lesser intelligence.  There are those who would argue however, that humans still possess a sexual instinct.  They are dead wrong.  The most definitive indication that humans do not possess a sexual instinct is the freedom every one of us has to choose NOT to reproduce – a reproductive freedom that has no parallel anywhere else in the animal world!  Instincts most characteristically, are compulsive in nature so this universal reproductive freedom is all the proof one needs that human beings uniquely lack a sexual instinct. 

Why is it that it was only our species, Homo Sapiens, that managed to lose its sexual instinct, and not a single other hominin species that ever existed?  The answer lies in the formidable barriers to losing it, which entailed first discovering a benefit to producing children, and then discovering what caused reproduction.  Only then would reproduction be relatively assured without a sexual instinct, and a species still be able to survive.   One of the barriers to losing the sexual instinct must have fallen at least a few hundred thousand years ago.  In the course of hominin evolution there was a progressive increase in intelligence.  At some stage, hominins would have acquired enough intelligence to understand the concept of aging and death.  And with this knowledge came the realization that the prospect of survival in old age without the assistance of younger individuals was bleak.  This was motivation enough to value having children.  Neanderthals a couple of hundred thousand years ago show some evidence of having cared for the elderly, implying that perhaps they already understood the predictive nature of aging, and formed social units in which prolonged parental investment in offspring was geared toward insuring care and protection in old age.  But what of the other barrier – the knowledge of reproduction? 

The knowledge of reproduction is so fundamental to human existence that it is easy to believe we have always possessed it.  But like all knowledge, it had to be acquired at some point.  How, and when, did we learn the role of heterosexual intercourse in reproduction?  And furthermore, did other hominins also acquire this knowledge?  Though there has been scant speculation about these matters, the unstated assumption is that hominins must have already understood reproduction by as early as perhaps a million or more years ago.  This view does indeed appear reasonable when one considers that hominids were already displaying considerable skill in building stone tools by that point in time,  an ability that requires forward planning, design conceptualization, selection of appropriate materials, and fine motor skill control to create the desired form from stone.   Additionally, hominin species had also demonstrated remarkable adeptness at meeting new environmental challenges after spreading widely over the African continent, and then crossing into Eurasia about 1.8 million years ago.  Surely, a mind capable of such feats would have likewise been able to deduce what made reproduction possible, wouldn’t it?  I believe a compelling argument can be made to answer this question in the negative. 

The reason is that  instincts are triggered to operate solely by environmental stimuli, without the need, or ability,  to reference past experience.  Hence, there’s a disconnect between instinct and long term working memory, and this presumably exists to prevent past experience from adversely affecting the operation of instincts.   But in order to figure out the role of heterosexual intercourse in reproduction we require to correlate 2 events that are significantly separated in time: the incidence of heterosexual intercourse, and the resulting pregnancy.   It was therefore an impossible task for any hominin species possessing a sexual instinct – irrespective of brain size – to have solved the mystery of reproduction by scrutinizing its  own sexual behaviour.  They had to deduce the role of heterosexual intercourse in reproduction by making the necessary observations on another animal species first.  These prolonged observations on another animal’s sexual behaviour were only likely to have been made with the first steps toward animal domestication.   Accordingly, we have to focus attention to the dog, the first animal to be domesticated.

The places and dates of wolf domestication are much debated.  What is certain however, is that all the archaeological evidence indicates only humans domesticated dogs.  Studies comparing the haplotypes ( a combination of alleles (for different genes) that are located closely together on the same chromosome and that tend to be inherited together) of dogs with that of wolves from different parts of the world, show that dog domestication may have begun as early as 135,000 years ago.  The domestication process however, may have had multiple starts that lacked continuity even before this date, so we may be justified in speculating an upper limit for the advent of wolf domestication to be in the range of 200,000 years ago.   

It is likely that humanity’s first steps toward that domestication process had its roots in Africa, perhaps in Ethiopia -the cradle of mankind – where the Ethiopian wolf is found in mountainous regions there.  In fact, the basenji dog – the only canid in Africa that lives in the rainforest of central and western Africa – has an annual estrus timing that closely matches that of the Ethiopian wolf.  Curiously, feral or domestic dogs in south Asia living in the tropic forest also match the Basenji’s annual cycle  ( http://www.dibubasenjis.com/papers/comparison.pdf  ).  This may be of significance because the colonization of the world outside of Africa did trace a southerly path through Asia, and humans would have likely carried their dogs with them.  

What was it about our species that made us adopt a wolf pup? Why had Neanderthals never been inclined to do so?  We’ll never know for sure, but we can conjecture.  We see differences in culture presently between 2 closely related chimpanzee species – the bonobo and the common chimpanzee.   Bonobos show less aggression toward each other than the common chimpanzee, and resolve disputes with sex and hugs/kisses.  Similarly, there may have been a difference culturally between Homo Sapiens and Neanderthals – one that caused Homo to have empathy in certain situations, like when coming across an orphaned wolf pup.  Neanderthals conversely, may have always killed wolf pups on sight because they saw them as competitors.  It is also likely that from the start our species was just a little more intelligent, even while still possessing a sexual instinct, because we were the newest branch of the family tree and  Africa’s Rift Valley had for millions of years consistently periodically produced a more advanced offshoot to the human line.  Perhaps this latest increase in intelligence gave Homo an increased self confidence and prowess in all areas, including hunting, and it did not see the wolf any longer as a formidable competitor.   

Based on this neural model, it is clear that the key to higher human intelligence was losing the sexual instinct.  My hypothesis is that of all hominins that ever existed, only Homo Sapiens – our species – was ever able to lose the sexual instinct.  Losing the sexual instinct allowed Homo Sapiens to start on the road to maximizing the potential intelligence derivable from the existing size of their brain, allowing huge increases in intelligence without significantly increasing brain size.  Neanderthals conversely, must never have lost their sexual instinct, and this would account for their lesser intelligence.  There are those who would argue however, that humans still possess a sexual instinct.  They are dead wrong.  The most definitive indication that humans do not possess a sexual instinct is the freedom every one of us has to choose NOT to reproduce – a reproductive freedom that has no parallel anywhere else in the animal world!  Instincts most characteristically, are compulsive in nature so this universal reproductive freedom is all the proof one needs that human beings uniquely lack a sexual instinct. 

Why is it that it was only our species, Homo Sapiens, that managed to lose their sexual instinct, and not a single other hominin species that ever existed?  The answer lies in the formidable barriers to losing it, which entailed first discovering a benefit to producing children, and then discovering what caused reproduction.  Only then would reproduction be relatively assured without a sexual instinct, and our species still been able to survive.  . One of the barriers to losing the sexual instinct must have fallen at least a few hundred thousand years ago.  In the course of hominin evolution there was a progressive increase in intelligence.  At some stage, hominins would have acquired enough intelligence to understand the concept of aging and death.  And with this knowledge came the realization that the prospect of survival in old age without the assistance of younger individuals was bleak.  This was motivation enough to value having children.  Neanderthals a couple of hundred thousand years ago show some evidence of having cared for the elderly, implying that perhaps they already understood the predictive nature of aging, and formed social units in which prolonged parental investment in offspring was geared toward insuring care and protection in old age.  But what of the other barrier – the knowledge of reproduction? 

The knowledge of reproduction is so fundamental to human existence that it is easy to believe we have always possessed it.  But like all knowledge, it had to be acquired at some point.  How, and when, did we learn the role of heterosexual intercourse in reproduction?  And furthermore, did other hominids also acquire this knowledge?  Though there has been scant speculation about these matters, the unstated assumption is that hominids must have already understood reproduction by as early as perhaps a million or more years ago.  This view does indeed appear reasonable when one considers that hominids were already displaying considerable skill in building stone tools by that point in time,  an ability that requires forward planning, design conceptualization, selection of appropriate materials, and fine motor skill control to create the desired form from stone.   Additionally, hominid species has also demonstrated remarkable adeptness at meeting new environmental challenges after spreading widely over the African continent, and then crossing into Eurasia about 1.8 million years ago.  Surely, a mind capable of such feats would have likewise been able to deduce what made reproduction possible, wouldn’t it?  I believe a compelling argument can be made to answer this question in the negative. 

The reason is that  instincts are triggered to operate solely by environmental stimuli, without the need, or ability,  to reference past experience.  Hence, there’s a disconnect between instinct and long term working memory, and this presumably exists to prevent past experience from adversely affecting the operation of instincts.   But in order to figure out the role of heterosexual intercourse in reproduction we require to correlate 2 events that are significantly separated in time: the incidence of heterosexual intercourse, and the resulting pregnancy.   It was therefore an impossible task for any hominid possessing a sexual instinct – irrespective of brain size – to have solved the mystery of reproduction by scrutinizing its  own sexual behaviour.  They had to deduce the role of heterosexual intercourse in reproduction by making the necessary observations on another animal species first.  These prolonged observations on another animal’s sexual behaviour were only likely to have been made with the first steps toward animal domestication.   Accordingly, we have to focus attention to the dog, the first animal to be domesticated.

The places and dates of wolf domestication are much debated.  What is certain however, is that all the archaeological evidence indicates only humans domesticated dogs.  Studies comparing the haplotypes ( a combination of alleles (for different genes) that are located closely together on the same chromosome and that tend to be inherited together) of dogs with that of wolves from different parts of the world, show that dog domestication may have begun as early as 135,000 years ago.  The domestication process however, may have had multiple starts that lacked continuity even before this date, so we may be justified in speculating an upper limit for the advent of wolf domestication to be in the range of 200,000 years ago.   

It is likely that humanity’s first steps toward that domestication process had its roots in Africa, perhaps in Ethiopia -the cradle of mankind – where the Ethiopian wolf is found in mountainous regions there.  In fact, the basenji dog – the only canid in Africa that lives in the rainforest of central and western Africa – has an annual estrus timing that closely matches that of the Ethiopian wolf.  Curiously, feral or domestic dogs in south Asia living in the tropic forest also match the Basenji’s annual cycle.   http://www.dibubasenjis.com/papers/comparison.pdf  This may be of significance because the colonization of the world outside of Africa did trace a southerly path through Asia, and humans would have likely carried their dogs with them.  

What was it about our species that made us adopt a different attitude toward wolves, a species that must have long been regarded as a competitor? Why had Neanderthals never been inclined to do so?  We’ll never know for sure, but we can conjecture.  We see differences in culture presently between 2 closely related chimpanzee species – the bonobo and the common chimpanzee.   Bonobos show less aggression toward each other than the common chimpanzee, and resolve disputes with sex and hugs/kisses.  Similarly, there may have been a difference culturally between Homo Sapiens and Neanderthals – one that caused Homo to have empathy in certain situations, like when coming across an orphaned wolf pup, or throwing scraps of food at a wolf that stayed begging.  Neanderthals conversely, may have always killed wolf pups on sight, or shooed away any lingering wolf, because they saw them as rivals.  It is also likely that from the start our species was just a little more intelligent, even while still possessing a sexual instinct, because we were the newest branch of the family tree and  Africa’s Rift Valley had for millions of years consistently thrown up better and better versions of homins leading eventually to us.    Perhaps this latest increase in intelligence gave Homo an increased self confidence and prowess in all areas, including hunting, and it did not see the wolf any longer as a formidable competitor.  Whatever the true story of wolf domestication, it had a most profound effect on our species’ intelligence, and it eventually spelled doom for the Neanderthals.

A curious fact has always escaped being reconciled with any explanation for homosexuality: societies have always, without exception, found it necessary to suppress or constrain homosexual behaviour, while concurrently needing to promote and reinforce heterosexuality through various means.  The need for this, in the face of paltry statistics for homosexuality in the range of 2-10%, defies explanation in terms of genetics and points to an experience-based sexuality for human beings.   This is clearly evidenced by the historically numerous examples where mere societal endorsement of homosexuality led to it becoming overwhelmingly prevalent.    In all such historical cases, the innate heterosexual drive to reproduce widely believed to be present in the vast majority of human beings was arguably nowhere to be seen, for why then, would all such societies have resorted to promoting, one way or another, a level of heterosexual activity sufficient for population maintenance.  This apparent synthetic quality of human sexuality points to a uniquely human attribute – a freedom from compulsory reproduction – and an attendant bias toward homosexuality. 

The conclusions regarding human sexuality appearing below are largely derived from a paper that was published in the Journal Of the Gay And Lesbian Medical Association in 2000 (True Nature – A Theory Of Human Sexual Evolution, C. Gomes, JGLMA Vol. 4, No1. and Vol. 4, No. 2), but also reflect new insights gained since publication.  They are a restatement of what appears at  www.humansexualevolution.com.

1.  We are unique  in the animal world  in not possessing a sexual instinct that would compel us to engage in heterosexual intercourse. 

                      What indications are there that this is true?

• Humans are the only animal species that can choose not to have offspring.  All other sexually reproducing animals are compelled to engage in heterosexual intercourse and reproduce when they sense the right combination of seasonal, pheromonal, and/or visual cues.  This proves that humans do not rely on environmental cues, neither pheromonal nor visual, to dictate their sexual behaviour. 
• Humans are the only species where exclusive homosexual subgroups exist.  In all other animal species where homosexual activity is seen, the same individuals invariably also engage in heterosexual intercourse because their sexual behaviour is underpinned by a reproductive instinct. 

2.   It was the tremendous rise in intelligence in the course of human evolution that made the loss of our sexual instinct possible.

                      Why was a sufficiently high intelligence level necessary? 

• For our species to continue surviving, the human line could not lose its sexual instinct until it was possible for reproduction to be relatively assured without it.  And this was only possible after humans had first found a benefit in     producing offspring (realizing that children could provide care and protection in old age), and then discovered what caused reproduction (linking heterosexual intercourse to it).  The tremendous insight required for both discoveries was only made possible by a sufficiently high intelligence level. 

3. Humans discovered the role of heterosexual intercourse not by scrutinizing their own sexual behaviour, but by making that correlation on another species first.  The reason this was necessary is that instincts are not tied to memory, and  hence leave no memory trace of their operation with which to correlate a future event.  Crucially then, the domestication of dogs provided the first opportunity to closely observe the sexual behaviour of another animals species, and eventually make the breakthrough correlation. 

4.Once the mystery of reproduction had been solved, the road was paved for a short-lived nasal plug during fetal development to eliminate the sexual instinct in the human line. It did so by isolating the developing vomeronasal organ (VN0)- critical for pheromone detection and response – from chemical ‘set-up’ signals that would have likely emanated from the concurrently differentiating sex organs, thus inhibiting the VNO’s proper development and functionality. This developmental change appeared within the last 200,0000 years. Of all hominid species that ever existed, only homo sapiens gained knowledge of the essential role of heterosexual intercourse in reproduction.  Hence, all other hominid species necessarily continued to possess a sexual instinct (viz. a functional VNO), irrespective of their brain size.

5. The loss of the sexual instinct conferred upon homo sapiens a vastly increased intelligence level, and allowed them to outthink, out innovate, and out compete the Neanderthals into extinction.

                       How did losing the sexual instinct accomplish this? 

• Brains require neurons to tell them what to do, and this requires neurons to get activated and send a nervous impulse to other neurons
• A neuron never works alone, but instead forms a temporary working group with other neurons that all fire synchronously (viz. together) to produce a combined neural signal whose strength is the summed strength of all neurons comprising the group
• At any instant, there are many such independent neural groups.  Each of these temporary groups of activated neurons represents one different thing that the brain could do in the next instant to time, for example have a particular thought, observe something, initiate a movement, focus visual attention at some object, etc.
•  The group of neurons with the greatest neural strength of operation wins out over all the other neural groups with lesser neural strength of operation, in so doing is able to dictate what the brain commands next, and occupies the seat of consciousness for the instant that it operates
• Another neural-group battle begins anew in the next instant of time between different groups of neurons, all vying for control of consciousness.  The content of the succession of dominant neural groups defines what we perceive as the stream of consciousness. 
• Intelligence is simply any experience-based response, and is categorically different from instincts, which are inborn responses to environmental stimuli. 
• Experience-based responses (viz. intelligence) and instincts vie for control of consciousness because both require large scale control of movement, and therefore can’t work properly simultaneously because each may be trying to tell the brain to respond to the environment in ways that require conflicting movement responses. 
• In nature, operation of instincts have such essential life-supporting and species-survival roles, that nature ensures that they must generally be able to displace from the seat of consciousness any prescription for behavioural response stemming from experience.  To be able to do so, the number of experience-linked neurons that can form a single group, and their combined strength, must be less than that corresponding to instincts.
• Increased intelligence however, requires more and more input from past experience, and this requires more and more neurons becoming simultaneously involved in conscious decision-making - which is  to say, larger neural groups.  However, given than instincts are characterized by neural groups that are relatively fixed in size – and do not grow proportionately with increases in brain size -  they therefore constrain intelligence level in all animals possessing them.   
• The loss of the sexual instinct in homo sapiens eliminated the constraint on the number of neurons allowed to form a single group, thus permitting greater use of prior experience in decision making, and giving rise to unprecedented powers of observation, deduction, intuition, invention, and abstraction. 
• This allowed homo sapiens to start on the road to maximizing the potential intelligence derivable from the existing size of their brain, allowing huge increases in intelligence without significantly increasing brain size.  This is evidenced by the comparable brain sizes of Neanderthals and homo sapiens, yet the quantum leap in technology, art, and culture made by human beings.  

6. The loss of the sexual instinct and the resulting full conscious control of reproduction was highly advantageous to humans.

• It facilitated monogamy within a multi-family group setting because individuals were no longer compulsively drawn to mate with other individuals of the opposite sex emitting sexual pheromones, thus reducing sexual tension and permitting increased social cohesion.
• It allowed births to be planned and timed appropriately with the availability of food and shelter resources as humans forged their way into new environments during various periods of global expansion, thereby reducing the mortality of infants and expectant mothers.
• It allowed competing groups of human beings to increase their populations in response to ongoing conflict and competition.

7. Lacking a sexual instinct, human sexuality is completely determined by individual experience.

             What are the implications of this?

• Heterosexuality is not genetic in human beings.  No genes have ever been found as a cause for heterosexuality.  Heterosexuality is learned.
• Homosexuality is not genetic in human beings.  No genes have ever been found as a cause for homosexuality.  Homosexuality is learned.

8. A universal set of childhood sexual exploration behaviours exists that most strongly biases a homosexual orientation development, over a heterosexual one, or a bisexual one.  Therefore, though not inborn, homosexuality is natural in humans, heterosexuality is not. 

            What gives rise to these childhood sexual exploration behaviours?

• All children have a natural tendency to sexually explore and stimulate their bodies from infancy, primarily the sensitive genital area, in attempts to derive tactile and olfactory pleasure from it.  This pleasurable behaviour has a much stronger potential to create same-sex attraction than opposite-sex attraction – if societal deterrents and/or a sufficiently strong heterosexual conditioning environment are absent.  Male circumcision was invented to deter a homosexual orientation development by reducing the penis’s production of smegma, and its sensitivity to tactile stimulation. 

            What indication is there that homosexuality is indeed natural in human beings?

• If we review the history of human sexuality, we see that throughout recorded history in diverse cultures spread across the globe whenever homosexual behaviour has been embraced and permitted, it has been so widespread and dominant that every such culture found it necessary to condemn exclusive homosexuality in order to ensure that a sufficient level of heterosexual activity existed to enable its survival.  If heterosexuality was indeed an innate, largely universal characteristic of human beings, this historical regulation of homosexuality and enforcement of heterosexuality would not have been necessary.

9. Heterosexuals vastly outnumber homosexuals in the world because societies – needing to maintain their populations – universally encourage heterosexuality while discouraging, or forbidding, homosexuality.

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A nasal plug appears in human fetal development for roughly 8 weeks, beginning at around the 7th week after conception and lasting until about the 15th week.  Structurally, it is a mass of epithelial cells that completely seals the nostril openings.  A clue to its function is its location, right within the area of olfaction and pheromone detection. In mammals, a sexual instinct is most often dependent upon detecting pheromones via a specialized organ – the vomeronasal organ (VNO) – and passing signals onto the brain areas responsible for initiating the appropriate instinctive behavioural responses.    Significantly,  the presence of the short-lived nasal plug is concurrent with the onset of important changes in sexual differentiation of the fetus, which also begins at week 7.  The ovaries appear in the embryo by week 7, while is males, the testes begin to differentiate. Until the 9th week both males and females have a creased bump that is the phallus. In the 9th week of development in boys, the testis releases hormones that induces the crease to fuse and disappear, leaving the phallus. In girls, nothing of great significance genitally happens in week 9, but over the next few weeks the crease stays and the phallus retracts to become a clitoris.  It is my hypothesis that the differentiating sex organs were the origin of the chemical messengers in the amniotic fluid the nasal plug once served to block.  More specifically, a sexual instinct requires that the correct gender-specific form of the sexual instinct be set up at a receptor/neural level, and this would presumably require instructions from chemical signals denoting gender (arising from sexual differentiation of the foetus) to be delivered to the developing pheromonal receptors, and perhaps the developing fetus’s brain. 

I believe that this developmental change appeared within the last 200,000 years.  Of all hominid species that ever  existed, only homo sapiens gained knowledge of the essential role of heterosexual intercourse in reproduction.  Hence, all other hominid species necessarily continued to possess a sexual instinct (viz. a functional VNO), irrespective of their brain size.  It is most probable that the nasal plug is an evolutionary artefact presently in humans, no longer serving the function it once did. Its absence today would be inconsequential because for thousands of years the sexual instinct has not operated in humans, leaving its associated receptor cells and neural programs outside the controls of natural selection, thus allowing random mutations to accumulate over time and render the  sexual instinct permanently destroyed and irrecoverable.  Prolonged disuse of receptors and neural programs would have resulted in atrophying of pheromonal receptor areas in the nose.  Also, the brain would likely have recruited neural cells from a non-functional sexual instinct network for use in other brain functions.   It is therefore very improbable that the nasal plug currently has the functional role outlined above .  However, I believe that timing of the nasal plug - during a crucial stage of sexual differentiation of the fetus, as well as the formation of the VNO – points to it being a veritable ’smoking gun’ of human sexual evolution, highly suggestive on its own that humans lack a sexual instinct.

Yet, in fairness to the writer one must dispel all prior notions and open one’s mind to the author’s point of view. The validity and explanatory power of the paper must be assessed only after reading it carefully and understanding the paper fully. A useful exercise is to try to summarize the paper in an appropriately detailed fashion, fleshing out the key points and their supporting arguments. Doing so will give you the author’s reference frame, momentarily allowing you to suspend disbelief and umbrage, and will then hopefully enable you to challenge the paper more objectively.

What is the nature of childhood sexuality, and how does it arise? Childhood sexuality most often begins with ‘self-love’, and only later transcends the self to include others. But why? From the very first moments of life we are faced with the task of becoming acquainted with all aspects of our physical being. As children, we do this by using our hands to explore the boundaries of our bodies, and in the process, we quickly discover that the highly innervated genital area is very sensitive and pleasurable to touch. Being pleasure seeking beings at the core, we repetitively stimulate our sex organs to derive physical pleasure from them.

But the sex organs are also a source of olfactory pleasure – smegma – a combination of shed cells, skin oils, and moisture that is produced under the foreskin in males, and around the clitoris and between the labia minora in females. Though never scientifically researched or written about in academic literature – because it evidently represents one of the bigger societal taboos – the smell of smegma is intrinsically pleasurable to all of us, yet is something generally never acknowledged openly for fear of social rejection. And so, children will deliberately contaminate their fingers with smegma in the process of stimulating the genital area, so that they can then smell their fingers and derive olfactory pleasure from doing so.

Though society strongly discourages both behaviours, all children tend to do it, and in great secret. If one ascribes to the belief that most of us are born inherently heterosexual, there would be no reason to believe that the childhood sexual behavioural tendencies described might have any repercussions for sexual orientation development. However, in a published paper ‘ True Nature – A Theory Of Human Sexual Evolution’ found at www.humansexualevolution.com , it is shown using various lines of argument that humans, as a species, no longer possess a sexual instinct due to our higher intelligence, thus making such behaviours capable of influencing sexual orientation development. But how, exactly?

If we are not born with a pre-determined sexual orientation, we acquire it through our life experiences and environmental influences. So what then, is the potential effect of childhood sexual exploration behaviours? In Chapter 3 (http://www.humansexualevolution.com/sexual-orientation-development.htm) we learn that because of the pleasurable tactile stimulation of the genital, and the addictive odour of smegma, there is the greatest potential – in the absence of all societal influences – to view others of our own perceived gender as sexually attractive because they possess sex organs identical to the our own – to which we have become so dependent upon for tactile and olfactory pleasure. In this same light, the sexual attraction to others of the opposite sex is much less likely to occur, because we cannot similarly associate with them – unless we are immersed in a heterosexual environment where the conditioning elements are sufficiently strong and effective enough to steer our sexual orientation development in a heterosexual path instead. Evidently, this is what societies are able to do successfully most of the time. Being born into a family with a mother and father certainly most strongly impresses upon a developing child what is expected in terms of sexual orientation. It is only when a child, through personal experience, does not respond to the vast array for heterosexually conditioning elements around it, that a homosexual orientation development (or a bixexual one,) is likely to occur.

The tendency for self-love, and its potential for homosexual orientation development, can offer us an explanation for the origin of circumcision, which has always remained a mystery. Both male and female circumcision were actually attempts by various societies across the globe to discourage homosexuality by reducing the tendency for children to fall in love with their own bodies, thereby also reducing the tendency for same-sex attraction. In the case of male circumcision, the removal of the foreskin reduces the formation of smegma, and also reduces the sensitivity of the glans penis to touch. In the case of female circumcision, the excision of the clitoris eliminates their ability to feel pleasure from tactile stimulation. In cases where the labia is also removed in female circumcision, it can be viewed as an attempt to reduce the accumulation of smega and keep the area clean.

But first, let us examine the shortcomings of the competing explanations.

The Savannah/Thermoregulatory Hypothesis says that when humans ventured out into the more open savannah environment from their arboreal habitats (shared with chimpanzees), they experienced considerable heat stress and consequently evolved the ability to sweat, whereby body heat is dissipated through sweat evaporation from skin surface. Such evaporation becomes enhanced when skin is more bare, and thus it is argued that the evolution of sweating concurrently favoured an accompanying thinning/loss of hair in humans. Here’s the death blow to this hypothesis – why were humans unique in their response to this heat stress? No other furred species of animals on the savannah have responded to the savannah heat stress in this way, and in fact, if you examine all those furred animals, you’ll find they have longer hair on the top surface – which is most exposed to the sun – appearing to invalidate the argument that humans lost their body hair due to the action of the sun.

The Aquatic Ape Theory essentially says that the human line went through an aquatic or semi-aquatic stage during evolution that required adaptation via various changes in anatomy and physiology, chief among them, the loss of hair and the development of a subcutaneous fat layer, claimed to have decreased resistance in the water, and increased streamlining and insulation, respectively. Several damning objections can be raised. First, it appears odd that if humans had indeed passed through an aquatic stage they did not retain some innate swimming ability. Secondly, the benefits of losing body hair were presumably to gain added speed through the water, or increased ability for long distance swimming. But why would increased speed have been needed? Certainly not for catching prey, because humans have no specialized adaptations for doing so – i.e. no large jaws, and no claws, etc. As for the swimming speed of humans, it is very unimpressive when compared to even a non-aquatic mammal like a dog. So, any purported increased speed could not have been of much use in escaping predation either. With respect to long distance swimming, the proboscis monkey provides ample proof that a primate can be fully furred, yet still be a proficient swimmer capable of swimming for miles – in the proboscis’s case, from island to island. Anyway, it is a fact that only trained athletes can swim long distances, and this ability is therefore not a species-wide characteristic. Lastly human beings, despite their subcutaneous fat layer would have been ill-equipped to spending most of their time in the water as the theory proposes, because the insulation it provides is not substantial, and humans would have been ever in danger of hypothermia in even relatively warm waters, which would have still been significantly cooler than their body temperature.

The ectoparasite hypothesis says that hairlessness was favoured as an evolutionary strategy to combat fleas, ticks, lice and other biting insects that commonly plague furred animals. Once again, we see a theory calling for humans to have employed a strategy that no other species has used when confronted with the same challenges, for reasons that are never specified. Additionally, this strategy itself is arguably not very effective, since leaving hair on the head, armpits, and genital areas still subject human beings to considerable infestation with ectoparasites.

So now to the sexual selection hypothesis. In a nutshell, it proposes that hairlessness was selected for because humans found it sexier. It might seem absurd to ask why hairlessness might have been considered more appealing, given that most people would tell you that the thought of a fully furred human would be repulsive. But this is preference based merely on hairlessness being ubiquitous today. This question is important to ask, because the answer is not obvious. Darwin, an early proponent of sexual selection as an explanation for human hairlessness, did not offer this needed insight.

A more reasonable hypothesis is that hairlessness in humans forced them to clothe themselves, and in the process it heightened sexual curiosity by obscuring the sex organs. The retention of hair in the armpits and genital area is indirect proof that when this change occurred humans still had a sexual instinct, since these areas develop hair beginning at puberty, and are known to produce chemicals that might have served as pheromones at one time. True Nature Theory says that humans lost the sexual instinct at some point during their evolution because their increased intelligence level made it both expendable, and advantageous to do so. But it was in the transition period – when we still possessed a sexual instinct, albeit a diminished one – that a mutation for hairlessness arose and was favoured so that the adoption of clothing could trigger increased sexual desire, and work in unison with the declining sexual instinct to still trigger heterosexual intercourse. Ironically then, nudity, which before then had never been considered sexually stimulating because it was everywhere, now became more titillating only because it became more scarce. Hence, it was not hairlessness in itself that was initially considered more attractive, but instead, it was more likely that hairlessness was selected for because of the response to use clothing it necessitated, and the consequent triggering of sexual curiosity and desire that was born from concealing the sex organs.

The question of whether humans possess a sexual instinct is easily answered by noting that human beings as a species are uniquely capable of choosing not to reproduce. This is an amazing fact and is proof that we do not possess a sexual instinct like that seen in all other animals. As I will show in future blogs there are reasons why this control over our reproductive abilites exists, and why we continue to reproduce despite not being compelled to do so by any internal, genetically programmed drive.

There is further dramatic proof that human beings lack a sexual instinct – the capability within out species for exclusively homosexual individuals to exist, and the supreme lack of it in all other species. It is true that homosexual activity has been routinely observed in over 450 species of animals (and counting), but there have been no exclusively homosexual animals ever observed in natural settings. Any animal that has been observed to engage in homosexual activity has as a rule also been observed to mate with an individual of the opposite sex when its sexual instinct was called into action.

So humans are the only species where exclusively homosexual subgroups can exist – where individuals can be truly homosexual. This is indirect proof that the sexual pheromones which trigger a heterosexual mating response in all other species of animals must clearly not exist in human beings. The grand conclusion here is that we humans have risen above animal sexuality, having lost our sexual instinct sometime in the course of human evolution. We thus as a species don’t have an instinct to reproduce, or to engage in heterosexual intercourse, and have the ultimate reproductive freedom.

The world had a much politicized reaction to this paper than surprised even the lead researcher, who was not trying to explain homosexual behavior, merely the albatross. Some gay rights advocates welcomed the news of same-sex families in the albatross world, interpreting it as further justification of their rights and lifestyle, while detractors were quick to point out that parallels in the animal world were meaningless as reflections of what society should embrace or permit, given that in many animal species there is infanticide and rape as well.

While the head researchers making the observations were quick to opine that they do not consider such same-sex pairs to be examples of lesbianism, they are also not sure what conclusions to draw from their observations, noting that while same-sex pairs appear to do everything male-female pairs do (preen each others feathers, nuzzle together, take turns nest-sitting while the other goes fishing, etc.), they do not have sex.

Why is this happening, and what can explain this abundance of female-female pairings within this colony of Laysan albatrosses? The researchers gave the following explanation: there are fewer male than female albatrosses in the colony and the ‘excess’ females – needing a partner to share parenting duties to enhance a hatchling’s survival chances – opt to each mate with an already paired male, but incubate their egg with another unpaired female. This way, paired females have a better chance of passing on their genes.

Even though in the case of the Laysan albatrosses there is no homosexual activity (viz. actual sex) going on within female-female pairs, it is noteworthy that homosexual activity is sometimes observed when there’s a shortage of one type of gender – in the wild but more often in zoos (known as the prison effect). In fact, the article points out that ‘same-sex sexual activity has been recorded in more than 450 different species of animals, from flamingos to bison to beetles to warthogs’ – but not exclusive homosexual sex! So, to answer the central question of this blog entry – No, animals can’t be gay. Humans are the only species where exclusively homosexual individuals and subgroups exist. We are unique in all of nature in this respect, and I will show in a future blog how it is our vastly superior intelligence relative to all other animals that makes it possible.

The many researchers in the article admit being incapable of making sense of homosexual activity seen in so many diverse species of animals, and speculate that a single unifying theory might not ever exist. I believe a good overall unifying explanation can only be arrived at when we examine the relationship between 2 biological variables – instinct and intelligence – and how they interact with environment. That will be the topic of my next blog.