Human Sexual Evolution:
The Road To Humans Losing Their Sexual Instinct
& Sex Pheromones, and Becoming Hairless


**** THIS SECTION NEEDS UPDATING - My blogs reflect some of the changes that will be made at a future date.

A reasonable question that should be asked is why our species did not become extinct after we lost our sexual instinct. After all, the central hypothesis of this essay is that after we lost our sexual instinct, the greatest tendency in human beings was to be homosexual. The fact that we still exist is obviously proof that heterosexuality never disappeared completely during any period of our evolution. Why and how did it survive? What were the reasons that caused human beings to begin consciously regulating their own sexuality? The validity of the central hypothesis of this essay will depend of whether we can answer these important questions.


It is believed that the last common ancestor of the hominoids – that is, the Asian apes (orangutan, gibbon, and siamang), the African apes (chimpanzee, bonobo chimpanzee, and gorilla), and the hominids – existed around 10 million years ago. The Asian apes then split off. The division between the African apes and the hominids then took place roughly 5-7 million years ago, at a time of extensive climatic and environmental changes (36). The forests and woodland were giving way to more open grassland at this time, and one branch of the simian line ventured out onto the grasslands and eventually evolved into the hominid line, whereas the branch that remained in the forest environment evolved into the chimpanzees we see today. Because chimpanzees are genetically our closest evolutionary relatives and because they are probably very similar to the earliest hominid branch that evolved, it is unlikely that the branch that initially ventured out into the grasslands was monogamous because chimpanzees are not monogamous. The open grassland would have posed many hazards for an ape species beginning to exploit this new environment, and such an environment would have best been tackled by small groups of individuals similar to the baboon troops that are found on the open savannah today, and which are controlled by dominant males; they are also not monogamous. The only apes that are monogamous today are the gibbons, and it is noteworthy that gibbon pairs live in relative isolation from other pairs. Hence, it is all the more unlikely that the simian line that initially ventured out onto the savannah was monogamous because it would have proved too difficult for single monogamous pairs to exploit the new environment alone, without the protection and cooperation that group living would have offered. We can also say that at this initial stage this pre-hominid species that began to venture out into the open savannah still possessed a sexual instinct, as well as other instincts that were important to survival. Males would have instinctively protected the females and their young, but like chimpanzees, likely would not have been involved in parenting. And like chimpanzees, we can safely characterize the sexuality of pre-hominids as being bisexual, but underpinned by a heterosexual instinct.


The progressive rise in intelligence as pre-hominids evolved into hominids had some important consequences. We know that as the intelligence of a species increases, the neural output of any given instinct grows proportionately, and continues to remain slightly larger than the neural outputs pertaining to regions of neural activity associated with intelligence, if and only if the environmental stimuli that trigger the instinct continue to exist, the instinct continues to perform a function of survival value, and the intelligence level is not sufficiently high to allow the species to survive without operation of the particular instinct. It has already been stated that because the sexual instinct the human line once possessed performed a critical function, natural selection could not favor its complete loss (irrespective of intelligence level) until human beings began to consciously perceive a benefit to reproduce based on experience, and discovered the knowledge of how to do it.


As the intelligence level kept rising in the course of human evolution, eventually a critical level of intelligence was reached where for the first time the human line possessed the required intelligence that made it possible to find an experience-based motivation to reproduce, and the knowledge of how to do it. But acquiring this knowledge would take time, insight, and keen observation. At this pivotal stage, a parallel increase in the strength of the sexual instinct (which had till now always accompanied increases in intelligence, thereby ensuring that the sexual instinct would continue to be able to suppress intelligence-driven motivations and express itself as required) was for the first time NOT favored by natural selection. This was the case because the conditions were prime for the human line (by virtue of its newly attained intelligence level) to being going through a transitional period of learning during which the benefits and mechanism of reproduction would eventually become apparent, thereby initiating a decline in dependence on the sexual instinct and paving the way for an increased long-term adaptability and flexibility of behavior that would only be possible by eventually losing every significant shred of a sexual instinct. A further increase in intelligence was also not favored by natural selection at this point because it would have allowed intelligence-driven motivations to suppress the sexual instinct, with obvious dire consequences for the survival of the human line – since the knowledge and benefits of reproduction had not yet been discovered. Hence, at this critical stage the neural activity associated with experience-driven motivations would have roughly equaled the neural activity associated with the sexual instinct.




—   Page 2   —


The consequence of this was that for the first time in our evolution the sexual instinct began to have trouble expressing itself, and consequently, heterosexual intercourse may have begun to decrease somewhat in frequency. Paralleling the increase in intelligence to this point, an increasing homosexual bias in the bisexual behavior of early hominids may also have been developing. The reason for this was that the increased intelligence level at this stage would also have enabled a greater ability to form same-sex associations and desires through the homosexual developmental pathway involving pleasurable smell and touch sensations. Something had to occur at this point – something was needed to tip the balance in favor of the sexual instinct as it competed, at times in somewhat virtual stalemate with experience-driven responses (including homosexual desires) for the control of consciousness. At this point a mutation arose that increased the heterosexual sex drive sufficiently and allowed reproduction to occur more readily. The mutation that emerged was able to augment the sexual instinct and thus tip the balance in its favor by capitalizing on, and manipulating, one of the hallmarks of intelligence – curiosity. This mutation was the loss of the thick coat of body hair.


Before going on to discuss how the loss of body hair was able to boost the heterosexual instinct, it will be beneficial to review some of what was said in ‘Part 2 – Instinct and Intelligence’ regarding the conditions under which two or more neural regions can work cooperatively in suppressing rival regions, thus explaining how augmentation of the sexual instinct by some experience-based motivation would be possible in the first place. Recall that while multitasking is permitted by brain function, one of the functions of consciousness is to eliminate possible conflicts of movement that would impair purposive behavior. However, what if an experience-based motivation and an instinctive drive happen to share a common behavioral objective and hence require the same movement controls to be fulfilled? It was stated in Part 2 that in principle at least, the potential for conflict for movement would become a nonissue in such cases. The ensuing discussion of why humans lost their thick coat of body hair in indirect evidence that reinforcement of the heterosexual instinct by an experience-based sexual desire did indeed occur at some point in our evolution.


One of the most distinguishing features of human beings is their relative hairlessness compared to all other primates. The most widely believed hypothesis of why human beings lost their thick coast of body hair is that it was related to the simultaneous emergence of sweat glands. The argument is that when humans began hunting on the savannah after becoming bipedal, running at high speed became more of an exertion, and consequently, hunting in the hot sun caused evolution to favor a cooling mechanism provided by the simultaneous loss of body hair and the evolution of sweat glands. This argument is weak for several reasons. Early hominids would likely have relied more heavily on stealth, deception, ambush, and missiles than on the speed of the chase (34). Also, there are plenty of animals constantly having to escape predation on the plains of Africa and there are also many predators such as cheetah that exert themselves daily, all of them to an extent equal to or far greater than what our hominid ancestors would have been subjected to. Despite this, none of these animals have become similarly denuded or show any signs of heading in that direction. The hunting hypothesis also runs into trouble trying to explain why men have generally retained more hair than women even though it would have clearly been the males that did most of the hunting. Darwin himself rejected the cooling hypothesis on the grounds that “the other members of the order of Primates, to which man belongs, are well clothed with hair, generally thickest on the upper surface,” contrary to the supposition that man lost his body hair by the action of the sun (37). He favored sexual selection instead, and suggested that men found hairlessness attractive, leading to an accompanying but less marked loss of hair in men.


In keeping with Darwin’s view, I believe the real reason the loss of the thick coat of body hair was favored by evolution was that it forced human beings to clothe themselves in order to keep warm, and in so doing, the genital became obscured from sight, thus creating a sexual curiosity that heightened the sex drive. Implicit in this view is that this mutation occurred during a period in human evolution when the climate was sufficiently cool to necessitate clothing as a response to the thinning of body hair. Using this hypothesis, we can say that the thinning of body hair must have arisen as a single mutation in which hair loss was significant enough to cause the individual born with this mutation to require clothing, as opposed to a long, slow, and incremental species-wide loss of hair over many thousands of years – something which could not be supported using this hypothesis. Although the homosexual sex drive would also logically have been heightened by the use of clothing, what was important was that the heterosexual instinct was now boosted by the conscious desire for heterosexual intercourse due to the sexual curiosity created by concealment of the genitals. This is what tipped the scale and allowed the sexual instinct to assume the seat of consciousness with sufficiently more success. Therefore, although a homosexual bias may have continued to exist, in situations where the only decision involved was whether or not to have heterosexual intercourse (i.e. not a choice between homosexual intercourse and heterosexual intercourse), more often than not the sexual instinct would now be able to assume the seat of consciousness and reproduction would be a possibility.




—   Page 3   —


Looking objectively at human beings there is plenty of indication that much of our sex drive is indeed related to the fact that we live in societies where clothes are worn. It is true that we find nudity sexually stimulating, but understanding the psychology of human beings it is obvious that we find it stimulating only because we don’t see enough of it, not because we possess some instinctively programmed, insatiable, and irrepressible sexual fascination with it. To a person who visits a nude beach for the first time, the experience at first may be visually very stimulating, but after a few hours the novelty of the experience wears off, the individual’s curiosity becomes satiated, and nudity ceases to be as stimulating. With nudity, it is undeniably true that too much of a good thing wrecks it. Strip clubs effectively exploit the power of clothing and its ability to tease our curiosities. It is the tease factor generated by the scantiness of a stripper’s clothing that generates much of the interest. Another indication that the curiosity provided by clothing is what largely fuels our sex drives is that the frequency of sex between most married couples is highest in the first couple of months, and drops significantly after the first year. After couples have had sex hundreds of times and know each others bodies from head to toe, the sexual curiosity is gone and with it so too has a lot of the sex drive. For married couples, even clothing eventually loses much of its power to incite sexual curiosity because each partner knows exactly what lies under it.


It is with this hypothesis about the role of clothing in artificially boosting the sex drive that I believe we can partly explain the low population of simple hunting groups that live in the tropical regions encircling the globe. These tropical environments, of which the Amazon regions are typical, are characterized by dense rain forests, extensive swamps, and thick vegetative undergrowth, that together with the poisonous snakes and dangerous predatory animals they harbor, appear to those lacking knowledge of how to survive in such environments as explanations for the low population of these primitive tribes. Such tropical areas however, also contain an amazing variety of animal species, birds, fish, fruit, berries, nuts, and plant foods, all of which are sufficiently abundant food sources that become available with knowledge of the environment. So, possessing proper knowledge of such environments, why should groups that have existed for hundreds of years, and in some cases thousands of years, continue to be so lowly numbered? It is all the more surprising and significant that the populations of primitive tribes are universally small when one considers that most of them have historically been in constant regional conflict with each other – and there are obvious advantages to being large in number than your rivals.


The tropical regions are among the hottest and most humid on earth, and in many areas virtually no clothing is worn by the indigenous peoples. Tribes such as the Waura, Paresi, Sherente, and Kaigang or Brazil, the Witoto and Tanimuka of Colombia, the Hoti of Guinea, the Guarayu of Bolivia, and the Chayahuita of Peru wore no clothing when discovered by Europeans, and all had relatively small populations. It is noteworthy that in these tropical areas where clothing is completely dispensable most of the time, it is nevertheless worn by some groups – often just enough clothing to cover the genital area. One has to wonder why clothing exists in such tropical areas at all, and what need there is to conceal the genitals. The concept of clothing in such tropical regions quite likely had its origins in eras and places where clothing was a necessity to keep warm, and has been a carryover from such earlier time periods. The very presence of clothing, however minimal, among some primitive tribes living in tropical regions today must obviously be seen as an example of something that continued to be socially reinforced (though on unrelated and deflected moral grounds) because it benefited the tribe by keeping the sex drive sufficiently high, thereby ensuring a reproductive rate that allowed it to survive and defend itself from competing tribes. In other cases it was the influence of Western explorers and missionaries who regarded nudity as a sin that resulted in the imposition of an acceptable level of clothing. Although from our perspective the scant clothing would be expected to increase the sex drive of such people, individuals growing up in such societies are not similarly aroused because they have since birth viewed it as routine, everyday attire. Therefore, there is no element of tease or sexual display associated with the meagreness of their clothing style; in reality it functions not to enhance sexuality, but instead to preserve a necessary modicum of it.


From what has been said so far, the thinning and relative decline of body hair occurred when we still had a sexual instinct. But is there any proof of this? Yes, the proof is the existence of hair in the armpits and genital area. When we became denuded, why did we retain hair in these regions? A current line of thought is that we have hair in these areas because after losing all our hair everywhere in the course of evolution for purposes of cooling down, we grew hair in the armpits to reduce friction during walking, and in the genital area to reduce friction during sexual intercourse after humans began to copulate face to face, instead of from behind like other primates. These arguments are not valid for several reasons. To begin with, women in many parts of the world shave their armpit hair without experiencing any discomfort due to friction, and only feel discomfort as the stubble grows. Second, the genital regions don’t rub themselves against each other nearly enough during frontal sex to have initiated an evolutionary change in the direction of genital hair growth. The fact that the hair in the armpits and genital area first begins to appear at the onset of puberty - a




—   Page 4   —


period of sexual maturation in both males and females – is the first clue that it may have at one time been linked to reproduction. The armpits especially, but also the nipples and genitals, are the primary areas where a particular type of sweat gland, the aprocrine sweat glands, emerge at puberty. Unlike the other type of sweat glands, namely the eccrine sweat glands, which develop shortly after birth and whose function is to release heat, the aprocrine sweat glands secrete a clear, odorless liquid which is usually broken down by bacteria native to these regions of the body. It is these degraded by-products which emit the characteristic odor we associate with sweat. What is the purpose of this clear, odorless liquid? We know that many other animals release pheromones, chemical substances which, secreted by one organism, influence the behavior or physiology of other organisms of the same species. In mammalian species, most pheromones are detected by means of olfaction. Pheromones may be divided into three general classes: releaser pheromones stimulate rapid behavioral changes, whereas primer pheromones result, through the neuroendocrine system, in delayed physiological or behavioral changes. Other, information pheromones are indicators of an animal’s identity or territory. (38). A sex attractant pheromone is an example of a releaser pheromone; it induces sexual activity in members of the opposite sex and is the one that is typically associated with a functioning sexual instinct in many mammal species. A familiar example of a sex attractant pheromone in action is that of a female dog in heat triggering a sexual instinct to mate in males sometimes miles downwind from her. I believe that the emergence of the aprocrine glands right at puberty in areas where the sweat byproducts can become trapped by hair and linger for hours, increasing their effectiveness, is suggestive that the aprocrine glands produce substances that at one time triggered automatic, stereotypical, gender-specific reproductive behaviors in human beings.


A study of the menstrual cycles in al all-female college in 1971 showed that women who spent a large amount of time together tended to have synchronized cycles – their menstrual periods began within a day or two of one another (39). A subsequent experiment showed that this synchronization of female menstrual cycles occurs as a result of their olfactory mechanisms sensing the chemical properties in each other’s underarm sweat (40). The investigators collected daily samples of a woman’s underarm sweat. They dissolved the samples in alcohol and swabbed them on the upper lips of a group of women three times a week, in the order in which they were originally taken. The cycles of women who received the extract (but not those of control subjects whose lips were swabbed with pure alcohol) began to synchronize with the cycle of the donor. *** UPDATE: Recently, this 1971 study on female menstrual synchrony by Barbara McClintock was invalidated. A junior collaborator in that research study (who was apparently coerced and silenced at the time,) has now come forward and stated that McClintock deliberately falsified the study results in the following manner - women’s menstrual cycles are known to be erratic in duration month-to-month, tending at times to randomly vary in length by a day or two over any reasonably extended measurement period. So, if two women cohabit there is a good chance that they will have synchronized cycles at some point in time – if the study period is sufficiently long enough – but they will then just as likely go out of synch if observations are continued to be made (as the collaborator claims was the case in McClintock’s study). McClintock chose to stop the reporting of study results beyond the point of synchrony, thus deliberately reporting the false conclusion that cohabiting females are capable of sensing the menstrual cycles of each other through olfactory mechanisms involving pheromones, and becoming synchronized. *** A more recent study showed that odorless axillary (underarm) compounds of women in the late follicular phase of their menstrual cycles accelerated the preovulatory surge of luteinizing hormone of recipient women and shortened their menstrual cycles. Axillary compounds from the same donors which were collected later in the menstrual cycle (at ovulation) had the opposite effect: they delayed the luteinizing hormone surge of the recipients and lengthened their menstrual cycles (41).


Even though menstrual synchrony in human females appears not to exist after all, results from other studies (mentioned above) appear to indicate that at least some (primer) pheromones do still operate in humans. But this does not prove that human females have a sexual intinct, which may be defined as a rather irrepressible urge to engage in heterosexual intercourse during reproductive cycles. Clearly, women do not lose complete control over their sexual behavior (either due to pheromones released by men, or due to activational effects of their own sex hormones) and seek out males to copulate with when they are ovulating each time. Most studies have reported that fluctuations in the level of the ovarian hormones have only a minor effect on women’s sexual interest (42, 43). Such findings suggest that human females have largely transcended the sexual compulsions that once stemmed from their ovarian cycles, making it all the more improbable that putative pheromones released by males (at least in the quantities produced naturally) still trigger a significant sexual response in women. This contrasts with studies of female monkeys which showed that their sexual activity closely corresponded with their cycle of ovarian hormones (44). Although in comparison to monkeys the observed sexual activity of female chimpanzees corresponds much less closely with their cycle of ovarian hormones, they are nonetheless still compulsively sexually receptive during reproductive cycles. Investigators have studied the possibility that odors produced by vaginal secretions may affect a woman’s sexual attractiveness (45). Both males and females rated these odors as unpleasant, although secretions obtained around the time of ovulation were rated as less unpleasant. Thus, a woman’s menstrual cycle appears to affect the odors of her vaginal secretions, but there is no direct evidence that these changes increase her sexual attractiveness.




—   Page 5   —


In mammals, chemical signals may be transduced via a number of distinct neural subsystems, including the nervus terminalis, septal organ, trigeminal nerve (CNV5), gustatory system, main olfactory system (CNV 1), and accessory olfactory (vomeronasal) system (46). Mammals usually (although not exclusively) detect pheromones through receptors found in the VNO (vomeronasal organ). In the past, most investigators believed that the human nose did not contain a VNO and thus assumed that all effects of pheromones on humans involved the main olfactory system. Recently however, a clearly identifiable VNO has been found to exist near the base of the nasal septum in adults (47). Recent studies (48-50) have examined the physiological effects of independently stimulating the VNO and main olfactory areas (OE) of subjects of both sexes with femtomole (viz. really miniscule) amounts of odorless substances derived from aprocrine secretions – putative pheromones, as well as olfactants. Stimulation of the VNO with these supposed pheromones produced a local depolarization with the characteristics of a receptor potential. The same substances produced only a small response from the olfactory epithelium (OE), and no response from the nasal respiratory mucosa. Responses to virtually all the putative pheromones exhibited a sexual dimorphism, some producing pronounced depolarization only in males, others primarily in females. Stimulation of the OE with the same quantity of odorants produced a depolarization response, but little or no response in the VNO. Therefore, the human VNO seems to have a unique specificity to certain chemosensory substances when compared to the OE. Furthermore, the stimulation of the VNO with different axillary substances resulted in different patterns of local and autonomic response, suggesting that multiple VNO receptor sites with different specificities exist.


Significantly, it was shown that in both male and female subjects the depolarization of the VNO – but not the OE – triggered substance-specific autonomic changes in electrodermal activity, skin temperature, core temperature, respiratory rate, and cardiac activity. These autonomic responses to several of the putative pheromones were consistent with a relaxation response and were accompanied by an increased percentage of alpha-cortical activity, something that was not observed following depolarization of the OE. Interestingly, it was also shown that delivery of a naturally occurring axillary substance, namely androstadienone, to the VNO induced changes in physiological state that were evaluated using the Derogatis 70-question psychometric test. Androstadienone’s effect was to decrease negative feelings such as nervousness, tension, anxiety, irritability, anger, shame, and rage. Through stimulation of the VNO some of the putative pheromones were also found to trigger changes in the pattern of release of luteinizing hormone, follicle-stimulating hormone, and testosterone in males. The release of gonadotropins might lead one to believe it is especially significant evidence of a sexual instinct, given that in several mammalian species the release of gonadotropins, and hence the gonadal hormones, is important during mating and pregnancy, and for the onset of puberty. (51-56).


At first glance, the overwhelming nature of all this data certainly appears to indicate that a fully functioning sexual instinct still exists in human beings, waiting to be completely exposed and characterized with further study. Keeping in mind however, that a sexual instinct involves the expression of programmed behavioral drives and all their necessary controls over movement, we should ask whether any of the aforementioned physiologic effects of putative pheromones give rise to stereotypical, gender-specific, behavioral responses (involving movement responses) that are sufficiently dominant and persistent enough to resist the expression of alternate, experience-based behavioral objectives and choices of movement. No such compulsive behavioral responses have been shown to exist; the search for sex-attractant pheromones in humans has so far been fruitless, despite plenty of research.


Do any of the physiologic responses to axillary compounds have a perceptible and meaningful effect in our everyday lives, away from the ideal conditions of the lab, where subjects were placed in quiet rooms in a relaxed supine position, with very little else impinging upon the seat of consciousness? Our living experience tells us that despite being habitually exposed to such putative pheromones, out psychological state is very much more a function of our conscious experiences and can seemingly easily override any relaxation effect such pheromones may induce. The autonomic responses attributed to such substances, namely changes in respiratory rate, cardiac activity, electrodermal activity, core temperature, etc., can also be (variably) affected by emotional states arising from our conscious, intelligence-based experiences. For example, a heterosexual male in the presence of an ovulating female – aside from being totally oblivious to her fertile state - will not necessarily feel relaxed in accordance with the described physiologic responses to sensing her pheromones; he may feel a whole range of emotions, and experience an equal latitude of physiologic responses which may stem from sources unrelated to pheromone action – the rain outside that is preventing him from golfing, an argument with a friend 10 minutes earlier, the anticipation of his wife delivering their first baby, etc. Even the putative pheromones’ effect on the release of gonadotropins from the pituitary gland does not have an unassailable and deterministic effect on behavioral response, for this too, can be significantly affect by our everyday experiences, emotions, and activities. Certainly, given the relative ease with which the physiologic responses to the putative pheromones may be suppressed and altered by conscious experience, we would intuitively not expect the manifestation of any associated instinctive behavioral response either. What then are we to make of all the observed physiologic responses to axillary compounds and their derivatives?




—   Page 6   —


In evolutionary biology there is a name given to anatomic traits which at one time served a useful function, but which in the course of evolution ceased to do so but still continue to exist – they are called vestigial traits. Vestigial traits are by definition not detrimental and hence cannot be independently eliminated by natural selection. They tend to become eliminated only if in the course of evolution a beneficial mutation occurs whose associated gene(s) occupy the same location in the DNA that the vestigial trait would normally have occupied, and which therefore precludes the possibility of both being inherited simultaneously. The likelihood of this occurring is evidently probabilistically rare, and it would appear that vestigial traits require very long evolutionary periods to be eliminated, given that they are a common feature of many species. A well-known example of a vestigial trait in humans is the appendix. The appendix is an organ that is filled with beneficial bacteria that break down cellulose, and is commonly found in grass-eating animals that have to digest large volumes of it, such as cows. It is believed to have served a similar purpose early in human evolution when tough, hard-to-digest grasses were still the main part of our diet.


Armpit hair and pubic hair should also be viewed as vestigial traits. The physiologic responses to aprocrine secretions may be interpreted as vestigial components of a more complete and complex sexual instinct that we no longer possess. No greeter proof exists that humans possess no sexual instinct and that pheromones play no role whatsoever in sexual attraction and reproduction, than the striking fact that of ALL animal species humans are the ONLY one that can choose not to reproduce. The sexual pheromones that are so intimately tied with a functioning sexual instinct in all other mammals, and which trigger sexual attraction and reproduction, must clearly not be present in human beings to afford us such sexual freedom! And by logical inference, given that pheromones do not account for heterosexual reproductive sex in humans, they must analogously not exist and play no role in homosexual behavior either! Hence, the aprocrine secretions and armpit and genital hair no longer serve the critical function they once did. The aprocrine sweat glands, far from producing a sexual attractant, actually give rise to odors which most human beings can tolerate only in small doses, and which accumulate to levels that necessitate daily bathing to prevent social rejection. Certainly there are people who love the smell of sweat on their lover’s bodies, but if such odors were universally appealing perfumes and colognes would not be a multi-billion dollar industry worldwide.


A lot can be deduced from knowing that human beings had to clothe themselves as a response to losing their body hair. It has already been stated that the branch of apes that initially ventured into more open territory and which eventually evolved into the hominid line was likely not monogamous, and that similar to what is seen in chimpanzees, males would not have been involved in child rearing, although they would have defended the females and their young from predators. This pre-hominid branch of apes would have had a diet similar to that of baboons on the savannah today, which accordingly would have consisted mainly of grasses and roots, but which would have occasionally included small animals such as young gazelle. These speculations about the diet of pre-hominids and early hominids are in fact confirmed both by fossil evidence, which shows the presence of large, strong jaw bones and large flattened molars, signatures of animals that have to chew bulk quantities of tough, cellulose-laden grasses of low nutritious quality, and also by the presence of an appendix in humans, a vestigial organ which has survived from such a period and whose function has already been elaborated upon. The important point is that because of the relative availability of grasses and their accessibility, very early in our evolution females nurturing young on the savannah would have still been able to live relatively independent lives without requiring parental assistance from males. In this context, the lives of females were much like the existence they once had in the forest environments of their earlier evolutionary periods, where trees were laden with fruit and leaves that were easily accessible to the mother and her young.


However, by the time evolution had progressed to the stage where humans had lost their thick coat of body hair and were forced to clothe themselves, there is proof that the relationship between the sexes with respect to male involvement in aiding a female with young had changed drastically. It is reasonable to assume that in light of man’s hunting history, animal hides and furs would have logically been the first materials exploited for clothing. It is clear that females encumbered with young could not have hunted and would have been dependent on males to provide them with the animal hides and furs they would have needed for clothing. Why were males, who had not started out being involved in the care of females and their young, now prepared to get involved? Was this behavior the product of a newly evolved instinctive drive? It could not have been instinctive because, on the contrary, it was the loss of instincts (due to their lower adaptive value) and the rise of intelligence that characterized the evolution of human beings. So, if the behavior was not instinctive it had to be experience-based. The incentive for males doing this could not have been to get sexual rewards from females because the heterosexual instinct had decreased and indeed, species survival only became possible due to the increased curiosity provided by clothing in response to the loss of body hair. Even though clothing increased the heterosexual drive, there was likely still a homosexual bias and the heterosexual sex drive did not increase to the point where females could have manipulated males using sexual rewards. In building up a picture of the environment our hominid ancestors faced, we will see that it was for self-serving reasons other than sexual rewards that males provided females and their young with the animal hides and furs they required for clothing.




—   Page 7   —


As the intelligence of hominids increased in the course of evolution, at some point they began to possess the intelligence to understand the concepts of aging and death, something unknown to all other living organisms. They came to know that each of them had a highly predictable fate, that their physical strength would inevitably decline with time, and that they would one day die. I believe that this knowledge must have already been possessed by human beings when they lost their body hair because it would explain why males were willing to provide the aforementioned assistance: a very significant portion of the diet had changed from mainly tough grasses and roots to largely meat and this would have meant that, especially in old age, it would not have been possible to even remotely live an independent life because whereas grasses are easily accessible, the acquisition of meat would have required the ability to hunt (or perhaps scavenge) and therefore would have necessitated an adequate level of physical fitness, something which obviously declines with age. There must therefore have been the realization by males that alliances with younger individuals would ensure that when they grew old and would no longer be able to participate in hunting or scavenging, they would be taken care of and provided meat by those they had themselves cared for when young.


Even if one were to make the argument that vegetables and other soft, easily digestible plant foods continued to form a significant part of the human diet after hunting assumed prominence, procuring such widely dispersed and random food sources with the infirmities of old age, illness, or injury would still have proved most difficult without assistance from more able-bodied individuals. Moreover, alliances with youth would also have ensured that their rights and individual needs were not violated by others within the group. The increased intelligence of the human line, after all, allowed individuals to profit from the psychological and physical domination of others in ways – and to an extent – unparalleled in other animal species. In response to all these needs, producing offspring became the only logical countermeasure. Although the sexual instinct still existed and hence we may assume that females still instinctively took care of their young, their motivation to do so would also have been strengthened by the knowledge that in old age, illness, or injury, they too would need assistance in terms of protection and food, and hence parental care was a wise investment that would pay dividends in the future.


Our lives are so different from the ones that our early hominid ancestors faced, and indeed even from that of people in past centuries, that it is easy to fail to see the self-serving motivations behind parental care. Today, people (especially in developed countries) have children either because they feel it will be an interesting experience, some because they feel it is a natural consequence of getting married, some because they feel that children will strengthen their relationship by giving both partners something they can mutually love and care for, some because of a need to produce an heir, and some couples have children because of boredom – because they feel that children will take away the monotony of their lives. In past times however, these were not the primary reasons why people had children. They did so because their very future survival depended on their ability to produce children that could help them, especially when they grew old and required care. No one has children today because they feel they will die prematurely if they don’t, and this is why we cannot relate to people in earlier times in this respect. It times past, much more markedly so in the prehistory times of our early evolutionary ancestors the prospects for survival in old age, especially without familiar care, must have been bleak. Hesiod, the peasant poet who lived in the latter part of the eight century B.C., and whom the Greeks revered only slightly less than Homer, was in agreement with this view. He explained why it was necessary to marry at all: “He who evades, by refusing marriage, the miseries that women bring upon us, will have no support [children] in the wretchedness of old age… “. (7)


All that is changed now. We live in societies where, for the most part, if we have planned our finances wisely during our working years we no longer need assistance from our children when we grow old. Our modern societies give each of us the ability to live independent lives even in old age. Modern technology offers unprecedented mobility, even to those who are old and physically disabled. Telecommunications pervade our society and allow many services to be purchased from the home. Grocery stores are packed with a surplus of food for consumers to buy. Medical care is generally available to all and routinely saves lives. A most modern feature of our societies is institutionalized care for the old in the form of nursing homes. Such senior homes, along with this unprecedented potential each of us has to save money toward our retirement, gives each of us the realistic opportunity to remain independent throughout our lives. Most people don’t realize that never before has there been such widespread prosperity, particularly in developed countries, nor have there existed investment opportunities that have allowed average people to acquire such relative wealth as they approached old age.




—   Page 8   —


I believe that the importance of children to future survival, which must have been realized some time before the loss of body hair evolved, may have been one of the factors which favored the emergence of monogamy, despite the fact that a homosexual bias in sexual relationships may have existed at the time. One thing we can safely deduce is that at the stage when the loss of body hair was favored human beings could not have had any clue about the role of heterosexual intercourse in reproduction, because despite the known future survival value that children offered, the frequency of heterosexual intercourse had decreased to the point where the loss of the thick coat of body hair was favored to increase it. The role of heterosexual intercourse in reproduction is not altogether obvious. Hence, monogamy could not have been chosen at this stage for reasons of males wanting to be sure about paternity. There was another reason. The realization that somehow only females gave birth created a competition between males for females, though not predominantly for sexual reasons. The emergence of a preference for monogamous heterosexual relationships in which homosexual encounters may have been allowed was a natural consequence of this competition because inherent differences between individuals with respect to personality, physical attributes, and capabilities made multi-individual sexual units unworkable in the long run due to the intense rivalries, jealousies, and bitterness such differences inevitably created between individuals. Also, within such multi-individual sexual units individuals could never be sure that their good deeds toward children, aimed at forging relationships and instilling future loyalty, were not being outdone by others in the group. So monogamy must have quickly won out, not only because it allowed each individual to believe that they were loved and valued above all others by their partner, thereby reducing tensions and insecurities, but also because it allowed individuals to be certain that their parental investment was not being undermined by others.


To this point, human beings had found the value of offspring to future survival, but still did not know what made reproduction possible. The stage was now set for this important discovery. Humans may have acquired this knowledge in any number of ways. It is known that recessive traits, sometimes traits that are a throwback to some earlier evolutionary period, can randomly surface and find expression. For example, there are recorded cases, though very rare, of individuals being born with a full thick coat of body hair reminiscent of what human being once possessed. Such occurrences would have been relatively more common closer to the period when the mutation for thinning of body hair first took place, because it is largely the passage of evolutionary time that increasingly dilutes the presence and expression of unfavorable genes. We can imagine a scenario in which a female with a full coat of body hair was born into a group where hairlessness was already prevalent and sexual curiosity arising from clothing was an essential component of the heterosexual sex drive. Such an individual would not have needed to wear clothing and consequently may not have triggered a sufficiently high heterosexual response in males to have been mated. Perhaps such females would have been shunned due to their conspicuous difference from others. Alternatively, some injuries incurred by females may have incapacitated females to the point where they were not chosen as mates, though they would have presumably been taken care of by relatives. Another possibility is that a slight surplus of females may have routinely existed in primitive hunting bands owing to a higher mortality rate for males resulting from the dangers associated with hunting. Such a surplus could have resulted in some females remaining virgin or even becoming exclusively homosexual through the developmental pathway already described. Whatever the actual circumstances may have been, it would have been noticed in particular that females that became exclusively homosexual, remained virgin, or who found themselves without a partner as a result of a mate’s untimely death, did not bear children. It was through such keen observations that the role of heterosexual intercourse in procreation was eventually learned. It should be emphasized that it was only after the benefits of producing offspring became apparent that such observations would have had significance, and were more likely to be made.


This knowledge had a most dramatic effect on the sexuality of human beings. In addition to personal survival being one of the driving forces behind having children, as the population of the human line increased and groups inevitably splintered into rival groups, group survival also depended on increased numbers through childbirth. There must have existed an incessant competition between rival groups for the same resources. For instance, a particularly good valley through which animals naturally became channeled as they passed through, or a good watering hole where animals congregated to drink would both have been good hunting spots. Such valued and limited resources would have created an intense rivalry for control. Also, groups that could get away with it would try to steal away a hard-earned kill from another group. In addition, larger groups would have displaced smaller groups from caves and other protected shelters - which were preciously rare commodities. In all these competitive situations it must have become readily apparent that group size was important – there was safety and power in numbers. Hence, with this new-found knowledge individuals and groups of people for the first time had a greater control over their destinies. Given the advantages of having increased numbers, once the role of heterosexual intercourse in reproduction became known, the regulation of sexuality began to be enforced by group societies. Although individuals by necessity continued to perceive the advantages of having children, the group’s population requirements to defend itself may have now encouraged even larger birth rates. But not all individuals are equally prudent, even when the consequences are dire. In cases where individuals became complacent about their own need to have children, perhaps because they had developed sufficiently strong bonds with younger relatives or friends who they felt would not abandon them in times of need, the group’s pressure to produce children would have been critically important.


Exclusive homosexuality must have begun to be socially banned, irrespective of whether individuals could survive to old age with the excesses of food and shelter that group living produced. In groups where segregation of the sexes was not practiced and both parents partook in raising the children, the presentation of the family unit as a basic micro constituent of society became one of the more powerful conditioning agents, instructing growing children at an early age without the use of words, the sexual roles they were expected to play in the future. Bisexuality, whenever it was permitted, was from now on regulated by group customs and laws that ensured that heterosexual intercourse was always enforced to the extent dictated by the external pressures from other groups, and by each group’s own ambitions for conquest and expansion. It was only after the connection between heterosexual intercourse and reproduction was learned that it became possible for the complete loss of sexual instinct to be favored by evolution, for it was only with this knowledge and the necessity that individuals and groups placed on reproduction that heterosexual intercourse became relatively guaranteed without the need for a sexual instinct. Henceforth, evolutionary increases in intelligence, and also perhaps successive mutations that destroyed or weakened the neural output of the sexual instinct network, began to increasingly inhibit the expression of the sexual instinct, eventually culminating in the complete loss of the sexual instinct in the human line.


And here we were at last, free from the sexual constraint that had ensured our perpetuity to that point, but which had now become an impasse to greater freedom and was no longer needed. We would go forth, multiply prodigiously within the parameters of societally imposed rules for sexual conduct, and conquer the far ends of the earth. Ironically, we would know more about the universe at large before we would understand the most fundamental aspects of our own being. Although we were both living witnesses and participants in the processes that forever changed us and shaped us, we were to remain mute for perhaps a few million years to all that transpired because we were like automatons that participated without understanding. As a wicked price, we have had to do battle with the ‘beast’ from within, the homosexual germ that has always thrived within the locus of humanity, unabated by the efforts to quell it or bargain with it. And it will always be with us because it is a legacy of the privileged path we ascended, and the dividing line that separated us from all other living creatures.





References


1. Blumenfeld WJ, Raymond, D. Looking at Gay an dLesbian Life. Boston: Beacon Press, 1988:44.
2. Weinrich JD. Is homosexuality biologically natural? In: Paul W, Weinrich JD, Gonsiorek JC, Hotvedt, ME, editors,         Homosexuality: Social, Psychological, and Biological Issues. Beverly Hill, CA: Sage, 1982.
3. Ernulf KE, Innala SM, Whitam FL. Biological explanation, psychological explanation, and tolerance of homosexuals:      a cross-national analysis of beliefs and attitudes. Psychol Rep 1989;65:1003-10.
4. Sanderson SK, Ellis L. Theoretical and political perspectives of American sociologist in the 1990’s. Am Sociol
    1992;23:26-42.
5. Bhugra D. Doctor’s attitudes to male homosexuality: a survey, Sexual Marital Ther 1990:5:167-74.
6. Leo J. Homosexuality: tolerance versus approval. Time Jan 8, 1979:48-49, 51.
7. Tannahill, R. Sex in History. Chelsea, MI: Scarborough House, 1992.
8. Spencer C. Homosexuality: A History. London: Fourth Estate Limited, 1995:14.
9. Geist V. Mountain Sheep: A Study in Behaviour and Evolution. Chicago: University of Chicago Press, 1971.
10. D Wall F. Peacemaking Among Primates. Cambridge, MA: Harvard University Press, 1989.
11. Bingham HC. Sex Development in Apes. Baltimore, MD: Johns Hopkins Press, 1928.
12. Ehrhardt AA, Meyer-Bahlburg, HFL. Effects of prenatal sex hormones on gender-related behavior. Science
      1981;211:1312-1318.
13. Janus S, Janue C. The Janus Report on Sexual Behavior. New York: Wiley, 1993.
14. Herdt G. Same Sex, Different Cultures, Boulder, CO: Westview Press, 1997:11,13.
15. Herdt GH. Ritualized Homosexuality in Melanesia Berkeley, CA: University of California Press, 1984.
16. Deacon B. Malekula: A Vanishing People in the New Hebrides. London: Routledge, 1934.
17. Ford CS, Beach FA. Patterns of Sexual Behaviour. New York: Harper, 1951.
18. Greenberg DF. The Construction of Homosexuality. Chicago: University of Chicago Press, 1988.
19. Hinsch B. Passions of the Cut Sleeve. Berkeley, CA: University Of California Press, 1990.
20. Cantarella E. Bisexuality in the Ancient World. New Haven, CT: Yale University Press. 1992.
21. Veyne P. Homosexuality in ancient Rome. In: Aries P, Bejin A., editors, Western Sexuality: Practice and Precept in       Past and Present Times. Oxford: Blackwell, 1985.
22. Watanabe T, Iwata J. The Love of the Samurai. London: Gay Men’s Press, 1991.
23. Trumbach R. The birth of the queen: sodomy and the emergence of gender equality in modern culture, 1660-1750.       In: Duberman MB, Vicimus M, Chauncey G, editors. Hidden from History: Reclaiming the Gay and Lesbian Past,
      London: Pentuin, 1991.
24. Rich A. Compulsory heterosexuality. Signs J Women Culture Soc 1980;5(4):635.
25. Blackwood E. Breaking the mirror: the construction of lesbianism and the anthropological approaches to
      homosexual behavior. In: Blackwood E, editor, The Many Faces of Homosexuality: Anthropological Approaches to       Homosexual Behavior. New York: Harrington Park Press, 1986, p. 10.
26. Sankar A. Sisters and brothers, lovers and enemies: marriage resistance in Southern Kwangtung. In: Blackwood E,       editor, The Many Faces of Homosexuality: Anthropological Approaches to Homosexual Behavior. New York:
      Harrington Park Press, 1986.
27. Gough K. The origin of the family. In: Reiter R, editor, Toward an Anthropology of Women. New York: Monthly
      Review Press, 1975:69-70.
28. Keeton WT. Biological Science, 3rd ed, New York: Norton, 1980:492.
29. Calvin WH. How Brains Think. New York: Basic Books, 1996:59-60.
30. Restak R. Brainscapes. New York: Hyperion, 1995:34.
31. Gomes, C. True Nature: a theory of human sexual evolution. Part 1. J. Gay Lesbian med Assoc 2000; 2:19-29.
32. Circumcision. In Encyclopedia Britannica, Fifteenth edition, 1997, volume 3:328.
33. Taylor T. The Prehistory of Sex. London: Fourth Estate Limited, 1996.
34. Topp S. Why not to circumcise your baby boy. In: O’Mara P, editor, Circumcision: The Rest of the Story, A
      Selection of Articles, Letters, and Resources 1979-1993. Santa Fe, NM: Mothering, 1993.
35. Parrinder G. Sex in the World’s Religions. London: Sheldon, 1980.
36. Leakey RE. The Making of Mankind. New York: Rainbird, 1981.
37. Morgan E. The Aquatic Ape. London: Souvenir Press, 1982.
38. Weller A. Human pheromones. Communication through body odour (news; comment). Nature 1998; 392:126-127.
39. McClintock MK. Menstrual synchrony and suppression. Nature 1971; 229:244-45.
40. Russel MJ, Switz GM, Thompson K. Olfactory influences on the human menstrual cycle. Pharmacol Biochem
      Behav 1980;13(5):737-38.
41. Stern K, and McClintock M K. Regulation of ovulation by human pheromones. Nature 1998;392:177-179.
42. Adams DB, Gold AR, Burt AD. Rise in female-initiated sexual activity at ovulation and its suppression by
      oral contraceptives. N Engl J Med 1978; 299:1145-50.
43. Morris NM, Udry JR, Khan-Dawood E, Dawood MY. Marital sex frequency and midcycle female testerone. Archiv
      Sex Behav 1987; 16:27-37.
44. Wallen K, Mann DR, Davis-DaSilva M, Gaventa S, Lovejoy JC, Collins DC. Chronic gonadotropins-releasing
      hormone agonist treatment suppresses ovulation and sexual behavior in group-living female rhesus monkey
      (Macaca mulatta). Anim Behav 1896:36:369-75.
45. Doty RL, Ford M, Preti G, Huggins GR. Changes in the intensity and pleasantness of human vaginal odours during
      the menstrual cycle. Science 1975; 190:1316-1318.
46. Graziadei PPP. Functional anatomy of the mammalian chemoreceptor system. In: Muller-Schwarze D, Mozell MM,
      editors. Chemical Signals in Vertebrates. New York: Plenum Press, 1977:435-54.
47. Garcia-Velasco J, Mondragon M. The incidence of the vomeronasal organ in 1000 human subjects and its possible
      clinical significance. J. Ster Bioch Mol Biol 1991;29:651-63.
48. Monti-Bloch L, Diaz-Sanchez V, Jennings-White C, Berliner DL. Modulation of serum testosterone and autonomic
      function through stimulation of the male human vomeronasal system (VNO) with pregna-4,20-diene-3,6-dione. J
      Ster Bioch Mol Biol 1998; 65:237-42.
49. Berliner DL, Monti-Bloch L, Jennings-White C, Diaz-Sanchez V. The functionality of the human vomeronasal organ
      (VNO): evidence for steroid receptors. J. Ster Bioch Mol Biol 1996: 58(3):259-65.
50. Monti-Bloch L, Jennings-White C, Dolberg DS, Berliner DL. The human vomeronasal system
      Psychoneuroendocrinology 1994; 19:673-86.
51. Johns MA, Feder HH, Komisaruk BR, Mayer AD. Urine-induced ovulation in anovulatory rats may be a
      vomeronasal effect. Nature 1978; 272:446-48.
52. Wysocki CJ. Neurobehavioral evidence for the involvement of the vomeronasal system in mammalian
      reproduction. Neurosci Biobehav Rev 1979;3:301-41.
53. Meredith M, Fernandez-Fewell G. Vomeronasal system, LHRH, and sex behavior. Psychoneuroendocrinology
      1994; 19:657-72.
54. Johns Ma. The role of the vomeronasal system in mammalian reproductive physiology. In: Muller-Schwarze D,
      Silverstein RM, editors, Chemical Signals, Vertebrates and Aquatic Invertebrates. New York: Plenum Press, 1980.
55. Keverne EB. Pheromonal influences on the endocrine regulation of reproduction. Trends Neurosci 1983; 6:381-84.
56. Beltramino C, McGrew W. Menstrual synchrony in female undergraduates living on coeducational campus.
      Psychoneuroendocrinology 1983; 5:245-52.



Selected Bibliography


1. Allman WF. Apprentices of Wonder – Inside the Neural Network Revolution. New York: Bantam Books, 1989.
1. Black IB. Information in the Brain – A Molecular perspective. Cambridge, MA: MIT Press, 1991.
3. Churchland PM. The Engine of Reason, the Seat of the Soul – A Philosophical Journey into the Brain. Cambridge,
    MA: MIT Press, 1995.
4. Hearth E. Windows on the Mind – Reflections on the Physical Basis of Consciousness. New York: Morrow, 1982.
5. Hearth E. the Creative Loop – How the Brain Makes a Mind. Reading, MA: Addison-Wesley, 1993.
6. Leakey RE. The Making of Mankind. New York: Elsevier-Dutton, 1981.



All material copyright 1991-2010 / Christopher Gomes