The Philosophy of Sex, Part III: Human Nature, Monogamy, and Adultery

The Philosophy of Sex, Part III: Human Nature, Monogamy, and Adultery

Man is a highly complex and social animal, with strong cultural norms that help keep societies together, and yet these norms are sometimes violated, often in secret.  What we have left to examine in the philosophy of sex is its part in the formation of human nature; in evolution, culture, and divided duties.  What we will see, in the end, is that, like many animal species, human beings are ‘designed for a system of monogamy plagued by adultery’.  (Ridley, 176)

                In the first Part, we examined a theory of the metaphysics of sexual love, through Schopenhauer’s writings on the subject.  He hypothesized, c. 1860, that the sexual impulse in man, and in all of nature, is the will of the next generation, not yet existing, willing itself to be born.  That, in a sense, we (and all animals) are tricked by this impulse into begetting the next generation, raising them, all the while thinking it is our own will that we are following.

In Part II, we saw how sexual reproduction produces more complexity and diversity than asexual production, through the mixing of genes.  These genes not only get shuffled around during sex, but certain key ‘switches’ (known for short as ‘Hox’ genes), which control the major elements of body formation, can be moved around the genome to create new phylogenic forms, step by step, as organisms adapt to their respective environments.

Here, in Part III, we will take a look at some of the broader implications of sex, for life in general, and for human nature, specifically.  In order to hypothesize about the sexual behavior of humans, we will examine in general the sexual behavior and habits of the animal kingdom, and then compare them to humans to see if any insight can be gained.  For example, it will be easier in our study to examine the social and mating habits of birds who live in colonies, and have direct correlations to our own societies.  Birds living in colonies often have monogamous mates, but are also free to move about the colony in a semi-anonymous fashion, much like human beings.  We can also gather data from primitive hunter / gatherer societies still extant today, as well as archeological evidence from past hominid [pre-ancestors of humans] sites.

The very first question that must be asked in any exploration of the human condition through its evolutionary past is, how and why did the brains of our human ancestors get so big?  It is only through having such a large and complicated brain that modern civilization is possible; but what led to the evolution of such an organ?  It would be easy to say that big brains evolved in order to produce technology and culture, but such an explanation would be looking at human evolution through hindsight.  There must have been certain immediate advantages to having a larger brain, in order for it to evolve to so large a size, in so relatively short a span of evolutionary time (about 3 million years). 

After a period of about ten million years of relative stagnation, ‘The cerebrum of homo was expanded enormously during a relatively short span of evolutionary time .  (Wilson, 548)  In a period of about three million years, the adult cranial capacity of our ancestors went from about 500 cubic centimeters, to a height of 2,000 cubic centimeters in modern homo sapiens.  Again, we must ask, what kind of environmental and genetic pressures would lead to such a hypertrophy of the human brain? 

                The answer, I believe, is two-fold; first, early hominids moved, through environmental changes, from woodlands to a more open savannah, where their bipedal stance and modern anatomy could lead to further adaptations, and second, that sexual competition and selection between individuals of the same species led to there being a premium on intelligence, in order to outwit one’s fellow individuals, and reproduce more.  In the first case, the group of hominids that would eventually split off to form modern man had to adapt to a more grassland type of environment, more so than when they had been living in the dense trees of the forest.  (This was a result of natural climate and environmental change, as Africa became drier and more savannah-like.)  It has been hypothesized that the bipedal stance of hominids formed initially as an adaptation to pick seeds or fruit, as this would clearly be an advantage in such a living environment.  (Wilson, 569)  An easy example in support of such a theory is the human loss of the gene to create vitamin C.  It has been concluded that this gene was lost, as being unnecessary, since our ancestor hominids got enough from their diet that they did not ‘need’ the gene, anymore.  Perhaps rising on two feet and picking such seeds and fruit led to the eventually bipedal stance of the early hominids.

               

                Such would be an explanation of the hominid’s early ability to manipulate small objects, differentiate colors, etc.  But how would sexual selection lead to a second explosion in the enlargement of the human brain?  The answer, I believe, in this case, is that through the eventual addition of meat to the diet of hominids, and the competition among individual males for females to reproduce with, led to the enlargement of the brain.  First, the additional calories needed to create stronger embryos that would adapt faster and more effectually required the addition of meat, and its extra calories, to the hominid diet.  This raises the question of how a previously herbivorous species developed the ability to eat meat?  The archeological evidence tells us that early hominids, like the Australopithecus ,

“Were catholic in their choice of small animals.  Their sites contain the remains of tortoises, lizards, snakes, mice, rabbits, porcupines, and other small  vulnerable prey that must have abounded on the savanna.’ (Wilson, 567)

This would explain how, over time, the early hominids could have evolved the ability to digest small animals, even before the discovery of fire for cooking meat, which makes meat much more easily digestible by hominids.

                Next, with the caloric intake needed, came the next steps in sociality involving hunting, gathering, and the specialization of tasks for males and females.  This essentially involved outwitting one’s male competitors for the monopoly of females, and so required a greater amount of intelligence.  Human society became much more complex with the advent of organized hunting, specialized tasks, and ritualistic traditions around the group.  This meant that women were interested in not only a man’s hunting prowess, but also his ability to be a decent mate and father, as well as his genetic fitness for producing children.

                There is another facet of sexual selection that plays an important part in producing healthy and viable children; hereditary immunity against disease and parasites.  This is because as each generation comes into being, it will be attacked by many types of bacteria and other parasites,  and a key requirement is to keep such parasites guessing as to the immune defenses of the child in question.  Ridley explains it like so:

“Sexual species can call on a sort of library of locks that is unavailable to asexual species… There are different versions of the same gene at any one time… It transpires that many of the most notoriously polymorphic [multiple versions of genes] genes… Are the very genes that affect resistance to disease – the genes for locks.”  (Ridley, p. 72 – 73)

What Ridley is arguing here is that just as disease tries to invade an organism, that organism will try to defend itself with built in immunities.  As parasites evolve, they develop new ‘keys’ for the ‘locks’ of our genetically based immune system.  And so a sexual species has an advantage because they can also shuffle around the different immunities, or locks, every generation.  This keeps the parasites guessing, and gives the next generation a better chance for survival.

                So far we have covered the male motivation for having ‘more’ sexual partners; more offspring.  But what could be the motivation for a female to have multiple sexual partners, and what kind of defenses have evolved to combat such inter-species competition for the rights to reproduce?

                The answers to these questions are complex, indeed.  It will assist in understanding to compare humans to colonial birds, again, in order to address these issues.  Take female swallows, for example.  They are a colonial bird, and their reproductive strategy is as follows:

“A female swallow needs a husband who will help look after her young, but by the time she arrives at the breeding site, she might find all the best husbands taken.  Her best tactic is therefore to mate with a mediocre husband… and have an affair with a genetically superior neighbor… In short, the reason adultery is so common in colonial birds is that it enables a male bird to have more young and enables a female bird to have better young.”  (Ridley, 223 – 224)

Such an analogy may work in theory, but humans and birds are descended from much different lines; humans, or homo sapiens, are descended from the ape family, while birds are a part of the larger reptile family.  (One that descended from the dinosaurs, but that is outside our scope, here.)  So what then, are the special mechanisms hominid females developed to better their chances at having successful young?

“The answer may lie in our evolutionary past with the other members of the ape family.  Female primates seemed to be ‘Initiators of much promiscuity… A whole new light has been shed on the evolution of female behavior by a group of ideas known as ‘sperm competition theory’… In fact, as subsequent research revealed, infanticide is common in rodents, carnivores, and primates.”  (Ridley, 213)

The main goal of such behavior is to eliminate the genetic offspring of other males… And then, when the new ‘troop’ of males and females coalesces, it is of great advantage to the females to share her sexual favors with as many male members of the troop as possible, as this will prevent the knowledge of who is the male parent, and therefore prevent infanticide.  (Such is the basis of sperm competition theory.)  “An alpha male … has only a short time at the top, and infanticide helps these animals to father the maximum number of offspring during that time.”  (Ridley, 213) 

                And so groups of females found it a better investment to remain with one group of males, to prevent the murder of their offspring.  But, does this kind of evolved behavior belong to mankind?  The answer is no.  We are a social species, with a complex social hierarchy; infanticide goes against our most core social norms (although it still happens in more primitive cultures, to increase the number of males, for instance.)  But the question still remains: Why have a monogamous male mate to help care for the offspring, and then seek some other male’s better genes?

                Although a woman’s tendency is towards monogamy, and the monopoly of a man for life, it is still a fact that women are, ‘sometimes unfaithful.  Not all adultery is caused by men.”  (Ridley, 218)  Although there is evidence for sperm competition in humans in the past, it is now evident that different sexual strategies are at use.  This, in turn, led to a ‘bizarre and astonishing explanation of the female orgasm.’  (Ridley, 224)

It was, “discovered that the amount of sperm that is retained in a woman’s vagina after sex varies according to whether she had an orgasm, and when… In faithful women, about 55 percent of the orgasms were of the high retention type (that is, the most fertile type).  In unfaithful women, only 40 percent of the copulations were of this kind, but 70 percent of the copulations with the lover were of this fertile type… The unfaithful women were [also] having sex with their lovers at times of the month when they were most fertile.”

In other words, while seeking a decent husband for life, an unfaithful woman was still capable of orchestrating her sexual relations so that she was more fertile with her lover than her mate.  This would suggest a reason for the female ‘fake’ orgasm; she is trying to convince her mate that she had a fertile orgasm, when in fact she may have not.

                The male of the species can counter such cuckolding techniques through some genetic trickery of his own.  Perhaps the simplest method is to guard his mate until he is sure that no other male can have sex with her.  This is evidenced by the close guarding of other mammalian females during their estrous period.  Direct connections can be made to human history and society easily, such as the infamous chastity belt of the middle ages, or the strict laws against any female consorting with unmarried males, without an escort. 

However, by mating with a genetically superior male, a female’s offspring will share the qualities of that male, increasing their chances of survival, and of reproducing, themselves.  In other words, it is a better strategy for the female, in order to have a greater number of grandchildren, and of spreading her genes further.  Her sons will inherit the qualities of the genetically superior male, making it more likely that they themselves will mate and have descendants.  Ironically, it seems to be the fact across the animal kingdom that the more genetically attractive a male is, the less attentive a father he is.

But how can a female (or a male) know which individuals of their species have better genes?  This eventually revolves around to sexual ornaments and genetic fitness.  If a male is symmetrical, has superior ornaments that are attractive to the female (a longer tail in birds, for example) than it is more likely that his genes are all in order.  In such a way can genetic fitness be observed from physical characteristics.

And so we see, as descendants of the mammal and primate families, we will always be plagued with a society of monogamy mixed with adultery.  Such is the evolved sexual condition of human beings.  This is not to say, of course, that all people are unfaithful.  But, rather, that their strategies when they are unfaithful, aim for the best genetic fitness of their children.  Men may get around, but women have a whole bag of tricks of their own.  In such a way we can relate the first part of our philosophy of sex to our current part – the next generation, yearning to be born.  Whatever it may take.

Sources Cited:

Ridley, Matt. The Red Queen: Sex and the Evolution of Human Nature. Harper Perennial, London (2003).

            Wilson, E.O. Sociobiology: The New Synthesis. Harvard Press, Cambridge (1975).