If animals could talk, most any animal you asked would tell you that human sexuality is more than a little aberrant by their standards. As I just said above, fully appreciating just how different human sexuality is requires setting aside our human-centric thinking to look at humans as just another animal among all animals. Only 3% of mammals are monogamous and this percentage plummets when one considers the many millions of animal species in the world. This one trait alone places humans far beyond the +/-2 standard deviations from the mean that is generally considered to be the “normal” range for statistical purposes.

Comparing multiple sexual behaviors only increases the abnormality of human sexuality. Human females have evolved concealed ovulation, are sexually receptive at all times during their cycles and experience menopause (cessation of fertility long before death). Most human copulation occurs horizontally with the male on top of and facing the female (missionary position). We wear clothes, which cover up our built-in sexual signals while at the same time wearing cosmetics such as makeup and perfume to enhance our sex appeal. Our sex normally takes place in private. We have recreational sex; in fact, we have most of our sex for the sheer fun of it with no intention of reproducing. Modern technology has even allowed us to prevent conception from taking place. Any one of these is an oddity among animals and no species besides homo sapient possesses our truly unique package of sexual traits.

Why?

The best way to answer this question is to see how natural selection works followed by a look at some of the many reproductive strategies animals use. We’ll then look at some of the pressures facing human men and women and the lengths humans and animals will go to reproduce. This will provide the foundation we need to narrow our focus toward humans in the coming weeks.

No Looking Back

Human sexuality has been evolving for millions of years and most closely resembles a combination of chimpanzee and bonobo sexuality plus some additional, uniquely human traits. From how human eggs get fertilized to nursing infants and unequal parental investments, evolution has come too far down this particular path for it to change direction or backtrack, barring both some compelling reason to change and plenty of time to make that change. Put another way, I hope you like your evolved sexual traits because those are the sexual traits you’re stuck with.

Why Sex?

All joking aside, sex is a costly, messy affair. It would be much easier to reproduce asexually like bacteria. Imagine being able to reproduce at will by simply splitting yourself in two. Mutations introduced by imperfect gene copying and either encouraged or suppressed by environmental factors drives evolution of the species. No more dating, courtship, sex, morning-after blues, child rearing, marriage, divorce, nothing. Asexual reproduction is simplicity itself. It makes sense for simple organisms that may not live long enough to have a reasonable chance of finding a suitable mate.

Complex organisms such as humans and most animals benefit from sexual reproduction because it creates genetic diversity, particularly when long life spans are involved because this limits opportunities for mutation and evolution. Humans tend to be strongly attracted to people whose genotypes are very different than their own, the more different the better. Mixing these disparate genotypes can give the child a stronger immune system, which helps the child pass on its genes and continue the parents’ genetic legacy. At least that’s how it works in theory. Environmental factors and changes can snuff out an otherwise promising genetic lineage while creating conditions for a previously undesirable lineage to flourish. Those individuals best suited to current environmental conditions have more children. Remember that the ultimate point of life is to reproduce.

Sexual reproduction also creates conflict because what’s in each parent’s genetic interests is often contradictory. The battle of the sexes is a very real phenomenon that exists for very good reasons, as we saw in a previous article. This conflict may seem awful, particularly in the heat of the moment, but it serves a strong evolutionary purpose: Those best able to mitigate or resolve their conflicts enjoy increased reproductive potential. It there comes as no surprise that humans couples who have devised mutually agreeable conflict-resolution strategies and/or who have similar ways of responding to various situations tend to remain together the longest. Even so, sexual reproduction in humans favors males who court many females, who respond by being highly selective. This explains (among many other things) why women placing personal ads seeking to meet men can usually count on receiving far more responses than men who place ads seeking women.

Natural Selection

Life exists to beget life. Natural selection therefore favors adaptations that improve the odds of successful reproduction, defined here as both having more children and helping those children survive to have children of their own. These adaptations can be physical, such as breasts that mimic buttocks and thus serve as sexual signals. They can also be mental and/or psychological. For example, the average human would be hard pressed to recognize individual penguins in a huge Antarctic flock let alone tell which chick belongs to which parent. You can bet your bottom dollar that penguins can recognize each other and discern their young in a penguin crowd just like humans can spot a familiar face in a human crowd. I can’t imagine any species whose children require parental care lacking the ability to recognize individuals because that would lead to parents raising just any child, a clear no-no in evolutionary terms under most circumstances.

This is a quantity game; parents who can have the most offspring are theoretically the ones who are best suited to their current environment. Any change in the environment could strip a given set of genes of its favored status and replace it with a different set. Extinction occurs when insufficient numbers of individuals with any sets of genetic traits exist to repopulate the species. How exactly parents manage to have the most possible children is wide open to question- and therein lie the seeds of parental conflict. Please review my article on conflict in the home for more details.

Natural selection chooses among currently available options. Two parents represent two sets of genetic traits, or options and their child represents a third trait that combines the first two. This is the menu open to natural selection. Two parents won’t create a child with completely different genetic material, meaning that natural selection cannot simply invent a new option any more than patrons at most restaurants can’t cook their own food or invent special dishes.

I must take a short detour to explain that words such as choose and invent usually imply deliberate, conscious action. Applied to natural selection, these words can imply the presence of an unseen super-intellect, which can be referred to as a god or super-intellect. I don’t necessarily mean to imply this because no conscious action, blueprint, or designer may be necessary for natural selection to occur in at least some if not most or even all cases. For example, the mix of parental genes inside a child could predispose it to store extra body fat. If the environment cools, then this child and anyone else with a similar trait may be better able to survive and have children of their own. If the climate warms, then this child and others like it may be unable to survive long enough to reproduce. This “choice” may be an example of natural selection with no guiding intellect or design behind it. Then again, it could be proof positive that some super-intellect (God) is indeed real, As for “invention”, imperfections in gene copying can introduce mutations, or changes in the child’s genes that are not present in the parents’ genes. Imagine transcribing a letter and omitting or misspelling a word. That is completely different than writing a completely new letter from scratch without trying to faithfully copy the original.

Reproductive Strategies

Let’s take a look at some of the many ways animals reproduce.

No Contact

Many female fish lay eggs directly into the water, whereupon the male releases a cloud of sperm. There is no actual contact between the mates. This works well because many of the shapes best suited for various underwater environments may not lend themselves to actual coitus. Some fish species guard their eggs and protect the hatched young while others swim away leaving the eggs to their fate. It makes little sense to guard a large clutch of eggs where the sheer numbers all but guarantee successful reproduction. On the other hand, fish who lay fewer eggs and/or whose eggs have longer gestation periods may gain by hanging around to protect their offspring. The basic formula is simple: Investing energy in any one egg that results in less protection for other eggs and lower resulting odds of reproduction makes no sense. Remember, evolution is a numbers game.

Single Queen

Ants, bees and termites have a unique caste system where sterile workers tend to the young, grow food (ants and termites were the world’s first farmers) and keep the colony clean and maintained. Soldiers, also sterile, guard the colony and invade other colonies. Fertile males mate with a queen who then establishes a new colony, settles down (she will never move again after this) and starts cranking out eggs. Eliminating reproductive issues from most of the population provides an absolutely loyal and efficient workforce that in turn helps ensure the great number of births and survivors, a few of whom will go on to become fertile males or queens. Eggs and queens are carefully guarded and the young fed and raised.

Polygyny

Animals who give birth to live offspring may benefit from polygyny where one male maintains a harem of several females. This benefits the females since they don’t have to worry about rival male advances, giving them more time to look after their young. Their reproductive ability is not slowed down by sharing the male since they may only give birth to one child at a time (such as walruses). Dominant males win more mates and thus an increased opportunity to pass on their genetic material. Battles for supremacy tend to go to the largest males, so the pressure is on males to grow as large as possible. Male walruses can weigh twice as much as females and possibly even more. The average size of a harem depends on the ratio of male/female size. Human males are larger and approximately 20% heavier than human females. Humans are therefore at least mildly polygynous by nature. We’ll return to this topic in a future article.

Serial Monogamy

Most birds form pair bonds for a single season, although some do mate for life. Eggs and chicks are extremely vulnerable to both environmental factors like temperature and predators. One parent must therefore guard the nest at all times while the other finds food for the brood. Some species have both parents taking turns on the nest while other birds have well-designated gender roles. Chicks generally become mature enough to no longer need constant watching after one season, so it makes little sense to limit one’s reproductive potential by sticking around too long.

It may be to one parent’s advantage to pass the child rearing buck to the other parent and go off to reproduce some more. The parent with the most invested in the outcome (typically the female) has a harder time shirking its duty. This may leave males free to leave the nest ostensibly on a hunting run and simply mate with another female, who is then committed to raising the chick. Birds can’t abort their eggs, unlike human fetuses.

Monogamy

Parents who both invest heavily their children may benefit from monogamy. Human babies are born helpless and remain more or less helpless for a long time- over two decades once one factors in a potential college education. A human child can spend between 1/4 and 1/3 of its life preparing for adulthood- a fraction that may be relatively constant throughout our evolutionary history as life spans increased along with the complexity of education. Children with only one parent face a significantly higher risk of starvation and predation, particularly when that parent is a mother who is not as well suited for fighting off enemies as the father. Thus, if the father wants to see his children grow to reproduce and bear grandchildren, he’d better be by the mother’s side doing his part.

It is no coincidence that human sexual signals and behaviors evolved to fit this exact scenario. Why do women conceal ovulation and why are they sexually receptive throughout their entire fertility cycles (unlike chimpanzees and bonobos who do neither)? Because sex is fun. It has to be in order to motivate us to try and reproduce as much as possible. A person’s body responds in exactly the same manner whether the sex is procreationally or recreationally intended. The male gets to enjoy sex all the time and thus has little need to seek satisfaction elsewhere. The female get to enjoy sex all the time while protecting her enormous investment that begins with eggs that are roughly 1,000,000 times the size of sperm. and continues through a risky pregnancy, nursing and carrying the baby.

Polyandry

One female with more than one male (as seen in the movie Paint Your Wagon) conveys significant advantages for the female because she enjoys increased protection and a more reliable food supply. It does nothing, however, to help her reproduce more rapidly or nurse more than 1-2 infants at once. All of the males who did not sire the child lose the great game of life (passing on the almighty DNA) because they are helping another male’s genes succeed at their own expense. Which brings me to…

Cuckoldry

Any animal, humans included, that can sire a child and then get another individual to raise it as its own has won the evolutionary lottery because it gets to pass on its genetic material without doing any of the work. The cuckold (animal raising the other child as its own) is at a double loss because it is both not passing on its own genes and working as if it was. Cuckoldry occurs far more often than one might think, even among humans.

Don’t confuse cuckoldry (raising someone else’s genes thinking they’re your own) and adoption (deliberately raising someone else’s genes, which also occurs surprisingly often, including with me). Both of these are also distinct from relatives helping in child care because by doing they are helping pass on at least some of their own genes.

Incest

I’ve already mentioned that humans tend to be most strongly attracted to people whose genotypes are the opposite of their own. Does your significant other have a unique scent that makes you weak at the knees? You’re smelling her or his opposite genotype and your body is telling you this mating has a strong likelihood of producing the kind of robust offspring that would be well able to reproduce in its own turn.

If partnering with someone of the opposite genotype is good, then it stands to reason that mating with someone of a similar genotype is bad. The people with the closest genotypes are our blood relatives: siblings, parents, uncles and aunts, cousins, etc. Incest (sexual relations with blood relatives) carries a heightened risk of birth defects, mental retardation, etc. Small wonder that most (if not all) animals, humans included, have a built-in taboo against committing incest.

Our built-in incest taboo is so strong that it can even extend to non-relatives who were raised near us as children. A survey of over 2,700 Israeli marriages turned up only 13 (just under half a percent) from children raised in the same kibbutz- and all of these children had moved in after age 6. A prepubescent human is not ready for sex, but she or he already knows who not to mate with.

Internal vs. External Fertilization

Fish that simply release eggs and sperm into the water (as well as other animals that fertilize their eggs externally) have invested roughly equally in the reproduction process. Internal fertilization requires a large up-front investment on the mother’s part in the form of specialized structures (genitalia) that allow mating and insemination to occur. Animals that give live birth (as opposed to birds that lay fertilized eggs) require extensive specialized organs including genitalia, uterus and placenta.

External fertilization gives both parents an equal opportunity to either ditch the other to watch the offspring or even to be cuckolded. Female animals that either lay fertilized eggs or give birth to live offspring can be absolutely certain that they are, in fact, the mother with rare exception. Ensuring paternal certainty is another consideration altogether, one that in humans has almost all societies to adopt complex laws designed to ensure marital fidelity and even premarital virginity, particularly of females.

Mixed Strategies

Internal fertilization sets up the inherently unequal investments I’ve previously described, making males more likely to have to pitch in because it’s almost impossible for the female to raise the young solo. Humans are an extreme example because our children remain helpless after weaning but even that isn’t enough to completely level the playing field nor to completely align the parents’ interests (as evidenced by human males being larger than women). The man, like some male birds, will be tempted to let his eye- and more- wander somewhat. Polygyny and deception can work, as we’ll see in a future article, because the fraud may not be discovered in time. This mostly-monogamous-with-occasional-side-trips approach is called a mixed reproductive strategy. It can work but it’s a pretty risky gamble.

I hate to say this, ladies, but this fundamental male drive won’t disappear any time soon. It would be wonderful if all fathers stuck by their mates and devoted themselves wholeheartedly to one family and one set of children. The problem is that natural variances in temperament would produce men who were more likely to cheat. These men would have more offspring, who would eventually crowd out their faithful brethren. Evolution is a numbers game. Period.

Sexual Cannibalism

If you’re a man, imagine having sex with a woman. As you finish, you experience an uncontrollable urge to lean down and offer yourself to your mate, who proceeds to kill and eat you, perhaps while you’re still ejaculating. If you’re a woman, imagine feeling uncontrollably hungry, so hungry that you start eating your mate while still having sex. It’s OK to be freaked out and a little disgusted at this visual. After all, you’re human. This scenario makes no sense to you because your life span is measured in decades, giving you plenty of time to find food. Besides, killing the male during sex makes it awfully hard for the mother to raise her child and reduces the child’s chances of survival.

Now put yourself in the position of an insect (such as some species of mantis). Your life span is measured in days. After sex, the mother lays a bunch of eggs and flies off to die, leaving the eggs to fend for themselves. There is no need for parental involvement beyond copulation and egg laying. The short life span makes potential mates a rare commodity, meaning you’d best do it with the first candidate who happens along. Producing and laying eggs consumes a lot of energy, particularly when your reproductive strategy involves laying as many eggs as possible in the ultimate numbers-game hope that a precious few will survive.

Life exists for the purpose of begetting the next generation. If you’re the father, your entire reason for being ends the moment you finish mating. Remaining alive would be a waste of resources and nature wastes nothing. If you’re the mother, then you need a big meal to gather the energy you’ll need to put into growing all those eggs. Flying around trying to find food consumes precious energy in the same way that every failed hunt increase a predator’s risk of starvation. You need a big meal and the big male you just gone mating with has no more reason to live. Seen in this light, not eating your mate becomes the foolish choice.

If you think this sounds cruel, consider that the only reason you’re alive to read this article is because plants and animals died to give you nutrition. All life requires death in order to continue, from organic compounds released by decomposing corpses that feed plants to the antelope that feeds a tiger. Nature does not care for any individual in the slightest; it cares for the species as a whole, meaning that it cares for the genes. You, dear reader, are little more than a mobile laboratory built for the sole purpose of mixing and remixing DNA and ensuring your unique mixture lives to mix again. Everything else is fluff, as far as dear old Mother Nature is concerned. That includes you reading this article.

This holds true even if you never actually have children. The best moments of your life will happen when you are with someone in a pair-bonded relationship as I am with Jennifer. And just what are you doing in said relationship? Why, you’re going through the reproductive motions, of course!

Productivity

The average human woman can produce somewhere between 10 (breast-fed) and 30 (bottle-fed) children in a lifetime despite having about 400 available eggs, because she can’t incubate or breast-feed more than one uterus load of 1-2 (usually) children at once. Meanwhile, the man is ready at a moment’s notice and can theoretically sire thousands of children. Staying around to help raise the kids puts a serious crimp in his style, as I just noted above. The exception is when he can be positive that the children he raising are his genetic legacy. Cuckoldry is a real risk for human fathers. Human mothers have zero risk of cuckoldry. If the baby came out of a woman’s body, it’s hers. The joy of this certainty may at times be tempered by her utter inability to hand off caring for her children.

Vasopressin

Prairie voles (microtus ochrogaster) are small rodents that resemble mice with small ears and rotund bodies. They are roughly the size of small to medium rats. What makes this particular species of vole noteworthy is its human-like mating habits, right down to the nominal monogamy (mostly monogamous with occasional side action). Males guard their mates and young, fetch food, clean the burrow and more. They do this thanks to vasopressin, a hormone that increases both aggression and fathering instincts. The more vasopressin, the more faithful the male vole is likely to be.

Humans also have vasopressin. Early experiments seem to indicate that vasopressin in human males may perform the same functions. A surge of vasopressin during sex seems to enhance pair-bonding while also triggering aggression towards other males. This jealousy causes the male to attempt to keep other males away from his woman while being very devoted to her. I can’t help wondering if any relationship exists between excessive vasopressin and domestic abuse.

Rolling The Dice

Your head may still be reeling from what you just read about sexual cannibalism and how it’s just one more example of the reproduction imperative. Sexual cannibalism may be relatively rare, but consider that starving animals will routinely choose sex over food when given the choice. Deliberately pushing an animal to the brink of starvation and then giving it a choice between sex and food strikes me as a particularly awful experiment but it does prove my point about the absolutely central role that reproduction plays in all of our lives.

Let’s look at sex in the context of all we’ve discussed so far. Sex is expensive (and I don’t just mean fancy dinners and jewelry)! It consumes a lot of energy. It consumes a lot of time that could go toward finding food. Humans normally mate lying down, making them easy targets for roaming predators. Sex can even trigger heart attacks and other health issues. Fighting over sex and mates can be injurious or even fatal. Sex isn’t cheap. Then again, human sex is a lot cheaper than, say, mantis sex.

Welcome to the third article in my ongoing series that looks at how the human animal has evolved and how evolutionary pressures continue to influence how men and women relate to each other. People like to think that we’ve moved beyond our evolutionary history but nothing could be further from the truth. Our bodies may inhabit themodern world but our brains still inhabit the primordial jungles and savannas of our evolutionary youth.

Today, I’m going to explain how the seeds of conflict are built into the fabric of our closest relationships. Home Sweet Home is a sweet myth but the truth is that home life is rife with built-in opportunities for strife. The common notion that humans are becoming more violent thanks to TV, declining morals, etc. is pure myth. The truth is that humans today are far less violent today than at any time in our 5-million year history. The difference is that mass media feeds us horror stories in an ongoing ratings war using the maxim “if it bleeds, it leads.” I am certainly not advocating child or spousal abuse and I am just as horrified by some of the news reports I see as anyone else. Understanding how and why the potential for these conflicts are hardwired into our existence is a critical first step to making conscious changes in how we choose to live our lives… because as much as we are slaves to our evolutionary history, we are also capable of making deliberate choices.

Here are just a few examples of the built-in domestic conflict humans can face at home.

In The Womb

Conflict may begin in the womb. A fetus has its own interests to protect and is therefore more interested in its own survival than the mother’s, even if its own survival depends on its mother. Meanwhile, the mother is evaluating the fetus’s reproductive potential and may spontaneously abort the pregnancy if the fetus is found lacking. Far from uncommon, miscarriages (spontaneous abortions) occur about half the time.

Once born, the baby may still face infanticide at the hands of a rival male or even its own mother. Mothers who kill their babies tend to be young, poor and unmarried. In other words, they lack the experience, resources and help normally needed to raise a healthy child that is capable of passing along the mother’s genes. The mother’s own reproductive potential has been proven by virtue of a successful pregnancy; the child represents a huge gamble that could result in both mother and child losing the ability to reproduce. From an evolutionary standpoint, individuals who fail to reproduce have missed the entire point of living. As horrible as infanticide is, it is nonetheless justifiable when seen from the evolutionary point of view. I am certainly not advocating or defending infanticide; I am merely saying that I understand it.

Medical technology has enabled women to consciously make the same evaluations their bodies have been making automatically for millions of years and opt to terminate the pregnancy through an abortion procedure. The only difference between spontaneous abortion (miscarriage) and deliberate abortion is the deliberateness of the action. Either way, a failed pregnancy is the natural result of a decision process that finds the fetus lacking.

Weaning And Walking

The next major conflict occurs around weaning as the child is increasingly expected to fend for itself instead of simply nursing. Around this time, the child’s increasing mobility and natural curiosity foster a growing need for independence while at the same time needing the reassurance of parental presence and involvement.

Sibling Rivalry

Siblings are another source of conflict. Every sibling carries some percentage of each other’s genetic material but only an identical twin is 100% genetically identical to the other. Here again, the competing needs of each individual to pass along her or his genes comes into play as each sibling vies for food and status within the family. Helping parents raise siblings is a good way to help ensure that at least some of one’s genes get passed on but that fractional benefit can come at the expense of delaying the ability to reproduce on one’s own. Siblings also tax parental resources such the amount of time and attention that can be lavished on any one child. Firstborn children are often accorded special privileges and attention. The youngest sibling often receives extra attention such as diapering and feeding while older children take care of themselves. Middle children are the ones who usually receive the least attention because they lack both the firstborn’s status and the last-born’s needs. This can result in a middle child making extra efforts to gain attention. I’ve witnessed this firsthand in several families, including some very close friends of mine. One of these friends once expounded at length about an argument he was having with his older (firstborn) brother and his frustration at feeling unheard and misunderstood. He wanted his older brother to sit down and listen to his side in exquisite detail. I remember advising my friend repeatedly to just let it go only to realize much later that he couldn’t for all of the reasons I’ve just described.

Parents vs. Children

Conflict between parents and children is also part of the scheme of things. Think about this: Every resource that goes into feeding and raising a child is one less resource that the parents have for themselves. This is a fine line to walk. Allocate too many resources to the children and the parents’ own fitness will be reduced, potentially impacting their ability to care for their young and thus pass on their genes. Too few resources and the children will suffer, with consequences for the parents. It really is a fine line. It is even possible that some child and parent attributes might have evolved to compete with each other.

The analogy of loaning increasing resources to someone with the potential for payback versus cutting one’s losses applies here as well. The lifeboat adage “women and children first” makes evolutionary sense because one man can impregnate many women while each woman can only experience one pregnancy at a time. Sacrificing men to save women therefore makes sense because it has the least long-term impact on the population. One could argue that making an adult consumes far more resources than making a child and thus the children should be sacrificed. This argument ignores the fact that children carry their parents’ genes, which means that the parents have already won the great game of life. From an evolutionary perspective, saving the women and children is the best thing to do. Thank goodness that modern ships are required to carry enough lifeboats for all!

Spousal Conflict

Few comedic routines are complete without at least a few lines devoted to marital strife. Untold thousands of articles discuss the most common topics of conflict between spouses and advice columns routinely offer advice to people who are at odds with their significant others. These address the stated cause of the problem (such as money) and some even delve into the feelings and motives behind the scenes. Few sources designed for mass consumption approach marital conflict from an evolutionary perspective.

Couples with children share the goal of successfully raising their young and passing along their combined genetic material. There’s just one problem: The mates themselves share no genetic material under normal circumstances and a child carries 50% of either parent’s genes at best. Each mate’s investment in the couple’s children confers a fitness benefit on the other mate. This paves the way for one or both mates to take undue advantage of the other. The male’s natural instinct is to seek out as many mates as possible to pass on as much of his genes as possible. The woman’s incentive is to throw all she has into raising her current child because she can’t hope to compete with the male in sheer numbers and must therefore focus on every child. It’s the old quantity versus quality conundrum. Even the most monogamous male has thought about investing some resources in an extramarital encounter. Any male reading this who hasn’t just did.

It doesn’t end there. Under normal circumstances, each partner in a couple has their own family of blood relatives. Devoting all of one’s attention to one’s own child helps a non-relation (the other parent) pass along her or his genes while possibly limiting the ability of other family members to pass along at least some of one’s own genes. Strife over the amount of time and energy spent on family is a common refrain in many, many marriages. If you’ve ever argued about your in-laws or seen or otherwise know about such an argument then you know exactly what I’m talking about.

I just purchased a new laptop computer. I did my homework, researching brands, prices and value before placing my order. Nevertheless, I found myself eying a competing model longingly within moments of clicking the “Place Order” button on the seller’s Web site because it suddenly occurred to me that I may have missed out on an even better value. This buyer’s remorse isn’t limited to consumer electronics. One or both parties in a marriage or other pairing may become convinced that they can get a better value for what she or he has to offer by leaving the relationship. Cases where both parties want out have the best chance for peaceful resolution. My former wife and I both decided to end our marriage and we’re better friends today than we’ve been in many years. Cases where one party wants out are where problems arise. A man I know decided to leave his marriage. The cost in time, energy and money spent on the divorce proceedings themselves could literally have purchased a comfortable house and that’s not including the division of marital property. Women who decide to end a relationship risk violence or other pressure not to go through with the breakup.

Power is another huge source of conflict. The woman invests more in child-rearing but most societies recognize the man as the head of the household. Women even give up their family names when married and the typical Western family wedding ceremony has the woman’s father “giving away” the bride in a procedure not unlike handing off a piece of property.

No discussion about spousal conflict would be complete without at least mentioning sexual infidelity. I’ll cover sexuality in depth in future articles.

As if this wasn’t enough, one or more parents may also have children from a previous partner. Children born from the current relationship reflect a mutual investment and more than one couple has remained together “for the kid’s sake”. Children born from past relationships only carry one parent’s genes and the other parent has no evolutionary incentive to invest anything in them. In fact, the stepparent has every evolutionary reason to prevent resources from going to the stepchild for the same reason that male lions kill cubs they haven’t sired: to increase their odds of passing on their own genes. Tales about children doomed to live with rotten stepparents abound all over the world and are based in real-world truth. Several studies have shown that stepchildren are far more likely to be abused than biological children regardless of external factors such as socioeconomic status. Stepchildren are a large source of conflict.

I must take care to distinguish stepchildren and adopted children where both parents opt to rear a child that is not related to either of them. Adopted children fare very well overall. Adoptive parents allegedly commit child abuse in 1% of reported cases while comprising 2 to 4 percent of the general population according to the United States Census Bureau. According to the United States Department of Health and Human Services, 12 children out of every 1,000 aged 18 or younger were abused in 2005. The figure for adopted children is therefore 12 out of 100,000.

Most people have a strong aversion to violence against genetic relatives. That aversion does not extend to spouses, who normally aren’t genetically related to each other. Approximately 7% of married people experience spousal abuse (Statistics Canada, 2004).

This is the second in a series of articles that will look at human sexuality and relationships from a purely evolutionary point of view and will compare and contrast that with the many layers of confusion that civilization has added on top of our evolved instincts.

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Man inseminates woman. From a purely biological point of view, his job is done. Should something happen to the mother and/or the unborn child, the man is free to inseminate another woman. The woman, by contrast, must devote an ever-increasing share of her own resources toward raising what is essentially a parasite in the form of a child that relies on its mother to survive. The more the mother provides, the more the child needs. Imagine loaning money to someone who needs ever-increasing infusions of cash in order to possibly repay the growing mountain of debt. Should you keep on loaning money on the possibility of recouping your investment or cut your losses? That is the question every mother asks herself whether she’s aware of it or not. The high percentage of babies that end up miscarried, aborted, adopted, abandoned, or killed bears witness to this questioning. The mere act of bringing a baby to term inside the womb carries potentially fatal consequences for the mother should complications arise.

Meanwhile, as I’ve already mentioned, the man is free to inseminate other women. There is no hard biological need for him to stick around to help the mother raise the child, especially in modern times where babysitting and groceries are more available than they’ve ever been at any time in our evolutionary history. A child can theoretically survive without any paternal involvement whatsoever and many children do just that. The father’s incentive to help comes from both his confidence that the children in question really are his and the increased childbearing potential the mother gains through his support. You may think this a flimsy foundation on which to build a two-parent life but the male instinct to stay with a single woman is strong enough to affect even those relationships where children aren’t part of the picture. My partner Jennifer and I neither have nor want children with each other. Our bond is as monogamous as they come.

If a woman’s chief investment in the child-rearing equation is physical and the man’s economic, then logic demands that men should be attracted to women with certain physical attributes while women should be more discerning about the male’s ability to provide for her and her children. This is precisely what happens, as we’ll see in a later article.

Investment vs. Power

Men and women have very uneven reproductive investments that benefit from a sexually-based division of labor as we learned last week. Women tend to be smaller, weaker and slower than men on average. This is true for humans, chimpanzees and bonobos. Still, there is nothing intrinsically stopping women from being in charge. Bonobo societies are matriarchal while chimpanzees and the vast majority of humans are patriarchal. Bonobos enjoy a very peaceful lifestyle where conflicts are usually resolved quickly with no harm done. Chimpanzees endure a violent lifestyle where conflicts can lead to serious injury and even death.

Most human societies tend to follow the chimpanzee’s lead. Even so, there is no intrinsic connection between women’s relative powerlessness and their preference for economically viable mates. On the contrary, my guess is that a woman’s power and drive to find an economically viable mate may be inversely proportional to some extent. A woman who is independently wealthy or has a solid career may be able to overlook a man’s financial shortcomings. A woman who lacks the means to raise a child on her own may be more driven to find a good provider. One interesting exception can occur among very poor women. I’ll discuss this more in a later article.

Fundamental Errors?

I believe that men have made the fundamental mistake of devaluing women, their contributions to society (and the species) and the tremendous amount of effort required to sustain any household. Only in 2001 was the United States Labor Department studying how to include housework as part of measuring the nation’s Gross Domestic Product (GDP). The Genuine Progress Index for Atlantic Canada (report prepared by Ronald Colman, PhD) estimates that replacing housework with pay would add $275 billion to the Canadian economy. According to this report, non-employed single mothers work 50 hours per week while working mothers routinely work 73 hours per week. Salary.com placed a “salary equivalent” value of $134,121 on housework for stay-at-home mothers in 2006. The actual numbers are debatable. What is beyond debate is that housework, raising children and other “women’s work” has tremendous value. How men could devalue and demean this sort of contribution is both baffling and inexcusable in this man’s never-humble opinion.

Women, on the other hand, fought long and hard for the equal treatment they deserve, finally winning the right to vote and being accepted into the workforce in droves. Whole advertising campaigns launched telling women that they could have it all: A solid career, children and a rewarding home life. The actual results have been less than spectacular. Women are increasingly dying of the same diseases as men because of the added stresses of having jobs. Children are sent off to day-care centers, sometimes for eight or more hours per day. Despite this, women are still expected to perform housework on top of their other duties. Even worse, many families have reached the point where they can no longer maintain their lifestyle on a single income. Or can they?

I once added up the potential costs of full-time child care, housekeeping, second car, dining out, etc. and arrived at a figure that’s just over half my former wife’s current gross salary. 30% of that salary goes to taxes, leaving about 20% in net income gains per month. I can’t imagine anyone who would voluntarily work their current job for 20% of her or his current salary! My calculations don’t factor in other potential costs such as the potential inflation caused by massive influxes of workers to the economy and demanding goods and services. I also didn’t factor in potential savings from economizing elsewhere in the monthly budget. If you currently rely on two incomes, then you may want to perform the same calculations for your own situation. The results may startle you.

Then again, maybe they won’t. Every situation is unique. For example, my former wife and I are fortunate in that in our son currently attends school during the same hours that she is at her teaching job. There is no extra car payment and I can spend lots of time with our son thanks to my self-employed status. We therefore realize a significantly higher return from her work thanks to our situation. I am clearly not saying that two-income situations are wrong. I am saying that you need to look beyond the extra salary at the added costs in both dollars and quality time, then make an informed decision. You probably have a lot more flexibility than you think.

I am also not saying that a woman’s place is at home. A “reverse nuclear family” where the husband stays home and the wife works can be a perfectly viable solution as can a dual-income situation. Still, the sexual division of labor exists for solid evolutionary reasons. Men should not devalue or oppress women for their biologically designed roles and women should not feel that their only path to equality lies in emulating men. Sure, women may make better fighter pilots than men. What exactly does that prove? And why do women feel the need to prove that?

Next week, we’ll look at conflict in the home. Believe it or not, ‘Home Sweet Home’ is little more than wishful thinking. Stay tuned!

Understanding why men and women relate to each other the way we do requires peeling back the layers of customs, taboos, social mores, etc., to look at the physical human animal. To best understand the human animal, we must examine the conditions under which we evolved and how those conditions manifest themselves into our daily lives. Doing this gives us a completely different picture of what a truly healthy relationship looks like because it begins with the most fundamental building blocks available and goes from there to its own conclusion.

This is the first in a series of articles that will look at human sexuality and relationships from a purely evolutionary point of view and will compare and contrast that with the many layers of confusion that civilization has added on top of our evolved instincts. As you read, put aside your preconceived ideas of right, wrong and political correctness. Pretend that you’re reading about a completely different species if you like. Ask yourself how what you learn has already manifested itself in your life every day and in the lives of those around you. Above all, enjoy the ride… and remember, no matter how good or bad your current relationship situation may be, it is a direct result of instincts that have been evolving for millions of years. You, dear reader, are on the cutting edge of human evolution and are building on a legacy that extends back at least 5.5 million years. What a neat position to be in!

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I firmly believe that “women’s work” is a very real thing driven by biological imperatives that are hard-wired into our genetic code. Yes, this is a sexist remark in that I am discriminating (making fine distinctions between) based on gender. This should not be confused with chauvinism (claiming the relative superiority of either gender). To me, the concept of gender-based roles falls squarely in the “separate but equal” camp. By this I mean that men and women are built for entirely separate tasks, both of which are equally necessary for maximizing the odds of successful reproduction.

Why Women?

Sexual division of labor exists because our children are born completely helpless and take a long resource-intensive time to mature. It is simply impossible for a human mother to leave her infant behind while she goes off to hunt. Unable to feed itself, the infant must unmistakably communicate its needs to the mother. Nothing says “easy lunch” to a predator quite like a crying infant. Older children can walk on their own and gather their own food, with some help, but remain vulnerable until reaching sexual maturity. Someone must therefore remain with the child at all times.

I’ve done my share of hiking with my son, Logan, starting when he was too small to walk. His weight on my shoulders slowed me down, particularly when he would fall asleep leaning to one side in his carrier. His stamina has increased exponentially since then and he can usually take on steep 5-mile treks. I say “usually” because it’s getting harder and harder to carry him along with my normal burden of food, water, warm clothing, etc. It’s like driving with the brakes on, this from someone who isn’t normally worried about predators, foraging, or finding shelter. Mothers living before the days of waterproof-yet-breathable synthetic fabrics, ergonomic child-carrying backpacks, packaged rations, and forests cleared of most carnivorous animals had rough passage.

Why mothers? The wide hips that allow their babies’ large skulls to pass through during birth come at a price of reduced speed while men don’t have that impediment. A woman’s sensitive breasts resting squarely in the middle of her largest bodily mass are easy- and extremely painful- targets, making women less suited for fighting than men. It makes little evolutionary sense to have one parent give birth and the other nurse the infant because this would increase the vulnerability of both genders with no discernible benefit. As long as one gender is slower and more vulnerable, having that gender remain at home to care for the young while the other hunts makes the most sense. The same adaptations that make childbirth and feeding the child possible also make ongoing survival more difficult. In humans, women fall into this category.

Win-Win

Children require an astonishing amount of food. At nearly eight years old, Logan goes through groceries with gusto. Feeding him is a bit like ceaselessly shoveling coal into a ship’s boiler. I can only imagine the carnage to ensue once he hits puberty! My point is that a lone human in the wilderness must devote significant time and energy to finding food, as any survival show will demonstrate. Finding enough food for two while burdened with a heavy, hungry, and noisy child that both scares prey and attracts predators is a tall order indeed. It stands to reason that having one parent dedicated to finding food is a great idea, especially when that food comes in the form of densely packed calories rich in protein and electrolytes. If the hunter has a clean, dry, and warm place to come home to then it is so much better. The hunter benefits from having a home worth hunting and fighting for where he can return to rest and recharge, and mother and children benefit from the food in addition to their own foraging. It truly is a win-win scenario.

The proverbial “bacon” that Dad brings home has another benefit: More food allows earlier weaning, which allows the mother to have more children in a given time frame than a woman lacking this support. Having more children boosts the odds of passing on genetic material to another generation and thereby winning the great game of life. This kind of collective, mutually dependent living allows both partners to do more and with greater efficiency than they could alone. It also requires both partners to have a stake in the outcome. A woman must be able to rely on a man to share the fruits of his labors and a man needs to be at least reasonably certain that the children he is feeding really are his own.

Monogamy

Welcome to the wonderful world of monogamy where a woman makes herself available to one man and one man only to ensure that the man will have a vested interest in both her well-being and the conception and well-being of any children. It is no coincidence that human males have smaller testes than our freewheeling chimpanzee and bonobo cousins who have zero concept of monogamy. For them, the biggest balls win because they can out-produce the competition and increase the odds of winning the evolutionary jackpot by securing a genetic legacy. Monogamous humans with slow-growing children have no need of large testes because our sperm need not compete with that of other males.

This may sound good in theory but life isn’t quite that simple. Next week, we’ll look at the uneven investments that men and women make in the reproductive process.