Is Monogamy Natural? (rant)

[AtheistMommy]

Recently I called into the American Heathen TM show on Freethought Radio and asked a question. It was a simple one but it was taken offensively. However it got me thinking.

 

You see, RJ, the talk show host, does a lot of sexual antics on his show (yes, if you listen in you will be pleased). This last time he had his wife on the show along with another woman. A few things happened and I wanted to know, "Is she really ok with him having another woman stroke his penis?" The answer in a nutshell is yes.

 

However, when I called RJ said, "Monogamy isn't natural." Now, of course I'm not going to tell anyone they can't have what most refer to as an "open" relationship. It's really up to them. I suppose my relationship with Reverend Atheistar is so sealed shut you'd have to call it a "locked down" relationship.

 

Either way, I was having a hard time keeping up the debate with three people coming at me and two children trying to divert my attention. Even the Great AtheistMommy has her limits. : )

 

So we come back to my question, "Is monogamy natural?

 

I've been reading up on it. And this is what I've found: Yes. You can find monogamy in nature just like you can find polygamy. Now, don't get this confused with morality. If you think either one is moral or immoral is totally subjective and a case by case issue.

 

Moving on, monogamy and polygamy are effected by chemicals in the brain.

 

"Researchers believe that a chemical produced in the brain may turn on monogamous behavior. But also for those who would like to package the stuff, scientists have only been able to tie this love potion to a mouse-like mammal known as the prairie vole -- not to humans. Scientists just don't know whether this chemical, or any other like it, mediates human behavior (Science News; 11/27/1993; Fackelmann, Kathy A.)"

 

If you have more of one or the other decides greatly on which you are more prone to. Which makes a hell of a lot of sense, considering almost everything we do is highly dependent on the chemicals in our brain.

 

Another article I read on this subject talked about love. Meaning relationships success is highly dependent on "trust." I totally agree. Trust is a big big issue in relationships. I think communication and common goals have a bigger impact on relationships than trust but that's another story and another debate.

 

Another issue most of these articles talked about is family. Monogamy is mostly a reproductive success measure. Polygamy seems to benefit the man or male more than the female. Which of course strikes against my feminist cord.

 

Before delving into the specifics of the team's investigation, it may be helpful to define monogamy. The average person probably thinks of monogamy as a sexually exclusive relationship. Biologists, however, define the word a little differently. The monogamous animal is one that spends most of its time with one mate but is not entirely faithful, points out Insel. Most monogamous animals will, on occasion, mate with a stranger, he says. In addition, the monogamous male vole often takes a fiercely protective stance when a stranger threatens the nest. Finally, such males often help their mates with child-rearing tasks.

 

So I can understand why someone would choose one over the other regardless of which one. However, both are natural.

[Lycorth]

I agree; there's nothing wrong with either way, so long as all parties are open and honest with each other, same as anything.

[AtheistMommy]

Some how, I created two threads while trying to edit one. Sorry, Dave.

 

Yes, I'm not against other people living differently than I would choose. One thing these couples have in common is the absent kids. Monogamy is more about kids less about sex. It makes total sense. Is it immoral? Immorality is so very subjective, but I'd have to say no.

[Dhampir]

polygamy or rather polyamory has a benefit to women as well, as by choosing the provider candidate to be with, while mating with the intent to concieve with the more virile physical specimen, a women ensures that the most healthy, attractive offspring will have the best protection and provision. Actually, it's more insidious in it's way.

 

Most of the time, though, a man in an 'open' relationship, is apt to not mind being with another woman, or his woman being with another woman, but how frequently does the woman bring another man into their shared bed?

[chefranden]

Depending on the species monogamy is natural. I haven't heard of any primates that are naturally monogamus. It seems like alpha males and females get most of the action. That is probably the case with humans too. It is one of those things that we pretend not to know about, don't you think?

[Thurisaz]

I agree; there's nothing wrong with either way, so long as all parties are open and honest with each other, same as anything.

 

Absolutely. And let me add, for the sake of safety, "open and honest from the very start".

 

Aaaah, don't we all know that goo' ol' talk show/soap/whatever clichee about him asking her "fancy a fuck?", she agrees, then afterwards calls him a bastard? Hey baby, what's wrong with your ears? You don't want to just have a night of fun with him, just say no!

 

(The opposite, of course, is him lying to her about really loving her blah yadda just to do her once. Both is in effect disgusting)

[Guest Emerson]

There are no guarantees in life. There just aren't. Someone can be married and cheat, or be married and give in a moment of temptation and not choose to tell their spouse to spare their feelings and moment of idioticy.

 

I don't know if monogamy is for everyone since I can't speak for everyone on the planet. Its up to you really to define what it'll be like for your life. Like, some people can't accept partners who cheat even once. If that's you then you have to stick by that. Some people are really into swinging! Let the swingers swing! lol.

 

I'm just a huge skeptic and cynic about monogamy, marriage, and relationships in general. I've seen my parents divorce and remarry, and ugh I don't believe in anything really. Its all just a scam to me. I don't believe in the "one" or in monogamy completely. I think that very few people are lucky to have that one love in their marriage and lifetime and keep it 100% monogamous until one of the person's death.

[Clearview]

Depending on the species monogamy is natural. I haven't heard of any primates that are naturally monogamus. It seems like alpha males and females get most of the action. That is probably the case with humans too. It is one of those things that we pretend not to know about, don't you think?

 

 

As far as humans go, it seems to me that the alpha males & females are the most promiscuous, while the others use monogamy as a safety net. Once they find someone who will do them, they figure they need to hang on to them.

[♦ nivek ♦]

AM:

 

'Taint no degreed "expert" by any means..

 

Will say there are few men wired so tight that they canpractice the "One and Only".

 

Give a human man a shot at some "strange" and BAM, we're off like a shot..

 

Yeah, there are the guys who *will say* "Oh she is my ONLY, and I NEVER look at another woman, pr0n, chixx in public, etc.."

 

I'll show you a guy whose balls are so in pain from SRD, or her noose that they are gonna fall off from mis-use..

 

Thing is for the subject, if persons want to do the multi-poly-serial life, they've gotta be up front with all those involved, things worked out and the way life is gonna be lived discussed.

(I'm not talking the silly_assed_game/role_playing_servant-master_bullshit)

 

Life happens, and if that life has more than one upfront partner, cool.

Things can work...

 

Anyway any guy who says he doesn't look and think about *it* is a fucking bullshittter and a liar..

 

kL

[AtheistMommy]

 

Anyway any guy who says he doesn't look and think about *it* is a fucking bullshittter and a liar..

 

kL

 

 

KL,

 

This is pretty much the response I got from RJ's wife, Peeper. It sounds too much like an absoulte to me. Can we really say that a man is a liar if he says he doesn't think of "all" women sexually? I mean is it possible or probable that a heterosexual man in a long term relationship (like RJ's, who is 25 years deep in marriage) could walk down a street see a half naked beautiful woman and not think of her sexually? I'm not saying he doesn't look, it's hard not too look (we often are drawn to stare at things we find pretty/beautiful, ugly, mind boggling and so on), but couldn't it be possible that he admires her beauty and not think about fucking her?

 

I have to admit, I'm very detached. I don't think very many men are "good looking." I don't see a good looking man and think of him sexually. Now this might be because of the differences in male to female brain make up but I'm pretty sure it's just me. I need emotion to go with the good looks or it's just not happening. I've pretty much always been this way.

 

So is it highly improbable or impossible for a man to see a beautiful woman and not think of her sexually?

 

 

 

As far as humans go, it seems to me that the alpha males & females are the most promiscuous, while the others use monogamy as a safety net. Once they find someone who will do them, they figure they need to hang on to them.

 

That makes sense. But we have to also consider the hormonal levels.

[Ouroboros]

Depending on the species monogamy is natural. I haven't heard of any primates that are naturally monogamus.

I think I heard once there are some birds that are. Even stay with the same partner for years. (I haven't verified this though.)

[AtheistMommy]

polygamy or rather polyamory has a benefit to women as well, as by choosing the provider candidate to be with, while mating with the intent to concieve with the more virile physical specimen, a women ensures that the most healthy, attractive offspring will have the best protection and provision. Actually, it's more insidious in it's way.

 

Most of the time, though, a man in an 'open' relationship, is apt to not mind being with another woman, or his woman being with another woman, but how frequently does the woman bring another man into their shared bed?

 

 

Right, I can see how it would benefit a woman, but in most cases it looks a bit like the woman in the relationship is trying too hard to please her man.

 

Which is why you don't see too many women sharing their bed. Besides this we have to think about how it's viewed by most as immoral for a woman to just give it up to anyone let alone if their in a relationship. Religious undertones are applied.

 

Keep in mind, I'm not saying this is wrong, I'm just saying this is how it's majority viewed.

 

 

Depending on the species monogamy is natural. I haven't heard of any primates that are naturally monogamus. It seems like alpha males and females get most of the action. That is probably the case with humans too. It is one of those things that we pretend not to know about, don't you think?

 

 

Well that's just it, I want to know. It doesn't make sense that one would be natural and the other wouldn't. It does make sense that it would be determained by the chemicals in our brain. It makes sense (from all the cheating going on) that most primates would prefer polygamy.

 

There are no guarantees in life. There just aren't. Someone can be married and cheat, or be married and give in a moment of temptation and not choose to tell their spouse to spare their feelings and moment of idioticy.

 

I don't know if monogamy is for everyone since I can't speak for everyone on the planet. Its up to you really to define what it'll be like for your life. Like, some people can't accept partners who cheat even once. If that's you then you have to stick by that. Some people are really into swinging! Let the swingers swing! lol.

 

I'm just a huge skeptic and cynic about monogamy, marriage, and relationships in general. I've seen my parents divorce and remarry, and ugh I don't believe in anything really. Its all just a scam to me. I don't believe in the "one" or in monogamy completely. I think that very few people are lucky to have that one love in their marriage and lifetime and keep it 100% monogamous until one of the person's death.

 

 

Exactly, one of the things RJ wife said to me was "I know we are going to be together at age 85 and beyond." I didn't think about it much but, you can not be absoultly sure that you are going to be right were you are with who you are with that far in life. Things happen. For one, if the frontal lobe is damaged enough, that person you know and love will no longer be that person. If that at all makes any sense.

 

My parents are divorced too. I've seem both of them struggle to find that "one and only." I've had nothing but long relationships, starting with my first boyfriend. I do believe I've found my "one and only," but I've made it clear, painfully clear to him that its my children who matter to me most.

 

Oh, and I made a comment about swinging and RJ said they don't swing. So this is a matter of being able to have sex with other people and it not matter. I guess in the way a married porn star would have sex with other people.

[chefranden]

Depending on the species monogamy is natural. I haven't heard of any primates that are naturally monogamus.

I think I heard once there are some birds that are. Even stay with the same partner for years. (I haven't verified this though.)

 

Canadian Geese

[Dhampir]

Bald Eagles.

 

Bald Eagles. They mate for life.

[woodsmoke]

Really, can't add much to what's already been said. Some folks are wired one way, others t'other.

 

As with just about everything else in life, the proverbial "lynch pin" of the whole issue is whether the involved parties are willing to handle the situation as honest, responsible adults.

[dr_funkenstein]

I happen to believe that the human species is pretty much like all other primates - we're naturally polygamous... BUT - and this is a big but...

 

We also want to monopolise our sexual partners so they only mate with us. And this is also a natural human behaviour.

 

We see primates like chimps doing this all the time - fighting for alpha status so they can not only mate with multiple individuals but also prevent other individuals mating with them.

 

I think that monogomy developed as a social construct, as a way of compromising these two extremes. Essentially it's a way of letting everybody have one sexual partner and not allowing anyone to monopolise - but I think it's artificial. The desire to be polygamous is still there and manifests through cheating.

 

Not only that, but studies have shown that the initial attraction which draws a couple together and makes them monogamous to one another only lasts 2-3 years. After that, the chemical indicators for sexual attraction to that person fade away.

 

Maybe it's natural for us to be "serially monogamous". In other words... have a series of monogamous long term relationships throughout life. I think that idea appeals to me most.

[Ouroboros]

Bald Eagles.

 

Bald Eagles. They mate for life.

Of course they do. If they're all already bald, then who of them care how the neighbor eagle looks...

[spamandham]

So we come back to my question, "Is monogamy natural?

 

Of course it is, look at the number of people who engage in it. But, polygamy is also natural, so is monogamy for a time and then move on to a different monogamy for a time - which is probably the most common.

 

But why do we even care what is "natural"? Have sex with ducks if that's what you enjoy, and as long as the ducks are legal consenting adults.

[AtheistMommy]

 

Maybe it's natural for us to be "serially monogamous". In other words... have a series of monogamous long term relationships throughout life. I think that idea appeals to me most.

 

I have to wonder if you read what I wrote. The definition given by the scientists fits just that. It's not mate for life with one partner but mate for long spans of time with one partner, which is seen in monogamas animals. They also said only 3% of mamles are monogmas.

 

I have always had long relationships. I think I'm part of this three percent.

 

I think it's safe (with the evidence we do have) to say that both sides are natural.

 

 

 

Of course it is, look at the number of people who engage in it. But, polygamy is also natural, so is monogamy for a time and then move on to a different monogamy for a time - which is probably the most common.

 

But why do we even care what is "natural"? Have sex with ducks if that's what you enjoy, and as long as the ducks are legal consenting adults.

 

 

LOL

 

My husband brought this up last night. He was saying how we go against our nature all the time. He made a joke a while back when his sister announced she was having a "natural" birth. He said, "So you're going to give birth out in a filed alone and eat the placenta?" It was funny at the time.

 

Anyway, it is true that we go against our nature. And I have no problem with people who live differently than I do. I don't see it as my authority to tell them what they can and cannot do unless it's somehow taking other's rights away. I'm not an absolutist.

[Taphophilia]

I think if animals were given the choice, I'm not sure they would choose natural childbirth.

 

As far as monogamy, human males help rear the young, so monogamy makes sense as far as an evolutionary standpoint, to ensure the survival of their offspring. Some primates are monogamous, gibbons, for instance mate for life.

Human males have the biggest penises of the primates (Do I hear woo hoo!), they had to develop them to attract the best female to produce offspring with. Also, human women have breasts and hips before they reproduce, again to attract the best male to reproduce with.

 

Taph

[Reverend AtheiStar]

http://www.ncbi.nlm.nih.gov/entrez/query.f...2&dopt=Abstract

 

The evolution of monogamy in primates.

 

Rutberg AT.

 

The evolution of primate monogamy is described as an ordered sequence of choices by generalized, hypothetical females and males. Females first choose whether or not to associate with other females. Predators encourage gregariousness in diurnal primates; however, nocturnality or scarce and evenly distributed food supplies may enforce separation. A testable group size model based on food patch size is developed and qualitatively supported. If females choose solitude, males then choose either to defend a single female and invest in her offspring, or to compete with other males for access to several females, usually by defending a territory or establishing dominance over the home ranges of several females. The decision rests on the defensibility of females and on the availability of an effective form of male parental investment. Both of these factors are dependent on local female population density. A model is developed that assumes that territorial defense is the principal form of male parental investment, and it predicts that monogamy should occur at intermediate densities: at high densities, males should switch to defense of multiple females, and at low densities there is no investment value in male territorial defense. The model is shown to be only partly adequate. Variation in local population densities prevents the establishment of obligate monogamy through territoriality in small monkeys, since male territorial behavior is inconsistent over the long run. Here, carrying of offspring by males can succeed territoriality, providing an effective and reliable form of parental investment to maintain the pair bond in the face of population fluctuations and changes in group structures. This hypothesis is supported by the scarcity of obligate monogamy among the prosimians, which frequently do not carry their young.

 

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http://www-personal.umich.edu/~phyl/anthro/mating.html

 

Diversity of primate mating systems

 

Remember the terminology:

(x means multiple)

 

1m:1f=monogamy.

1m:Xf=polygyny.

1f:Xm=polyandry.

Xm:Xf=promiscuity

 

 

Prototypes from each of our primate groups:

Monogamy:

Prosimian- at least one species of tarsier.

New world monkey- titi monkey, night monkey, callitrichids.

Old world monkey- langur/mentawi island leaf monkey.

Ape- Gibbon.

Polygyny:

Prosimian- lemur.

New world monkey- howlers, cebus monkey.

Old world monkey- most of leaf monkeys, langurs, family presbytis, macaques.

Ape- gorilla.

 

Polyandry: (rare in primates)

New world monkey only- some of the callitrichids are "facultatively" polyandrous. This means they're not always so, but they can and in some cases tend to be.

 

Promiscuity:

New world monkey- marikis.

Apes- chimps.

 

 

What factors shape the evolution of mating systems?

Sexual selection:

Think about parental investment. Females do more than males especially in primates since they do gestation and lactation. So females become a limiting resource for males. Males can't increase their reproductive success by caring for their kids since they don't know who their kids are, but they can seek more matings.

 

In polygyny, males put forth more mating effort while females put forth more parental effort. In monogamy, both do more parental effort. In polygyny there's stronger or more intense sexual selection, but in monogamy it's not so intense. Usually in primates you don't see equal parental efforts because females have the ability and tendency to put more into parental effort since they gestate and lactate.

So, females go where the food is and males go where the females are. This is a good generalization for cases when male involvement is minor.

 

Ecological factors:

Environmental Potential for Polygyny (EPP)- how resources are distributed.

 

Females choose their limiting resource which is food and males choose theirs which is females. So males will always be under selection to monopolize multiple females. For instance whether they'll be able to get access to females depends on how females are dispersed in space and in time. If they're evenly distributed in space, it'll be hard to hold on to more than one female so there's little potential for polygamy. But if resources, and therefore females, are clumped then one male can control access to many females. In this case there's a lot of potential for males to remain polygynous.

 

Also females' distribution in time affects the EPP- if they are synchronized in breeding /estrous, then it's more difficult for a single male to monopolize females since they're all receptive at once and it's too easy for other guys to sneak in while he's working on one. If they're spread out in time then it's easier for the same male to control the few females who are ready at each time. Note that these two kinds of clumping have the opposite effect of each other. Synchrony reduces defendability of mates while spatial clumping increases defendability.

 

 

Polygyny

Two preconditions for the evolution of polygyny

1. It must be economically feasible for males to defend females. (Costs vs. Benefits.)

2. Males must be able to capitalize on potential for polygyny. This depends on characteristics that have evolved in their phylogeny, for instance, how much male parental care is required to raise offspring.

So, like, there might be high polygyny potential, but males might not be free to take advantage of it because babies will die without their contribution. Ecological factors determine both EPP and ability to capitalize on the EPP. Phylogenic factors also determine how well the male can capitalize on the EPP. Economic feasibility and capitalization ability both determine the degree of monopolization of mates which determines mating system.

 

(There's a flow chart diagram for this which makes it easier to understand than mere words)

 

 

Why most primates are polygynous

In most primate species, given the distribution of resources, females do usually congregate. You know, primates are mostly social. Because they're clustered but not in huge groups, they're both possible and beneficial to defend. Also important, females have long intervals means that they're receptive more or less one at a time so they're easier to defend.

 

To sum up:

 

"In most primate species, females congregate spatially in small, stable groups.

In addition, long interbirth intervals create a situation in which there are only a few reproductively active females per sexually active male.

These factors set the stage for intense male-male competition for the limited number of fertilizable females, and polygyny typically results."

 

 

Monogamy

Ok, so if polygyny is so great then why do some end up being monogamous? It's certainly not very common:

Birds- 90% monogamous.

Mammals- under 5% monogamous

Primates- 37/200=~18% monogamous.

(Traditional human societies are about 20% monogamous.)

Characteristics of monogamous primates

 

 

Limited mating opportunities

 

Male investment in offspring is high

 

Male confidence in paternity is high (we're just talking probability here, not mental awareness)

 

Little sexual dimorphism

 

Territoriality & sex-specific aggression

 

Hypothesis for the evolution of monogamy

Evolves when males can only economically defend one female. This could be because of ecological constraints or because of the demands of parental care. Quite different from birds where parental care is the main factor. Someone always has to be brooding the eggs so they have to take turns so they can eat. This doesn't apply to primates so monogamy is driven more by the spatial distribution of females. Usually it's just too hard for males to defend more than one female.

 

To sum up:

 

"Monogamy evolves when either sex has the ability to monopolize multiple members of the opposite sex either because of ecological factors do not permit them to or because of the constraints imposed by parental care.

1. Monogamy evolves when male parental care is indispensable to female reproduction.

2. Monogamy evolves when aggression by mated females leads to their spatial separation and prevents males from acquiring additional mates."

 

#1 seems to be the case in new world monkeys. Crucial point is body size. They're really small but they have offspring that are large relative to the adult size to its really hard for a lone female to raise offspring. Males could abandon and mate more often, but they wouldn't end up passing along more genes.

In gibbons however, females are very evenly distributed in the environment and this seems to be because of mutual aggression between females. So a male might like to have a harem but the females won't have any of it. This has been difficult to prove experimentally, but they have done playback experiments. When you play female sounds then the female of a pair will charge over to the speaker to attack but the male will just sit there and be a dork. So the females reduce males' options until they have no choice but to be monogamous.

 

Promiscuity

 

Generally happens when males don't succeed in monopolizing access to any females. This may be because of the minimal mammalian social system where males are ranging widely through the home ranges of several females. Because they don't have defended territories, they can't monopolize any females. This is seen in the orangutans as well as some prosimians.

It also happens in large groups with multiple males and females. There may be two factors happening- it may not be economically feasible to restrict access to a large group, too big a job for one male. It has also been suggested that in like chimps and maybe marikis(brachyteles) it's that males need to reduce aggressive interactions between themselves because they've got to cooperate to defend joint territory from outsiders. They suppress their natural competition otherwise they'd all lose all the females. At least when they share they get some females. So this is all why males might be into promiscuity. What do the females get out of it?

 

Females must have a reason for mating with more than one male, too. Females' reasons haven't been studied as much. One reason might be to ensure fertilization. Also it might confuse paternity so it's not sure which male fathered her offspring so they're less likely to kill the kid. Or, maybe it's easier for a female to just mate with a male than to be subjected to aggression if she refuses. More on this later, but maybe it's just less risky for females to lie back and have done with it.

 

 

Polyandry

 

Rare in mammals in general, but occurs facultatively in tamarins.

Data from six populations of saddleback tamarins studied over 4 years.

Percentage of groups displaying each type of composition:

(X=multiple)

1f-1m 22%

1f-Xm 61%

Xf-Xm 14%

single-sex 3%

So maybe they're not completely polyandrous but it's the most common result. This may occur because they have unusual reproductive biology. For one thing they usually have twins. Offspring are quite large at birth; their combined weight can be up to 25% of the mother's weight. (OUCH!) By the time they wean, each offspring is about half the size of the mother. So she's providing enough milk to provide enough for two who together weigh as much as her! So females don't usually even carry offspring after second week. Males do this, or previous offspring. So males do much more carrying and seem to be completely necessary especially to escape from predators. Male parental care is limiting to reproductive success, and it's even higher with more than one male helping, so sometimes it takes two males just to raise one female's offspring.

 

 

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http://www.trinity.edu/rnadeau/FYS/Barash%...%20monogamy.htm

 

DEFLATING THE MYTH OF MONOGAMY

 

David P. Barash

 

The Nobel Prize-winning ethologist Konrad Lorenz used to recommend that every scientist discard at least one cherished notion every day, before breakfast. It is excellent advice (although Lorenz wasn't known for tossing away many of his own prized ideas). In any event, good science doesn't really require that its practitioners intentionally turn their backs on what they believe to be true, or what they devoutly wish were so. Tincture of time and the accumulation of new findings generally accomplish that: If we wait long enough, the world has a habit of making mincemeat of even our most strongly held ideas. The only thing necessary is to remain open to the evidence.

 

Case in point: the widely held view that certain animals -- notably the great majority of bird species -- are monogamous. Second case in point: the belief that females of most species, including our own, strongly tend toward sexual fidelity -- in contrast to males, who are known to have a penchant for sexual variety, if not promiscuity.

 

Biologists have long understood that monogamy is rare in mammals. Of about 4,000 mammalian species, only a handful have ever been called monogamous. The tiny list includes beavers and a couple of other rodents, otters, bats, certain foxes, a few hoofed mammals, and some primates -- notably gibbons and the tamarins and marmosets of the tropical New World. By contrast, birds have long been the poster children of monogamous fidelity. A common figure, first reported by the great ornithologist David Lack in the 1960's, has been that 92 percent of the 9,700 bird species are monogamous. Picture an archetypal male and female robin, collaborating in nest building, then devotedly taking turns incubating the eggs and feeding their young.

 

The notion has even penetrated into popular culture. In the movie Heartburn, a barely fictionalized account by Nora Ephron of her marriage to Carl Bernstein, the lead character complains to her father, who responds, "You want monogamy? Marry a swan!" Now we are learning that even swans aren't monogamous.

 

Actually, the myth of monogamy didn't disappear overnight. The tell-tale hiss of its deflation began several decades ago. One now-famous study, for example, sought to assess vasectomy as a possible means of population control among red-winged blackbirds. To their surprise, the researchers discovered that female blackbirds, mated to vasectomized males, were nonetheless laying eggs that hatched! Evidently, there was some hanky-panky going on in the blackbird world.

 

And not just blackbirds. By the 1980's, studies employing blood typing as well as analyses of proteins were leading researchers to question whether social monogamy and sexual monogamy were necessarily synonymous. Then came DNA fingerprinting in the 1990's, and a veritable avalanche of new findings. Time and again, it was revealed that 10, 20, even sometimes 40 percent of nestlings were not fathered by the social father. The apparent mother, on the other hand, usually is what she seems to be, reinforcing the adage "Mommy's babies, Daddy's maybes."

 

Reports of extra-pair copulations -- henceforth, E.P.C.'s -- in animals previously thought to be monogamous have come hot and heavy during the last decade. Increasingly, biology journals have featured articles with titles such as "Behavioral, Demographic, and Environmental Correlates of Extra-Pair Fertilizations in Eastern Bluebirds," "Extra-Pair Copulations in the Mating System of the White Ibis," "Extra-Pair Paternity in the Shag, as Determined by DNA Fingerprinting," "Genetic Evidence for Multiple Parentage in Eastern Kingbirds," "Extra-Pair Paternity in the Black-Capped Chickadee," "Density-Dependent Extra-Pair Copulations in the Swallow," and "Patterns of Extra-Pair Fertilizations in Bobolinks." We've even seen these oxymoronic reports: "Promiscuity in Monogamous Colonial Birds" and "Extra-Pair Paternity in Monogamous Tree Swallows."

 

The situation has reached a point whereby a failure to find E.P.C.'s in ostensibly monogamous species -- that is, cases in which monogamous species really turn out to be monogamous -- is itself reportable, leading to the occasional appearance of such reassuring accounts as "DNA Fingerprinting Reveals a Low Incidence of Extra-Pair Fertilizations in the Lesser Kestrel" or "Genetic Evidence for Monogamy in the Cooperatively Breeding Red-Cockaded Woodpecker."

 

Nor have mammals been exempt. Gibbons, for example, were long thought to be lifetime monogamists. No longer. Ditto for essentially every species that has been investigated with any thoroughness.

 

THE QUESTION ARISES: Why is sexual fidelity so rare, even among animals that are socially monogamous? For most evolutionary biologists, the real question is: Why do socially mated females have E.P.C.'s? There has never been much doubt about why males do. Males make sperm, which are extraordinarily small, are produced in amazingly large numbers, and require essentially no biologically mandated follow-through in order for reproduction to succeed. As a result, the optimal tactic for males is typically to be easily stimulated, not terribly discriminating as to sexual partners, and generally willing -- indeed eager -- to fertilize as many eggs as possible.

 

As the sociobiologist Robert Trivers first pointed out in 1972, and as subsequent theoretical and empirical research has shown, males tend to follow a "mixed reproductive strategy," whereby they establish a mateship with a designated female (and perhaps assist in nest building, territorial defense, care of the young, and so forth insofar as those activities increase their reproductive success) while also making themselves available for E.P.C.'s with other females, whom they will not assist.

 

To be sure, males can be expected to be at least minimally discriminating, because there may be costs associated with too much sexual gallivanting: A careless Lothario might be attacked, for example, by an outraged "husband." Or, while seeking his own E.P.C.'s, a philanderer might be cuckolded by other males having similar designs on his mate, unavoidably left unguarded.

 

But on balance, it seems likely that the payoff to males engaging in successful E.P.C.'s would be great. That is especially true in species in which the males do some child care, because the successful philanderer thus uses other males' energy to raise his offspring.

 

When it comes to females, on the other hand, the evolutionary advantage of E.P.C.'s is much less clear. After all, although eggs are fewer and more costly to produce than sperm, most eggs are fertilized while most sperm is wasted. (Evolution has produced males who make lots of sperm for just that reason.)

 

If a female already has a mate to fertilize her eggs, what does she gain from an E.P.C.? In species where the male helps care for the young, the unfaithful female might risk the loss of her mate's help. Yet the DNA data are unequivocal: Female animals, in species after species, are sexual adventurers in their own right. Why?

 

It appears that there is no one-size-fits-all answer. For some species, notably certain lizards and insects, there appears to be a payoff in increasing the genetic diversity of one's offspring by copulating with multiple partners. For some birds, there may be an immediate benefit --such as being fed by one's lover. In many cases, the payoff appears to be more indirect, via genetic benefits accruing to the "out-of-wedlock" offspring. By mating with males who are especially fit and/or who possess secondary sexual traits that are particularly appealing to other females, would-be mothers apparently can increase the fitness as well as the eventual sexual attractiveness of their offspring. (Among barn swallows, for example, a deeply forked tail is a sexually desirable male trait. Females paired to males whose tails are not especially impressive in this regard are prone to mate on the sly with those neighboring males whose tails have been made more forked by researchers.)

 

The anthropologist Sarah Hrdy has suggested that among primates in particular, females solicit E.P.C.'s in order to buy a kind of tolerance from their extra-pair sexual partners: Males of many species (including langurs, chimpanzees, and certain macaques) often kill offspring they have not fathered. By copulating with males from outside the troop, females could well be bribing them to avoid such violence toward offspring that might be their own.

 

NEXT STOP, Homo sapiens. Social conservatives like to point out what they see as threats to "family values." But they don't have the slightest idea how great that real threat is, or where it comes from. Monogamy is definitely under siege, not by government, declining morals, or some vast homosexual conspiracy -- but by our own evolutionary biology. Infants have their infancy. And adults? Adultery.

 

To begin with, we probably never occupied an Edenic paradise of one-to-one fidelity. The evidence is as follows: First, men are significantly larger than females, a pattern consistently found among polygynous species. From deer to seals to primates, the harem-keeping sex is the larger one, because competition among harem keepers rewards those who are larger and brawnier. Second, around the world, men are more violent than women (see Evidence No. 1; it avails little in acquiring a large number of mates for a male to be physically intimidating unless he is also inclined to make use of his assets). Third, girls become sexually mature earlier than do boys -- another tell-tale sign of polygyny, because the intense competition among harem keepers conveys an evolutionary payoff for the "keeping" sex to delay maturation until individuals are large, strong, and possibly canny enough to have some chance of success. And fourth, before the cultural homogenization that came with Western colonialism, more than three-quarters of all human societies were polygynous.

 

But it's one thing to conclude that our biology favors polygyny, and quite another to decide that most people, most of the time, were either keepers or members of harems. The likelihood is that only a few succeeded at polygyny, just as only a small proportion of females were chosen (or coerced). The great majority of people -- of both sexes --undoubtedly practiced monogamy, at least its social variety. As to sexual monogamy, the situation is obscure, but -- given the high frequency of E.P.C.'s among ostensibly monogamous animals -- it is hard not to suspect something similar among Homo sapiens. Certainly, the intense sexual jealousy and competitiveness among human beings strongly suggest that adultery has a long history in our species. (Why would our biology have outfitted us with such traits if utter fidelity were the rule?) In this regard, moreover, testicles have a tale to tell.

 

Gorillas, despite their large bodies, have comparatively tiny testicles. Those of chimpanzees, by contrast, are immense. The reason for the difference seems clear: Gorilla males compete with their bodies, not their sperm. Once a dominant silverback male has achieved control over a harem of females, he is pretty much guaranteed to be the only male who copulates with them. Chimps, by contrast, experience a sexual free-for-all, with many different males often copulating in succession with the same adult female. As a result, male chimpanzees compete with their sperm, and they have evolved big testicles to produce large quantities of it. In most species, the ratio of testicle size to body size is a good predictor of how many sexual partners an animal is likely to have.

 

How, then, do human beings rate in this regard? The testicles of Homo sapiens are, relatively speaking, larger than those of gorillas but smaller than those of the champion chimpanzees. The most likely interpretation? Human beings are less certain of sexual monopoly than are gorillas, but are not as promiscuous as chimps. Another way of putting it: We are (somewhat) biologically primed to form mateships, but at the same time, adultery is no stranger in our evolutionary past.

 

Given how much we have been learning about extra-pair matings among animals, and considering the current availability of DNA testimony, it is remarkable how rarely genetic paternity tests have been run on human beings. On the other hand, considering the inflammatory potential of the results -- as well as, perhaps, a hesitancy to open such a Pandora's box -- Homo sapiens' reluctance to test for paternity may be sapient indeed. Even before DNA fingerprinting, blood-group studies in England found that the purported father of a child is the real father about 94 percent of the time; that means that in six out of every hundred cases, someone else is. In response to surveys, 25 to 50 percent of American men report having had at least one episode of extramarital sex. The numbers for women are perhaps a bit lower, but in the same ballpark.

 

Many people already know quite a lot -- probably more than they would choose -- about the disruptive effects of extramarital sex. It wouldn't be surprising if a majority would rather not be informed about its possible genetic consequence, extramarital fatherhood. Maybe ignorance is bliss.

 

The poet Ezra Pound once observed (somewhat self-servingly) that artists are the "antennae of the race." Those antennae have long been twitching about extramarital affairs. If literature is any reflection of human concerns, infidelity has been one of humankind's most compelling interests, long before biologists had anything to say about it. The first great work of Western literature, Homer's Iliad, recounts the consequences of Helen's adultery. And in the Odyssey, we learn of Ulysses' return from the Trojan War, whereupon he slays a virtual army of suitors, each of whom was trying to seduce his faithful wife, Penelope. (By contrast, incidentally, Ulysses himself had dallied with Circe the sorceress, but was not considered an adulterer as a result. The double standard is ancient and by definition unfair; yet it, too, seems firmly rooted in biology.)

 

Monogamy's failures are recorded in many great works of literature: Tolstoy's Anna Karenina, Flaubert's Madame Bovary, Lawrence's Lady Chatterley's Lover, Hawthorne's The Scarlet Letter, Henry James's The Golden Bowl. More recently, John Updike's marriage novels -- not to mention scores of soap operas and movies -- describe a succession of affairs. And then there is the small matter of real life.

 

As G. K. Chesterton once observed about Christianity, the ideal of monogamy hasn't so much been tried and found wanting; rather, it has been found difficult and often left untried. Or at least, not tried for very long.

 

There is no question about monogamy's being natural. It isn't. But at the same time, there is no reason to conclude that adultery is unavoidable, or that it is good. "Smallpox is natural," wrote Ogden Nash. "Vaccine ain't." Animals, most likely, can't help "doing what comes naturally." But humans can. A strong case can even be made that we are never so human as when we behave contrary to our natural inclinations, those most in tune with our biological impulses.

 

In Civilization and Its Discontents, Freud argued that civilization is founded on the repression of instincts. It now seems clear that one of those instincts leads us away from monogamy. Whether we choose to follow, on the other hand, is up to us.

 

~~~~~~~~

 

David P. Barash is a professor of psychology at the University of Washington. His most recent book, written with his wife, the psychiatrist Judith Eve Lipton, is The Myth of Monogamy: Fidelity and Infidelity in Animals and People, published this month by W. H. Freeman

[Reverend AtheiStar]

It is interesting to study the sexuality of other primates and other animals, as well, but I really don't think anyone should go and base their life on what they see in nature. There is much that is not desirable. Killing rival males and babies -- completely natural. Having multiple sex partners and rape -- completely natural. Dying from STDs -- completely natural. Sure, there are things in nature that are wonderful, but to take all of nature as an open book to take advice from? Not a good idea, at all.

 

I personally subscribe to mongamy because I like it. I love the structure. My sex life is not boring as we are always doing something new. I would say it's great, actually! I don't want another woman. I have the love of my life and I wouldn't want it any other way. This is why I say you should be very careful when choosing a life partner. Don't just marry the first or even the tenth, maybe, that comes along. Make sure they fit your criteria. Don't settle. Go for what you want and get it!

[Guest georgemacdonald]

From what I've read (I believe it was in Dawkins "The Selfish Gene") the way to understand procreative choices is that our genes "want" to replicate themselves as much as possible, and historically this means that men have been naturally polygamous (promiscuous) -- they wish to spread their seed as much as possible. The woman, however, is naturally monogamous (actually - naturally loyal to one man, which could include polygamy) since perpetuating her genes requires a long period of care and protection for the young.

 

In other words, the promiscuous man's genes will be over-represented in the gene pool, as will the monogamous or polygamous (but not promiscuous) woman's. Over time nature has selected for men who are promiscuous and women who stay loyal to the father of their children.

[Reverend AtheiStar]

From what I've read (I believe it was in Dawkins "The Selfish Gene") the way to understand procreative choices is that our genes "want" to replicate themselves as much as possible, and historically this means that men have been naturally polygamous (promiscuous) -- they wish to spread their seed as much as possible. The woman, however, is naturally monogamous (actually - naturally loyal to one man, which could include polygamy) since perpetuating her genes requires a long period of care and protection for the young.

 

In other words, the promiscuous man's genes will be over-represented in the gene pool, as will the monogamous or polygamous (but not promiscuous) woman's. Over time nature has selected for men who are promiscuous and women who stay loyal to the father of their children.

 

I'm more than happy with the two instances of my DNA being spread. I understand the science behind what Dawkins has wrote and I agree with it, but it's just not for me. I guess I'm just a waster! lol...

[Joyous1]

Human monogamy is not natural, it is an intelligent choice made by a species capable of understanding the consequences of bad choices. I don't see the point in comparing human behavior to that of any species incapable of understanding long term consequences of choices.

 

Maybe I skimmed through this thread too quickly, but I did not see any references to STDs. IMHO, they represent the single most powerful reason for any human being to choose monogamy. Throughout most of human history STDs have been fatal, and the deaths they caused were horrifying. To make matters worse, you could give this horrible disease to your children and watch them die horrible deaths.

 

While we are on the subject, consider pre-marital sex in a primitive society where girls are married off as soon as they reach puberty. For the most part, fornication would have been committed only by pedophiles molesting pre-pubescent girls.

 

I would agree with those on this thread who say polygamy is fine as long as everyone is honest AND everyone takes appropriate precautions to prevent STDs.