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Your_Majesty's avatar

How could monogamy have existed in evolution history?

Asked by Your_Majesty (8212 points ) May 27th, 2011

Without make it any longer we know that humans belong to the great ape family,or at least,share the same ancestor that share one common family lifestyle among other things that is known as polygamy lifestyle,where a number of females are led by one single dominant male and only dominant males could mate with a lot of females. Religion that teach and has a great influence on monogamy lifestyle hasn’t yet existed. Women were also not very independent so they had no power and sex equality at that times. This is of course very different from the situation nowadays where most people are on monogamy lifestyle even though there are a number of people that still retain their primitive polygamy lifestyle and with a little bit of modification (like the Islamic people).

So the question lies here; how could monogamy lifestyle could has existed at that very primitive and adamant age? How monogamy lifestyle suddenly crossed their mind?

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37 Answers

crisw's avatar

Although I agree that we evolved as a polygamous species, your depiction of our ancestral lifestyle is probably a bit off.

In chimps and, especially, bonobos, the females have a great deal of choice in whom they mate with. It isn’t always the big, dominant males; they will sneak off and mate with males that they like.

I believe that humans were polygamous for most of their history- see the great book Sex at Dawn for some scientific exploration of this topic. Monogamy was a cultural invention spurred by the concept of property and our desire to control it.

nikipedia's avatar

Monogamy is the evolutionary ideal in some situations, namely when offspring need more energetic investment than one parent can realistically provide. If the father spreads his resources among so many kids that they’re spread too thin, he ends up with zero offspring.

LuckyGuy's avatar

This is just a theory. I am not so old as to have lived in prehistoric times so I really don’t know for sure. .

Maybe the males who did not have mates became frustrated and killed the males that were greedy and took two or more mates.

Also it took more energy and resources to feed extra females. All you wold need is a few years of hard times and the ones with too many females would die off. The ones that mated for a long time survived.

I’d need a time machine to really tell.

crisw's avatar

@nikipedia

“Monogamy is the evolutionary ideal in some situations, namely when offspring need more energetic investment than one parent can realistically provide”

What we find in many, if not most, cases, though, is social monogamy, such as in many birds- where the pair appears to be monogamous and two parents feed the young- but genetic testing shows that the caretaker of the young often isn’t really their father! And even social monogamy is very rare in mammals- only 3–7% of species.

incendiary_dan's avatar

@crisw Is right in terms of the depiction of ancestral living. It appears that in basically all cultures before the advent of monocrop agriculture, women and men have more or less the same “power” in society, and this remains to for basically all non-agricultural people afterward.

As far as monogomy, it’s a social contract that has often worked out well, so people continue it. In some cases, it does not work out well, so they don’t. It should be noted that most cultures have permitted polygamy and polyandry, even when they’re practiced rarely.

Mamradpivo's avatar

While complex skills such as tool use are easy for big-brained animals to comprehend, we typically have to be shown them, or learn them. To put it simply, as we developed more intricate ways of interacting with the environment and each other, the amount of learning/repetition we needed grew. Combine that with the security provided by being the top of the food chain and delegation of tasks within a small group of primates (i.e. someone is taking care of security, so others don’t have to worry as much about it), primates had more time to devote to raising their young.

These two things combined with very small litter size (one at a time, instead of several) means that both parents have an interest in the survival of their offspring for their own evolutionary fitness.

A very simple explanation, and it’s late at night, but it’s my basic understanding of the situation.

ETpro's avatar

@Your_Majesty I follow your logic, and like @crisw I agree early man was likely polygamous throughout most of history. But individual species are capable of varying from other species in their family. While most birds mate for a single season, and chose new mates next season (serial monogamy) Canadian geese evolved to generally mate for life.

AdamF's avatar

Also, cases of poylandry highlight the range of relationships possible and the influence that available resources can have on driving the resultant pattern.

So if polygyny can be favoured in some societies, as can polyandry in others, then so can monogamy be selected for.

http://en.wikipedia.org/wiki/Polyandry

crisw's avatar

@ETpro

Actually, a lot of the Anatidae are socially monogamous, especially geese and swans. But, once again, DNA testing tells a different story- for example, 29.6% of gadwall ducklings were fathered by a drake other than the hen’s apparent mate. 27–40% of black swan broods contained at least one cygnet not fathered by the apparent father. I couldn’t find specific statistics for the Canada goose, but I would think they are similar.

Hibernate's avatar

@Your_Majesty maybe your family descends from apes. Mine doesn’t.

Not to mention that most animals when choosing a life partner stick with IT.

In the beginning polygamy was incouraged by God to increase the number of the species. [ animals and humans too ]

Even without taking into consideration I think you won’t like your partner to have sex with someone else or to procreate with someone else. [ or maybe you are naive and you enjoy it ]

But here we have different opinions.

ETpro's avatar

@crisw The best of both worlds. A reliable mate, and the hens still get to sleep around. Sign me up.

@Hibernate I won’t even ask you to supply proof that your contention regarding a common ancestor of the great apes and man is true. I know that you can’t do that. But please supply some evidence for your contention that most animals form lifelong mated pairs.

crisw's avatar

@Hibernate

“maybe your family descends from apes. Mine doesn’t.”

Well, what do they descend from then? Remember, this is a discussion of evolution, not your theology.

“In the beginning polygamy was incouraged by God to increase the number of the species. [ animals and humans too ]”

And your scientific source for this statement is?

“Even without taking into consideration I think you won’t like your partner to have sex with someone else or to procreate with someone else. ”

You are making many assumptions about what other people think, aren’t you?

@Hibernate – can we just stick to the facts here? The vast, vast majority of animal species are not monogamous. There is little support for any theory that humans evolved to be monogamous, and many humans, while they may see monogamy as an ideal, have difficulty actually executing the concept. Sexual monogamy (as opposed to social monogamy) in our species is a societal construct, not an evolved behavior.

crisw's avatar

@ETpro

One of my pet theories is that concealed ovulation evolved in female humans not as a mate-keeping tool (the usual explanation), but so that female humans could choose whom they wanted to father their children, as only they knew they were fertile.

Hibernate's avatar

No matter what proofs I’ll bring won’t be enough top suffice your way of seeing things though you should take a look around and open your eyes and you guys will see that most [ I did not say ALL ] animals live with just another of their specie.
Proofs are irrelevant for any matter since anyone can say they are counterfeits or they are not true or they could simply believe what they were believing before. Take a look in the past .. few people believe that things in the past are true even with solid evidence. [ this is a matter for another discussion ]

A common ancestor for humans and apes is inexistent. Why ? well for a start that evolution doesn’t occur anymore. Then it’s the cognitive process of the human mind .. we are the only specie that discerns good from wrong [ no matter what we see as good and wrong ]. The apes [ no other animal for that matter ] discerns. Not to mention that if that evolution did exist .. well the human did not change anymore. All the cavern bullcrap can’t be true or else the human would evolve even grater than it’s current form. [ but this is just the way I see things and I do not incline to see you understand it ]

Cheers ^^

crisw's avatar

@Hibernate

I don’t know about you, but I have looked around- as well as studied- for all of my life. Natural history is my passion.

If you were correct, you’d be able to supply facts to support your position, not just claims. And the facts are (looking just at vertebrates, even though the vast majority of species are invertebrates, which do not display even social monogamy)-

• Of the hundreds of families of fish, only 18 famiies have any socially monogamous species.
• Only one species of amphibian is socially monogamous.
• Among the reptiles, only a few species of lizard are socially monogamous, and even these lizards have a rate of at least 14% extra-pair fertilizations.
Although birds have a high rate of social monogamy, 90% of species exhibit extra-pair paternity. “Contrary to prior expectations, birds are only very rarely sexually monogamous.”
• Among mammals, less than 3% of species are socially monogamous and almost all of these have a high rate of extra-pair fertilization.

Take a look around and open your eyes – even looking at the animals with which you may be familiar, do you see monogamous dogs? Chickens? Cows? Sheep? Goats? Cats? Rabbits? Nope.

“Proofs are irrelevant for any matter since anyone can say they are counterfeits or they are not true or they could simply believe what they were believing before. ”

This is not true. A scientific theory is supported by evidence. If you want to say that most animal species are monogamous, you have to provide some evidence for your point. And, if you are shown the evidence, and it contradicts your belief, yet you go on believing what you want to believe, that is simply being illogical. And being illogical cannot rightly invalidate any theory.

“A common ancestor for humans and apes is inexistent.”

Sorry, but that’s incorrect. Any two species, no matter what they are, have a common ancestor. In the words of my favorite rapping evolutionist, Baba Brinkman -

Okay, it’s time to reveal my identity
I’m the manifestation of tens of millions
Of centuries of sexual selection, best believe
I’m the best of the best of the best of the best
Of generations of competitive pressure genetically
But don’t get upset, ‘cause we’ve got the same pedigree
You and I will find a common ancestor eventually
If we rewind geological time regressively
And I could say the same for this hibiscus tree
And this lizard and this flea and this sesame seed

“Why ? well for a start that evolution doesn’t occur anymore.”

Sorry, wrong again. We see evolution happening around us all the time. It’s easiest to observe in fast-reproducing organisms like bacteria, and we see its results constantly as new strains of drug-resistant bacteria emerge.

“we are the only specie that discerns good from wrong”

First of all, there are plenty of traits that only one or a few species have. We can’t shoot blood from our eyes, horned lizards can. This doesn’t disprove evolution, it just shows the results that selective pressures can have on it. Secondly, proto-morality is indeed found in apes.

“The apes [ no other animal for that matter ] discerns.”

Sorry, but I don’t know what this is supposed to mean.

“Not to mention that if that evolution did exist .. well the human did not change anymore.”

Actually, there are plenty of things that are evolving in humans. For example, three areas in which we can observe evolution in action are malarial resistance, lactose tolerance, and resistance to HIV.

@Hibernate – you can indeed hold any belief that you wish to. But if you actually expect other people to accept your beliefs seriously, you will need to provide some evidence for them. That’s just how science works.

Hibernate's avatar

Okay.
If you put it like that show me your proof of “our” ape ancestor [ which I should accept not just a caveman skeleton ].
And morality in apes does not exist like in humans. Go to a Zoo or a safari park and feed the apes .. after a while you’ll see how they start to act.

And I want to see evolution in humans [ not the sickness resistance And believe me if you take an infected needle you do get HIV ] I wanna see something like breathing underwater for hours OR flying without machines / parachutes OR humans living again for over 2 hundred years etc etc

Not to mention that science contradicts itself a lot.

Someone said “let’s agree to disagree” I’m not trying to force my beliefs upon you n’or I’ll accept yours easy.

incendiary_dan's avatar

@Hibernate Go to a prison and see how those humans act. Did you ever think it might have something to do with apes being imprisoned?

Hell, look at some non-imprisoned humans. I’ve yet to see living examples that suggest any consistent “morality” (however you’re defining it) amongst humans.

And really, you have no idea what evolution actually is, do you?

crisw's avatar

@Hibernate

What, exactly, do you think evolution is?

I have given you many examples. We do not need to fly without parachutes to determine that evolution exists. You have not provided one shred of evidence to invalidate anything I said.

Evolution is not a “belief.” Populations of organisms evolve. Period. That is an indisputable fact. How and why they evolve is the subject of the theory of evolution.

Smashley's avatar

@Hibernate – Evolution isn’t magic. You don’t just have a baby that can fly like in Marvel comics because you lived under power lines. Put a selective pressure on humans to learn to fly or die, and in a few million years, we might just pull it off, or, more likely, we’d find some technological workaround: the modern form of human evolution. We’ve evolved such a capacity for thought, design, survival, manufacturing, etc. that random genetic variation has a much smaller impact on our ability to survive and reproduce. We don’t need to develop new traits if we are already populating just fine. Oh, and if you consider disease resistance to not be evolution, then you’re really not on the same page.

Ten people are infected with HIV. 9 develop AIDS and die. The tenth is fine and never has AIDS and remains healthy. Isn’t that incredible? It’s about as close to superpowers as real life gets.

Smashley's avatar

I suspect, as others have mentioned, that monogamy is deeply tied to monocrops and early agriculture, and the subsequent treatment of women as property.

As soon as these specializations happened in agriculture, people became reliant on trade as a means for survival, having abandoned the relative inefficiency of subsistence farming. If you trade, someone must have something of value. If it is not their labor they are selling, it must be their property. As economics began to figure into human survival, it’s easy to see how a female became a necessary part of survival. The more children one has, the more workers one has, the more secure a person is.

Since sperm is relatively abundant, it is female’s sex cells and her reproductive capacity the determines the number of children that will be born. Without at least the females being monogamous, there would be no guarantee that the child would be your worker, or that she wasn’t already pregnant. Owning at least one suitable woman was the cornerstone of any successful, agricultural business.

Did the women have a say? Probably not. The simple fact that women are typically less strong and large then men would have made it easy for gender roles to be created along these lines. Of course, women had their own goals too, and mutual monogamy seems like one possible trade-off for women as property. The woman has an interest in being provided for, if she is to be a breeder and caregiver her whole life, and if a man is splitting his resources to several women, raising several children, it would be harder to make sure all women are provided for. Though monogamy doesn’t suit us biologically, it became a mutually beneficial arrangement. The woman receives protection, provender and sex, and the man receives children and sex. This is probably around the time that “cheating” developed. That is, secretly being non-monogamous. People still crave sex with others, but the reprisal from the other will be so strong it is easier just to hide it.

Even in polygamous societies, there is some evidence of this trade off of rights and responsibilities. In the Qur’an, it is required that a man must love his wives equally and care for them all, and is ultimately responsible for the well being of each one. If such an arrangement is achieved, multiple wives becomes an indicator of wealth, since one must have much to provide for so many. The women have no reason to compete, since they receive an equal share of the proceeds of marriage (food, shelter, sex).

I’ve probably messed up an element here or there, but this is as far as I can suppose, and seems to make a lot of sense, but if you look at other societies through history, true monogamy is the exception and not the rule. Probably because we really, really, suck at denying biological urges.

mattbrowne's avatar

There are two male evolutionary strategies for passing on their genes.

1) Have sex with as many healthy women as possible being always on the move.

2) Have sex with one healthy woman and make sure that as many children as possible from this relationship grow up to have sex themselves.

Some men are implementing strategy 1, but the majority goes with strategy 2.
Monogamy is a success story.

ETpro's avatar

@mattbrowne Excellent point. I think you may have just nailed what led humans to value monagamy. With all the threats to infant and mother survival, it’s quite likely that in the early days of mankind, strategy 2 was far more successful and thus, for the most part, prevailed.

crisw's avatar

@mattbrowne

You’re overlooking the role of female choice. It’s not just men who make choices about when and how they mate!

It’s in the interests of the female to choose the best possible male genetic combination for her children- which may be totally different than the best male companion to assist in rearing those children. That’s why, as I dicussed several times above, social monogamy is rather common across animal species, but sexual monogamy is very rare.

mattbrowne's avatar

@crisw – Females mainly have to rely on strategy 2. They can’t get pregnant with as many healthy men as possible at the same time (disregarding the rare cases of fraternal twins with two different fathers). Females look for good support. That’s their selective mating strategy. But sometimes they get the wrong impression. Then they might look for a new partner to become the father of their second child. Do we have reliable data on human sexual monogamy?

crisw's avatar

@mattbrowne

“Do we have reliable data on human sexual monogamy?”

As you might imagine, ethical considerations make studies of such testing in humans (as compared to other animals) rare. I did find a study from China which found “the results obtained from anonymous parentage testing indicate that the number of families containing children of doubtful parentage is much greater than expected previously.” There is also the work of Robin Baker, who has done a lot of work showing that women are most likely to engage in extra-pair copulations when they are most fertile.

Here’s an interesting article about how paternity issues are often found during genetic testing for other issues. “As families gather this festive season, here is a spicy fact that mothers might be loath to dish out at the holiday table: It’s now widely accepted among those who work in genetics that roughly 10 per cent of us are not fathered by the man we believe to be dad.”

Anecdotally, the huge number of businesses offering DNA paternity testing, the popularity of jokes about the mailman, and the number of divorce cases in which paternity is an issue point to a fairly high rate of what ethologists call “extra-pair paternity.”

mattbrowne's avatar

Thanks for the link, @crisw ! So does this mean that the role of oxytocin in humans is just about social monogamy not sexual monogamy? There are interesting studies involving prairie voles

http://en.wikipedia.org/wiki/Psychology_of_sexual_monogamy#Neural_processes_of_attachment

Maybe you’ve heard about them.

Hibernate's avatar

@incendiary_dan I’ve been to a lot of prisons and I like to tell you that not all prisoners act like mongrels AND not all countries encourage beatings / rapes etc inside the prison walls .. after one they find who’s responsible or punish all the other inmates till they find the truth.

Define evolution for me if it’s not from unicellular organisms to more complex AND not from chimpanzees to Neanderthals then humans [ etc you are familiar with all the link here ]

Why should I believe ? Evolution has its flaws just like creation has its flaws. THis if someone tries to interpret any of them. I stick to creation no matter what physical / geological / chemical etc proof someone wants to bring [ I prefer my narrow minded way of looking at things ]

@crisw indeed ” why and how they evolve ” is just another way of saying ” I do not share your way of seeing things ”

@Smashley put a pressure on humans ? Are you sure that the earth will endure us 3 or 4 more centuries [ forget about million years ] We barely found frozen water on the moon .. we can’t move [ mass migration ] humans to another planet because those planets got no atmosphere for us so we can breathe. Earth resources are depleting [ we are to many ].

——————————————————

This was supposed to be a different question . TO continue in this matter one of you should ask a more appropriate question so we won’t ruin this one.

Though I’m not so sure it will do any good since nobody wants to hear the other side ^^

Cheers.

Smashley's avatar

@Hibernate Okkkaayyy…. I was speaking about evolution, not ecology. Yes, true, whatever, the earth could become drastically overpopulated and we would start having issues with the food supply and it would put a pressure to adapt on humans. We still wouldn’t change overnight, and it wouldn’t give us superpowers. Yes we could run out of resources, but until the day that this potential shortage actually starts preventing large amounts of people from reproducing, we aren’t going to change much.

Oh, and for the record: evolution has holes. Creation has flaws.

crisw's avatar

@Hibernate

“Evolution has its flaws just like creation has its flaws.”

Evolution is a falsifiable theory that has never been falsified, despite decades of research. Creationism is a mythical story, not even a theory. Any real theory is falsifiable and makes testable predictions that are then verified by the evidence. Creationism doesn’t do this.

“Define evolution for me if it’s not from unicellular organisms to more complex AND not from chimpanzees to Neanderthals then humans”

Evolution- the change in allele frequency in a population over time.

And, BTW, no scientist claims that we evolved from chimpanzees! This is a myth perpetuated by those who are ignorant of evolution. Chimpanzees and humans share a common ancestor.

“indeed ” why and how they evolve ” is just another way of saying ” I do not share your way of seeing things ””

Hardly. I haven’t a clue where you get that interpretation.

Hibernate's avatar

And in the end it doesn’t even matter.

crisw's avatar

@Hibernate

Yes it does. It matters very much.

If creationists win out in the US, we would have religious dogma taught as fact, and the education of our children would suffer even more. US citizens would deepen their already-abysmal ignorance of science.

Creationism is a religious belief system- period. It has no place whatsoever in our schools.

crisw's avatar

@mattbrowne

By the way, before I get totally sidetracked :>)

Yes, I have heard of the prairie vole studies- interesting critters. And yes, their monogamy is social.

“You may have a partner you come home to every night,” says Alexander Ophir, a biologist at the University of Florida in Gainesville, “but that’s not necessarily the one that you’re mating with.”

Ophir and his colleagues found that infidelity had no effect on reproductive success: a cheating vole was just as likely to reproduce as a faithful one, so long as the cheater maintained a socially monogamous relationship. Sue Carter, a biologist at the University of Illinois at Chicago, says that these findings highlight the importance of social bonding. “Humans want to believe in sexual monogamy,” says Carter. That focus may have distracted people from the relative importance of social monogamy, she says.

Carter has observed philandering voles in her own lab, and notes that the infidelity did not disrupt pre-existing partnerships. When a female initiates contact with an outside male, for example, the relationship remains strictly sexual. “She mated with him,” says Carter, “and then she attacked him, ran him off and went back to her established partner.”

crisw's avatar

@mattbrowne

Probably :>)

Hibernate's avatar

@crisw no matter how long people will hate God He’ll find ways of attracting people.

You might disapprove Christianity but others will find more adepts Hindu , Buddhism , Islam so it does matter which one people hate others will take a step forward.

I did not say I want it in your schools or make it a day to day habit.
Continue to teach your children your “loop holes ” evolutions and after a while some will open their eyes. e have flaws but not as big as others. Not to mention that taking morality out of a society brought only sh*t over that nation. Monogamy or not in the US there are the most divorces / the most pornography / and a lot of sexual stuff happen because people believe in Nothing.

I repeat myself. In the end it doesn’t matter.
Everyone can believe in whatever he wants.

mattbrowne's avatar

@Hibernate – Disapproving of creationism does not necessarily mean disapproving of Christianity. I’m a Christian and I fight for a world where every child has the opportunity to learn good science in our schools, where they learn that the Earth is not flat, that the Sun does not orbit the Earth, and that the Earth did not pop into existence 6000 years ago by the wave of a magic wand. I want these children to cultivate feelings of awe and inspiration by understanding the process of evolution which can be seen as creation in progress.

I consider it highly immoral to tell our children in school that witches have to be burned, that the Earth is flat or that Eve was literally created out of Adam’s rib. It’s people spreading such nonsense who contribute to taking morality out of a society.

A lot of sexual stuff happens, such as unwanted pregnancies, when children do not get proper sex education at home or at school. And when they do not learn refusal skills. A good example is the daughter of the ultra-conservative Christian and evolution denier Sarah Palin.

crisw's avatar

@mattbrowne

Excellent answer- thank you.

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