Discuss monogamy & polygamy

[deostroll]

Research suggests that primordial humans are polygamous. Meaning they mate with two or more partners of the opposite sex. The basic rule here however is that a person should transmit his/her traits to as many offspring as possible. But how is this explained through the eyes of natural selection? (I'd like to know). That apart, I realize gestation is a difficult and a crucial part in a female's life cycle. She could die of miscarriage or out of exerting too much physical strain on her body. Does this indicate that females were not "designed" to be concurrently polygamous? If so how does a female try to satisfy the 'basic rule'?

We could have lead a normal polygamous life. But what went wrong? How did we start exhibiting monogamy all of a sudden? What benefits does monogamy have over polygamy? Did monogamy result out of cultural evolution? Or is there a more basic explanation...?

[Cat]

Arhhh… We did not start exhibiting monogamy (as you put it) all of a sudden. The primordial ‘mating drive’ is still there. That is why infidelity occurs and prostitution is still in business. There are still many societies today that allow men to have multiple wives. What is not there – is the desire to have extended offspring coupled with the ability to prevent it. Money has a lot to do with that consideration.

As far as women are concerned, you are right in saying that they are “not "designed" to be concurrently polygamous”. However, I don’t think that your reasons are correct. The problem, as far as I understand it, is that women cannot have multiple offspring from different fathers at the same time (unlike female cats, for example). That does not mean that women are monogamous for life though.

“The basic rule here however is that a person should transmit his/her traits to as many offspring as possible. But how is this explained through the eyes of natural selection? (I'd like to know).”

Well, the idea is that more offspring you have – the more chances you have of transmitting your traits/genes to future generations (more grandkids, great grandkids, etc.), insuring the survival of your traits through generations to come. As far as natural selection is concerned, more different combinations of traits (more offspring from different parents) raises the chances of at least some of them producing phenotypes that will be selected for further reproduction.

“What benefits does monogamy have over polygamy?”

Most benefits of monogamy are social; most the benefits of polygamy are evolutionary. Aside from that, STDs play a large role in promoting monogamy these days.

[deostroll]

That is why infidelity occurs and prostitution is still in business.

So is "female infidelity" or "the fear of female infidelity" the reason why males became monogamous? I agree with the STD part. But if this was the prime reason I think humans would be strictly monogamous then?

Well, the idea is that more offspring you have – the more chances you have of transmitting your traits/genes to future generations (more grandkids, great grandkids, etc.), insuring the survival of your traits through generations to come. As far as natural selection is concerned, more different combinations of traits (more offspring from different parents) raises the chances of at least some of them producing phenotypes that will be selected for further reproduction

So does this technically mean that it is our genes/phenotypes that is trying to replicate? So this has nothing to do with the species? Genes have a life of their own?

[Cat]

“So is "female infidelity" or "the fear of female infidelity" the reason why males became monogamous?”

It might play a part, but I think main problem is money. It is more like ‘how many children and wives can one man support?’ type of thing.

“ I agree with the STD part. But if this was the prime reason I think humans would be strictly monogamous then?”

You underestimate sex drive. While some people can control it well, others are not as effective. STDs play a part in making monogamous relationships desirable to rational mind, but don’t have any effect on the sex drive itself.

“So does this technically mean that it is our genes/phenotypes that is trying to replicate? So this has nothing to do with the species? Genes have a life of their own?”

Well… If you want to put it this way, sex drive is innate desire to reproduce and predominantly within the same species. However, we have circumvented it somewhat a long time ago – sex does not necessarily results in offspring, so I would not say that genes have a life of their own.

[Darby]

The idea that "primordial humans" were one or the other is not even close to conclusive.

And multiple but serial partners, another possibility (and found in bonobo chimps) is neither.

[deostroll]

From the point of view of genes trying to combine themselves with other genes from two different phylogeny the phenomenon of polygamy occurring within the species can be argued to be a natural thing. Can monogamy ever be considered to be a natural thing likewise?

[Darby]

Where the investment of two stable parents into long-lived offspring, or into territory or some other epigenetic "reward" for a sequence of offspring, there can be a real adaptive benefit to longterm monogamy. And, of course, serial monogamy, as often found in birds, has many benefits.

[deostroll]

And, of course, serial monogamy, as often found in birds, has many benefits.

I don't understand serial monogamy in birds...the benefit part?

I still don't understand why would you turn monogamous?

[Darby]

In birds, especially ones with fly-to nests, you need two invested parents to increase offspring survival - so you need a bonded pair, but they don't necessarily need to stay together season after season.

In some situations, a long-term bonded pair has advantages over seasonal pairs - perhaps cooperation beyond mere parenting is beneficial.

In humans, one could argue that our odd social structure - we need many adult males working together - requires the investment of reproduction. Longterm monogamy in humans reduces conflicts while giving the males a chance for reproductive success, a powerful biological enticement, as well as increasing offspring chances where the genders serve different but important support roles.

[deostroll]

Finally it is beginning to make some sense...

[deostroll]

I need to know more about the odd social structure...and why we needed many adult males working together. Did this have a specific purpose like for e.g. build an army to defend their species against enemies? Theoretically aren't the females polygamous too? I can understand a little as to why males have to invest in offspring rearing. I mean they also play their part in training the offspring to face many survival challenges. I just don't get the complete picture of females investing in offspring rearing. They do provide nourishment and develop the offspring to maturity...after that what is their role?

[joequirk]

It's not just how many babies you make. It's how many survive. The longer the period of childhood helplessness, the longer animals pair-bond. We have the longest childhood in the animal kingdom. Monogamy is an instinct. So is polygamy. I made a funny video about it, called "Is Monogamy Natural?"
http://www.youtube.com/watch?v=DEdHz0eIpm4