Looking for reasons why and when social monogamy arises in the course of evolution it might be helpful to look at other groups in which this type of mating is more common than in primates, especially birds (90% or so monogamous species).

See e.g. Ligon's (1999) book on the evolution of avian breeding systems.

http://www.getcited.org/pub/100353285

In birds the evolution of monogamy was probably linked to rise of biparental care. If both parents are needed to look after the offspring and gain the necessary ressources, monogamous relationships have an advantage over polygynous arrangements

Both have their pros and cons

They both have their advantages and disadvantages

I think that the biological history of the man teach to us that the poligamy is a winner strategy . Why? Because it had produced a greater and better genetic recombination. Furthermore it opened new biodynamic flow that have permit to human and hominin specie a great adaptation in every geographic, environmental and climatic condition.

Concentration to one sexual partner and his genom is a single chance to mix the genomic characteristics. So changing the partners increases the genomic mixtures. Off course this mixing is not limited to polygyny it holds also for polyandry.

But one can´t discuss about this question without also taking into account the social aspects!

Mmh, @Hanno and Mauro, from what I understand your views seem to contradict each other, right? I should phrase my question more clearly and ask "... favorable over serial monogamy, polygyny, and polyandry".

Hanno, I understand your view on considering social aspects, but I'm worried about a biased discussion. If we could assume that our social behavior is not independent of our natural behavior, what are biological reasons behind accepting (non-serial) monogamy? Is it that we would not choose another or other partners with completely different genomic characteristics than the one we have chosen already?

Another point is the fact of rising serial monogamy, which of course has many social aspects. But, Is this also a consequence of human evolution in some way? How could we investigate this further?

Mmh Michael, I don´t see a contradiction of Mauros and my argumentation. Just replace genetic recombination by genetic mixtures. My hint to social aspects is not meant to discuss to infinity the bad polygamists and to praise the good monogamists from ethical aspects or vice versa but to point to the importance of social continuity for breeding, education and reliability for the partners which enables an easier and more successfull common life.

I forgot one aspect. If you beliefe in epigenetics you will find out that a stable continuous life improves the genom of a species.

OK, @Hanno, I understand the views of both of you. I'm a bit slow in following your arguments being not an expert... but interested anyway. I also see you introducing social aspects through the backdoor, and I could (but I don't) ask is an easier common life really the intention of evolution. Full stop, not question mark. We can leave this for another thread, which will attract other contributors (EMMA, Eden).

If I believed in epigenetics, what would that mean regarding my question? And if I had to believe in it (and could not be convinced by data or arguments) what would that mean to the overall science behind this?

Hi Michael, first "believe" means that not all scientists accept the epigenetic changes of the genom. The epigenitic results are not yet generally established and are still far from completely beeing understood (by biochchemistry) .

Second If epigenetic mechanisms work, the regard to your question is the possibly better genom developping in a monogamy with its stable relations and conditions.

So multiple mixing the genom by serial changes of the partners has some advantages to improve genetically the chances of survival of the species. Monogamy with the single "mixing" chance improves possibly the survival by stable social conditions and the epigenetical improvements. The question is: Which mechanism is dominating?

Dear Michael,

The foremost theory on why monogamy was even established during human evolution concerns the fact that a larger brained hominid means greater development and dependence periods during infancy. Plus, the inter-birth intervales in hominids are rather large when compared to other primates, meaning that the cost for females of having a male disperse his attention and resource seeking to other females is too high. Given this scenario, monogamy becomes a viable strategy to gain exclusive access to a male.

That does not mean however, that the male or female reproduce exclusively with each other. For example, in challitrichid monogamous monkeys it was found that over 60% of births were not genetiically related to the male that was bound to the female. So in this case, females chose to reproduce with the more genetically appealing monkeys, but paired up with the most caring ones to ensure the survival of the offspring.

What this ultmately means is that monogamy is mostly a female driven mode of sociality and not exactly reproduction, that is aimed at greater chances of offspring survival and one that has proven successful. This would answer the question of genetic diversity being maintained, and at the same time, of the ammount of care invested to ensure the survival of the offsrping.

There are two distinct issues here:

1) What are biological & psychological consequences of mating systems for human development. This gets into the area of the "naturalistic fallacy" http://en.wikipedia.org/wiki/Naturalistic_fallacy

2) What are evolved functions of human family relationships. Key here is long period of child development with intense parental and alloparental investment, especially in regard to training for social competition.

Walker, R.S., Hill, K., Flinn, M.V., & Ellsworth, R. (2011). Evolutionary history of hunter-gatherer marriage practices. PLoS ONE, 6(4), e19066. doi:10.1371/ journal.pone.0019066

Flinn, M.V. (2011a). Evolutionary anthropology of the human family. In Oxford handbook of evolutionary family psychology, C. Salmon & T. Shackleford (Eds.), chapter 2, pp. 12-32. Oxford: Oxford University Press.

Flinn, M.V. (2011b). Social inequalities, family relationships, and child health. In: Biosocial research contributions to understanding family processes and problems, A. Booth, S. McHale, & N. Landale (Eds.), chapter 14, pp. 205-220. New York: Springer-Verlag.

Muehlenbein, M. & Flinn, M.V. (2011). Pattern and process of human life history evolution. In: Oxford handbook of life history, T. Flatt & A. Heyland (Eds.), chapter 23, pp. 153-168. Oxford: Oxford University Press.

Walker, R.S., Flinn, M.V., & Hill, K. (2010). The evolutionary history of partible paternity in lowland South America. Proceedings of the National Academy of Sciences 107(45), 19195-19200.

Here is an anecdote: In one of my lectures I mentioned that females with Down syndrome rarely marry and when they get pregnant, it is often from sexual abuse. After class one of my students, a native of Sudan, told me that it is not generally true that women with Down syndrome rarely marry. In Sudan they often do because the family arranges a marriage for them. I could readily imagine how a father would negotiate a marriage for one of his normal daughters under condition that the husband would marry his retarded daughter as well. And because a good Muslim has to treat all his wives equally, the Down syndrome wife would have a chance to get pregnant and transmit her extra chromosome 21 to her children.

What does this show? Some people believe that polygyny is a superior mating system because it propagates preferentially the genes of rich and successful men, thereby improving the gene pool. In reality, polygyny selects only for male qualities while monogamy selects for useful traits in women and men alike. Just compare the cultural trajectories of the Muslim Middle East and Europe during the last 1 1/2 millennia! This of course does not prove that monogamy is better than polygyny for gene-culture coevolution because cultures are distinguished in many other traits as well. For example, contraceptive practices were widespread in the Muslim Middle East (Basim Musallam wrote an excellent book about this) but were suppressed by church doctrine in Europe until fairly recently. Perhaps that is the difference that is responsible for the rise of Europe and decline of the Muslim countries, rather than monogamy or polygyny.

Dear André,

The behaviour you mentioned in case of challitrichid monogamous monkeys can be found as a useful evolutionary technique practised also by women. One can learn it as an example in psychological textbooks. However, the unfaithfulness of such a female is difficult to prove. This is a strange situation because infidelity of the female is a success as she can get the “best” genes (from the “lover”) and the best care (from the permanent companion). Of course, the permanent companion has but costs when caring the offspring of a foreigner. The lover male has got also an advantage: an offspring without care. However, regarding human conditions this behaviour may have some risks.

Andre;

     The comments above skirt around a couple of useful concepts that are derived from observations of many species.

1. Certainty of paternity. Females nearly always know that the offspring they are caring for are their own. Males cannot have nearly such high confidence that they are caring for their own offspring. That difference leads to specific gender-specific "strategies".

2. Bet hedging. Among monogamous species there is a certain amount of philandering. Both sexes seem to behave as if they are attempting to broaden their reproductive investment.

Much of what is discussed in the comments above can be interpreted in the context of these ideas.

Cheers, Jim

I have done a research about the evolution of polygamy which you can find it here:

https://peachyessay.com/sample-essay/the-evolutionary-pros-and-moral-cons-of-polygamy/