Does polygamy promote happy marriage?

While in Senegal for a conference, I got pulled into perhaps not the most bizarre but certainly the most unexpected situation.  Being my first time in Dakar, I wanted to stay an extra day to explore the town.  My 40-or-so year old local translator was kind enough to offer his mom's home for 2 nights, so that I don't have to couchsurf with random people (which is a strange and unacceptable arrangement in his view).   I was under the impression that he had a wife back in Canada but has been since separated; he also talked about a girlfriend and how he's not ready to marry her yet.  To my surprise, when I showed up at his mom's apartment, I realized that he is married to a 24 year old lady.  She was super nice and has a very kind heart, but a few minutes into our meeting, I sense something is not right.  

"Oh, she's jealous" he said..."he thinks I want to take you as my 2nd wife." 

"OK, well, tell her that I'm not in the market to be anything but a first wife, so nothing to worry about."

"Yeah, I know, she's silly, I'll talk to her"

So after a number of "family meetings" between him, the wife, and his mom, the wife came out, continue to be cordial, and made me a lovely meal.

"See, isn't she nice? She loves me that's why she cooked you such a nice meal"

"Yeah, this is lovely, thank you so much!" .. the meal was indeed delicious, but I was feeling extremely awkward

Next day, further drama ensued... my entire tourist plan was overturned because she didn't want to join and it is scandalous to go alone with her husband.  So after much negotiation, I was allowed to go out on my own.  When I return in the evening, it's obvious some air need to be cleared.  

"I hope you feel better, I don't want to cause any trouble or misunderstanding, I'm not going to be your husband's 2nd wife... I have a boyfriend at home (lie)" I said

"No, it's OK, it's better that it's you vs. some Senegalese women, you guys should have gone w/o me!" she replied

"..." Why is this such a negotiation? Didn't I already declare that I'm NOT interested?

Next day, I asked my friend..."So, when do you plan on taking a 2nd wife? you just got married? Why is this topic on the mind so quickly?" ... "I will take a 2nd wife when you accept"... WHAT?! I thought we've made that cleared!  "You guys are clearly madly in love and can't get your hands off each other, why are you thinking about a 2nd wife so soon? (PS: I'm NOT interested)"  "Well, it's good to have that option open.  Sometimes woman bring trouble and if you have another option, they behave better, it's good for marriage.  Plus, I will have my wives live in separate places, so they can't fight or anything.  She doesn't have to see me when she's mad at me, and vice versa.  "

This is the 2nd time I've heard the argument that polygamy is "good for marriage".  First time in Kenya, this time in Senegal.  I suppose when polygamy is an option, people (the woman) are willing to "put up" with more and control their emotion better to delay the arrival of future wives and also to maintain a favorable status of the man.  In West Africa (unlike Kenya), the good thing is that the men also feel a strong sense of responsibility for their various wives, and are proud to be able to provide for as many wives as possible...It didn't seem like it's ONLY about having a prettier, younger lady toy to satisfy their needs and vanity...and the woman generally do seem pretty accepting of the tradition and genuinely happy.

Taking this home to the US, programs like the Sister Wives shows a similar picture.  Happy women, sharing a husband, respectfully...much more civilized than what one would see from The Real Housewives series. Sure, feelings of jealousy is there, but these women seem to deal with it much better and more maturely than the monogamous couples who have this endless fear of infidelity.

So I can't help but wonder, why do we (those who grew up in a western-minded society) believe polygamy is so bad?  Where did this idea of monogamy come from?  What social purpose does it fulfill (except perhaps population control and avoidance of inheritance disputes)?  Is monogamy a moral issue or are we simply following the social norm subconsciously?  

To my surprise, polygamy is actually more common than I had expected!  Anthropologists say 83 percent of societies permitted polygyny, and just 17 percent insisted on monogamous marriage.   According to the Ethnographic Atlas Codebook, of 1,231 societies noted, 186 were monogamous. 453 had occasional polygyny, 588 had more frequent polygyny, and 4 had polyandry.  So, those of us monogamous kind might actually consider a paradigm shift and re-evaluate the idea that monogamy is a more "advanced" or "superior" way of life, and perhaps begin to take a more open view of polygamy as a different way of life and a personal choice?  What do you think?

For a fun read, check out The Secret Lives of Baba Segi's Wive, a well-written, entertaining piece of work talking about the lives of a polygamous Nigerian family.