First article:
I want to know is there a 100% correlation between heterosexual fidelity and cultural development? The author says that monogamy was the reason for the success of past civilizations that he studied. This sounds like an indictment of polygamy.
I don't think he said monogamy was the cause of success, rather fidelity. Fidelity means sexual faithfulness. You can have complete fidelity within polygamy. If the wives only ever sleep with their husband, and he only ever sleeps with his wives, that is sexual fidelity. It is promiscuity that he points out as destroying cultures.
He is a bit sloppy with his terminology though as he is writing from a post-Christian western mindset, for instance he says "the world’s three major religions ... have been structured around the ideals of monogamy and sexual restraint". Which is nonsense, since Islam is obviously not built around monogamy, and Judaism has only required monogamy for about a thousand years and not in all branches of it, and that was only introduced to avoid persecution by Christians. It is only Christianity that has promoted monogamy. The point he is really making is that all three religions stress "sexual restraint" in various ways, which is true. In other words, fidelity. Which brings us back to the fact that it is fidelity that matters, not monogamy.
I also want to know what do you guys make of the criticisms by some people that polygamy could leave many men without a wife and the men will turn to violence? They usually cite the Middle East as an example where polygamy is legal.
The Middle East is violent because it's full of Muslims, and Islam is fundamentally violent. Any suggestion that this is due to polygamy is simply a PC way of ignoring the obvious.
Remember that just because a society is polygamous doesn't mean that the majority of men have multiple wives. Statistically, most men will always be monogamous. A polygamous society is one that accepts polygamy as an option, that is all. Now if you look at census data for any normal country, except those that kill off baby girls through sex-selective abortion (e.g. China), you'll find that there are more women of marriageable age than men. With monogamy, there will always be more single women than men. And that's what we see around us - a society of single mothers, used and thrown away by useless men to move on to their new "monogamous" bit of fun, before they abandon her also. In a polygamous society, every one of these women has the opportunity to marry a decent man.
Polygamy matches the statistics far better than monogamy does, because polygamy allows everyone to marry and be happy, while monogamy does not and leaves some lonely.
Another criticism is that countries where polygamy is tolerated are usually poor; for instance, Middle East and Africa.
Correlation does not equal causation. Israel in the time of Solomon was polygamous. China used to be polygamous, back when they had massive wealthy dynasties and ruled much of Asia they were polygamous. On the other hand, the Romans were monogamous and also rich and ruled a vast empire at the time of Christ, while the British Empire was likewise monogamous. It's got nothing to do with monogamy or polygamy. We're just living at a moment in time when the monogamous countries happen to be wealthier, that doesn't mean it's normal.