Humankind is NOT a monogamous species, serially monogamous, but not continually monogamous. Some men are able to overcome instinct... many are not. Religeon helps one use their mind to overcome their basic instinctual desires.
Very few men are truly satisified with long term monogamy. As much as this truth may offend some.... it is true and all men know it. Some are less honest than I am and will deny this... flame away.
Since the ratio of males to females is about 1:1, and the raising of young takes so many years, it would imply humans are meant to be monogamous. Marriage is really for raising a family, a woman will know her children if she's monogamous or not but the only way a man could hope to know his own children was to convince a woman to live in a monogamous relationship.
What a Line! How many women fall for this Bu!!sh!t? sheeeesh.
That's a phony theory because it implies a woman has one child that is self-sufficient at 7 and that men don't care to have a connection with older children. For one, there will be another baby in about 2 years...then another...then another. A man would prefer to support his own children, not the children of other men that he would do by dropping one wife and taking another. One man and one woman can produce more than enough kids for one man to support.