The question of monogomy being "natural" to human beings or not, somewhat leaves out the fact that we, unlike our animal relatives, in as far as we know, have a higher consciousness. True, a human male's biological tendencies would place him in the same category as the ape or "birds," in that he would have the instinctual urge to spread his seed to as many of the best females as possible. However, due to the fact that we are capable of conscious thought, sort of raises us above that level. As far as women go, we cannot forget that there are certain hormones such as oxytocin which bonds the female to the male after a certain period of monogamous sex, during and after which she is unnattracted to any other males. (at least in the basic instinctual sense.) I suppose the question that would be more to the point would be whether or not the MALES of the species are meant to be monogamous and whether the fact that we are capable of higher thought processes causes the "male instinctual urges" to fall back in the same category as the "urges that humans have evolved to suppress" to some degree or another. I suppose it all comes down to another nurture vs. nature question that would be difficult to test.