To find monogamy in animals is difficult. Usually if a species has developed this social system, it is because its environment demands that which we might refer to as a nuclear family. For example, often in primates, monogamy becomes common when the environment is such that it cannot support many individuals living together in one group. It is much easier to find smaller amounts of food and stay away from predators for these monogamous creatures than it would be if they traveled in large groups. The basic family unit found in most species is the mother-child unit. Some species find it more convenient to add one or more males to this, for various reasons.
Humans evolved in this way, or so current theory states. A female and a male together could produce and support more single-birth offspring than a female on her own in their hunter-gatherer societies.
Industrialism has proven to change many human patterns that previously had held up throughout much of time and space on Earth. One of the most drastic changes has been the rise of a previously rare form of family structure, serial monogamy. Serial monogamy means simply that we go from one monogamous partner to the next, whereas simple monogamy requires choosing one life partner. We might even have offspring with one partner before moving on to another.
What are the causes and effects of this? Industrialism has afforded some modern people luxuries that were never available in the past. Among these has been the ability for equality to exist in society. I am not claiming that it always does, but it can. One of the foremost groups that this equality has helped has been women. For the most part, women in the industrialized world have just as many educational, and therefore economic options as men have.
A direct effect of better education for women has been a drop in the birth rate. Educated women are having fewer children, but they are still having children. Today's upwardly mobile woman does not have the time that her agricultural or hunter-gatherer sisters have for raising children. She is busy obtaining economic resources in places that are not child friendly.
This new economic freedom for women has produced many side effects. One of these, in my opinion, is a heightened divorce rate. A woman can now afford to take herself and her children out of an abusive, or otherwise uncomfortable marriage situation. This is a freedom that (also in my opinion) every woman should be thankful to enjoy, as we are among the first to do so. As with everything though, this has a downside.
As women are no longer economically bound to their husbands, neither are men economically bound to their wives and children. His children are no longer his retirement plan; that is taken care of by his 401k. So whether he leaves or she leaves, both will theoretically be able to survive without a member of the opposite sex.
The mother-child relationship is still the basis for all other social relationships built upon it. Most often, children in divorced families stay with their mothers. This gives men and women unequal footing once again; the male is free to gain as many economic resources as he can without having to use them on anyone except for himself. Not only this, but he has the time to devote to specialization that will help him reach the decision-making echelons of society. The female, offspring in tow, often has reduced options. All of a sudden she has been put in the role of sole caregiver and provider. It stands to reason that she will no longer have the resources (time, energy) to devote entirely to these two areas. Each will have to suffer. For this reason, it is now harder for the female to reach those upper, decision-making echelons of society. She must split her time between work and children.
Perhaps she will find another male with whom she will settle. Perhaps not. But in the end equation it is inevitable that males will continue to have more power for sometime to come under this system of serial monogamy. While we do have safety measures in place to prevent this from happening, they do not always work. Stories of deadbeat dads are commonplace. Oftentimes the males are able to disappear in order to avoid paying their alimony and child support, or else they simply do not pay and suffer the consequences, which amount to a slap on the wrist.
The system of serial monogamy both gives and takes freedom from women. They are free to determine the paths of their own lives, but are at the same time hemmed in again by different economic burdens.