I just finished having a discussion about this past weeks medical
news headline that in the next 10 years advances in science could extend
the average lifespan to 150 years. We thought that the increasing lifespan
is part of what is putting pressure on monogamy.
It used to be that you only expected to be around for only 40 years or so. There wasn't enough time to be thinking about more than one spouse, your kids and the job. 20 years or so with one person wasn't so much time.
Now however we can expect to live twice that time and we are thinking in terms of spending a good sixty years with someone. Now it begins to seem like a lot of time with just one person and there is time to do more in life.
Now think about spending between 100 to a potential 3 to 500 years with one person monogamously. That much time with a "one and only" can seem very limiting when there is so much time to experience what is good in life.
We think that the lengthening lifespan will make people rethink the loves of their lives and how they wish to spend the future with them when the future extends to centuries and not mere decades(or years, as it was in the past). Society as a whole will need to deal with the ramifications of an extended lifespan with monogamy being one of the issues.