Is Having Two Times As Many Wives Okay If We Live Two Times Longer?

So this is a continuation of a conversation Less and I had that we thought would be worth yelling about.
But first I must apologize for my prolonged absence, summer tends to be an intellectual dry spell for me. Now, I'm back and ready to rant.
Now, down to business. The question is, should new world marriages be subject to or judged by old world morals?
If you think about it, it's a lot easier to uphold a vow to love and cherish your significant other when you only expect to live to 40, rather than 80.
It really says a lot that 90% of Americans believe adultery to be morally wrong, but 22% of men and 14% of women admit to having an affair. Oh thats right, I just remembered, we as Americans are inherently hypocrites.
If you are able to set aside what you have been force fed since birth, monogamy simply isn't part of the human nature.
According to the US census bureau's world population clock as of midnight Oct 18/19 (sidebar, which side does midnight fall on?) we have reached the mind boggling number of 6,625,740,431 people. Why limit ourselves to just one?
In the age when the ethics of marriage were developed, people were limited in their choices in a mate; often bound to their, or nearby, villages. Now, we can hop on planes and get to three dates, on three continents, in three days.
This is where I will leave it for now, its only fair I give Less a chance to chime in.