I know that monogamy is accepted as the best path in most societies these days. One of my favorite primatologists, Franz de Waal, wrote somewhere that humans have been much more successful, measured by population size, than chimpanzees and other closely related apes. De Waal says that when one troop of chimps raids another, family members such as daughters can be attacked by fathers who no longer recognize their children. I found an estimate of the chimp population of 50,000 while the human population is about 8 billion.
However, DNA and other sources of evidence show that humans are not always monogamous as they like to let on. We recently watched the movie "Maybe I Do". It has an interesting plot premise. A young couple is more and more in love with each other and interested in getting married. It is time for each of them to meet the other's parents. We find early on that the four parents have been having affairs, male and female, without anyone yet knowing about such connections. We also find early on that these affairs are losing their spark, mostly due to aging and declining interest. The story is acted out by experienced actors Diane Keaton and Susan Sarandon, and Richard Gere and William Macy.
