Via Justin J. Lehmiller.
Relationship function, satisfaction, commitment, and passion were about the same in both consensually non-monogamous and monogamous relationships. Furthermore consensually non-monogamous couples had lower jealousy and higher trust.
But what about STIs?
STIs appear to be less frequent in consensually non-monogamous relationships than those which claim their relationship is monogamous. The suggestion in the video is that condom usage is more frequent and STI testing is more frequent in consensually non-monogamous couples and that this accounts for the less frequent STIs. I don’t have a data set of sufficient size without bias that could be useful in answering this question but I have a couple points that make me wonder.
A lifestyle woman in her 50’s told me that she estimated she has had sex with 600 men in her life. I asked about condoms usage and STIs. She claimed she didn’t use condoms and that the only vaginal infection she sometimes gets is bacterial vaginosis. But that she also sometimes gets this even when she has not had a different partner in quite some time. This website agrees, “Bacterial vaginosis is more common in women who are sexually active. But it can occur if you are not sexually active as well.”
Jo and I were somewhat shocked at this woman’s claim. A few months later a friend and I were discussing our mutual sexually prolific friend on a closely related topic and I mentioned the estimated 600 men. My friend said, “That’s nothing!” She went to suggest she herself had sex with far more than 600 in her ~65 years. I didn’t ask about STIs but she does have a condoms required policy.
Further personal research revealed other women with large numbers of partners, low condom usage, and STI infection rates that would appear to be similar to “monogamous” couples.
I could have a bias in my thinking because I’ve been reading An Epidemic of Absence: A New Way of Understanding Allergies and Autoimmune Diseases. This book claims that because we have created a much more sterile environment to live in than that which we were originally evolved we have a much higher rate of autoimmune disease. And in fact, infection with certain diseases at a relatively young age gives us immunity for dramatically different diseases much later in life. When infected with the same organism later in life the infection is quite detrimental.
The base hypothesis is that humans had a symbiotic relationship with parasites, bacteria, and viruses for 100s of thousands of years then in a (evolutionary) blink of the eye exterminated as many of them as possible. Some needed to be exterminated, such as small pox, but many, while exacting a cost, performed an important function. Minimizing contact with all microscopic organisms may not be the best game plan.
Could it be that somewhat frequent exposure to low levels of STIs, such as kissing and oral sex with a wide variety of people, cause an immunity to such bacteria and viruses?