Below is the video of our interview with Professor Nate Dominy of the Anthropology Department.  Professor Dominy is happily married with two children.  His interview provided wonderful insights into the balance of biology and culture that exists in marriage.

[Lauren]: How do you personally define and view marriage?

[Professor Dominy]: I view it as a commitment to your best friend, and it’s not only a commitment to each other but also a public commitment so that everybody else around you also recognizes that commitment. Marriage is also a legal concept, so there’s the whole legal concept that you’re recognized by the government.  Then there’s also a religious component. So I mainly view it as a commitment to an individual that’s also seen by your family and friends.  I also understand that it is recognized by the government and church, but in my case, we don’t really care about that.

[Michael]: When you were younger, did you think you would get married? And when you got to that point, why did you decide to get married?

[Professor Dominy]: So, the first part of the question is yes.  When I was younger, I always imagined it as an inevitable thing. But when I was actually ready to get married, I didn’t actually feel a strong need to do it. My wife and I had been living together for a long time at that point, and we were certainly acting and behaving like a married couple.  I saw no need to go through the expense of getting married to formalize it. What we were doing was sufficient, but my wife felt like we should get married, so we did.

[Lauren]: Can you talk about other species that pair bond? How unique is this behavior among primates?

[Professor Dominy]: Pair bonding, where you have a lifetime commitment of reproduction between two a male and female, is relatively common among primates, and it’s evolved multiple times in different groups of primates. It’s evolved at least twice in apes,  gibbons, and ourselves. It’s evolved in New World monkeys and night monkeys. So, we’ve seen it a couple times. There are some lemurs we think have pair bonded. So, in terms of reproducibility, it’s common. But in term of the proportion of total number of species, it’s relatively rare. It’s probably less than 5% of all primate species.

[Michael]: So why do you feel it is so unique? What kind of environmental characteristics might cause it?

[Professor Dominy]: Those are big questions in anthropology and primatology, and there is no clear answer. Most people view monogamy as an outcome associated with high reproductive costs. So, when raising an infant is extremely costly, either because resources are scarce or difficult to acquire, or because that infant has high physiological or metabolic costs, like it has a large brain or there’s two of them, monogamy is more common. So you’ll always see monogamy when twins are the norm. Under those conditions, you see a strong incentive for the male and female to work together and cooperate to raise that infant.  So, if you were to be extremely reductionist, monogamy is a byproduct or outcome of high reproductive costs. It allows the male and female to maximize reproduction costs. So that kind of takes the romance and love out of it, but it explains why marriage is functional.

[Lauren]: That actually explains the next question, which is what is the evolutionary reasoning behind the existence of marriage?

[Professor Dominy]: Yeah, our human infants are probably the costliest among all primate infants. The prevailing wisdom is that is would be extremely difficult for a female on her own to raise an infant. It’s certainly possible, but it’s very challenging, and it would certainly limit over a lifetime the number of infants the female could reproduce. So, if you can get a partner to help contribute to care, then both the male and female’s reproductive fitness gets higher. I know it’s so reductionist. And then the question is: Are there data to substantiate this? I’m not actually sure, but that’s the prevailing thought.

[Michael]: Was there an underlying notion in your own marriage that if you were to move forward and have kids there was a need to formalize it and have that stability?

[Professor Dominy]: So, there’s distinction between pair bonded — we were socially and functionally pair bonded — and societal convention and pressure to formalize that pair bond with a contract.  So marriage is essentially a contract that is performed in some religious ceremony or in front of a judge.  There’s the formal contractual basis of marriage, and then there’s the biological pair bonding. So, why did we get married? Well, I don’t know. We were already pair bonded, but I felt like there was this pressure to have a formal contract overlaying that basic relationship. Like I said, I didn’t think it was necessary, and I thought it was costly, which was my main reason to not do it. It’s a lot of money to spend for the sake of a contract.

[Michael]: Did you see any changes in your relationship after your formalized it?

[Professor Dominy]: Not for me, but I’d be curious to hear my wife’s answer to that. For some partners, it may be really significant to have that symbolism of the contract. For me, it was purely symbolic and didn’t change my feelings in any way. So, I don’t know — you might see a wide range of answers for that.

[Lauren]: Some people feel like monogamy is more unnatural with our longer lifespans. So, if the original function of marriage was to rear children until an age they were independent, but now couple are living longer, is monogamy more unnatural in our contemporary society?

[Professor Dominy]: So prolonged lifespans, delayed senescence, monogamy is lower. Possibly, but remember that culture is a really strong factor. If culture says that marriage is the norm, I think that would override any kind of selective argument like that. I think we’re sort of released from any of those Darwinian selective pressures because of culture. So the data to substantiate that would be really, really noisy and not convincing at all.

[Michael]: Kind of on the same stream as what was originally said, I know there’s a lot of research on the continuation of certain feelings and emotions in marriage. As you go on, you still have oxytocin pair bonding, but some of the other feelings may go away or decrease on average. Do you feel that if we have this longer period of time when culture is telling us to get married?  Culture itself also wants to replicate itself.

[Professor Dominy]: So your argument is that as your sensitivity to oxytocin becomes inhibited with time, that might be a contributing factor to reduction in pair bonding? Maybe. I will say that I was just at a conference where one of the talks was about kissing. They argued that kissing is a way to do chemical sampling. Through saliva, you can understand the immune system of your partner and get a sense of their MAC complex and find compatibility. Once you establish MAC compatibility, then there’s no incentive to kiss anymore. So over the lifetime of a relationship, kissing drops significantly.