Evolution and The Purpose Of Marriage

Evolution

In an article by Ross Andersen at The Atlantic, I read:

Evolutionary biologists tell us that we owe the singular bundle of feelings we call “love” to natural selection. As human brains grew larger and larger, the story goes, children needed more and more time to develop into adults that could fend for themselves. A child with two parents around was privy to extra resources and protection, and thus stood a better chance of reaching maturity. The longer parents’ chemical reward systems kept them in love, the more children they could shepherd to reproductive age.

Let me say right away that I have no idea if what ‘evolutionary biologists’ say in this case is solid science or not. (Evolution itself is proven beyond reasonable doubt, but that doesn’t mean that every theory someone has about how a particular behavior developed is well proven). But let’s say, for argument’s sake, that this is true.

It’s interesting to compare this to the arguments made by opponents of marriage equality. On the surface, the evolutionary account of sexual love fits well with the anti-equality account of marriage; just as pair-bonding sexual love evolved to facilitate successful child-rearing, the purpose of marriage, we are told, is to facilitate child-rearing.

But the analogy immediately fails, because when we look at the evolutionary account, what it tells us is that same-sex couples and opposite-sex couples actually have a lot in common. The chemicals that rush through straight couples’ brains when they are in love, which encourage them to stay together and raise children effectively, are the same chemicals that infuse the brains of lesbian and gay couples in love, and can serve the same purpose. In an evolutionary (and chemical) sense, same-sex couples fall in love for the same reasons straight couples do, including the need to facilitate healthy child-rearing.

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12 Responses to Evolution and The Purpose Of Marriage

  1. 1
    Mokele says:

    Nobody with the slightest hint of biological knowledge would use “It evolved this way, therefore it’s morally right” as an argument.

    Remember the Chest-burster in Alien? That’s basically the incubation and birth process of many wasps. The entire system is so horrific that when Darwin learned of it, it shook his belief in any benevolent deity.

    Let’s not get into the fact that it’s often suggested there may be more species of parasites than hosts, or that many species don’t bother to kill their prey before consuming it.

    The naturalistic fallacy isn’t just poor logic, as a moral system it’s nothing short of abhorrent.

    But it’s good to know that Ross Andersen supports infanticide, followed shortly by consuming the child to regain the lost nutrients. Or is he going to flail about with some pathetic excuse about how it only applies to marriage?

  2. 2
    Sebastian says:

    I do not know about evolutionary biologists, but evolutionary psychologists are a punch line amongst the members of both Psychology Department my wife has been a part of.

    Disclaimer: My wife’s colleagues are a source of amusement amongst the engineers with whom I hang out. But that’s because of the topics of their research – they at least use the scientific method, come up with testable hypotheses and obtain reproducible results. Evolutionary psychologists? Not so much.

  3. 3
    Simple Truth says:

    Anthropology called – they want their science back and would appreciate it if evolutionary psychologists would stop mucking about in it with absolutely no clue what they’re doing.

  4. 4
    Gar Lipow says:

    I doubt evolutionary biologists say this. Possibly evolutionary psychologists say this. But while I’m very open to the idea of evolutionary psychology, actual evolutionary psychology in practice appears to be most pseudo science.

  5. 5
    Kaija24 says:

    Agreed on the sneaking suspicion that this “hypothesis” is the product not only of the ev-psych crowd but is probably the pop culture “telephone” version of it, as relayed by bad reporting, conservative pundits, radio talk show hosts, and people who find it comforting that millions of years of evolution were all for the purpose of creating 50s TV show gender roles and a helicopter-attachment-heterocentrist-parenting/everything-in-the-whole-world-is-about-teh-babeyz!!! worldview. Can’t they go live in an enclave and feel superior/live their perfect lives somewhere quiet and stop mucking up the bandwidth with this crap?!?

  6. 6
    RonF says:

    The chemicals that rush through straight couples’ brains when they are in love, which encourage them to stay together and raise children effectively, are the same chemicals that infuse the brains of lesbian and gay couples in love, and can serve the same purpose.

    The biochemist in me asks how you know that. Is this based on what you would like to think, or has someone done biochemical assays of the brains of homo- and heterosexuals to see what hormones and neurotransmitters are involved in both?

  7. 7
    closetpuritan says:

    So… Who besides me & Amp actually read the article? I mean, I like mocking evo psych as much as the next person, but a lot of these criticisms don’t really apply to the linked article. A critique of the naturalistic fallacy is particularly out of place for an interview with someone advocating taking drugs to extend the “natural” duration of love. (Not that I’m entirely convinced by his natural-duration-of-love theory in the first place, but he believes it’s natural.) See this part, for example:

    If you look at this in the context of evolutionary biology, you realize that in order to maximize the survival of their genes, parents need to have emotional systems that keep them together until their children are sufficiently grown–but, what happens after that is of no concern to natural selection. As Donald Symons has written, “in analyzing the psychological underpinnings of marriage [we should] keep in mind that Homo sapiens is the product of evolution … we are designed to promote gene [survival], not individual survival, and reproductive [success], not marital success.” Since we now outlive our ancestors by decades, the evolved pair-bonding instincts upon which modern relationships are built often break down or dissolve long before “death do us part.”

    We see this in the high divorce rates and long term relationship break up rates in countries where both partners enjoy freedom–especially economic freedom. We are simply not built to pull off decades-long relationships in the modern world. Nature designed us to be together for a while, but not forever–and once we push beyond the natural childrearing boundary, we are, in a sense, living on borrowed time.

    As far as the quoted part in Amp’s post goes, it does have a bit of just-so-story about it* (I’m gonna have to re-read Gould’s article about the spandrels, aren’t I?), but studies of hunter-gatherers have shown that children who are missing one parent have lower survival rates, and I think most scientists agree that the evolutionary purpose of pair-bonding (in humans or animals) is to raise offspring (whether that involves both parents sharing equally in childcare, or one parent mostly finding food and bringing it to the mother and/or offspring).

    *On the other hand, it does imply a testable prediction, or maybe two, making it less of a just-so story: 1) offspring that require a great deal of care and species with more than one parent/alloparent providing care will likely be found together. 2) Monogamy (or polyandry) is more likely to be found in species where paternal care greatly affects offspring survival.

  8. 8
    AMM says:

    I tried to read the whole linked article, but I’m afraid my head kept exploding. There are simply so many assumptions about how humans have supposedly always lived that aren’t true.

    He talks about “pair bonding”, which seems to be the idea that a mommy and a daddy make this little nuclear family all held together by mommy and daddy being “in love” or something. I think the practice he’s talking about is called “marriage,” except that for pretty much all human societies we know anything about _except_ for modern Western ones, marriage has nothing to do with romantic love.

    As for “pair bonding” being necessary to provide for kids: human beings almost never live alone in mommy-daddy-kids groups. They live in groups, usually with a web of obligations and connections (usually described as “kinship” relationships.) In many societies, the father-child relationship is not as important as the child’s relationships with the mother’s blood relatives. If there’s any enduring connection that seems to be common to most societies, it’s between blood relatives. If you look at our nearest relatives, the great apes, “pair bonding” is absent. So it seems unlikely that romantic love-based “pair bonding” was the basis of survival for long enough to build it into our genes.

    Finally, there’s the question as to whether the behavior that he’s interpreting as “pair bonding” is a phenomenon specific to two opposite sex parents (or parents-to-be), or whether it’s just a special case of a more general phenomenon.

  9. 9
    closetpuritan says:

    Finally, there’s the question as to whether the behavior that he’s interpreting as “pair bonding” is a phenomenon specific to two opposite sex parents (or parents-to-be), or whether it’s just a special case of a more general phenomenon.
    Opposite sex parents vs more general phenomenon: Do you mean opposite-sex vs same-sex, or vs. not romantic love? I don’t think he makes any claims whatsoever about same-sex vs. opposite sex. (I would describe his claims as heteronormative but not homophobic.) Given the whole two-male-or-female-birds-raise-an-egg phenomenon, I would expect he’d put same-sex romantic love into the pair bonding category if he’d bothered to mention it.

    As for “pair bonding” being necessary to provide for kids: human beings almost never live alone in mommy-daddy-kids groups. They live in groups, usually with a web of obligations and connections (usually described as “kinship” relationships.) In many societies, the father-child relationship is not as important as the child’s relationships with the mother’s blood relatives.
    No, I know that humans lived in larger groups than nuclear families. That doesn’t mean that the father didn’t help provide resources to the mother and child (and hunter-gatherer groups vary–some had more paternal care than others, e.g. the Aka). Having a maternal grandmother is great but not always available. Also, it’s not as black-and-white as “necessary” or “unnecessary” most of the time, I don’t think. More “better chance” vs. “worse chance”.

    If you look at our nearest relatives, the great apes, “pair bonding” is absent. So it seems unlikely that romantic love-based “pair bonding” was the basis of survival for long enough to build it into our genes.
    A lot of things that humans have are absent in the great apes. And there are some species of voles that are monogamous and others that are polygamous within the same genus. And the reduced difference in size between men and women compared to our recent answers is generally attributed to us become less polygynous and more monogamous–generally, species that are monogamous have little difference in size between sexes, and species that are polygynous have bigger and showier males. (The fact that female beauty is at least as important as male beauty may be another argument that we’re at least monogam-ish.)

    I think the practice he’s talking about is called “marriage,” except that for pretty much all human societies we know anything about _except_ for modern Western ones, marriage has nothing to do with romantic love.
    In patriarchal societies where accumulation of property is possible, marriage is usually about passing on that property to sons and women must be controlled in order to assure paternity. (Patriarchal societies are also much more polygynous–it’s not that polygyny is necessarily forbidden in hunter-gatherer societies, but it’s less frequent in practice.) In the societies that humans lived in for most of human evolution, it was not possible to accumulate much property. I’m not sure if arranged marriages are unheard of in hunter-gatherer societies, but from what I’ve read of hunter-gatherers, in most cases either women and men can choose spouses, or women are “spoils of war” (depending in part on how much war there is). Hunter-gatherer societies weren’t/aren’t feminist paradises, but there’s only so much you can control women if you can’t accumulate much property and the women have to go out and actually do some gathering.

    Also, modern Eastern societies where love marriages are more common than arranged marriages exist. Not important to the debate but important in not erasing them.

    I’m actually not as confident as Earp that romantic love prevents cheating or multiple pair bonds for a single person, but I think I agree that romantic love is about bonding the two potential parents to each other to increase survival of their children.

  10. 10
    closetpuritan says:

    (Apparently it’s a little more complicated than I thought. See this study arguing that arranged marriages are ancient, and this critique of it. As you might guess, I pretty much agree with the critique. There’s also the idea of people in arranged marriages “learning to love each other” but that’s a lot weaker argument–and I seem to remember from my “Gender in Japan” course that when arranged marriages were still the norm in Japan, love was not thought of as something you’d find in marriage, but something you’d find with prostitutes. Higher-status prostitutes.)

  11. 11
    mythago says:

    If you look at this in the context of evolutionary biology, you realize that in order to maximize the survival of their genes, parents need to have emotional systems that keep them together until their children are sufficiently grown

    This, again, goes back to the just-so story problem: it assumes humans have always grown up in isolated nuclear families. Even David Blankenhorn admitted at the Prop 8 trial that this isn’t the human norm. The “emotional systems” that keep parents together are called “societies”.

  12. 12
    closetpuritan says:

    Mythago: See, I’m not sure where you guys are getting “This guy believes that humans live in isolated nuclear families” from this. I guess you’re interpreting “keep them together” as “otherwise they would be geographically separated”? I interpreted it as “stay a romantic couple” (like how we talk about couples “staying together” and “splitting up”).