Pair-Bonding: A Strength and A Weakness

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couple hit by a seagullAs we’ve seen in earlier articles, neurochemical urges motivate mammals to eat, drink and have sex. Specifically, dopamine surges in their primitive reward circuitry send them after the things that further their survival—or at least the survival of their genes.

But what about the handful of mammalian species who have evolved to team up in order to do a better job of raising their young? They may get all the food, water and sex they want, and still feel that something is missing—until they are mated.

Why this need for a pair-bond? It's probably not because they were insufficiently loved as infants. And they probably don't suffer from a character flaw of “neediness.” No, chances are they feel like something is missing until they find a long-term mate because they are molded that way.

Like it or not, we are pair-bonding mammals. This means that most of us humans are supposed to feel like something is missing when we're mateless, just as we're supposed to feel hungry or thirsty when we need to eat or drink.

Moving toward steady companionship is rewarding to pair-bonding mammals, just as mating itself is. This means that their brains react with the neurochemicals that induce feelings of well-being when they move toward sexual opportunities or long-term companionship. This makes pair-bonders different from the other 97% of mammal species, which don't get any buzz from pair-bonding. Most mammals only get a time-for-sex buzz. Pair-bonding voles (and humans), on the other hand, find love so rewarding that they can even fall in love through cage bars. They don't actually have to "get it on" to bond.

Incidentally, an urge to pair-bond is no guarantee of lasting fidelity. In pair-bonding mammals, the pair-bonding and mating programs produce an uneasy friction between a desire for a comforting bond, and a desire to add novel mates on the side. We believe this happens because our mating program pushes us toward sexual satiety and habituation. Our mate begins to look like a pizza we've eaten too many slices of. Novel mates then look especially tempting. This situation often causes our pair-bonds to unravel.

The origins of pair-bonding

Why are some mammals pair-bonders? Teaming up serves their species because it increases the likelihood that their offspring will gain the advantage of two caregivers. Most mammals do just fine with one caregiver, as long as mom’s mammaries hold out. But some, like humans, do significantly better with two.

In the case of us humans, we arrive in the world quite undeveloped. This risky situation evolved because we have to escape our mother’s pelvis before our skulls grow too large. Not only that, we are relatively helpless for so long that two caregivers substantially increase our chances of survival and future fitness to reproduce.

What if a pair-bonding mammal doesn’t find a mate? S/he is shaped to continue to search (“crave” a mate) until s/he finds one. This craving may not be conscious, but it’s there, courtesy of our mammalian desire neurochemistry (reward circuitry). A lonely pair-bonding mammal will feel like something is missing—as if there is an empty hole inside.

This “hole” is not a problem if it leads our pining mammal to a long-term companion. But if s/he is unlucky in love, it may leave him or her with increased susceptibility to substance abuse and depression (if a mate is lost). That’s not as much of a problem for animals, because they don’t have access to drugs, alcohol or porn. In most cases, they are correctly motivated to choose the healthiest possible course: find a partner.

It seems likely that these [neural reward] pathways and genes evolved not for drug abuse, but for mediating the motivational aspects of social interaction, including pair bonding, maternal attachment to infants, and presumably infant attachment to mother.—Thomas R. Insel MD, behavioral neuroscientist

The risks of loneliness

Humans are pair-bonders, and it is becoming more and more evident that loneliness is a risk for us. Addictions have been rising in humans as romantic bonds have become more fragile. So has depression. True, divorce rates have leveled off, but the percentage of adults who never marry is growing steadily…and their break-ups aren’t counted in the divorce statistics.

Did you know that the percentage of addicts is higher among singles than among married people? And we here at Reuniting think that percentage could be far lower still, if couples knew how to use bonding behaviors and careful lovemaking to make their unions havens of playful safety and emotional comfort. (Sometimes it seems like our culture encourages us in the opposite direction. It seems to support the idea that there are no costs to turning relationships into mere pit stops on the Hook-up Highway.)

It's true that we might have to rethink our belief that indulging our built-in attraction to novel mates and more orgasm is the sine qua non of well-being, if we want to put more emphasis on lasting union.

Interestingly, pair-bonded animals spend a lot of time grooming and hanging out. They are not constantly occupied with sexual frenzy. It may be that we humans are currently trying desperately to find a degree of satisfaction through sex or orgasm, which can only be found in contented companionship based on generous bonding behaviors.bonded gibbons

Susceptibility among pair-bonders

So why are pair-bonding mammals more susceptible to substance abuse? Because the same neural circuitry that governs pair-bonding also governs susceptibility to substance abuse, and pair-bonders seem to have a more sensitive version of it than most mammals. When pair-bonding mammals are longing for a mate (whether or not they correctly analyze the roots of that longing), they are vulnerable to any neurochemical buzz that signals “relief.”

Scientists saw this recently when they compared the effects of amphetamine on two types of voles: pair-bonding prairie voles, and promiscuous montane voles. Dopamine rose significantly more in response to the drug use in the pair-bonding voles than in the voles who were not wired to seek long-term mates. The monogamous voles were inclined to find certain dopamine-based rewards more rewarding than their promiscuous vole cousins. In short, a lonely pair-bonder would have a greater risk of becoming an addict than would a mammal with no built-in urge to form a pair-bond.

It seems likely that humans are similar in this respect. A human adult who is mateless may also have that sense of “an empty hole” inside—although s/he may not connect that feeling with a longing for romance. Such a disconnect is especially likely if one’s childhood experience of intimacy was fear-producing.

Of course, humans are vulnerable on a second front as well. We can analyze, rationalize, and find clever ways to pursue (or advertise!) substitute activities and substances, which seem to offer the neurochemical relief that a pair-bond would ideally supply. We can temporarily fill our nagging sense of emptiness, at least in the short run, with orgasm, alcohol, drugs, pharmaceuticals, video games, junk food and so forth. However, the costs of those substitutes can be high—including the risk of addiction and increased depression in the long run. For example, seventy percent of chronic problem drinkers are either divorced or separated, and single men are more than three times as likely as married men to die of cirrhosis of the liver.

The fact is that none of our substitutes offer the same lasting well-being as the evolutionary solution for that "little hole" in us, namely, a close, trusted companion. Companionship has been shown to be a more powerful determinant of good health than drugs, exercise, genetic make-up, changing diet, or stopping smoking—according to Dean Ornish, MD. A trusted companion fills our built-in empty spot, and wards off the ills that result from loneliness. For us pair-bonders, companionship is closely tied to well-being.

The irony and the ecstasy

It's ironic that our capacity to behave like Romeo and Juliet may be what leaves us especially susceptible to substance dependency. Or, to state it differently, if we were truly promiscuous, we would be happy just hooking up, and wouldn't be as likely to get hooked. The good news is that we have the capacity to tap our relationships for greater well-being if we're willing to make both lasting bonds and intimacy top priorities. Sex alone—thrilling as it may be—just won't completely cut it for us pair-bonders. Loneliness is associated with slower wound healing, greater risk of mortality and decreased longevity.

Of course, spiritual paths teach us that there are other ways of filling our neurochemical "something's missing" signal. These include feelings of union with the divine, making music, companionship with friends and community, nurturing touch, generous service. And yet, the simplest path may be right in front of us: mating behavior that doesn't trigger the desire for a novel mate. When we master it, it can meet both our built-in "sex" need and our built-in companionship need. And according to various ancient traditions, such unions may also be a spiritual path in themselves.

So if you are mateless in Manitoba (or anywhere else), and feeling like something is missing, don’t reach for unhealthy relief, or mere orgasms. Reach for companionship. Whether or not you find a mate immediately, you can certainly find a hiking, biking or running club, a congregation, a Toastmaster’s group, a support group, online companions, or some other group that will improve your well-being naturally. It seems likely that companionship without sex is far more healthful than orgasm without companionship, in cases where one can't immediately combine careful intercourse with companionship.

Finally, instead of making ourselves wrong for our mate-cravings, let's acknowledge them, make peace with them, and set about filling this built-in "empty space" in ourselves. After all, the desire for close companionship is part of our design. We are the ones who suffer when we refuse to acknowledge it, and instead fall for the false promises of the empty activities and substances that give our reward circuitry a short-term buzz. We can focus on true—and mutual—comfort instead.

Here's the abstract of the study about amphetamines and voles:

Amphetamine effects in microtine rodents- A comparative study using monogamous and promiscuous vole species
J.T. Curtis and Z. Wanga

Accepted 12 July 2007.
Available online 17 July 2007.

We compared amphetamine-induced dopamine release in the nucleus accumbens of vole species that exhibit differing mating systems to examine potential interactions between social organization and substance abuse. We found no species or regional differences in basal extracellular dopamine, however, monogamous voles had greater and longer-lasting increases in extracellular dopamine after amphetamine treatment than did promiscuous voles. We then examined whether amphetamine-induced increase in extracellular dopamine could induce pair bonds in monogamous voles. We found that, despite increasing dopamine in the nucleus accumbens, amphetamine administration did not induce pair-bonds in male prairie voles unless the animals were pretreated to preclude D1 receptor activation, which is known to inhibit pair-bond formation. These results support suggestions that social attachment and substance abuse share a common neural substrate.

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