Loneliness is not a gnawing, chronic disease without redeeming features, social isolation is just a different scale of organization that can't be grasped outside evolutionary time and evolutionary forces. Well, maybe.

If you are alone this Valentine's Day, you are not...alone, you are part of a giant biological imperative, according to the psychologists behind an evolutionary theory of loneliness, who write in Cogntion  &  Emotion about its potential adaptive value on an evolutionary timescale.

In modern psychology, because some people are some ways, like being being loners, there is a desire to show that it must have a heritable component - loners beget loners, like Lamarckian psychology, except less well thought out. All culture will have a biological function to an evolutionary psychologist somewhere. Loneliness is only recently (evolutionary timescale speaking) an indictment of our psychosocial functioning and attractiveness - if you are lonely others believe there is something wrong with you - and so you feel like there is something wrong with you if you are alone.

Guys learn this quickly - or maybe it is biologically hardwired into their dating DNA - that is why if they are single they take a girl places with them whenever possible. If they are with a girl, other women like them more. If they are alone at the bar, they are not worth approaching.

But that won't make my blog on Valentine's day, so let's talk about the results of some people filling out a survey. If they are twins, even better, because that makes weak observational studies look methodologically terrific. And if the heritability of loneliness changes from 60 percent at age 7 to only 17 percent at age 12, like the data in a recent paper, it can be dismissed as non-shared environmental factors, anything except wondering how a null hypothesis might help.

Right behind surveys of college students and 'twin studies', fMRI images are the most poorly used device in making suspect claims. This image from another paper by the lead author is showing what happens when people are lonely, thus it was determined that loneliness changes brain function (From Cacioppo, J. T.,&Hawkley, L. C. (2009). Perceived social isolation. Trends in Cognitive Sciences, 13, 447–454.)

Obviously people inclined to want to be social stood a better chance of survival back when nature was really trying to kill us all. Dogs like to run in packs also. So if groups stood a better chance of survival then people who are social stood a better chance of survival also. But is that really heritability? With the fuzziness of epigenetics, it is sure is. Almost anything can be heritable in such a gray area - if you want to assert that Republicans are born that way or Democrats have prettier daughters or that a Ford Mustang car grill is popular because we evolved to like it, just invoke epigenetics. You can't really be proved wrong, and it will annoy biologists. 

We can think of more modern examples. The French are ridiculed today for not being very brave and an evolutionary psychology explanation would be World War I. Who died first when 19th strategy and heroics met 20th century weapons? The bravest warriors, the loners. The ones who gave birth to future generations were those who ran and hid. Now we are stuck with existentialism.

Loners get a bad rap. Link: Mike Blumenthal

What if you are lonely despite the evolutionary disadvantage? Even that can good, the authors write, because many people will change your behavior to be less lonely - that is the whole nature of peer pressure. 

The authors recognize that lonely people sometimes have advantages. Loners are more likely to focus on survival in dangerous circumstances. Brain pictures of lonely people found that loners preferred pictures of objects (like a mountain or a forest) while social people preferred pictures of people. The early days of America were filled with just such loners, often from Scotland, where psychologists can likely find all kinds of behaviors that are not social and wonder if they are epigenetic.

Today, being a loner is not going to be correlated to trekking across the wilderness, it is going to be associated with sitting on the couch and eating Doritos and watching all 800 episodes of Doctor Who. But we still like some loners. James Bond gets it done and he does not sit around and cry because he is not married. Does that mean there is a loneliness phenotype? If so, it may also mean there is a respecting loners phenotype.

If there is a heritable component to loneliness, it may also make raising kids more scientific once we figure it out. It's become commonplace to put kids in timeout though it is often ineffective. Without knowing if the child has that particular bundle of genes, it's hit and miss. Time out is also used a lot in the Amish community, where you will be shunned for inappropriate behavior (raise your own barn, Ezekiel!) so perhaps there is an Amish phenotype.

No one can prove there isn't. That's the downside to a young field like epigenetics, almost anything can be shown to have a biological function.

Happy Valentine's Day. Now, whether you are a loner or not, you have a science explanation for why you need to get out there and satisfy the biological imperative of promoting your genetic legacy, even if you don't want that special someone to spend the night.

Citation: John T. Cacioppo, Stephanie Cacioppo, Dorret I. Boomsma, 'Evolutionary mechanisms for loneliness', Cognition&Emotion  Volume 28, Issue 1, 2014 DOI:10.1080/02699931.2013.837379