Do Humans Pick Friends Who Have Similar Genetic Makeup?

Nicholas A. Christakis and James H. Fowler, in a recent paper titled “Friendship and Natural Selection,” make an interesting hypothesis: that we select friends who have similar genetic makeup as ourselves. The dataset used was the famous Framingham Heart Study. From their abstract:

More than any other species, humans form social ties to individuals who are neither kin nor mates, and these ties tend to be with similar people. Here, we show that this similarity extends to genotypes. Across the whole genome, friends’ genotypes at the SNP level tend to be positively correlated (homophilic); however, certain genotypes are negatively correlated (heterophilic). A focused gene set analysis suggests that some of the overall correlation can be explained by specific systems; for example, an olfactory gene set is homophilic and an immune system gene set is heterophilic. Finally, homophilic genotypes exhibit significantly higher measures of positive selection, suggesting that, on average, they may yield a synergistic fitness advantage that has been helping to drive recent human evolution.

So the interesting question is why would this happen? The arXiv blog goes into possible explanations:

Perhaps the genetic links are simply a reflection of this common background. Not so, say Christakis and Fowler. The correlation they have found exists only between friends but not between strangers. If this was a reflection of their common ancestry, then the genomes of strangers should be correlated just as strongly. “Pairs of (strictly unrelated) friends generally tend to be more genetically homophilic than pairs of strangers from the same population,” they point out.

There are certainly other processes that could lead to friends having similar genomes. One idea that dates back some 30 years is that a person’s genes causes them to seek out circumstances that are compatible with their phenotype. If that’s the case, then people with similar genes should end up in similar environments.

Personally, I don’t buy this:

There may be another mechanism at work. One idea is that humans can somehow identify people with similar genetic make up, perhaps with some kind of pheromone detector. Indeed, Christakis and Fowler say that some of the genes they found in common are related to olfaction, a discovery they describe as “intriguing and supportive”.

While interesting, I’m not entirely convinced of the overall findings and would be curious to see this study expand. What do you think?

On Growing Up Feeling Unattractive

In a post titled “I Was Not a Pretty Child,” Hannah Dale Thompson reflects on what it was like growing up feeling unattractive and being made fun of by peers:

Being unattractive in your youth forces you to develop positive personality traits. That’s why comedians are not sexy. Relying on something other than appearance for attention breeds a larger-than-life personality. It breeds a confidence that is more than superficial. It breeds humor, and a social awareness and empathy that, I think, can only be developed from the outside. I am more charismatic, confident, interesting, and funny because I was an ugly sixteen-year-old. I am slightly less superficial and marginally more open-minded. I can stand up for myself. Three days after the best first date I have ever been on, my half-drunk suitor called to tell me I have more moxie than anyone else he’s ever met. I am proud of all of these things; people should take pride in overcoming obstacles and developing better personality traits. Even if the obstacles involve bushy eyebrows and the personality bonus leads to self-diagnosed histrionic personality disorder.

Being unattractive in your youth separates you from even the other awkward, unattractive kids. I never had a real date to a high school dance. The entire concept of “Sadie Hawkins” terrified me. I never made anyone’s “top five girls” list. I never made anybody’s “girls” list. By the age of eighteen, I had approximately zero experience with games or manipulation or difficult social interaction. 

It’s interesting to read about how she developed as a person as she grew more attractive in her twenties:

Sometime around my twentieth birthday, I became reasonably good-looking. I started dating lawyers and financiers in their late twenties and early thirties. I became the kind of girl other women approach. I live with a model. All of my friends are beautiful and interesting. If I’m being very honest, I’m always a little angry when I have to purchase my own drink. At the grocery store last November, a boy who was mercilessly cruel to me in high school approached my mom and told her that he was “sorry for being so mean to HD in high school” because he “saw on Facebook” that I was “pretty hot now.” My mother, God bless her, pointed out to him the ridiculousness of that apology.

But what of friendship?

Women my age, particularly the bright-young-thing-in-a-big-city set that I am lucky to be a part of, are inundated with advice. About sex, careers, feminism, children, boyfriends, hook-ups, grad school. Lean in, but not too far. You can do anything a man can do, as long as you’re well put-together and relatively inoffensive. Ask for more, but don’t get cocky. No one tells women my age about the importance of friendship.

In the end, these two sentences dig deep:

This wound is new, but feels familiar. It’s something I remember being used to.

I’ve gotten used to being ignored as well…

On Friends Without Benefits

One of the most heartbreaking Modern Love stories I’ve ever read is in this week’s New York Times:

He wanted nothing, and I wanted the world. I lay in bed with my phone cradled to my ear, taking the news as one might receive a diagnosis of cancer. I stayed there all weekend, unable to move, paralyzed by the knowledge that now it was over. Even our friendship was too damaged to repair. This is what happens, I learned, when happily ever after does not happen.

I moved to New York City that spring. He met another girl he loved, one that probably knew him a little less well. They married two years ago, but I wasn’t invited. When I saw him after the fact, he told me not to take it personally, but we both knew that with another twist of fate, it could have been us up there at the altar.

I couldn’t help but take it personally; it’s always personal.

Sigh.

Some would find the ending a triumph; I found it devastating.

Can Men and Women Just Be Friends?

This was a timely piece for me, as this was on my mind over the weekend: can men and women just be friends? In an op-ed for The New York Times, William Deresiewicz writes:

There’s a history here, and it’s a surprisingly political one. Friendship between the sexes was more or less unknown in traditional society. Men and women occupied different spheres, and women were regarded as inferior in any case. A few epistolary friendships between monastics, a few relationships in literary and court circles, but beyond that, cross-sex friendship was as unthinkable in Western society as it still is in many cultures.

From his own personal experience, the author concludes:

Consult your own experience, but as I look around, I don’t see that platonic friendships are actually rare at all or worthy of a lot of winks and nudges. Which is why you don’t much hear the term anymore. Platonic friendships now are simply friendships.

The one portion I disagree with:

Friendship isn’t courtship. It doesn’t have a beginning, a middle and an end.

Friendships can begin and end as easily as romantic relationships. Your thoughts?

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Related: a must-read on solitude and leadership, also by William Deresiewicz.

The Upside of Facebook Use

How is being active on Facebook and other social media sites affecting your friendships in real life?

According to Matthew Brashears, a Cornell University sociologist who surveyed more than 2,000 adults from a national database and found that from 1985 to 2010, the number of truly close friends people cited has dropped (even if we’re more active in socialization than ever before). On average, participants listed 2.03 close friends in Brashears’ survey. That number was down from about three in a 1985 study.

Here’s the gist:

Does that mean we’re more isolated in these times when we seem to meet more people online than in person? (How many of your Facebook “friends” are really friends of yours?) Defying some of the stereotypes of the digital age, social scientists say Facebook may actually be healthy for us. Keith Hampton at the Annenberg School for Communication at the University of Pennsylvania wrote a report for the Pew Research Center in which he found that “Internet users in general, but Facebook users even more so, have more close relationships than other people.”

“Facebook users get more overall social support, and in particular they report more emotional support and companionship than other people,” wrote Hampton in a blog post. “And, it is not a trivial amount of support. Compared to other things that matter for support — like being married or living with a partner — it really matters. Frequent Facebook use is equivalent to about half the boost in support you get from being married.

That last sentence is both encouraging and frightening at the same time.

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For one personal perspective on virtual friendships, please check out Cheri’s five-part series, beginning here. Then move on to Part II, Part III, Part IV, and Part V. Highly recommended reading.