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Humans Choose Friends With Similar DNA
KentuckyFC writes "The study of social networks has long shown that people tend to pick friends who are similar to them — birds of a feather stick together (PDF). Now a study of the genomes of almost 2000 Americans has found that those who are friends also share remarkable genetic similarities. 'Pairs of friends are, on average, as genetically similar to one another as fourth cousins,' the study concludes. By contrast, strangers share few genetic similarities. The result seems to confirm a 30-year-old theory 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 and so be more likely to become friends."
How dare you insult my friends by comparing them to me!
No kidding. I'm thinking that the majority of people live, breed and die within a few hundred miles of where they were born and this goes on generation after generation. One would expect a certain homogeneity in the range of genes within that population.
I find this study to be extremely flawed, not to say elitist / racist.
Yes, rednecks who listen to country music and drink cheap beer and whisky like to have friends who are also rednecks who listen to country music and drink cheap beer and whisky.
If the study had been conducted with 2000 subjects from culturally diverse places, like NY or Tokyo, I'm sure the results would've been a lot diferent.
I was going to post AC, but fuck it, I got karma to burn...
In a number of different memoirs from actors in the original Planet of the Apes, it was noted that people playing different types of apes always sat with each other at lunch. It was a bizarre granfalloon - baboons with baboons and orangs with orangs for no other reason than that they looked the same. And these were people that knew each other before the film.
People have a natural inclination to like people that look more like them whether it makes sense in modern society or not.
After all, many friends fuck their friends' wives, so after a couple of generations, they are all a happy family.
If there are only six degrees of separation between you and just about everybody on earth, the classification "fourth cousin" probably covers a large part of the earth's population!
I'm reminded of the Better Off Ted episode Get Happy
Linda suggests that Veridian let its employees have decorations in their company. Veronica agrees, but the company selects the decorations and assigns them to the employees. Linda discovers that she's suddenly a cat person, while other employees have cars, Green Bay Packers, or space decorations.
"Veridian Dynamics. Teamwork. It keeps our employees gruntled."
It must have been something you assimilated. . . .
... white people are racist
how dare you say white people are racist!
Indeed! This is quite possibly, without exaggeration, the single most cruel and inhumane thing you can do to another person. Accusing another person of racism is so low that, I daresay, it ought to be considered a hate crime! I know I certainly won't stand for being accused of racism. I am a white human being with dignity, and I deserve better than that!
Almost all of the participants in the dataset were Americans of European descent. They controlled for the possibility of distant relatedness as aggressively as they could, which is a well-understood requirement of many GWAS experiments.
Bio questions? Ask me to start a Q&A journal. Computer analogies available for most topics!
I've lived around the world and have a variety of friends.
Well neat. You alone must be a representative sample set of humanity that dwarfs this mere 1932 person sample group for statistical relevance. Thank goodness you know more about statistics than people doing a population study!
I'm assuming these 2000 individuals for the study were in environments that just happened to have similar genes around them.
Actually, if you read the study (OMG! I must be new here!), then you'll see that they address this point:
"There are (at least) four possible reasons that friends may exhibit homophily in their genotypes. First, correlation in genotypes may be a trivial by-product of the tendency of people to make friends with geographically proximate or ethnoracially similar individuals who also tend to share the same ancestry. Thus, it is important to use strict controls for population stratification in tests of genetic correlation (below, we rely on the widely used principal components method to control for ancestry). [...] Third, people may actively choose particular environments, and, in those environments, they may be more likely to encounter people with similar phenotypes influenced by specific genotypes. If people then choose friends from within these environments (even at random), it would tend to generate correlated genotypes."
[...]
"To eliminate the possibility that the results are influenced by people tending to make friends with distant relatives, we use only the 907 friend pairs where kinship â 0 (recall that kinship can be less than zero when unrelated individuals tend to have negatively correlated genotypes)." (ed: They do the same with 907 stranger pairs.)
In the end, they find that people prefer friends that share genes for the same sense of smell and the same linoleic acid metabolism. We also strongly prefer people with different genotypes for immune system function. While there are hundreds more homophilic and heterophilic gene correlations, those were the three that were most over-represented between people. There are many other genes that friends share, but most of those vary from pair to pair of people and are either idiosyncratic preferences or possibly just coincidences. Those three genes are not.
It's pretty well known that human select their lovers in part by smell. It's interesting that we pick our friends too that way. The paper gives a few good theories for why that's true (based on older research) and also does so for the immune system. The linoleic acid thing seems to have baffled them a bit, though they make a stab at explaining it as possibly being related to food safety and keeping the community on the same page about what's good to eat.
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
I dont get how everyone on here keeps making the equation: genetics = race. Thats not what this is about.
I'm an engineer. Since I was a kid, I've loved to take things apart and put them back together. The closest friends I have in life are all from different parts of the world but they tend to be like me in that they also grew up taking things apart and putting them back together. So whatever gene-grouping is responsible for that behavior is probably shared by my friends from India, Russia and Sweden.
Genetics != race
The suspicion that part of social compatibility can be explained through superficial genetic traits has been explored before. The bibliography on page 21 of the totally free and unpaywalled arxiv PDF has a few citations that seem pretty similar.
That being said, I'm not so sure about some of their conclusions; they make it sound like there are purely mechanistic reasons why we seek out the friends we do. Consider the following:
The implications of the finding regarding homophily on genes related to linoleic acid metabolism are unclear. Linoleic acid is a precursor for substances involved in a broad range of important bodily processes (ranging from adipocyte function to bone formation to the regulation of gene expression) (42), and the component genes in the pathway are related to the metabolism of cholesterol, steroids, and various ingested substances, though it is intriguing that linoleic acid compounds might be used by moths as pheromones (43). Possibly, this pathway is related to the restrained consumption or the specific metabolism of various foodstuffs, traits for which homophily may be advantageous and heterophily self-injurious.
Personally, I think this is patently absurd and that there is no way this could influence personality or human behaviour. It seems to me to be more likely that the linoleic acid genes either have some wildly obscure indirect effect on personality that we can detect, or that they're simply inherited by chance with something that does.
It would have been wonderful if people here actually bothered to RTFA so we could argue about whether or not biochemically-inclined sociologists are out to destroy civilization by being too narrow-minded. On the plus side, this is a biology paper that was submitted to Arxiv, which means that it probably is having trouble getting into a major journal (i.e. it's very possibly being regarded as crap by journal editors due to its weird conclusions.)
Bio questions? Ask me to start a Q&A journal. Computer analogies available for most topics!
This doesn't really work in today's world, though. Sure, in suburbs and villages, that probably has something to do with it. Cities, though? A city hash millions of people living in it, many of them not even originating from that city at all. Walk a hundred meters and you'll probably stumble on people from 10 different countries at the very least. I have serious doubts that you, by happenstance, always pick people who grew near your own place of birth.
That doesn't make the findings impossible. The genetic variation is known or could be estimated given the demographics of a person's locale, and you could compare the profile of expected (if friend making was completely random) to actual pretty easily. If they don't match up, then there's some selection going on.
For example, if you're white and live in the bronx, and significantly less than half of your local friends are hispanic, then obviously race factors into who you make friends with in some way. You could do the same thing with genetic markers.