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Friends Are Genetically Similar (2014) (nature.com)
280 points by jacobr 5 months ago | hide | past | web | favorite | 190 comments

This is interesting as I've typically made friends along lines of interest. I guess my next question would be are genetically similar people more likely to have similar interests.

edit: corrected grammer

> I guess my next question would be are genetically people that have genetic similarities more likely to have similar interests.

If that is the case, it would lead to the politically uncomfortable question of different genders or ethnic groups being more likely to have particular interests.

I think it's trivially obvious that they do?

The uncomfortable questions are whether people are genetically predisposed to, or naturally have a greater aptitude for, some particular interest, particularly on racial or gender lines. For many physical activities this is a settled question for gender, but that's about all we know.

Even this alone is not necessarily controversial, the problem as we've seen time and again is that the reaults of such a study are taken as a basis for discrimination. If we could rigorously quantify and prove a statement like "people of East Asian descent show a 2.3% greater aptitude for mathematics," it doesn't mean that the Chinese guy sitting in front of you has any such aptitude. Historically the metrics by which we have attempted to measure such things have been deeply flawed and biased. I'm not sure it will ever be possible to make such assertions in any rigorous manner, the factors behind cognitive tasks are just too complex.

> The uncomfortable questions are whether people are genetically predisposed to, or naturally have a greater aptitude for, some particular interest, particularly on racial or gender lines.

The answer is obvious here: yes. The only question is the size of the effect.

> The answer is obvious here: yes.

Let's say the statistical size of the effect is something around a millionth of a millionth of a percent, then I think most people would answer the question with "no" and be understood correctly by everyone. These kinds of questions almost always have a "big enough to have a perceptible impact"-clause implied. Pretending they don't feels needlessly pedantic.

I took the comment as saying obviously it's not "millionth of a millionth of a percent". You are strawpersoning here.

There are going to be definite real world measurable differences.

OP leaves open the possibility, for instance, of cultural differences that have a effect an order or two of magnitude larger though.

Personally I doubt this, but OP seems open to the idea the size might be small.

In that case I would like them to define a lower bound of a "measurable difference" and give a clear case why the effect is obviously higher than that. Simply saying it's obvious when many people actually disagree is not very constructive.

I'm not saying they are wrong, I just disagree with the tone.

Homophily is the term used to describe this phenomenon of groups forming on the basis of some kind of affinity (in the broadest sense): https://en.wikipedia.org/wiki/Homophily

2.3% greater aptitude for mathematics? Better spot the other races 50 points on the SAT.

They only report scores up to 800, so adding 50 to my 920 isn't really doing anything for me.

The shared interest groups most people are involved in in their regular lives are far too small to make any extrapolation to the larger population.

Also, for many human traits (i.e height), the intra-population variation is much greater than the inter-population variance, especially when controlling for the effect of environment.

We have a tendency to anchor our biases on the extreme examples of any population when we form our biases, often through mediums like elite/pro sports which select those at the extremes.

Ethnic groups are defined by appearance and cultural history, not by genes. Many ethnic groups (e.g. African Americans) are extremely diverse genetically.

If you're talking about the fact that many African Americans are about 20% European genetically, but many share "hip hop culture" or African American culture, or whatever, that seems somewhat of a contrived point and it's not clear exactly what the point is you're meaning to make.

If your talking about the often vaunted genetic diversity on the continent of Africa, that has no bearing on the existence of clusters of relative genetic similarity around the world we have come to refer to variously as ethnicity, race, population group, etc. In fact that African genetic diversity supports the reality of distinct population groups and ethnicities because it is a bunch of genetic material that other groups don't have.

The very basis for ethnicity/race/population groups is a genomic "alphabet"/string within certain bounds. In considering the global level distinctions between populations it makes no difference the level of genetic diversity in any particular group.

The defining factor is that various groups share traits that no other group does.

Asians and Europeans have stretches of DNA that we've determined through the magic of modern science come from an extinct species of human called Neanderthals. None of these stretches of DNA are found in Africans.

Likewise, Africans have stretches of DNA that come from as yet identified extinct species, these stretches of DNA aren't found in Asians or Europeans.

Then of course there are the myriad other genetic structures that while having origins in the ancestors of all living humans have nonetheless diverged through the process of evolution over the millennia into reliable genetic markers for the various population groups.

And it is true that ethnic groups are defined as well by visual appearance, for example cranium shape and size, nostril diameter, length of nasal bridge, hair color/texture etc. but these things aren't the result of members of your culture gathering around at your birth and molding these things like clay, these things are encoded in genes and what molded their shape into your genes are evolutionary pressures in your ancestral environment.

The point is a very simple one. People who appear similar, or have a similar cultural background (and hence belong to the same "race" in American terms) are often no more similar genetically than two randomly selected members of the population.

>by appearance not genes

I'm sorry, but genes clearly determine appearance.

> I'm sorry, but genes clearly determine appearance.

Genes, along with other factors, contribute to appearance, but it is possible to be (for a pair of humans) relatively close in appearance and generically dissimilar, or vice versa.

Genetic similarity and appearance similarity aren't the same thing.

I'm not sure that you could extrapolate to that wide an audience. One of the largest factors would have to be exposure to that interest, if you aren't exposed to it, then you can't know if you enjoy it (Nurture).

In small groups that are already interested in something, finding genetic similarity would mean that their nature is similar, and that nurture has also had an opportunity to take effect.

So small groups of people interested in something, can't necessarily be extrapolated to a larger group.

Sure you can, you just need to make an appropriate study - e.g. if you compare how similar are the expressed interests in identical twins vs nonidentical twins vs ordinary siblings vs nonrelated children adopted as babies (who all share the same environment), then you can measure the nature/nurture split; if the interests of identical twins are just as similar as siblings, then that's evidence that interests are determined solely by nurture, but if identical twins have significantly more similar interests than genetically nonidentical twins (which IMHO was the case, but I'm not going to look for the studies) then that would be evidence that at least part of these differences are innate.

But you aren't aloud to talk about that openly.

It’s obvious that gender and genetics have an effect on interests. I doubt that anybody challenges that, and you can go talk about that without anyone raising an eyebrow.

What is a problem is if you use that to justify discrimination. Just because members of a demographic are statistically different, it isn’t okay to treat individuals differently because they belong to a certain demographic. And that’s what people are complaining about!

People don’t complain when you say: “A lot of the fastest marathon runners are from Kenia”. People will complain if you use that fact to justify an imbalance in your workforce: “Well, it’s obvious that we hire only people from Kenia since marathons show they are much faster!”

So why do companies fire people who say stuff like that? Because discrimination is stupid from a business point of view: variance within demographics is much larger than variance of the mean between demographics. So if you hire people based on them being part of a “good” demographic, you will end up with worse hires than if you actually selected for individual aptitude.

I don't mean to start a flame war here, but when you say:

People don’t complain when you say: “A lot of the fastest marathon runners are from Kenia”. People will complain if you use that fact to justify an imbalance in your workforce: “Well, it’s obvious that we hire only people from Kenia since marathons show they are much faster!”

This is precisely the point. If objectively they are better, why is it discrimination to only hire them? Definitely you give everyone the opportunity to work for you, but if a singular group always performs better, is it really your fault? And if society did determine that it was your fault, how long could that go on for? Forever? How long can that charade last? Hasn't a Darwinian economy (capitalism) done the best ever for man kind (massively raised standards of living over the last 200 years).

One thing you might be mixing up is population vs individual. If you hold some sort of hiring process where the skill tested is similar to that tested in marathon running, then yes, Kenyans will tend to do better as a population. That does not mean you should actively discourage everyone else from applying. Your process should be blind to race/class of applicants, if some race/class does show a higher affinity towards specific skills, that will be the natural outcome of your process.

TL;DR - Don't hire only Kenyans, that's discrimination. You might end up with a lot of Kenyans if you hire only marathoners, but that's not the same.

Bingo. It’s fair to reject someone because they scored low on a test. It’s not fair to reject someone because they belong to a demographic that on average scores low on a test — that would be discrimination.

Of course, a lot of the discussion is about faulty tests, that claim to test for individual aptitude, but end up testing for demographics instead (eg. interviewers inadvertently giving higher scores to people similar to themselves)

It's not even all Kenians. It's Kalenjin minority in Kenia. If you need to hire people with best endurance why not ask them to run a marathon as a test instead hiring only people from ethic group that on average is better than others.

The point is, when you have everyone take that test, you end up hiring only Kenyans. And then everyone cries about discrimination

If the test is adequate for the job I don't think most people would mind. For example nobody says that short whites, latinos and asians are victims of discrimination because there's so few of them in NBA.

Discrimination is suspected if the test has little to do with actual job requirements.

Whats your opinion on diversity in tech and the whiteboarding interview process at the big tech companies?

Whiteboards interviews are inadequate. I'd opt for time boxed (for a month?) trial employment. Paid but probably less than actual job. After a short test for absolute basics to verify that person has the skills to even start.

Lack of diversity in tech is sad for me, but I don't think that there should be any additional incentives or bonus points on entry based on minority status. The problem for me is that large companies pretty much shy away from responsibility of training new employees for themselves and only hire people who got themselves fully educated already. This causes artificial barriers in entry to tech that let in only the people who in the past had the means and the will.

I'd put responsibility on the companies to hire for entry level positions people that have not previously worked in tech and attempt to train them. This could be proportional to company headcount and if company refuses to hire it should contibute significant amount of money to a fund that sponsors free tech education initiatives for anyone who's willing.

I think this approach would increase diversity and even help other groups disadvantaged on the job market.

It would put burden on companies but I haven't heard of company bankrupt because it spent too much on new employee training.

This kind of scheme is in place in my country to support employment of the disabled people. I think it should work on entry level employees too.

"Whiteboards interviews are inadequate. I'd opt for time boxed (for a month?) trial employment."

How is this even possible? People have to work full time jobs while interviewing.

parent specifically addressed this question:

> variance within demographics is much larger than variance of the mean between demographics. So if you hire people based on them being part of a “good” demographic, you will end up with worse hires than if you actually selected for individual aptitude.

did you not read the comment fully? that last part seems to pretty clearly address what you're asking here.

Counterpoint: Here we are, talking about it openly. Even Mr. Damore who previously was employed at Google was and is able to talk about it openly.

"Openly" as in "anonymously through the Internet"

Ideas deserve to rise or fall independent of the people who utter them.

he was fired?

Free speech doesn't mean you get to keep your job when you say it. It means it isn't illegal or impossible to speak your opinion. That doesn't mean being as ass has no consequences.

I disagree but even leaving that comment aside, the OP is saying you aren't allowed to talk about it openly. "Allowed" does not imply a government here, but society/employers/etc. If your employer fires you for saying "fuck", clearly you aren't allowed to say "fuck" at work.

> The tendency for friends to have similar genomes might result from people befriending those of similar ancestry, but the duo are confident that isn't the case. Not only did they control for the effect of population structure and ancestry, but the Framingham data is relatively homogeneous in terms of ethnicity, consisting largely of people of European descent.

How did they control it? Even amongst Europeans, I imagine French people are just more likely to have French friends.

Population structure is controlled through the use of the structure as a co-factor in the analyses. They use a principal component analysis on the genotypes to estimate the structure, and then use the first few principal components (PCs) as cofactors in the analyses.

So if the European population they used consisted of half English and half French participants, then the first PC would likely divide the two. So if British or French ethnicity affected the analysis, this effect would be reduced or eliminated using just the first PC.

How many PCs should be used? Well, ten is a common number chosen. Is it enough? Probably for most studies including this one.

So ancestry and ethnicity in this type of research emerges purely from a PC analysis on the genotypes. They do not use self-reported ethnicity or any other type of common ethnic grouping. To control for population structure, self-reported ethnicity is rarely useful. Its far too unreliable. But these groupings do sometimes loosely correspond to the PCs found in the analysis, supporting the use of PC as a method to control for ethnicity.

Do you believe these findings though?

(original article: http://www.pnas.org/content/111/Supplement_3/10796.full )

To me there are a few things worth highlighting, that are at least tangentially relevant:

1. This article was a PNAS Direct Submission. PNAS Direct Submission, a privilege typically reserved for members of the National Academy of Sciences, is like using trump-card to basically skip peer review. Since NAS members are usually great scientists with a track-record of publishing in high-impact peer reviewed journals, PNAS Direct Submissions are usually saved for pet-projects where the underlying science is... mmmm... of dubious quality. This is not always the case, but when all-star scientists opt for PNAS DS, it's certainly a reason to be speculative.

2. Nick Christakis and James Fowler have teamed up for a number of fancy-ass studies (the type that ensure people will want to write wikipedia pages about them, and lead to TED talk invites); some suggesting personal attributes like obesity, smoking, and happiness arise via 'social contagion', that is, behavioral propensities are transmitted over social networks. And studies like this one, where they find friendship affinities embedded in the genome.

3. I recently read a genome-wide association study (GWAS) with over 400 authors (https://www.ncbi.nlm.nih.gov/pubmed/28714976). I think 400 authors is way above median, but even relatively tame GWAS typically require a group effort just for data QC. Here, somehow these two guys did it all themselves.

4. Not only did they find that some SNPs were positively correlated, they also found some that were negatively correlated... "Across the whole genome, friends’ genotypes at the single nucleotide polymorphism level tend to be positively correlated (homophilic). In fact, the increase in similarity relative to strangers is at the level of fourth cousins. However, certain genotypes are also negatively correlated (heterophilic) in friends. And the degree of correlation in genotypes can be used to create a “friendship score” that predicts the existence of friendship ties in a hold-out sample." So the HN/Nature title might as well be: "Friends are Genetically similar, and Genetically Different".

1. You are perceptive, this is usually something to watch out for. However, it does not always indicate that a study is flawed, just that the research might have met with unwanted resistance, and the authors are in position to avoid that resistance.

2. Yes, these scientists are looking to make their research popular, highlighting an unfortunate conflict of interest present in academia. They do this to get big grants. Important observation, but insufficient to dismiss a finding out of hand.

3. So many authors, such a joke! These people mostly just help collect data, or sometimes simply share data they already have and then give the manuscript a quick read before publishing. But that is actually beside the point. If a lab already had data ready, and isn't pressured to add authors for political reasons, then two authors is not necessarily a red-flag. In fact, these analyses are relatively easy to do with available software. If they have the data, they just plug and chug.

4. The findings of the paper suggest strongly that friends are more genetically similar, on average, akin to fourth cousins. The results have yet to be rebutted to my knowledge. The fact they found some regions were negatively correlated does not conflict with their overall results. I have some doubts that their regional analyses should carry much weight (e.g. olfactory and immune regions). Furthermore, their explanations using natural selection appear to be a stretch. These are possible overstatements of results, allowed because of your points 1 and 2.

My overall impression of the paper is that main results are somewhat interesting and entirely novel. But there is a ton of stretching for just-so stories and "interesting" findings that will be unlikely to hold up. Typical PNAS.

Thanks for these replies. Also, very cool idea you have here: Cryptography for genetic material

> 3. I recently read a genome-wide association study (GWAS) with over 400 authors (https://www.ncbi.nlm.nih.gov/pubmed/28714976). I think 400 authors is way above median, but even relatively tame GWAS typically require a group effort just for data QC. Here, somehow these two guys did it all themselves.

This is from Framingham. The QC was all done well before, so not having 400 authors is no more suspicious than a one or two-author paper using UKBB data from 500k people - the point of having a long-running systematic study such as Framingham or UKBB or the twin registries is, among other things, to amortize the cost of data collection and preparation, instead of expecting every paper to collect an entire new sample and build a pipeline and analyze it.

>some suggesting personal attributes like obesity, smoking, and happiness arise via 'social contagion', that is, behavioral propensities are transmitted over social networks.

Don't know about happiness, but regarding smoking and obesity this seems so obvious to not even need a study (excluding pathological causes for obesity of course which are fewer and far between in people compared to the epidemic rates of obesity we see).

And perhaps happiness is quite impacted by living among other "positive looking/happy/chilled out" people as well -- it sure doesn't help if you're into a social network of depressed people, grumpiness and misery.

You seem to not like the result of the study and making non-arguments to try to discredit it.

I don't feel strongly one way or the other about these results, or their implications. If anything I think they are fairly interesting. You're right, these would be weak arguments if I were trying to discredit the findings (and are fairly ad hominem-y).

I am not a genomics expert, so my comment above was intended to be more of a question directed to Real_S and those versed in genomics analysis (i.e. given this list of concerns, are these findings still legit?).

Framingham, MA is old school New England. I wouldn't be surprised if 75+% of the participants are of direct English/Anglo-Saxon descent, even though the article describes it as "European" descent.

Framingham is pretty much just like that, although it's less than 75% it's still a supermajority.


Remember also that the dataset they are using began back in the 1940s when the towns demographics would have been much farther skewed towards English/Anglo-Saxon. And while they've included more participants over the course of the study, it's mainly been adding the descendants of the original participants.

Good points, but either way the go study is doubtful as hell.

As someone who lives in the area, this is a ludicrous statement. Framingham has one of the proportionally-largest immigrant populations of anywhere in the state, and, by extension, New England.

Statistics to the contrary are out-of-date or highly-misleading/inaccurate (counting Brazilians as "non-Hispanic white" and/or, for obvious reasons, undercounting illegal and non-English-speaking immigrants).

Further the non-Hispanic white population is itself ethnically diverse (Italian, Portuguese, Irish etc) with "English/Anglo-Saxons" a small minority.

Like I said below, the study this is based on started in 1940. Hence the 'old-school' New England.

Even if it isn't, I don't think there is much meaningful distinction left among Americans of English and French ancestry. How many people would even notice?

Depends on the area. I think in parts of Maine where there's a strong Quebecois influence there's definitely a meaningful distinction. There's other areas, especially in rural communities, where a specific European country has a lingering overstated influence.

But within any major metro area you're right, there's typically little meaningful distinction anyone would pick up on between two Americans of different European ancestry.

I live in Maine. You are correct. They teach French in school, to everyone. Some areas have classes in French that are not specifically French learning classes. The majority of those living here without documentation are Canadians. If you get into cities like Lewiston, you'll find whole areas where French is commonly spoken.

It's kinda neat, actually. I am also a citizen of Canada, but don't speak French. It's fun to learn and be exposed to the culture, but I digress.

Certainly that's strongest in New England. But I don't know most people are French-Canadian unless they tell me (especially given that intermarriage is pretty common so surnames aren't a reliable guide).

> there's typically little meaningful distinction anyone would pick up on

We don't know. At least I don't. But it would hugely surprise me if we are not constantly picking up on all sorts of subtle gene expressions. And this needs not in any way be a conscious process. Sophisticated ability to suss out degrees of relatedness would be a far too useful feature not to have been selected for again and again and again.

I have two thoughts there:

1. Surely very high intermarriage rates between different European ethnicities complicate that.

2. In that case, wouldn't the opposite behavior be expected? If the goal were to have as little genetic variation as possible humans would be better off reproducing asexually.

> Surely very high intermarriage rates between different European ethnicities complicate that

Very high intermarriage rates? Wherever did you pick up such an idea?

> In that case, wouldn't the opposite behavior be expected? If the goal were to have as little genetic variation as possible humans would be better off reproducing asexually

There is no 'goal'. And too little variation seems to be a universally bad idea. It is a simple, observablke fact that most of us stick to partners reminiscent of ourselves. We may argue about the reasons, but the thing itself is clear and obvious.

Marriages between different ethnicities of white Americans are so commonplace they're not even considered interracial.

To my second point, the whole benefit of sexual reproduction is genetic diversity, so it's odd to have some evolutionarily dictated behavior pulling the opposite way.

Oh, Americans. I am European and took 'European ethnicities' to refer to actual Europeans. We don't mix all that much.

Well, yeah, there are a whole different set of circumstances there.

Agreed, and it's hard for me to see how you control ancestry or ethnic perfectly, since ethnicity is just a relatively stable form of genetic diversity.

I might counter-hypothesize that the 1% they found is just the amount of variance in ethnic group that wasn't controlled for perfectly.

> How did they control it? Even amongst Europeans, I imagine French people are just more likely to have French friends.

This study is in the US. By "people of european descent", they are referring to white americans rather than actual europeans.

Also french is a linguist/national/ethnic classification rather than a genetic one.

I have anecdotally noticed this with tall people and short people, I will notice a group of friends who are all 6'2"+, or who are all <=5'7", both of which seem statistically unlikely. There are plenty of more diverse groups (in terms of height) but its hard to say whether they are work friends or something else where you have less overall choice.

A few possible explanations:

* People who are statistical outliers tend to seek out similar outliers to form a support network.

* People who are involved in activities in which their physical size is pertinent (e.g. dancers in the Rockettes) tend to befriend others in those activities.

* If height affects success (whether or not that is warranted) and if friendships are stratified along success-based lines, then you might expect groups of friends to have similarities in height.

Also: One might be more likely to notice groups of mostly tall or mostly short people more than generic, mixed groups.

simple explanation is that normies are quite diverse and group together, which then leads to non-normies to group by traits.

and then studies happen and less normies take part in them.

My experience is short people mostly get ignored in an otherwise tall group.

And to take this further, outside of jr. high/high school, this ignoring is unintentional. I'm 5'7" which makes me tall among the shorts, but the number of times I've felt like I had to jump, to make sure other guys pay attention when I interject, is high.

Seated meetings/meetups are my friend.

I'm your same height and have never observed this. Frankly a lot of stuff I see online about supposed travails of being my height are bewildering to me.

I'm 5' 4".

I've generally found that in a professional setting, my height is not generally an issue.

However, if, at a bar, my height is considerably (>= 6-8") below the median of the people i'm hanging out with, interjection does require more effort than it does amongst those who are closer to my own height.

It may just be pure acoustics :P

[Edit: in case it isn't clear, this is in situations where everyone is standing]

It works the other way too. I'm relatively tall and when I'm in a loud crowded place hanging around shorter people I have no idea what they are saying to each other.

If you are a western and wants to experience this, go to some countries in SEA like Philippines or Indonesia. It could get really uncomfortable.

Tall friends could be explained from sports which are useful to be tall like basketball or volleyball teams.

I've had that thought too, I would say there is some validity to that explanation.

I think we have a tendency to form groups in which the individuals have roughly the same ability to beat each other up. It's a primitive mutual respect.

"The opposite pattern held for genes related to immunity -- friends tended to be less similar at those parts of the genome."

It would have been more accurate to title this article "Friends Are Genetically Similar in Some Ways and Different in Others" but I guess that would not have been as edgy.

EDIT: The overall trend reported is that friends are more genetically similar than would be expected, as pointed out by user Real_S. Good title, after all.

It would be interesting to cross-reference this with the genetic dissimilarity between enemies, but that's problematic for obvious reasons.

Yeah I agree the results would be interesting as well as hard to collect.

If I were to volunteer for this study, all of my 'enemies' (more just people I don't care for) would either be people who I haven't seen in forever because I don't want to associate with them or people that I see too often that I wouldn't want to bluntly declare as my enemy and deal with the consequences.

The study mentions the 1% similarity, which is the genetic equivalent of fourth cousins. That's fine, but isn't there a heavy correlation between DNA origin and geography, and another correlation between friendship and geography??

Also friendship and family are tied together. I would think they controlled for these things? I did not read the paper.

There was a book I read in the 1970's about "sociobiology" that explained this. If I remember right:

People share exactly 50% of their genes with their parents and children, but only probably 50% of genes with siblings -- it could be 51%, or could be 48%. To preserve their own genes, people will feel altruistic to give their lives for three of their siblings (about 150% of their own genes saved), but not for one sibling (only about 50% saved). People share between 90% to 110% of their genes with two siblings (I'm guessing the variance here), so will give their lives for two siblings they share 110% of their genes with, but not two they only share 90% with. The feeling of "liking a sibling as a friend" is the same as being willing to give one's live for them, so in today's age of large urban groups where friendship is a proxy for one's siblings in small tribes during the hunter-gatherer era, it follows people choose their friends because they share more than the average genetic material with them.

> People share exactly 50% of their genes with their parents and children, but only probably 50% of genes with siblings -- it could be 51%, or could be 48%.

I don't see why the percent shared could not be higher than 50% with your parents or children. You can share a gene with someone that you did not get it from or give it to. For example, suppose some particular gene has three variants, V1, V2, and V3. If your mother has V1/V2, and your father has V2/V3, the possible cases for you are V1/V2, V1/V3, V2/V2, and V2/V3.

In two of those cases you share 50% of that gene with each parent. In the other two cases you share 50% with one parent and 100% with the other parent.

What I wrote is what I got from reading the book a long time ago. Of course biology has advanced since the 1970's -- and of course my memory or understanding of it could be faulty because I read it as a teenager.

What you wrote might explain why parents have "favorite" children they're more likely to give their life for.

Could it have been E.O. Wilson's Sociobiology: The New Synthesis?


The two brothers/eight cousins idea goes back as far as Haldane regarding kin selection:

> No, but I would to save two brothers or eight cousins.


Wikiquote has that as quoted in 2007, but I'm not sure how far back he originally stated it.

The version I heard was "I would gladly give up my life for two brothers or eight cousins.". I much prefer it.

It's more succinct and stands alone (as opposed to the actual quote, which requires additional context), I agree. It's just not quote attributed to anyone in particular, as far as I know.

It doesn't follow at all because the vast majority of genetic diversity is not tangibly self evident from just being friends with someone. We all share the same number of genes with each other. The common differences are tiny single base changes. The vast majority of these are not phenotypic but neutral chamges that dont impact the products produced by your genes.

> Topping the list for common genes were those related to our sense of smell. One explanation for this is that people with similar olfactory genes will smell things in the same way and so be drawn to (or repulsed by) similar environments... The opposite pattern held for genes related to immunity -- friends tended to be less similar at those parts of the genome.

This makes me think of the thesis of "Sex At Dawn" by Christopher Ryan and Cacilda Jetha. If humans evolved as polyamorous foragers for whom communal bonds were more important than paternal certainty, then it makes sense that you want your friends to like the same environments and add immunological diversity to your shared gene pool.

The same is true of spouses, and in fact, the healthiest couples (or at least those with the most children) seem to be third or fourth cousins:

"Third Cousins Have Greatest Number Of Offspring, Data From Iceland Shows"


Not exactly what you'd expect given how often we see "hybrid vigor" touted as a purported benefit of interracial marriage.

Yeah, I think "hybrid vigor" is probably nonsense. However, interracial couples tend to be left-leaning, which also implies fewer children, so I don't think it makes sense to infer causality (or lack thereof) the way you are. Too many competing factors.

At a minimum, the study suggests that the fitness golden mean between inbreeding depression and outbreeding depression is actually much closer to the intraracial side of the spectrum than the interracial.

Basing this on the Framingham study doesn’t say much. We do know homophily is very common world-wide, but Boston in particular is extremely segregated. Out in the burbs it’ll be largely small pools of ethnic (European) groups. While the summary at least touches on this, it would totally flop in diverse areas like SF or NYC. Most of my friends are from all around the world — if they all still shared some genes in a way that was uncommon I’d be extremely surprised.

Reminds me of this: http://www.neatorama.com/2013/12/15/When-the-Actors-in-Plane...

Humans are still amazingly tribal creatures.

Anyone know if the genetic similarities that we become friends around according to the study aren't related to race? To me that would be the most interesting part (if it wasn't).

I am pretty sceptic about this study and it seems kind of filled with opportunity for interpretation and bias plus have no idea of the data set.

As other's have mentioned in this thread I believe the group under study were primarily, if not all, Europeans. So in that case in a sense the genetic similarites weren't related to race because race wasn't a variable.

But as far the relation of genetics and genetic similarities to race, all genetics are related to race.

In terms of the fact that a single Adenine molecule alone is fairly useless, it is only when that molecule is combined into the structure of a genome that it takes on meaning[0], and genomes have a race, so I don't think in that sense there are any genes or genetic similarities that aren't related to race.

Every member of a race is more genetically related to every other member of that race than they are to any member of any other race.

What "genetic similarities" could there be that are more similar across races than within races?

[0]"Meaning" at the level under discussion in terms of human relationships and whatnot.

I figured friends were more driven by proximity first then shared experiences second.

This is the rare study I'd be really interested to see repeated with college students.

The population used in this study was the population in the Framingham Heart Study, presumably because they had the DNA and friendship graph already lying around. But starting from a small town's population, you've got pre-existing social networks which will both influence the future genetics and the future social networks of the town. You could get a lot of confounding correlations like "you're more likely to be friends with someone you live nearby to and you're more likely to live nearby to people you are related to".

If you repeated this with college students you'd have friendships formed between people with few if any previous connections.

And don't we fall in love with people that are genetically different? Something about not liking the smell of relatives

Only in the genetically different immune systems as discussed in this article, otherwise opposites don't really attract. I don't think it would be that surprising to find similar results(maybe less, but still greater than random in terms of similarity) among married couples.

This seems to make the kin selection vs. group selection controversy even more trivial: https://blog.oup.com/2015/01/kin-group-selection-controversy...

Hmmm... As someone of sub-continental heritage, I have close friends from about 3 different ethnic groups. I have NO friends from my own cultural/regional heritage at all in 5 decades of walking this planet.

Does this mean that if you have similar experiences, then your genes change? I have found that experiencing things together forms friendships much more than genes.

Is it anymore likely that people with 1% genetic similarity have that connection randomly than the possibility they in fact share g-g-great-grandparents? i.e. 2 slots in the 32 level of their family tree, or what if they are double fifth cousins, sharing four slots at the 64 level?(is that math correct?)

So in effect for these similarities to present, they have to be cousins on some level right? Whether that is sharing N slots at the 2048 level, or some other combination?

In a sense all of humanity are cousins, and races are clusters with a higher coefficient of cousin-ness than the global average.

i found out recently that my lifelong best friend and i share a relatively uncommon paternal haplogroup, despite our families coming respectively from germany and scotland for the most part (the group is relatively prominent in frisia). anecdote, not data obviously, but i'm curious if anyone else has any similar experiences.

R-M405? Me too; but my paternal line hails from Venice. Seems our forebears scattered around.

friends are economically similar and how much money you make relative to the rest of the society depends almost entirely on how much money your parents made relative to the society. Wealth passes alongs genetic lines so does friendship.

what about emotional epigenetics ?

Having read "The Selfish Gene" I wasn't surprised. This study conclusion fits pretty well within the general theme of the book.

If you haven't read it yet, I highly recommend it!

Upvote for "The Selfish Gene". Should be mandatory for anyone interested in science and/or biology! A great eye opener about how evolution really works.

Definitely. And you shouldn't let the fact that it was written by Richard Dawkins scare you off if you have a negative opinion of him -- it has very little to do with his atheism.

Also the subject of atheism should itself not scare you off. It is quite a reasonable position to hold.

People need to realize we are built on hardware that is hundreds of millions of years old. We share a similar hormonal dominance hierarchy system with fucking lobsters. You can't just say it's </CURRENT YEAR> and expect these things to disappear. Tribalism was important for survival, trusting someone who didn't look like you could mean death and thus was selected for over long periods of time.

And then we became human and started not acting like lobsters.

We have intellects, a sense of morality, and a will. Those allow us to drastically curtail what might otherwise be instinctive behaviors.

I know there are some determinists who say that free will is illusory and we're as much slaves to our genetics and instincts as lobsters are.

But it certainly seems as if, in practice, tribalism (at least the clear-cut type you're describing where we exclude people who don't look like us) is recognizable and avoidable.

> We have intellects, a sense of morality, and a will. Those allow us to drastically curtail what might otherwise be instinctive behaviors.

An excerpt from Julian Jaynes's 'Origin of Consciousness' comes to mind here:

> Consciousness is a much smaller part of our mental life than we are conscious of, because we cannot be conscious of what we are not conscious of. How simple that is to say; how difficult to appreciate! It is like asking a flashlight in a dark room to search around for something that does not have any light shining upon it. The flashlight, since there is light in whatever direction it turns, would have to conclude that there is light everywhere. And so consciousness can seem to pervade all mentality when actually it does not.

There exist a great deal of subconscious processes that effect behavior in ways that an 'individual' cannot necessarily perceive. Often, a person does something, then post-hoc uses narratization to fit those actions within their preexisting belief system and story of themselves. The important thing to note is that your perception of yourself is not you, and the world you perceive around you is not the world itself. Both act as very helpful mental models that help you navigate your world effectively. As with all models, however, they have holes, and the really damaging ones are the ones you're not aware you're not aware of (as you cannot even adjust for those weaknesses).

Even though it's far from precise, I like Jonathan Haidt's suggestion in The Happiness Hypothesis that our conscious mind is like someone riding an elephant: He can nudge it in this direction or that, and a lot of the time that works. But if the elephant wants to go a different direction, it will, and you're just along for the ride. At which point you can acknowledge you're not in control, or decide where the elephant went is where you really wanted to go all along. Often we choose the latter to retain the illusion of control.

That a process is non-conscious does not necessitate that it is primitive or incapable of sophisticated inference and computation. Sophistication and conscious reportability are absolutely not anti-correlated. Indeed, if I were to lean one way, it would be against the things we consciously perceive as difficult, inferring from the Moravec Paradox.

Non-consciously accessible processes play an important role in our ability to reason, predict and control behavior in a manner Evolution could not anticipate. They are no less us.

One might go so far as to say that substance and sustenance of life dwells in those holes. I won't go so far, but someone (not me, of course) might.

Sure, of course we curtail these behaviors. It's uncharitable to read the parent comment as suggesting that we ignore our conscious, moral minds. I understood him as simply saying that the dogmatic belief in humans-as-blank-slates is going to keep being belied by the way humans act in practice, even those who have as much a claim to conscious morality as anyone else. Something as subtle as why you get along with someone and choose to keep seeing them isn't fully-specified, and whenever something isnt fully-specified, our lizard brains have a strong chance to fill in the gap.

In case you think I'm arguing against a strawman, the blank slate view is _extremely_ popular, and likely even more so in the circles that this commentariat likely run in.

Tribalism is harder to avoid than just recognizing it, much harder. I think you underappreciate how incredibly emotional irrational creatures we all are, and how much how we behave is informed by cognitive biases.

> But it certainly seems as if, in practice, tribalism (at least the clear-cut type you're describing where we exclude people who don't look like us) is recognizable and avoidable.

No, it doesn't. I don't know anyone that has come even close to escaping tribalism.

If you choose friends who share values with you, "tribes" will naturally self segregate based on those values. Is that really so bad?

I, uh, do not see what that has to do with your friends being genetically similar.

If one considers that the conservative vs. liberal spectrum in America has a statistically significant genetic [0] why would it not?

[0] - Jonathan Haidt's "The Righteous Mind"

I have not found little correlation between sharing my values and phenotypes, and short of DNA testing my friends that's all I have to go on.

Further, while there may be a correlation, it's far from deterministic. Experiences count for a lot in developing values.

We aren't blank slates. Genes inform a lot about who we are.

That vague truism doesn't seem like enough to justify racially- or otherwise genetically-based separatism to me.

The fact that you can't discern between justifying racism and pointing out that racism comes from deep seated biological impulses is pretty scary

How else am I supposed to interpret "is that really so bad?" besides justification?

You quoted me but I actually didn't say anything about race or genetics. My original response was to the parent which was claiming that "tribalism is avoidable" and I was arguing against that saying that humans will always self-segregate into tribes so it's unavoidable.


- I had a friendship which originally started over shared nostalgia for a cantonese children show

- I was excluded from a group because I didn't know enough american pop culture references to get their jokes

- I stopped eating dinner with another group because I felt awkward being the only one not praying before the meal

- In another group, we only ever talked about programming puzzles and non-programmer friends (such as their girlfriends) learned quickly to leave us alone

All of these groups came together and/or left each other due to unwritten emergent social dynamics. You can never stop these clusters from forming. As long as you have groups/tribes, there will be people excluded based on the that tribe's values. Is that really so bad?

Hm, well, I don't know that I'd call those "tribes," and I (reasonably, I thought) interpreted "tribalism" to be ethnic or racial based on it appearing in a discussion of "Friends Are Genetically Similar."

Tribalism is sometimes used as a descriptor for general in-group/out-group behavior as well.

Yeah, of course that is true, but I was making what I thought was a reasonable reading in context. It seems like the OP is describing something more like groups of friends; you can't really be a member of multiple tribes, necessarily.

> And then we became human and started not acting like lobsters.

Thank you for saying this.

As history has shown, it's only too easy to take a scientific research paper and draw some godawful conclusions from it.

We can - and must - do better.

Drawing your argument to its logical conclusion, those that act on such impulses based on their genetics and instincts are less evolved than those who don't.

Sounds like something a plantation owner from the antebellum south would agree with.

Now obviously anti-racism isn't "the real racism", but I think it's kind of funny that many commentators here seem to think that by defining certain sects of people based on cherry picked attributes will somehow prove that we've moved beyond the biological impulses of discrimination.

It seems 'evolved' means whatever people want it to mean very early on into these types of discussion. Usually there's a notion floating around of 'more- or less-evolved' that's not very well thought-through. And often this kind of muddying is committed alongside wishful thinking in the first place ('Despite science, I am free will incarnate; it is that which separates man from beast, nobles from savages, wealthy from beggars!').

There are no moral imperatives to be found in genes or epigenetics, only moral factors. Hume's observation about is -> ought is as pressing as ever, despite what Sam Harris might have you think. It's particularly dangerous to believe the former is true, since we make such a habit of expanding and distorting the scope of empirical results to ideological fantasy-land near instantly.

Whether we tightly and uniformly prefer genetically similar friends, whether we conversely happen to like genetically diverse mates, or whether all of these are more generally attendant to environmental factors like diet and disease -- it remains that we can collaboratively use reason to decide on our 'oughts', not just pick the interpretation and scope of 'is' that we prefer at the time. Issues of justice and responsibility seem much more interesting than endlessly turning the wheel of sciencey-tribalism. We struggle enough to figure out how best to treat each other already.

I'm not so sure, as it seems anti-tribalism can become it's own tribe.

Even if we stop all overt biases, there is plenty of sub-conscious bias that is impossible to recognize as the personal level because of how small the effect is verses the sample size (and how poor we are at doing mental statistics). Until we get to the point that we have personal AIs letting us know every time we begin to favor in-groups slightly more than out-groups, there isn't the ability to correct for this.

You are on a cocktail party. Have had a few drinks with friends. You all start talking about spiders. How they are these wonderful tiny creatures to be protected. You know, they got rid of insects and it's actually good to be above this. After all we have intellects, a sense of morality, and a will. We're not some freaking lobsters driven by phobias. And you know what? At this wonderful evening party, we all agree, that this is just the case. And then we all go home. Where, right after opening the door, you see this diguisting, big spider crawling on the floor. Without thinking twice you crash it with your shoe. And then -- using toilet paper perhaps -- pick up its remains and flush it in the toilet. Just to be sure that the motherfucker is really dead. Not to mention your 3 year old and 5 year old living in this house. And then, then, you realize. What happened? Just talked about it an hour ago. And then I got rid of this poor bastard anyway...

In a social setting, with people around having conversations, your brain cortex fires off. It's spinning like crazy. And the cortex is all about logic. It's all about intellect, a sense of morality, about a will, and group hierarchy, and talking, and relaxation. You get the picture. When the phobia kicks in... guess what... the first thing that will happen is that cortisol will turn off your cortex. In the stressful situation, in fight or run situation, your cortex is switched off brother. That's why this spider is dead. That's why after 30 years of perfect marriage you might do stupid things when 23 year old hot blonde is sexually provoking you. That's why live isn't white and black. Even in 2017.

Or, like my father-in-law, you go and grab a paper towel, pick up the spider, and let it go outside on front lawn. I have never seen him kill a spider. And some percentage of the time, more and more with each passing year, even though I am terrified of spiders, I don't kill them because of conversations like the one you describe.

Just because some people react with their emotion doesn't mean everyone does and it doesn't mean we have to.

This depends on your up-rising for the most part. When I was very young, there was this spider that had its house below my small desk. I grew up accustomed to these spiders and didn't allow my mother to clean them up.

Now, I don't fear spiders and also don't mind them as long as they don't wreak the place with their filaments. I was surprised when a cousin of mine was freaked out by one of them and wanted to insta-kill it.

Now if there is a bug... that's a whole different story. Even though, logically thinking, these beasts are the same.

>I have never seen him kill a spider.

Given how many spiders are only inside or only outside spiders, you basically just said you seen him sending the spiders to their death. The person smashing the spider isn't much different than the person putting it outside.

Not the best source, but a good starting point: https://www.livescience.com/48479-spider-myths-busted.html

>Just because some people react with their emotion doesn't mean everyone does and it doesn't mean we have to.

And yet consider the example you gave in light of the current body of evidence.

Most serious people who talk about preserving insects and arachnids do so because these animals provide the feed-stock for other animal populations, similar to plankton in the oceans, and they are an indicator of the health of an ecosystem, not because they are taken with their appearance (although of course some people do genuinely love their appearance).

One can easily espouse something like that while not wanting a big spider scurrying around in your house. Also, plenty of people (myself included) escort such spiders outside alive instead of smashing them, not the least because I don't want to smear their guts everywhere, creating more work.

After the phobia kicks in, after the threat is neutralized, I encourage you to thoughtfully consider not wasting a flush to dispose of the dead spider/toilet paper combo.

> That's why after 30 years of perfect marriage you might do stupid things when 23 year old hot blonde is sexually provoking you.

How is that not logical? Spreading your genes to healthy young women seems like a straightforward choice.

It might be beneficial to the propagation of your genes and still really bad for your personal life.

If spreading your genes is your only goal in life, sure.

> That's why after 30 years of perfect marriage you might do stupid things when 23 year old hot blonde is sexually provoking you.

Actually you have to make a number of conscious decisions to have an affair. "It just happened" is an excuse.

Nobody said that. They're saying you cannot reason yourself out of your boner. Just that the impulse will always be there, I just choose to ignore it.

My reading of the post above yours, in the context of the conversation it appears in, is that you cannot overcome your instincts so there's no point in even trying to rein them in. If it just means to say we don't live up to our ideals all the time, well, OK, that's true, but I don't see where it's going.

Yes, but its hard work- and maybe that hard work is not always worth the effort.

So instead of doing hard work, we decided to make tools to circumvent the bugs, for example by avoiding buggy routine executing personal communication - and instead discuss that paper online.

Work with the smart, no matter what skin colour, instead of doing the PC-Dance.

>...trusting someone who didn't look like you could mean death...

If you read the article, it's actually not at all about people looking the same.

In the study, people had friends with similar smell genetics, and different immunity system genetics.

You understand genetic similarity does not mean you look similar or come from the same tribe necessarily? Especially since the age of heavier than air flying machines.

You understand genetic similarity does not mean you look similar or come from the same tribe necessarily?

That's exactly what it means. Knowing what we know about sexual reproduction and trait heredity what else could it mean? It's not like half your genome spontaneously arises in a zygote in some random location half way around the world.

Evolution doesn't move fast enough for any technology to be relevant to the discussion of how this works.

You've confused kin selection with kin discrimination. The idea "because friends are genetically similar, an individual with the opposite genotype at a specific allele poses a bigger threat to your survival/fitness than someone with the same genotype at that allele."


> formal analysis has shown that selection for group adaptations requires special circumstances, with negligible within group selection (Fig. 4), such as when (a) the group is composed of genetically identical individuals (clonal groups, r=1), or (b) there is complete repression of competition between groups (i.e., no conflict within groups; Gardner & Grafen, 2009). It is useful here to distinguish adaptation and design from dynamics of how selection leads to design. The dynamics of selection can be examined with either an individual (inclusive fitness or kin selection) or group selection approach. However, only the individual level approach provides a general model of adaptation. The idea that individuals strive to maximise their inclusive fitness holds irrespective of the intensity of selection operating within and between groups (Section 2; Fig. 4). In contrast, as discussed above, group adaptations or maximization of fitness at the group level are only expected in the extreme case where there is no within group selection.

I really doubt your view is consistent with the conditions for selection in the group. If non-tribe-member competition caused significant competition between groups, then it far outweighs the pressure of in-group adaptation. If "friends are genetically similar" is a genetic adaptation from tribalism, then it has to be an enhancement from within the group when it lacks competition - you benefit from the adaptation relative to people within your tribe that don't have it. FYI the paper disagrees with the notion that friend similarity is likely a result of decision.

Personally I think that 1% relative similarity could easily be explained in the ambiguous language they use to explain why it was "mostly" homogenously European - why would it surprise me that the non-Europeans would tend to have less DNA in common with the friends they have while also likely having fewer friends per capita?

Though, possibly, because the most likely to be similar SNPs were related to smell (and therefore taste), and to linoleic acid, maybe it reaffirms that people who break you bread are your companions - and that there is a real difference between butter cultures and olive oil cultures :P

[0] https://www.zoo.ox.ac.uk/group/west/pdf/WestElMoudenGardner_...

Adultery and murder have happened in just about every human society in the history of time but nobody thinks we shouldn't bother trying to suppress those impulses.

When murdering someone or cheating on your partner, you probably have a lot more time to second-guess your motives. When subconsciously judging a passer-by, you don't. In my case at least, they are long gone before I even realise that I've judged someone.

Yeah, but that's more akin to fantasizing about someone. Actually committing adultery is more akin to, say, refusing renters based on their race.

I don't think you could ever make an argument that murder is good, but tribes have their benefits. For example, we know that homogenous societies have less conflict, a greater sense of community, and higher social trust.

So do smaller towns, but that doesn't seem to stop people from advocating urbanization here.

Urbanization doesn't necessarily regress the issues I'm talking about, especially since cities can still have their own neighborhood and block communities.

Urbanization isn't unnatural and it agrees with our tribal instincts.

Look at Tokyo: extremely high density with extremely small social unrest. Paris, now a collection of different tribes, can't say the same.

Is that the only thing that's different about Tokyo and Paris? Beijing is over 95% Han Chinese and yet I don't think things look as harmonious.

On another note, I think Japan ends up with kind of a distorted picture since so much of the crime is associated with organized criminal groups with ties to legitimate business and government operating with a degree of openness that I think would surprise most Western observers. Dubro's Yakuza book is a great primer on the topic.

>Is that the only thing that's different about Tokyo and Paris?

I'm not claiming that. I am claiming that multiculturalism plays a role, which many people refuse to acknowledge.

I don't think the role is as significant as you are claiming.

Adultery has become vastly more socially acceptable. It isn't considered nice, but it doesn't get you killed anymore.

And for murder, that can be a bit of a tautology as socially unacceptable killing is murder and anything else isn't considered on the same level as murder. But if we consider killing that isn't considered murder and if you consider forms of killing that, if not legal, are punished lighter than murder, it becomes clear that our society does allow some forms of killing others.

Does this kind of nitpicking actually invalidate the argument? Use sexual assault if you prefer. The point is that a behavior being natural or instinctual doesn't make it moral or desirable.

>Does this kind of nitpicking actually invalidate the argument?

It does if there are enough nitpicks showing that natural behaviors are becoming more accepted because they are natural. That isn't to say they are acceptable, but they are more accepted. And this doesn't have to be true of all behaviors, because there are many factors at play. It is even possible there could be a trend where behaviors are becoming more acceptable because they are natural even if all behaviors were becoming less acceptable, if there was another stronger force acting to make all behaviors less acceptable.

But if we want to get to the actual argument first presented, we would have to realize that comparing it to murder, adultery, or sexual assault is a strawman to begin with. The OP wasn't defending going around and murdering people who didn't look like you. They were saying that millions of years of evolution will influence our behaviors in small ways. It would be compared to other preferences, such as preferences in intimate partners. So, is wanting to have a specific gender, race, etc. in an intimate partner wrong? Is it socially unacceptable?

This is a philosophical question as much as anything else, but I believe that, whether we are successful in perceiving it or not, there is such a thing as objective right and wrong as distinct from social acceptability. I'm hesitant to say anything about how people should pick romantic partners, but it seems to me as though that is actually rather considerably narrowing the scope of what we're talking about. I do think it is wrong to intentionally seek to form an ethnically homogenous group of friends and associates.

Most of us would agree with you, I think what OP is saying is that it's irrational to say things like "It's 2017, who murders people anymore!?". People still murder, but we should definitely continue to try suppress that behavior.

Usually a post like the OP's is a lead-in to an argument about why discrimination is actually fine and shouldn't be fought, so I guess I let my previous experiences get ahead of what the post actually says.

It's more nuanced than that though. The question is where to draw the line about which behaviors are bad and which ones aren't. Things like murder are obviously bad in most cases and should be suppressed, but social structures are not so clear cut. If there aren't any clear consequences to a instinctual behavior then it's probably better to not suppress it.

There are lots of clear consequences to "tribalist" behavior, especially if we mean the obvious example of racism.

Depends on the behavior and even the consequences are not as "clear" as you make it sound because reactions to behavior can be rather subjective. Context actually matters even tho it's too often ignored these days in favor of generating drama.

It's a factor way too often ignored with this issue: If "hurting people's feelings" will become a crime, then we will see no end of regulating "undesired behaviors" because people get their feelings hurt in the most subjective and unintended ways [0].

So much about "obvious examples of racism".

[0] http://thedmonline.com/greek-life-retreat-ends-abruptly-bias...

Redlining. School segregation. Unequal economic opportunity. Disproportionate use of force in encounters with police. You get the picture. These are all negative effects of racism.

there are countless facets to tribalism, and racism doesn't have to be one of them. But in any case my point is more general in nature and not about tribalism.

It's really hard for me to see how you can treat "genetically similar tribes" and races as unrelated concepts.

The concept of races and racism are completely orthogonal.

Well, that isn't really true, since the conception of what races exist and who belongs to which shows wide cultural variation.

More to the point, though, racism is an obvious manifestation of the kind of tribalism I think we are talking about and I don't think it's really controversial to argue that it is harmful at least to the marginalized groups. I'd personally even go further and say it harms all parties involved.

Am I the only one not seeing the adultery/murder connection here?

If it is true, as is often claimed, that racism is universal and therefore fighting it is pointless or should not be done, then the same should be true of other universally-occurring antisocial behaviors.

Aha. Several non obvious steps there for me :)

What does this say about racism? Segregation?

The article specifically mentions olfactory similarities being pro-friend and immune differences being pro-friend. It didn't mention ethnic markers like melanin, face shape, nose width, ear size, or relative toe length at all. In fact, it said they attempted to control for racial and ethnic differences. How well that was accomplished wasn't really made clear in the article.

I can imagine that whether or not cilantro tastes like soap, whether or not you love the smell of books, similar allergies, and if you can stand to eat spicy foods goes a long way toward the likelihood of friendship. There are bound to be social factors, geographic factors, and other factors. This study is just pointing out that friends are likely to be more similar in certain ways than people who aren't friends. Don't jump to too many conclusions on just the summary article about the study.

Nothing at all.

> They examined [polymorphisms from] 2,000 people and correlated their similarity within the roughly 1,400 pairs of friends within the group.

>the Framingham data is relatively homogeneous in terms of ethnicity, consisting largely of people of European descent.

The population they studied seems very close knit and ethnically homogeneous, and the study's inferences are conditioned on this sort of population.

Presumably the consistent background genetics of the population allowed them to control for larger genetic differences and detect the subtle differences correlated with friendships in the group.

I would be surprised if the observed effect held up in a more cosmopolitan population where other stronger factors, both genetic and sociocultural, have more of influence in the formation of friendships. And, as others have noted, the observed effect was real, but very small.

I think it means people have a natural genetic preference for similar genetics. It does not say whether or not we can overcome this preference as a society.

Not much at all. It's a small effect.

Segregation bad when its enforced by the government. There's a big difference from "White people like to talk with white people", and "White people only beyond this point" (with Police Officers on standby ready to enforce said rule)

Birds of a feather, no?

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