[Credit for horizontally transmitting these ideas to my brain goes mostly to Jennifer RM, except for the bits at the end about Bowling Alone and The Moral Economy. Apologies to Jennifer for further horizontally spreading.]

Vertical/Horizontal Transmission

The concept of vertical and horizontal transmission felt like a big upgrade in my ability to think about cooperative/noncooperative behavior in practice. The basic idea is to distinguish between symbiotes that are passed on primarily along genetic lines, vs symbiotes which are passed on primarily between unrelated organisms. A symbiote which is vertically transmitted is very likely to be helpful, whereas a symbiote which is horizontally transmitted is very likely to be harmful. (Remember that in biology, "symbiote" means any kind of close relationship between different organisms; symbiosis which is useful to both organisms is mutualistic, while symbiosis which is useful to one but harmful to another is parasitic.) (This is discussed here on LW in Martin Sustrik's Coordination Problems in Evolution.)

We can obviously generalize this quite a bit. 

  • Infectious diseases tend to be more deadly the higher their transmission rate is. (Diseases with a low transmission rate need to keep their hosts relatively healthy in order to make contact with other potential hosts.)
  • Memes which spread vertically are more likely to be beneficial to humans than memes which spread horizontally (at least, beneficial to those human's genes). Religions which are passed through family lines have an incentive to encourage big families, and include ideas which promote healthy, wealthy, sustainable living. Religions which spread primarily to unrelated people have a greater incentive to exploit those people, squeezing every last drop of proselytization out of them.
  • Long-term interactions between humans are more likely to be mutualistic, while short-term interactions are more likely to be predatory.
  • In general, cooperative behavior is more likely to arise in iterated games; moreso the more iterations there are, and the more probable continued iteration is.

Vertical transmission is just a highly iterated game between the genes of the host and the genes of the symbiote. 

Horizontal Transmission Abounds

Wait, but... horizontal transmission appears to be the norm all over the place, including some of the things I hold most dear!

  • Religion and tradition tend to favor vertical transmission, while science, education, and reason favor horizontal transmission.
  • Free-market economies seem to favor a whole lot of single-shot interactions, rather than the time-tested iterated relationships which would be more common in earlier economies.
    • To this day, small-town culture favors more highly iterated relationships, whereas big-city culture favors low-iteration. (I've had a decent amount of experience with small-town culture, and a common sentiment is that you have to live somewhere for 20 years before people trust you and treat you as a full member of the community.)

Paradox One: A lot of good things seem to have a horizontal transfer structure. Some things which I tend to regard with more suspicion have a vertical flavor.

Horizontal Transmission Seems Wonderful

  • The ability to travel easily from community to community allows a person to find the work, cultural environment, and set of friends that's right for them.
  • Similarly, the ability to work remotely can be a huge boon, by allowing separate selection of workplace and living environment.
  • The first thing I want to do when I hear that vertically-transmitted religion has beneficial memes is to try and get more of those memes for myself!
  • Similarly, I've read that many bacteria have the ability to pick up loose genetic material from their environment, and incorporate it into their own genes. (See horizontal gene transfer.) This can be beneficial if those genes are from organisms adapted to the local environment.

Paradox Two: In an environment where horizontal transfer is rare, opening things up for more horizontal transfer is usually pretty great. But an open environment gives rise to bad dynamics which incentivize closing down.

If you're in a world where people only ever trade with highly iterated partners, there is probably a lot of low-hanging fruit to be had from trading with a large number of untrusted partners. You could arbitrage price differences, get goods from areas where they're abundant to areas where they're scarce, and generally make a big profit while legitimately helping a lot of people. All for the low price of opening up trade a little bit.

But this threatens the environment of trust and goodwill that you're relying on. An environment with more free trade is one with more scammers, inferior goods, and outright thieves.

YouTube is great for learning things, but it's also full of absolutely terrible demonstration videos which purport to teach you some skill, but instead offer absurd and underdeveloped techniques (these videos are often called "lifehacks" for some reason, if you're unfamiliar with the phenomenon and want to search for it). The videos are being optimized for transmission rather than usefulness. Acquiring useful information requires prudent optimization against this.

Social Capital

Social Capital is, roughly, the amount of trust you have within a group. Bowling Alone is a book which researches America's decline in social capital over the course of the 1900s. Trust in the goodwill of strangers took a dramatic dive over that time period, with corresponding negative consequences (EG, the decline in hitchhiking, the rise of helicopter parenting). 

You might think this is due to the increasingly "horizontal" environment. More travel, more free-market capitalism, bigger cities, the decline of small towns; more horizontal spread of memes, by print, radio, television, and internet; more science and education. 

And you might be right.

But, counterpoint:

Paradox Three: Free-market societies have higher social capital. Citation: The Moral Economy, Samuel Bowles. 

More generally: a lot of things are a lot better than naive horizontal/vertical thinking would suggest. I've already mentioned that a lot of the things I hold dear seem to have a pretty horizontal transmission model. I don't think that's just because I've been taken over by virulent memes.

By the way, my favorite explanation of the decline in social capital over the 1900s is this: there was, for some reason, a huge burst of club-making in the late 1800s, which continued into the early 1900s. These clubs were often very civically active, contributing to a common perception that everyone cooperates together to improve society. This culminated in an extremely high degree of social capital in "The Greatest Generation" -- however, that generation was already starting to forget the club-making/club-attending culture which had fuelled the increase in social capital. Television ultimately killed or put the damper on the clubs, because most people wanted to catch their favorite shows in the evening rather than go out. Social capital gradually declined from then on.

(But, doubtless, there was more going on than just this, and I have no idea how big a factor club culture really plays.)


  1. Why do so many good things have horizontal transmission structures?
  2. How should we think about horizontal transmission, normatively? Specifically, "paradox two" is an argument that horizontal-transmission practices, while enticing, can "burn the commons" of collective goodwill by opening up things for predatory/parasitic dynamics. Yet the conclusion seems severe and counterintuitive.
  3. Why do free-market societies have higher social capital? How can this be fit into a larger picture in which horizontal transmission structures / few-shot interactions incentivize less cooperative strategies?


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1. Why do so many good things have horizontal transmission structures?

Memetic horizontal transmission that is mediated by human normative judgement routes around this filter... in some manner. Maybe they are slightly hacking your perceptions of goodness? Also, maybe these filters improve things some.

Far be it from me to claim that modern horizontally transmitted cultural ideas are bad. I would never...

However... between 1800 and 1950 it would have seemed to little children that smoking was terrible, but then if their peers smoke, smoking starts to seem like a way to minimize the disgust, and shortly it begins to seem pretty great, and this becomes the widely shared common wisdom among adults in a society with very high smoking rates. With smoking there was careful centralized analysis, with data collection, and peer review, and careful reasoning about causal models. Eventually we figured out: nope. I can tell you a story about how my mom stopped smoking when I was a kid, and then my brother and I copied her by not starting.

I would argue that "good careful reasoning" is the exception that proves the rule in some sense, because lots of so-called Official Science(!) is pretty shit (parts of tongues that taste different things? wtf? is it all just gossip? when did academia give up on "nullius in verba"?) and the good stuff tends to be invented by a TINY group of people and spreads via *baroquely* cautious transmission patterns.

2. The conclusion seems severe and counterintuitive...

In memetics, this is what trusted priests or scholars are an attempted patch on, I think? I'm sorry. I don't know any good news here.

Biologically, viruses prey on bacteria. Both are made of nucleic acid but some nucleic acid content is aligned with the protein inside the membrane... and some isn't. The "better" viruses are prophages (integrating with the genome and conferring useful phenotypes)... but often they go lytic eventually... and then the infected bacteria's daughter's daughter's daugher's daughters have a regret-worthy outcome.

If people have lots of unprotected sex, a venereal disease eventually finds the niche created by that aggregate behavior. If people fly around in airplanes while sneezing on each other, an aerosolized disease eventually finds that niche. If people drink from a river downstream of where other people poop in the river (especially if some of the the drinkers then travel back upstream), cholera happens. When you feed cows to cows, prions grow exponentially and eventually there's mad cow disease. If elementary school teachers who have never been outside of the school system teach school children who become teachers who teach children who become teachers... You will end up with the curricular equivalent of bovine spongiform encephalopathy.

How long until twitter collapses? Has twitter died already? I'm sorry. The circle of life is best when it circles very VERY widely. Gotta turn it to mulch. Then have fungus eat it. Then let the fungus dry out in direct sun for two years. Then use it CAREFULLY. It makes me sad, but I think it is true. Do not recycle "vital" things!

3. What about The Moral Economy by Samuel Bowles?

I have not read the book you cite. I want to defy the data. I would suggest that high social capital causes prosperity and enables trusted third party mediation, then, because people socially trust the third party mediators, it enables quick interactions based on shared traditions (that affirm trust and that often rely on deeper "trust rails" go back decades or often centuries (often literally to shared ancestors)). This could cause correlations in single temporal snapshots of data. Massaging such snapshots in modern academic writing, people have an incentive to tell happy lies in public like "prosperity causes social capital". The traditional theories here (and the long term economic demography), suggest to me that great wealth is generally squandered by the fourth generation, so the data collection I'd like to see would span 6 generations over various cultural cross-sections, or else it would span maybe like 10 generations (to hopefully see two full cycles)? I would love to be wrong about this, but my priors are strong enough that I want to see very very rigorous data collection methods as part of the presentation of why my priors here should be weakened. Maybe writing a rigorous book review of the contents of The Moral Economy would be virtuous!

If there was a key countervailing idea here, for me it is "acceleration itself". Progress. The increase in the number of humans, and per capita energy use, and humane culture-making activities. Old functional things are being copied and the "oomph" has not burned out... yet! :-)

0. Where did this theory come from and is it horizontal or vertical itself?

I'm going to assume you asked this, and answer it! I invented the theory, basically.

The geminating idea is: Dawkins is just wrong. He used to go around constantly dunking on TRADITIONAL religion about how it was a virus, and he was just... wrong. Many many many generations of shared co-evolution often tames parasites by aligning them deeply with more "metabolic" vertical replicators. Mitochondria are tamed bacterial parasites. The V(D)J combinatorial immune system is a tamed viral parasite. Endosymbiosis is a thing, but it works in a certain way.

Tiny fast evolving things (like cults) are sources of novelty, and larger slower things (like 1000 year old civilizations with old co-evolved religions) must tame them, or be devoured. Novel horizontal culture is often pretty bad. I have extended this theory in various conversational domains going back maybe 15 years to before the launch of Overcoming Bias but it always seemed gauche (and inconsistent with the theory itself) to bring it up ONLINE in a community deeply built around "the rejection of the supernatural mumbo-jumbo of one's parents".

I have talked about the importance of vertically transmitted ideas with my parents (who are themselves second generation atraditionalists), and they roll their eyes, but are happy enough to tolerate my antics when I "larp" "filial piety". In the meantime, filial piety occurs in many religions. The Abrahamic injunction is obvious. If Confucianism has ONE PUNCH, that punch is arguably "filial piety". I have purposefully not talked about horizontal meme transmission where Google can see, but if that goal is to fail at horizontal at this particular historical junction during a horizontally transmitted global plague then I guess I'm ok with it? Naturally it would be better if my children could teach the theory "as taught by their mother" (me), but they do not exist (yet?), and so they can't.

(I would not strongly object if you deleted this post before it can be seen by Google and generally become less of a vertical meme and more of a horizontal meme... Evangelism just seems mildly evil to me, but I'm not evangelical about evangelism being bad... because that would kinda defeat the point? My interest here is mostly... credit assignment I guess? I'm a HUGE fan of thinking about The Credit Assignment Problem. If I have done wrongly, or well, then it seems generally proper that I be credited as having done wrongly or well. Similarly for you. Similarly for all choice-making beings.)

Why do free-market societies have higher social capital? How can this be fit into a larger picture in which horizontal transmission structures / few-shot interactions incentivize less cooperative strategies?

You mentioned that in small-town culture, there's a lot of iterated interaction, but people are slow to trust outsiders. That seems to suggest that there's high social capital within a small group, but low social capital with outsiders. As small-towners will prefer to only interact with people who are known to be trustworthy, they will not have the opportunity to come to trust outsiders in general.

In contrast, if you live in a large market economy where your social environment incentivizes few-shot interaction and most people turn out to cooperate even in few-shot interactions (possibly because their brains are still running strategies that were evolved for iterated interaction), then you will learn that most people are generally reliable. While you might never develop the level of extreme high trust with a few select people that you'd get in a small town, you will have much more trust for random strangers than the small-towners would. That might translate to higher social capital overall.

  1. Why do so many good things have horizontal transmission structures?

I think the key to this is that while vertical transmission is more likely to be aligned, it is aligned with reproductive fitness in particular, which only partially matches the rest of what we value. Whereas horizontal transmission can come with an aligned, human-chosen filter attached. If I accept ideas from random unvetted sources, they will be optimized for transmission by that medium; if I want ideas that will make me a good thinker, and I have some ability to identify who the previous generation's good thinkers are, then I can selectively copy ideas from them, and they will be selected for that. (And if I succeed at becoming a recognizably good thinker, then future people may similarly copy ideas from me, and so on.)

(This kind of horizontal transmission is vulnerable to being taken over by fakes; if I lose the ability to distinguish who the good thinkers are, and start copying ideas from the wrong sources, then I'm back to the bad version of horizontal transmission in which ideas are selected mainly for virality, which in this case means memes that will turn me into a convincing faker.)

2. How should we think about horizontal transmission, normatively? Specifically, "paradox two" is an argument that horizontal-transmission practices, while enticing, can "burn the commons" of collective goodwill by opening up things for predatory/parasitic dynamics. Yet the conclusion seems severe and counterintuitive.

[Earlier in post:] The videos are being optimized for transmission rather than usefulness. Acquiring useful information requires prudent optimization against this.

It seems to me that the point where the damage is done is when someone signal boosts or retransmits the retransmission-optimized-low-quality information without doing this sort of prudent optimization. The more discriminating people are in what they signal boost, the more horizontal transmission becomes okay, both globally and within a particular information bubble.

This implies that the norms should be different in different groups, based on their inclination and ability to vet information before retransmitting it. Ie, most average people shouldn't be choosing their reading material based on what their friends chose to signal boost, because they have undiscriminating friends, but intellectuals with curated follow lists can probably get away with this.

  1. Why do so many good things have horizontal transmission structures?

A free market isn't a lawless jungle of arbitrary one-shot interactions. It's an engineered game where participants can't be forced into deals and should keep promises. That pushes the great mass of interactions away from "predatory" and toward "positive-sum".

-- cousin_it, in a comment to this post

There are many ways to help create cooperative rather than competitive outcomes -- vertical/horizontal is not the whole picture. Reputation networks achieve the same results as iteration, even if all interactions are basically one-shot. Enforcement mechanisms enable cooperation in one-shot scenarios. Many things which are apparently massively horizontal use these tools to mitigate virality.

1a. Information is almost as good as iteration. 

In a reputation network, you get to know about a potential interaction partner before interacting with them. This is useful for predicting them. Also, you know that if the interaction goes sour, you can reduce their reputation. This gives them an incentive to keep everything cooperative. (And likewise, gives you a similar incentive.)

At least in America, such reputation networks have been formalized in the credit bureau, as well as various other institutions such as Amazon seller ratings.

We can also talk more generally about getting information, not necessarily through an overt reputation network. Background checks, consumer reports, product reviews, ... (OK, you can technically think of all of that as reputation networks in a sense...)

In modern capitalism, you don't just encounter random people trying to sell things you've never heard before. You have quite a bit of information about products. Granted, not really enough information. (It's very difficult to evaluate what's really healthy, since the state of the research is often poor and difficult to evaluate. Making a food product is a complex affair which can't really be summarized by a list of ingredients and nutrition information. And so on.) But some information.

In science, obviously, information is the whole name of the game. Yes, there are problems. Serious problems. But a priori it's not clear whether we should expect "virulent meme" type problems in a scientific environment. There's a ton of horizontal transmission, but it's in a context where carefully vetting ideas is the whole project.

Education is another matter. You do get some rough information in the form of graduate employment statistics. However, there's a real information asymmetry problem. It's difficult to evaluate the quality of education if you don't know the stuff yet. You could rely on the assessment of experts, but this really doesn't alleviate the horizontal transmission concern; it's like asking smokers whether smoking is good.

1b. Enforcement mechanisms.

Free-market economies rely on a lot of enforceable contracts, as well as criminal law which disincentives general bad behavior.

Obviously, this only goes so far in eliminating "predatory" behavior.

2. How should we think about horizontal transmission, normatively?

Horizontal transmission can create hugely harmful dynamics. If we are in a position to "open things up", encouraging more horizontal transmission, we should think very carefully about this. Just because there is currently little evidence of predatory behavior (or virulent memes, etc) does not mean there won't be more in the future, if the incentives tip in their favor.

However, we're rarely in such a position. Most people/organizations have their own "immune system" which we would have to get around in order to "open things up" on a large scale.

In which case, how we would push to "open things up" would be to provide more mechanisms allowing for confidence in the robust goodness of interactions. Better reputation networks to enable bad actors to be filtered out. Better commitment mechanisms to ensure positive interactions. And other such things. Providing these will naturally "open things up" as people recognize that they can have safe interactions, allowing the fruits of horizontal transmission to be safely reaped.

However, I think this is far from providing a full answer to the question.

  • How should we think about open borders, or other mobility issues? Would the world be better in a significant sense if less people left their hometowns to work elsewhere? Or just the opposite?
  • How should we adjust the standard economic ideas about free international trade (IE: the standard argument that it should be a free-for-all)? Does the horizontal/vertical idea provide any significant argument against this?
  • To what degree should we really be careful of horizontally transmitted memes, and to what degree should we think that horizontally transmitting memes is bad? Jennifer RM seems to suggest a very significant degree of caution.

One more random thought. Exposing yourself for ideas from someone is much less risk than exposing yourself materially to him. But our trust has evolved for material interactions and there used to be an overkill of it for information interactions.

The replication crisis of science is a good example of how current way of 'horizontal spread mode of good things' reaches its limits and needs a correction mechanism. The question is if the correction mechanism can spread horizontally or if it can only come vertically. If we can understand it - that is simulate it in our heads and see the outcomes - then we probably can convince others about it and it can spread horizontally.

It might be that the dichotomy of horizontal and vertical is too limited - ideas spread in bubbles.

https://www.gwern.net/Littlewood shows some more limitations of the current horizontal spreading mechanisms.

Another example: antigen tests idea (https://medium.com/@zby/it-is-9-months-now-why-we-have-no-mass-testing-for-sars-cov-2-yet-27b5f409c7d2) - restated in medical/memetic metaphor - there was a cross reactivity of my (for example) memetic immune response system between the antigen and antibody tests.

2 just seems like another framing of Moloch: burn the commons, or be outcompeted by those who do.

3 I suspect is confounded by wealth, which enables people to take more risks. Free-market liberal societies are so much wealthier that this counterbalances the less cooperative general system.

For the third question, free-market capitalism might have fewer interactions between singular agents but more interactions between groups of agents. With the agents in free markets are still able to share information between each other changing it more into an iterated game. It does this while also increasing the punishment for defecting by having the group defect against the individual. Though the information sharing is not always consistent allowing for bad actors.