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For anyone who has been paying attention, it should be obvious that I get a lot of my material from Scott Alexander of Slate Star Codex. Optimistically, I take his ideas and expand upon them in an interesting fashion. Realistically, the relationship is more that of parasite and host. But regardless, I bring it up because I am once again going to that well. This time, to talk about a recent series of posts he did on cultural evolution.

What’s cultural evolution you ask? Well in brief it’s evolution that works by changing culture, rather than evolution which works by changing genes, but nevertheless evolution working in service of increased survival and reproduction. That this variety of evolution should exist and be embodied by certain “traditions” almost goes without saying.

(I put traditions in scare quotes because the elements of cultural evolution can take many forms, out of these some would definitely be called traditions, but others are more properly classified as taboos, habits, beliefs and so on. I’ll be using tradition throughout just to keep things simple.)

Some traditions so obviously serve to enhance the survival and reproduction of the people within that culture that their identification is trivial. A blatantly obvious example would be the tradition of wearing heavy clothing during the winter, a tradition which is present in all northern cultures. That such traditions exist is obvious, but for many if not most people it’s equally obvious that not all traditions work to increase survival, that some traditions are useless, probably silly and potentially harmful. That getting rid of these traditions would carry no long term consequences. Given the behavioral restrictions imposed by some traditions, there has been a lot of argument over which traditions should go into which bucket. Which traditions are important and which are inconsequential.

Initially you may be under the impression that it should be fairly obvious which traditions enhance survival and which are meaningless, but one of the key insights contained in Alexander’s posts, an insight based largely on his reading of The Secret of Our Success by Joseph Henrich, is that sometimes it’s not obvious at all. As an example, let me quote Alexander’s quote of Henrich (I told you I was a parasite) as he talks about cassava, or manioc as it’s sometimes known:

In the Americas, where manioc was first domesticated, societies who have relied on bitter varieties for thousands of years show no evidence of chronic cyanide poisoning. In the Colombian Amazon, for example, indigenous Tukanoans use a multistep, multiday processing technique that involves scraping, grating, and finally washing the roots in order to separate the fiber, starch, and liquid. Once separated, the liquid is boiled into a beverage, but the fiber and starch must then sit for two more days, when they can then be baked and eaten. Figure 7.1 shows the percentage of cyanogenic content in the liquid, fiber, and starch remaining through each major step in this processing.

Such processing techniques are crucial for living in many parts of Amazonia, where other crops are difficult to cultivate and often unproductive. However, despite their utility, one person would have a difficult time figuring out the detoxification technique. Consider the situation from the point of view of the children and adolescents who are learning the techniques. They would have rarely, if ever, seen anyone get cyanide poisoning, because the techniques work. And even if the processing was ineffective, such that cases of goiter (swollen necks) or neurological problems were common, it would still be hard to recognize the link between these chronic health issues and eating manioc. Most people would have eaten manioc for years with no apparent effects. Low cyanogenic varieties are typically boiled, but boiling alone is insufficient to prevent the chronic conditions for bitter varieties. Boiling does, however, remove or reduce the bitter taste and prevent the acute symptoms (e.g., diarrhea, stomach troubles, and vomiting).

So, if one did the common-sense thing and just boiled the high-cyanogenic manioc, everything would seem fine. Since the multistep task of processing manioc is long, arduous, and boring, sticking with it is certainly non-intuitive. Tukanoan women spend about a quarter of their day detoxifying manioc, so this is a costly technique in the short term. Now consider what might result if a self-reliant Tukanoan mother decided to drop any seemingly unnecessary steps from the processing of her bitter manioc. She might critically examine the procedure handed down to her from earlier generations and conclude that the goal of the procedure is to remove the bitter taste. She might then experiment with alternative procedures by dropping some of the more labor-intensive or time-consuming steps. She’d find that with a shorter and much less labor-intensive process, she could remove the bitter taste. Adopting this easier protocol, she would have more time for other activities, like caring for her children. Of course, years or decades later her family would begin to develop the symptoms of chronic cyanide poisoning.

Thus, the unwillingness of this mother to take on faith the practices handed down to her from earlier generations would result in sickness and early death for members of her family. Individual learning does not pay here, and intuitions are misleading. The problem is that the steps in this procedure are causally opaque—an individual cannot readily infer their functions, interrelationships, or importance. The causal opacity of many cultural adaptations had a big impact on our psychology.

Wait. Maybe I’m wrong about manioc processing. Perhaps it’s actually rather easy to individually figure out the detoxification steps for manioc? Fortunately, history has provided a test case. At the beginning of the seventeenth century, the Portuguese transported manioc from South America to West Africa for the first time. They did not, however, transport the age-old indigenous processing protocols or the underlying commitment to using those techniques. Because it is easy to plant and provides high yields in infertile or drought-prone areas, manioc spread rapidly across Africa and became a staple food for many populations. The processing techniques, however, were not readily or consistently regenerated. Even after hundreds of years, chronic cyanide poisoning remains a serious health problem in Africa. Detailed studies of local preparation techniques show that high levels of cyanide often remain and that many individuals carry low levels of cyanide in their blood or urine, which haven’t yet manifested in symptoms. In some places, there’s no processing at all, or sometimes the processing actually increases the cyanogenic content. On the positive side, some African groups have in fact culturally evolved effective processing techniques, but these techniques are spreading only slowly.

I understand that’s a long selection, but there’s a lot going on when you’re talking about cultural evolution and I wanted to make sure we got all of the various aspects out on the table. Also while I’m only going to include the example of cassava/manioc, there are numerous other examples of very similar things happening.

To begin with we can immediately see that it’s not easy to tell which traditions are important and which are inconsequential. Accordingly, right off the bat, we should exercise significant humility when we decide whether to put a given tradition into the “survival” or the “silly” bucket. In particular, one of the things which should be obvious is that cause and effect can be separated by a very large gap. Now that we have modern techniques for testing the cyanogenic content of something we can identify how much it’s reduced at each step in the process, but that wouldn’t have been clear to the Tukanoans. Rather they could only go by eventual health effects which could take years to manifest and would be unfamiliar when they eventually did end up appearing. As Henrich points out, you would first have to make the connection between someone’s health issues and eating manioc, and then further make the connection to whatever step you got rid of.

It’s also interesting to note that one tradition can seem to hold most or all of the utility. In the example of the cassava, just boiling it gets rid of all the immediately noticeable issues, it “removes or reduces the bitter taste and prevents the acute symptoms (e.g., diarrhea, stomach troubles, and vomiting).” We can imagine something similar happening with other traditions. Like cassava preparation lots of traditions come as packages, for example there are a whole host of prohibitions and injunctions related to sex contained in most religions. And you can imagine someone saying, oh what they’re really worried about is STIs and unplanned pregnancies, now that we’ve invented latex condoms, we don’t have to worry about any of the injunctions against extramarital sex. We’ve identified the bit that affected survival and now the rest of it is just silly. But all of this might be the same as someone deciding that boiling was the only tradition necessary to make cassava safe, and discarding all other steps as superfluous. When, in reality, the benefits of the other steps are just more subtle.

Finally, there’s Henrich’s point that traditions, and the benefits they provide, are often non-intuitive. Alexander even goes so far as to speculate, in his commentary, that trying to use reason to determine which traditions are important could actually take you farther away from the correct answer, at least in the near term. And this is one of the chief difficulties we encounter when grappling with that initial question. In our determination of whether something confers an advantage to survival and reproduction how long of a time horizon do we need to consider? Henrich points out with cassava that it would take several years before problems were even noticeable. How much longer after that would it take before people were able to make the connection between the problems and the tradition they’d eliminated. Note, that even hundreds of years after its introduction into Africa, cyanide poisoning is still a serious health problem. The fact that the African’s never had certain traditions of preparation to begin with, makes things harder, but you’re still looking at an awfully long time during which they haven’t made a connection between cause and effect.

It seems entirely possible that even if you were being very rational, and very careful about collecting data, that it might, nevertheless, take multiple generations, all building on one another, before you could make the connection between the harm being prevented by a tradition and the tradition itself. Certainly it takes numerous generations to come up with the traditions in the first place.

To sum it all up, when attempting to determine which traditions are important, you’re going to encounter numerous difficulties. Chief among this is just the enormous amount of time it’s going to take before you can say anything for certain. And during this time, when you are trying to make a determination, much of the evidence is going to point in the wrong direction. In particular there will be a bias towards dismissing traditions as unimportant. Modern technology might help (for example knowing cyanide is bad and being able to detect it), but it might also lead to giving undue weight to sources of harm or benefit which are easy to detect.

As I mentioned at the beginning there’s been a lot of arguing over this question. The question of which traditions are important and which are inconsequential. To be fair this argument has been going on for a long time, at least the last several hundred years and probably even longer, but I would argue that it’s accelerated considerably over the last few decades. In particular three things seemed to have changed recently:

First, support for traditional religion has gone into a nosedive. There are, of course, various statistics showing the percent of believers (in the US) going from 83 to 77 and the number of unbelievers rising by a nearly identical amount, and this may not seem like that big of a deal. Though given that this decline only took 7 years, that’s still fairly precipitous. But more importantly with relationship to this topic, even if 77% of people are still religious, the religions they belong to have jettisoned many of their traditional beliefs.

Second, technology has made it easier to work around traditions. For one, survival is no longer a concern for most people, meaning that traditions which increased survival, particularly in the near term, are no longer necessary. As another example, in the past, traditional gender roles were hard to subvert, but now we can go so far as to provide gender reassignment surgery for those that are unhappy. The list could go on and on, and while I’m sure that in some cases the fact that technology can subvert tradition means that it should. I don’t think that’s clear in all cases.

And finally, perhaps following from the first two points, or perhaps causing them, there’s intense suspicion of all traditions, particularly those whose utility is not immediately obviously. This seems particularly true of any traditions which impinge on individual autonomy. But I also have a sense of it being disproportionately applied to anything that might be considered a European tradition.

Pulling all of this together we are confronted with a very important question. The question of which traditions can be dispensed with. Recently, and increasingly, the answer has been “All of them!” And perhaps people are correct about this. Maybe we have ended up with a bunch of silly traditions which need to be gotten rid of, but if we can take anything from the lesson of cassava, it’s going to take a long time to be sure of that, and reason isn’t necessarily going to help.

If, in fact, the normal methods of collecting and evaluating evidence in a scientific manner take too long to operate effectively with respect to traditions, you might be wondering what other tools we have for deciding this question? I would submit four for your consideration:

  1. The duration of the tradition. How long has it been around?
  2. The strength of enforcement for the tradition. How severe are the penalties for going against it?
  3. The frequency of the tradition among the various cultures. How widespread is it? Is it present in many different cultures?
  4. The domain of the tradition. Is the tradition related to something which could impact survival or reproduction?

To the above I would add one other consideration which doesn’t necessarily speak to the intrinsic value of any given tradition, but might suggest to us another method for choosing whether to keep or discard it. This is the issue of tradeoffs. How costly is it to keep the tradition? How much time are we potentially wasting? What are the downsides of continuing as is? Reversing things, if we abandon the tradition what are the potential consequences? Is there any possibility of something catastrophic happening? Even if the actual probability is relatively low?

You might recognize this as a very Talebian way of thinking, and indeed he’s a pretty strong defender of traditions. He would probably go even farther at this point and declare that traditions must be either robust or antifragile, otherwise they’re fragile and would have “broken” long ago, but I spent a previous post going down that road, and at the moment I want to focus on other aspects of the argument.

So enough of generalities, starchy tubers and Taleb! It’s time to take the tools we’ve assembled and apply them to a current debate. In order to really test the limits of things we should take something that has recently been declared to be not just inconsequential and irrelevant but downright harmful and malicious. With these criteria in mind I think the taboo against Same Sex Marriage (SSM) is the perfect candidate.

Before we begin I want to clarify a few things. First it is obvious that historically gay individuals have been treated horribly. And I am by no means advocating that we should return to that. Honestly, I really hope that traditions and taboos around homosexuality and SSM can be discarded and that nothing bad will happen, but I can’t shake the feeling that these traditions and taboos were there for a reason. Also given that two-thirds of Americans support SSM not only is this a great tradition to use as an example for all of the above, it’s also very unlikely that anything I or anyone else says will change things. Finally my impression is that many people offer up homosexuality and SSM as the gold standard for where reason came up with the right answer and tradition came up with the wrong answer. And speaking of which, that’s a great place to start.

One of the key arguments in the broader discussion is that past individuals did things based on irrational biases, but now that we’re more rational, and can look at things in the cold light of reason, we can eliminate those biases and do the correct thing rather than the superstitious thing. But considered rationally what is the basis for SSM?

(I should mention I’m mostly going to restrict myself to the narrower question of SSM, than homosexuality more broadly).

Don’t get me wrong, I understand the moral argument, and it’s a powerful one, but I’m not sure I understand the argument from reason. Rationally, as a society there’s lots of things we should be encouraging, and though there are some arguments over what these things are, reproduction would seem like something most people can agree on, and whatever other arguments you want to make about SSM, reproduction is not its strong point. In other words it would seem that arguments in favor of SSM are mostly moral, which is fine, but in our increasingly post-religious world you have to wonder: Where is that morality coming from? What’s it grounded on? This is obviously a huge topic, my key point is: I think the case for SSM from reason is weaker than most people think.

Moving beyond that most SSM proponents seem to argue from a lack of harm. That it’s not only immoral to withhold marriage from individuals who want it, but that it doesn’t harm anyone else to give them this right. Here’s where I think the question of time horizons brought up be Henrich is particularly salient. He offers plenty of examples of traditions where the harm prevented by the tradition will only manifest many years later. And even without those examples, I think the idea that it could take a generation or two for certain kinds of harm to manifest and that the connection between cause and effect might not be clear even when it does, is entirely reasonable. (There’s that word again.) To put it another way, it’s impossible to know how long it takes for something to manifest, or to be entirely sure that we have “waited long enough”. As a reminder, Obergefell is still a few days away from its fourth anniversary. That definitely does not seem like long enough to draw a firm, and final conclusion.

To return to my parasitism, Alexander just barely posted about one explanation for the more general category of all sexual purity taboos (including homosexuality) and that’s to prevent the spread of sexually transmitted infections (STIs). A couple of selections:

STIs were a bigger problem in the past than most people think. Things got especially bad after the rise of syphilis: British studies find an urban syphilis rate of 8-10% from the 1700s to the early 1900s. At the time the condition was incurable, and progressed to insanity and death in about a quarter of patients.

[T]he AIDS epidemic proves that STIs transmitted primarily through homosexual contact can be real and deadly. Men who have sex with men are also forty times more likely to get syphilis and about three times more likely to get gonnorrhea (though they may be less likely to get other conditions like chlamydia).

In the previous thread, some people suggested that this could be an effect of stigma, where gays are afraid to get medical care, or where laws against gay marriage cause gays to have more partners. But Glick et al find that the biology of anal sex “would result in significant disparities in HIV rates between MSM and heterosexuals even if both populations had similar numbers of sex partners, frequency of sex, and condom use levels”.

This is probably part of the explanation for the taboo, and I would direct you to Alexander’s post if you want more detail. For my part I worry that uncovering the STI link is akin to finding out that boiling cassava “remove[s] or reduce[s] the bitter taste and prevent[s] the acute symptoms (e.g., diarrhea, stomach troubles, and vomiting)”. That in both cases it will lead someone to feel that they have uncovered everything they need to know about the reason for the taboo. That in the same way they might decide other parts of the cassava preparation tradition are unnecessary, they might also decide that if we have other ways of avoiding STIs that there’s no need to continue to worry about taboos around sexual purity either.

Thus far, regardless of the tools we’ve applied, we’re not really any closer to a definitive answer to our question: Did historical taboos against same sex marriage serve to increase survival and reproduction or were they just silly superstitions? Having examined the ways in which Henrich’s book might help, let’s turn to the standards I suggested:

1- The duration of the tradition. How long has it been around?

I’m not an expert on historical homosexuality, but it seems pretty clear that taboos against SSM have been around in one form or another for all of recorded history. Wikipedia’s Timeline of Same Sex Marriage dedicates 4% of it’s space to everything before 1970, and the other 96% to stuff that happened after 1970. So yes, it wasn’t entirely unknown, but there was definitely a taboo against it at every historical point you care to imagine.

2- The strength of enforcement for the tradition. How severe are the penalties for going against it?

Historically punishments for homosexuality have been severe. I assume that, at least on this point, I won’t get much of an argument from anyone. Though it is true that the most severe punishments seem to have been in Europe and the Middle East, severe punishment wasn’t limited to those areas either. Where the taboo existed (nearly everywhere) it was very strong. And even in times and places where the taboo against homosexuality was not particularly extreme it was still strong enough that it was extraordinarily rare for people to be in a position to confront the, yet further still taboo, against SSM.

3- The frequency of the tradition among the various cultures. How widespread is it? Is it present in many different cultures?

As I mentioned a taboo against SSM was basically present at all times throughout human history, but it’s clear that further it was present in nearly all places at all times as well. It should be noted that even today 75% of the world’s population still live in countries where it’s illegal.

At this point if I were on the other side of that argument (and I am, a little bit, but it’s also apparent that that side doesn’t need any help) then I would use the ubiquity of the taboo to argue that it’s not cultural, it’s technological. It’s not that everyone had the same culture, it’s that everyone still had the same, relatively primitive, technology. I’m not sure current technology makes as big of a difference to this sort of thing as we think, but there’s at least an interesting discussion to be had on the topic.

4- The domain of the tradition. Is the tradition related to something which could impact survival or reproduction?

I would argue that this is the point that most people overlook or at the very least minimize. If culture evolves to enhance survival, then you would expect a lot of what comes out of cultural evolution to involve things which directly impact not only survival but reproduction, since that’s what you’re selecting for. Meaning that, when you’re trying to decide whether a given tradition is important or not, asking whether it has any impact on those two things would be a good place to start. And clearly the traditions we’re talking about do. Up until the very recent past there were a lot of people who were born who otherwise wouldn’t have been, had there been no taboos. Anecdotally, I have four cousin in-laws who wouldn’t have existed if Stonewall had happened 20 years earlier.

I’ve been conflating and separating SSM from other taboos against homosexuality more or less as it suits me, and with, admittedly, less rigor than would be ideal, but it occurs to me that on at least one point the seperation is very clear. In terms of behavior, SSM doesn’t allow for behaviors that much different from general taboos against homosexuality, but it’s very different in terms of societal norms. With most taboos, there are always going to be significant violations that end up being overlooked. Where you might say an “understanding” exists. If the violation of the taboo impacts what’s considered publicly sanctioned behavior, then that’s more difficult to overlook and the taboo is both different and stronger. SSM definitely falls into this category, in that it intrinsically has to be both public and sanctioned. That the Rubicon we’re crossing (for good or ill) is not in what behaviors we overlook, but in what behaviors we sanction.

Because we are crossing a Rubicon, and there would appear to be a lot of things indicating that this crossing is not inconsequential. For reasons of charity, I hope I’m wrong about this, but also because I don’t see any chance of things reversing themselves, if I am right, and we are headed for a bad outcome. There is some chance I’m right about the role of these traditions, that they were important, but recent technology has changed them to being inconsequential. But given all of the above, I think the entire issue should be approached with more humility. That at a minimum we should back off from people who want to maintain the taboo, both practitioners of religion and bakers of cakes. Particularly if there’s nothing resembling coercion in the way they want to maintain those traditions.

In the end I keep coming back to a point I’ve made in the past. You have two options: You can assume that the vast majority of people in the vast majority of places throughout all of history down to the present day were hateful, irrational bigots, or you can assume that maybe somewhere in all of this that there was some wisdom, and we should attempt to understand what that wisdom was before we abandon it.


You know what else has broad historical precedent? Patronage. Yep, the practice of rich and powerful people supporting art they appreciated. This isn’t exactly art, and you’re probably not exactly rich and powerful, but consider donating anyway.