semiotics

I happened to be lecturing about cause-effect relationships in my Biology of Mind course today, and will continue the subject next time. So I was interested when I saw this story from New Scientist writer Evan Callaway:

The tendency to falsely link cause to effect – a superstition – is occasionally beneficial, says Kevin Foster, an evolutionary biologist at Harvard University.

For instance, a prehistoric human might associate rustling grass with the approach of a predator and hide. Most of the time, the wind will have caused the sound, but "if a group of lions is coming there’s a huge benefit to not being around," Foster says.

OK, so this seems fairly obvious on the surface. Sure, if you could avoid the lions by jumping at every sound in the grass, then this kind of "superstition" might pay off, and would be unlikely to hurt. But then, being afraid of wind in the grass is really not a superstition. There is reliable mutual information connecting grass sounds and lions. Jumping at every grass movement might lead to lots of false alarms, but will really help avoid the lions, too.

That's a different kind of scenario than what we usually mean by "superstition". Like never washing your game socks so that your team won't lose on Saturday. Or paying the witch doctor so that the demons will spare your little girl.

We can still say that these false beliefs have little fitness cost. After all, the difference between a witch doctor and a real doctor may be important in today's cosmopolitan society, but throughout most of human existence, faith healers, witch doctors, shamans and thaumaturges really didn't face any competition.

But still, the simple idea of false association doesn't seem to cover these kinds of superstitions. I mean, many of these beliefs are so complicated, with involved series of rules and taboos that must be observed. Human superstitions may involve false hypotheses of causation, but they are not only that. So it seems like there must be some active principle at work, prompting people to learn arbitrary sequences of behaviors on the basis of fictions.

Moreover, it is not easy to list cases where animals make false inferences of cause and effect in this way. To be sure, we can manipulate animals experimentally, getting them to learn arbitrary correlations (like Pavlov's dogs) and then switch them so that they're false. But that's not the same thing at all! That's like the case where other teams all collude with each other to make sure that your team always wins except when you wash your socks.

The research study is available in Proceedings of the Royal Society B, by Kevin Foster and Hanna Kokko. The paper defines "superstitious behavior" as behaviors that result from "the incorrect establishment of cause and effect". That definition doesn't include most of what people mean when they refer to "superstitions" -- it's really quite strictly limited to formally correct inferences based on spurious associations. The authors then derive conditions under which such errors may actually increase fitness.

Foster and Kokko assume a model in which the fitness of an individual is determined by some events in a series that includes many other events that do not affect fitness. If some of those benign events are correlated with fitness-determining events (that is, if there is mutual information linking them), then an individual might increase its fitness by exploiting this mutual information.

Of course, there is a problem of detecting the correlations. Suppose we observe for three consecutive months that it rains after the full moon. We might be tempted to think there is some causal connection here---that the full moon causes rain in some way. Maybe the moon goddess has an affinity for water. In any event, our observation may induce us to believe that other full moons will also be followed by rain. That's inductive reasoning.

To that end, Foster and Kokko's model might appear to provide an evolutionary account of the problem of induction. Their model entails a trade-off: A greater degree of precision in making correct inferences will have benefits, but the necessary effort will have costs. "Superstition" reigns below a certain threshold -- the point at which the costs of more accurate inferences are balanced by the benefits of rapid inference-making.

That's a simple model, and the trade-off is a mathematical necessity, given the assumptions.

Is that all "superstition" is?

It seems to me that "false inference" is not a sufficient definition for "superstition." For one thing, superstitions persist even in the face of considerable evidence against them. The player who loses a game may still keep wearing those dirty socks. The family whose first child dies may still employ the witch doctor when the second child falls ill.

Another thing is that superstitions do not really consist of false inferences. They consist of highly distinctive signs. Those dirty socks, or a rabbit's foot, or oracle bones. Walking under a ladder, broken mirrors, which direction the horseshoe is hanging. "Gesundheit" after a sneeze. You don't learn about them by inference from natural observations; you learn about them from other people who explain the "boundaries" of the signs -- what counts and doesn't count as part of the belief.

We might compose some sort of analogous argument to that presented by Forster and Kokko. Maybe learning about superstitious beliefs from other people is adaptive because we also learn about valid, true inferences from them, and it's too costly for us to try to tell the difference. There may be some truth to that idea. We accept superstitious beliefs because everyone around us accepts them, and how could so many people be wrong?

But there are other aspects we should consider. We can't freely take or leave the beliefs that are common in the society around us. Some of them are enforced at the point of a gun. Others are instilled by ritual repetition from early childhood onward. We can call it "social pressure" or "tradition," or simply "culture," but whatever we call it, we have to recognize that we are compelled to accept some beliefs based on what other people around us believe.

If we call a belief a "superstition," chances are it's already out of style. Belief in ghosts may have been the norm a hundred years ago; today it's a smaller niche. Or a "superstition" may be simply idiosyncratic in some way -- one person's eccentric belief. There are many, many equally silly beliefs that we call much more respectful things, like "laws" or "traditions" --- the difference being that large communities of people share those rituals.

Any account of superstition has to take into consideration those elements of human learning and sociality. It is far from obvious that any non-human animals have "superstition," even in the sense of false inferences. If we look at a truly human use of the term -- arbitrary sign sequences believed to alter natural phenomena and maintained by social learning -- then it is doubtful that any non-humans have such beliefs. Still, phenomena like the chimpanzee "rain dance" might fit the bill, if we could suitably define the concept of "belief" in a non-linguistic context.

At any rate, the kind of logic about costs and benefits of inference-making don't seem to describe the kind of phenomenon we really mean when we talk about "superstition." And that's disappointing. If we take the course of defining the term in an overly simplistic way, ignoring its evident social and semiotic components, then we rob ourselves of the depth of human cognitive creativity.

References:

Foster KR, Kokko H. 2008. The evolution of superstitious and superstition-like behaviour. Proc Roy Soc Lond B (online) doi:10.1098/rspb.2008.0981

Chapter 8 of Hoffmeyer's Signs of Meaning in the Universe is about the evolution of language. I really like the opening paragraph, which is worth remembering:

I have observed that many of my students -- who are, of course, studying to become biologists -- are extremely reluctant to accept the idea of human language as something special. They point out that animals such as dogs, whales or chimpanzees might well have a language that we human beings have just been too highfalutin to acknowledge. And, in my experience, my holding up of the novels of Dostoyevsky or the Bible as examples of how human language is something quite unique in this world seems to make no great impact. If anything, I have the feeling that these students look upon humanity, and human nature in general, as a warped work of nature epitomized by its destructive penchant for building concrete blocks of slums and waging war. And, seen in that light, the fact that a few sensitive individuals might find it in themselves to write emotionally harrowing works of fiction does not seem all that strange.

I have to say, I have had the identical experience with students -- down to their arguing that animals may have their own versions of Shakespeare. "Who is to say they don't?" is the argument I have heard a lot.

My reaction is different than Hoffmeyer's, though. For one thing, these students have a long upbringing of being told it is wrong to make value judgments; for another, they have a long upbringing of watching movies with talking animal characters who emote with real human feeling.

I surmise it is difficult for some to imagine how any animal could exist without human-like mental capabilities.

As a corollary, I often ask my classes whether they would rather be hunted by a human or by a chimpanzee. I have never yet had a class where more than a few students choose the chimpanzee -- even though a chimpanzee would be enormously less dangerous as an enemy than a human. (For one thing, a chimpanzee is rather less likely to continue to track you after dark...) It seems to come down to a fear of the unfamiliar, and the optimistic idea that you could reason with a human enemy.

I choose not to worry until the army breeds a legion of warrior chimps.

In any event, Hoffmeyer cites Merlin Donald (1991) for much of his scenario for language evolution. The basic idea was that there was an intermediate stage between apelike minds and human language that was based on mimetic abilities, "the ability to carry out collective motor-based reconstructions of earlier incidents." Mimetic culture required and built upon social intelligence (and associated social learning abilities), but it also required a link between episodic memory (remembering events) and procedural memory (remembering how to carry out an action). Ultimately, these led to an internal syntactic memory that helped organize conscious thought, a system from which language sprung.

Under this scenario, mimetic culture characterized Homo erectus, who lacked language, but shared most other mental characteristics with humans.

This passage raises an interesting idea:

It is a fascinating thought that Homo erectus, with a brain capacity not really so far removed from the present dimensions or our own brains, may have been very much like us in almost all respects -- and, especially from an emotional point of view, in the most profound ways. Why, were it not for that one little quirk -- the lexicon, that ability to send our inner experiences flowing from our lips in streams of words to be pondered and debated among ourselves, adopted or rejected -- we might be said to have been almost identical at birth. The difference between the talking Homo sapiens and Homo erectus may not have been any greater than that between the people of the later Stone Age and the people of today. Because what separates modern man from Stone Age man is the existence of external (extrasomatic) memory banks -- first and foremost the written word in the form of books, but also the legacy of sculptures, pictures, buildings, tools and, these days, computers. The presence of these external memory banks implies that we, as adults, bear the burden not only of our own inherent intellectual legacy but also of a hundred-generation-long struggle to extract the essence of our forefathers' experience. This struggle has taught us to live in a world saturated by science, technology and art -- a world which could quite conceivably create an even greater gap between us and the mind of Stone Age man than Stone Age man, by virtue of the spoken word, created between himself and the mind of Homo erectus.

Now, this seems vital to me: is the extent of human variation today -- a result of recent genetic and cultural differentiation -- as great as the difference between Homo erectus and modern humans? Hoffmeyer considers the problem in terms of culture alone, and concludes that the difference might well be as great.

In support of this, he suggests that the early effects of culture on brain development generate possibly vast phenotypic differences among humans:

[Differences in programmed cell death] results in the cultural stamp leaving a telling imprint on the neurological structure of the brain. If not at birth then certainly by the time they start school modern human beings are therefore already very different from the people of the Stone Age. Just to be on the safe side it ought also to be mentioned that this restructuring of the neurological terrain is not altogether irrevocable. It appears at any rate that, even in adults, the area of the cerebral cortex which registers hand movements can be expanded or reduced as required. But for anyone desirous of reverting to the Stone Age mentality it would hardly be enough just to journey back to the settlement at Vendsyssel-Thy. You would have to retreat pretty far into the Siberian taiga and stay there for years, and in fact it would be best to start out in early childhood.

Of course, there are modern humans living in such contexts today. What about them? The "Stone Age - modern" difference is not merely a temporal comparison (prehistoric vs. today), it is also a geographic and cultural comparison (civilization vs. hunter-gatherer). From this perspective, Hoffmeyer's point easily misfires -- the claim would seem to require that the integration of a Homo erectus-like human into a modern hunter-gatherer group should be no more difficult than the integration of today's hunter-gatherers into civilization.

But modern hunter-gatherers do have many problems integrating into larger societies. The ability to speak is not particularly a barrier, but linguistic differences are. Culture, technology, and economics are all barriers. Probably the most severe barrier is disease.

Archaeologists have a long history of using modern hunter-gatherers as analogues for ancient humans precisely because of their differences from larger societies in terms of economy, subsistence, and social organization. That analogy assumes that the gulf between Homo erectus or other ancient hominids and modern hunter-gatherers is not so great. This tradition has emphasized certain effects of language and symbolic culture, such as an increase in the possible size of social units, breadth of economic and trade relationships, and sophistication of technology.

Modern and historic hunter-gatherers are diverse in these aspects of behavior -- everything from marriage patterns, kinship ties, and food acquisition strategies to land tenure and dispersal strategies. Certainly such diversity itself would be impossible in the absence of language: could different kinship systems be possible in the absence of the linguistic structures that support them? Or different taboos?

Two perspectives present themselves. One point of view would see the variation among modern humans as highly significant; a clear indicator of symbolic culture and language and a strong element in shaping diversity in the minds of modern humans. The other point of view would see the minds of modern humans as essentially similar despite any cultural differences, in which case symbolic culture and language can have had little effect on minds outside the relatively narrow parts driving symbolic culture and language.

The two perspectives are very different in their predictions about differences among modern human minds. But they are essentially the same with regard to the archaic-modern human differences compared to modern human variation.

References:

Donald M. 1991. Origin of the Modern Mind: Three Stages in the Evolution of Culture and Cognition. Harvard University Press, Cambridge MA. Amazon

Hoffmeyer J. 1996. Signs of Meaning in the Universe. Indiana University Press, Bloomington IN. Amazon