September 13, 2008

How superstitions can be favored by evolution

Superstitious behaviour assigns importance to events that aren't likely to influence the future, e.g., "I saw a black cat, so I'll have a lousy day."

Superstitions are something that doesn't have an obvious adaptive value: if you make such irrational associations between events, you are not more likely to anticipate some future event.

Hamilton's rule, the foundation of kin selection theory, links together the "cost" that an organism is willing to pay with the "benefit" that he will heap.

Pascal's wager, on the other hand, aims to show that a very large payoff ("eternal life") is worth the price ("belief in god") even if one assigns a small probability to the event "god exists".

What this paper shows is that a strategy of making associations between events, even though some of them are superstitious and irrational (i.e. there is no causal relationship) may be selected by evolution.

A good way to see why is to think of three human types:
  • The "super-rationalist" overanalyzes everything, and wants to be convinced of a causal relationship before taking a decision. 
  • The "madman" sees connection between all sorts of events, most of which are unconnected.
  • The "average Joe" has a lower rationality threshold than the super-rationalist, thus often making decisions based on superstitious associations.
The "super-rationalist" will be right more often than the other two types, but his meticulousness may be a waste of energy and opportunity; the "madman" will be chasing shadows, going this way or that on a whim. The "average Joe" may fare better overall, since his willingness to bet on flimsier evidence will sometimes lead him to a large payoff.

Proceedings of the Royal Society B DOI 10.1098/rspb.2008.0981

The evolution of superstitious and superstition-like behaviour

Kevin R. Foster, Hanna Kokko


Superstitious behaviours, which arise through the incorrect assignment of cause and effect, receive considerable attention in psychology and popular culture. Perhaps owing to their seeming irrationality, however, they receive little attention in evolutionary biology. Here we develop a simple model to define the condition under which natural selection will favour assigning causality between two events. This leads to an intuitive inequality—akin to an amalgam of Hamilton's rule and Pascal's wager—-that shows that natural selection can favour strategies that lead to frequent errors in assessment as long as the occasional correct response carries a large fitness benefit. It follows that incorrect responses are the most common when the probability that two events are really associated is low to moderate: very strong associations are rarely incorrect, while natural selection will rarely favour making very weak associations. Extending the model to include multiple events identifies conditions under which natural selection can favour associating events that are never causally related. Specifically, limitations on assigning causal probabilities to pairs of events can favour strategies that lump non-causal associations with causal ones. We conclude that behaviours which are, or appear, superstitious are an inevitable feature of adaptive behaviour in all organisms, including ourselves.



Crimson Guard said...
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Crimson Guard said...

Would the same hold true for religion? Superstitions had to have been born outve the shamanism of the Paleolithic/Neolithic time