17 September 2008

Evolution favours superstitious beliefs

Cosmos Online
Superstitions, such as touching wood or avoiding the path of black cats, are seemingly irrational, but may have roots in behaviours which evolved to protect us from danger, says a new study.
Black cat

Don't cross my path!: Superstitions may seem daft, but maybe there's more to it. Credit: iStockphoto

SYDNEY: Superstitions, such as touching wood or avoiding the path of black cats, are seemingly irrational, but may have their roots in behaviours which evolved to protect us from danger, says a new study.

The research published in the British journal Proceedings of the Royal Society B reports evidence that a predisposition to incorrectly link cause and effect can sometimes be useful.

Kevin Foster, co-author of the study and evolutionary biologist at Harvard University in Massachusetts, U.S., was intrigued by the number and variety of documented human superstitions.

Daft beliefs

“I was reading a number of popular books that mostly portrayed superstitions as crazy and irrational… we then went to the scientific literature in psychology and sociology and found the same story,” said Foster. “This made us wonder: why would evolution lead to us having so many seemingly daft beliefs? Could there be a rational explanation behind the most irrational aspect of human psychology?”

To investigate further, Foster worked with Hanna Kokko of the University of Helsinki, in Finland, to devise a complex computer model that aimed to compare scenarios where an animal would link two events together; such as linking the sound of rustling grass to the approach of a predator.

In some situations, these were linked by cause and effect, in others they were spuriously linked (such as when the rustling is caused by wind and not a predator). The scientists explored the idea that incorrect associations between events can be beneficial as long as they don’t cost anything, and they lead to occasional correct associations that might save an animal’s life.

The mathematical model showed us that “it is worth carrying many mistaken beliefs just to ensure you get the important ones right,” said Foster. For example, even if an animal is often frightened by rustling grass caused by wind, if that causes it to avoid a predator in the grass on just one occasion, it may be enough to save its life.

A relevant human example is that of a primitive tribe using a whole range of medicinal plants even if only very few work as an effective treatment, he said.

Interesting, yet speculative

Mark Stokes an evolutionary psychologist at Deakin University in Melbourne, Australia, said that while the internal mental processes that lead to superstitious beliefs are also important, this work is significant in that proposes a potential value to these beliefs. “It is an interesting proposition, but it needs to be empirically tested,” he said.

Though the model is purely theoretical at this stage, “it does make a number of testable predictions,” countered Foster. “The goal is to produce a logical framework to start to understand the evolution of superstition.”

Andrew Lewis, also a psychologist at Deakin University, and not one of the study authors, said that if further tests could prove that a propensity for holding mistaken beliefs was favoured by evolution it might have implications for our understanding of mental health problems too.

He said that delusional schizophrenics often hold on to irrational beliefs despite evidence to the contrary.

“There is a substantial debate in this literature as to why conditions such as schizophrenia have not been eliminated via selection if they reduce reproductive fitness,” Lewis explained. “However if there is positive selection for traits that predispose us towards accepting [irrational] beliefs, then delusions are only an extension of the same capacity.”


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