Mortality and evolution

Well, it’s spring (in the northern hemisphere, anyway) and new life is bursting out everywhere you look, but again I’m going to talk to you about mortality.
Specifically, I’m going to talk about a recent paper that looked at the way that thoughts of death affect people’s beliefs about science. Like the paper I discussed in a recent post about tolerance, and mindfulness, this one uses terror management theory to frame an investigation into how people react to an existential threat. According to this theory, contemplating our own deaths produces anxiety that we ward off by various psychological defenses. Among these defenses is a stronger belief in worldviews that provide meaning, order, and perhaps a promise of immortality in some form or another.

Three researchers examined how thoughts of death affect people’s acceptance or rejection of evolutionary theory, the foundation of biological science, and intelligent design (ID), which is often couched in scientific language but in fact is not well founded in science. Evolutionary theory is obviously incompatible with belief in a literal instantaneous creation by a deity and arguably with any form of belief in an orderly world created with some purpose. Unfortunately, many people also see evolutionary theory as draining the meaning and purpose from human life. ID is essentially a response to this perception, and as such it offers a more obvious and more traditional sense of meaning.

In a series of studies, the researchers asked participants to write about either their own death or dental pain (which also arouses negative emotions but presumably does not tap into existential anxiety). Then the participants read brief selections from Michael Behe, arguing for ID, and/or Richard Dawkins, arguing for evolutionary theory, and answered questions about how they rated the author’s expertise and how much they agreed with what he was saying. In three studies with a range of participants (some undergrads, some older people from a variety of backgrounds), the authors found that by and large those who had written about death were more likely to agree with Behe than with Dawkins. This was pretty much what they had expected; they figured that ID bolsters the psychological defenses that people tend to draw on when confronted with thoughts of their own death.

The really fascinating stuff comes in the fourth and fifth studies. In the fourth, some of the participants were also given a brief reading from Carl Sagan in which he describes science as providing not just knowledge but meaning and comes down squarely on the side of being courageous enough to accept the universe as it really is, to the best of our current knowledge, and to make our own meaning. The fifth study used only the Behe and Dawkins readings; participants were all college students in the natural sciences. In both, the participants did not tend to accept ID or reject evolutionary theory even if they had written about their own deaths; in fact, they were more likely to reject ID.

I thought these were exciting results, particularly the study that included the Carl Sagan reading. I think our ability to use reason and careful observation to understand the world around us, and to be, as Sagan put it, courageous enough to accept the truths we find, is one of the greatest things about us as a species. The rejection of not just scientific findings but also the values that underlie scientific research is deeply troubling for a number of reasons. I don’t think that accepting science leads to an impoverished worldview; in fact, for me it’s exactly the opposite. Presenting science in a way that is unflinchingly honest about the situation in which we find ourselves and its implications for traditional religious beliefs and at the same time nurtures the deep sense of meaning that people hunger for is crucial. When I read the passage from Sagan that was used in this study, I was impressed at how well he did this. The fact that his words can change the way people react to an existential threat is heartening. A current debate in the online atheist community centers around whether unvarnished, honest rejection of the supernatural is compatible with (a) changing people’s minds or (b) persuading people of the beauty and meaning to be found in science. Although this study involves only a snapshot of people’s reactions to various readings, I think it suggests that science can be presented both honestly and compellingly. Now we need to understand and apply the best techniques that people have found for doing this.

This paper was published in PLoS One, so anyone can read it: Tracy JL, Hart J, Martens JP (2011) Death and Science: The Existential Underpinnings of Belief in Intelligent Design and Discomfort with Evolution. PLoS ONE 6(3): e17349. doi:10.1371/journal.pone.0017349. Published March 30, 2011.


  1. I love the experimental frame: feed someone meme A, then evaluate their susceptibility to meme B. It’s a little off-topic but it implies that we might evaluate the value of the memes. A’s value obviously depends upon B’s value — if B is (i.e.) evil then A probably isn’t that great (for people) regardless of any objective qualities of A.

    You can really go crazy with this experiment because the internet gives us most of the tools necessary to conduct it on a truly massive scale, analyzing an astoundingly large network of memes. This is marketting. Between them Facebook, Google, and Walmart know more about this susceptibility network than the entire sum of humanity.

    It’s probably this network (based on “susceptibility” as the node propagation function) which people speculate may become intelligent. I wonder if it suffers back-propagation (a popular method for training simulated neural networks). If people learn that hosting meme B causes death, will their susceptibility function change?

    I think this brings us to Bokononism. “Live by the foma [memes] that make you brave and kind and healthy and happy.”

    Life is squishy.

  2. Intriguing ideas, thanks! My first thought about death-causing memes is that when individual people learn that a meme causes death, the effect on meme propagation is mixed, but maybe an intelligent network would respond differently. Then it occurred to me that one reason the individual reaction is mixed is that some memes may cause death but also persuade their hosts that death is not that important compared to something else that hosting the meme achieves. (This is particularly true if it is others who die. E.g., Will Durant wrote: “There is a tide in the affairs of states which, if uncontrolled before it gathers strength, sweeps a nation into circumstances where its only choice is between humiliation and war; and men above military age tend to prefer war to humiliation.”) Seems like a death-dealing, death-ameliorating meme can be stable if the host population replenishes itself rapidly enough and the meme works slowly enough.

    I need to re-read Cat’s Cradle.

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