Evolving causal belief

Photo by Flickr user evoo73. Click for sourceThere’s an interesting letter in this week’s edition of Nature from biologist Lewis Wolpert making the speculative but interesting claim that the development of causal belief may have been a key turning point in human evolution.

Wolpert is responding to a recent Nature essay critiquing the idea that closely related species will have evolved similar psychological processes, suggesting that it is shared selection pressures rather than genetic similarity that more greatly influences mental make up.

He responds by saying that we should focus on some of things that have uniquely evolved in humans rather than shared processes. He cites the ability to understand cause as a key example.

The feature that is peculiar to humans is their understanding about the causal interactions between physical objects (see, for example, L. Wolpert Six Impossible Things Before Breakfast; Faber, 2006). For example, children realize from an early age that one moving object can make another move on impact. It is this primitive concept of mechanics that is a crucial feature of causal belief, and that conferred an advantage in tool-making and the use of tools — which, in turn, drove human evolution.

Animals, by contrast, have very limited causal beliefs, although they can learn to carry out complex tasks. According to Michael Tomasello (The Cultural Origins of Human Cognition; Harvard Univ. Press, 1999), only human primates understand the causal and intentional relations that hold among external entities. Tomasello illustrates this point for non-human primates with the claim that even though they might watch the wind shaking a branch until its fruit falls, they would never shake the branch themselves to obtain the fruit. Some primates are, nevertheless, at the edge of having causal understanding.

Once causal belief evolved in relation to tools and language, it was inevitable that people would want to understand the causes of all the events that might affect their lives — such as illness, changes in climate and death itself. Once there was a concept of cause and effect, ignorance was no longer bliss, and this could have led to the development of religious beliefs.

Link to Wolpert’s letter in Nature.


  1. Rob C.
    Posted May 27, 2009 at 10:33 pm | Permalink

    How does this square with the meta-tool use by rooks, discussed recently on the BBC website? [http://news.bbc.co.uk/2/hi/science/nature/8059688.stm] I suppose Wolpert could claim it was “limited” compared to humans, but, still, there seems to be clear evidence that the rooks, in using one stone to get a smaller stone to use to get food, understood a chain of causality.

  2. kcbrady
    Posted May 29, 2009 at 3:59 pm | Permalink

    personally, I think it was a two part process.
    First we developed the “why” module in our brain. But it was unconstrained by any connections to reality and led to things like religion.
    Fortunately, we then developed the “how” module, which allowed us to really investigate the world around us and thereby hangs a tale ….
    All our primate relatives (and lots of other mammals) share the other modules with us — who, what, where, and when.
    Its “why” that causes all the problems.

  3. Gransee
    Posted May 29, 2009 at 6:45 pm | Permalink

    Interesting article Vaughan. I have been reading your blog for over a year now but this is the first time I have posted to it.
    I understand belief as a scale on how self evident a particular bit of knowledge is.
    Knowledge that is more readily agreed by the maximum number of minimally qualified observers could be thought of as requiring less belief.
    It could be that compared to other animals we have a greater capacity for imagining and keeping track of hidden elements. This is essential in our ability to see cause and effect among more widely seperated observable phenomena.
    The more belief required, the greater the risk but there can also be greater reward. Also, with practice, we can learn to manage some of that risk while continueing to explore further and further.
    One thing we should remember is that to the animal that does not have a highly developed sense of belief, such an ability may seem useless. Even when trained to take advantage of the fruits of that belief, they may still poo poo the refined sense that discovered it.

  4. korax
    Posted May 31, 2009 at 7:48 pm | Permalink

    Please see:
    Chimpanzees infer the location of a reward on the basis of the effect of its weight
    The results of this experiment could arguable refute the statement “only human primates understand the causal and intentional relations that hold among external entities.”

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